XT 600 Piston issues
 

Xt 600 Kick start

Bike died while driving, felt loss of compression when kicked over.
Pictures show piston/cylinder condition.

Any ideas how this happened? To prevent it happening again.
Oil level was fine.

Previously posted on top end noise. Which I thought was lifter. I replaced head and rocker box a few hundred miles ago but noise was still there.
Perhaps it was piston.

The cylinder is gouged up and piston is done.
What steps should I be looking to do, examine etc.

Greg

Looks like a lack of oil to me...

Are you 100% sure the oil level was OK? The dip stick measuring is kind of stupid on this bike.

shaise.... if it's oil related would expect to see also badly socred cam bearing and rocker surfaces. if cam journals look ok, might be serious dirt entering motor through broken rubber booths...

Always at the back of the piston on XT`s, less oil? hottest part of the barrel?

Mezo.

Cam looks to be fine and there is quite a lot of oil in journals as well as what snuck past piston after it burned up.

Oil level is at high mark of dip.
Oil had about 500 miles.

Figuring this had something to do with the breakdown.

elemental watson :)

didnt see the pics of the cam before, but dark color all around = overheated oil indeed. you're pretty lucky it dint do that much damage, but check also the rockers surface...

have you opened the pump?

it might have something jammed inside and that could break the plastic drive gear

Just opened the cover up
Still didn't take clutch out.

With clutch basket their is pushrod behind the the ball and manual says to remove with magnet. Is there another option?

Never had clutch out of the xt before

The ball should roll out by itself.

The cause is obvious. Your oil pump gear shattered.

The question is why ???

I'd be checking the gears it's meshed on. Those gears are notorious for coming loose on their shafts. Stripping woodruff keys etc. That could be the noise you were hearing.

Those oil pump gears don't just shatter like that. The meshing has to be incorrect. Is it also possible the oil pump is dead and jammed up. This could happen if it was running dry.

You said the bikes been stripped down. Whoever did it might have got something wrong.

Your cam is sitting in an oil bath. If the pump is dead it won't be filling the rocker box but it won't be emptying it either. It's hard to tell.


Your best best is to find a replacement sleeve for your cylinder. New piston, rings, piston pin. Hopefully your conrod survived the trauma.

Took bottom end and head to machine shop and they seem to think the damage was isolated to cylinder and piston.

Oil pump: From reading up on here i'm looking up for a later year xt 600.
Did the TT 600 come with a stronger flow oil pump? or was it the same as the years for XT?

Can i replace with cylinder from TT? I might be able to get a very good condition cylinder with piston (stock) from 1983 TT 600.

I'm quoted about $320 US, for a rebore and piston for the rebore size.
Wondering if its better to look at other options. Ex: find cylinder and piston together on Ebay? But then I run into a combo that would be 25+ years at best.

Zylinder Kolben 3AJ00 Cylinder Piston Yamaha XT 600 | eBay

Its possible to buy only the sleeve for the cylinder.

Stock piston and rings are very expensive, your quote might just represent that.

A new non-oem piston only costs a fraction of one labeled from Yamaha.

Wiseco Piston Kit Yamaha XT600 84 96 97mm | eBay

YAMAHA XT600 TT600 SRX600 XT TT SRX 600 WISECO CYLINDER LINER SLEEVE SIZE 95-98 | eBay

If the sleeve in yours dont have much damage you can rebore it at lower cost, find a cheaper place to rebore if they charge 200dollars.

Thanks for that

I can get a salvage cylinder with piston for a $100 but its from a TT 600 1983.
I'm waiting on pictures to see condition. Was told it was in good condition.

Looking for advise on that as well please.

If its in good condition as shown in several pictures perhaps its a better option.

Problems I'm thinking of:
Would it still need new rings
Would it need to be honed

Doubtful any used cylinder bought off ebay would be good enough condition to use as is . The TT is plated so may be able to do a quick hone to get fresh hatch lines and new rings , IF the plating is still good and within spec. , no seller there will be able to tell you the true size other than guessing/BS'ing .

Getting a new sleeve still involves boring and honing to size once installed , waste of money .
Just bore cylinder to next size and Wiseco piston kit , done . I believe this had been gone over in the past.

The '83 TT cylinder will only fit '83-'85 or '86 XT's , change in bolt pattern somewhere there.

I recently had my 84 XT600 rebored to 2nd oversize and am using an OEM piston and rings. Parts purchased from Partzilla. Local labor to bore and hone to fit with proper clearances was $90.00US. In the process of re-installing now.

Sound advice! Thanks guys

I've not installed rings on pistons yet so I think i'm making a bigger deal out of it then need be. If I'm wrong please set me straight please.

Is anyone happy with a certain tool etc? I've seen several different technics to this.

Piston rings are very brittle. They snap easily and are only sold in a set.

There is no special tool that I know of.

You have to open them up and slide them over the piston. Do not twist them or they will snap. You will probably need a thin flat head screwdriver.

Be patient and don't rush it.

I've always just used my fingers, no problem at all...

Installing rings is pretty easy, oil control rings are the most difficult but patience pays. The rings will withstand the installation if you are careful.

There is special ring pliers made to grip the ring ends and spread under control to stop snapping them , but I've always used my hands . Just have to go slow , spread as little as possible and don't twist anymore than absolutely necessary .

http://www.jegs.com/i/JEGS+Performan...w4fhoC8rTw_wcB

Thanks guys

And to be clear. You can compress the rings by hand when putting into cylinder? Not needing a special tool?

Also what is the break in procedure for the new rings.

Just make sure all the ring ends are spaced as per the service manual , use hand to compress rings , pay particular attention to the ends of the oil control rings(bottom set of three) that they are not overlapped .

Below is just my method, subject to debate:

Have the bike ready to ride preferable before starting , can start it momentarily before hand to verify it will run but the first five minutes best to ride. Take it out on the flat , give it some gas fairly aggressive up to 1/2 to 2/3 throttle in second gear shift to third throttle throttle up,then release and slow, letting the motor slow the bike , repeat 8 to tens times , never going full throttle . Now ride for "normal" for ten -fifteen minutes , constantly varying throttle , never more than 3/4 throttle. Change oil and filter.

Ride it normal then , but for 100-200 miles try to not use full throttle for longer periods . Change oil again at 300-400 miles.

Why would you change the oil and filter after breaking in a new piston? If there by some reason should be so much material removed from the engine, as to clog up the oilfilter, and seriously contaminate the oil, the engine is beyound salvation...

I started to change my oil 1000km after having installed a new piston "cause the internet says so" and pure gulden oil came out. I installed the drainscrew, topped up the oil, and rode a couple thousand kilometers more. When chaning the oil (after 3500-4000km total) i cut open the oilfilter, which had no debrees in it (why would it...?) The filter was on its second oilchange, so just under 10.000km.

The bike is at 160.000km, I have around 35.000km on the piston after the installation, so nothing much.

I rode my bike normally, tried not to lug it, and made sure to enginebrake as much as possible. Dont rev the piss out of it, and you will be fine.

Knew I wouldn't get away with recommending something here without someone knowing better . If $15 bucks for oil and filter it too much to quickly get rid of all break-in particles, break-in lubes, and machining particles ect.. do what you want . I've never, ever, ever seen, heard or talked to a single engine builder , even the dumb ones , say to not bother changing the oil right away after break-in . It reminds me why I don't do as most claim on the internet and listen to the pros.

I dont get it, why change filter every 2 time you change oil? With spending on the bike in a year in gas, insurance, road taxes, parts etc.. a filter is like 0,1% spending. And why mix the old oil thats in the filter and filter housing with the new oil? I know your bike has done 160k Jens, honestly i think you have been lucky, most people have some kind of problems long before they reach 100k.

JJ, its not about someone knowing better, just somebody who has a different oppinion than you...:oops2:

Isnt that what were here for? disgussing stuff? :thumbup1:

Its not about the money for me, just common sense. You can do a lot of stuff like that, change the chain and sprockets every 5000km so you dont risk breaking it, change the brakedisc when its worn 0.0001mm, change the tires way before they're worn and so on...

I think there is a lot of "better safe than sorry" advice outthere. Have a look at your filter, then tell me why you want to change it...If it isnt dirty, why change it? If its dirty from installing a bored/honed cylinder, and a new piston, you have trouble elsewhere. Thats common sense for me. :D

If you REALLY feel like being good to your engine, then why cheap out and buy an oil and a filter for 15£ ? Seems a bit hypocritical to say that the oil and filter is so important as to change it so early, and the buy cheap oil.

Which material are you trying to get rid of? The oilfilter filters the oil, why would there be some material left in the oil? The oil certaintly isnt "worn" after a couple hundred kilometers. The filter is easy to cut open when you remove it, so if you're really concerned why not cut it open? I did, and didnt find a thing.... I try to back up my statements with actual experience, and looking in to things. Not saying others dont, I just do.

We fully agree that it wouldnt hurt the bike to change oil and filter often (only the environment)

Even a completely new engine goes 1000km before first service, and you would think the lawyers made sure that was well within the safe range....

Back in the early 80's where the bike was designed, yamaha wrote in the manual to change the oil at 1000km, then every 6000km, and the oilfilter every other time, with the oil and filters that was available at that time..
You'd think that would still be true today. Think about how much technology has evolved since then, oil should be way better than back then, so we should be able to go way beyound yamahas level. So there should be a big buffer by just going with the factory intervals, with modern oil.

So just different oppinions, and perhaps different ways of life. Im not saying I know better, just saying what my personal experience was, with the oil and oilfilter after installing a bored/honed cylinder and changing my piston. :D

Hmm, 2 quarts regular dyno oil ( COMMON sense to not use synthetic for breakin) $11 + $4 for the filter = $15 , https://www.rockymountainatvmc.com/p...term=motor+oil Pretty easy to add .

Give me a break , if you want to take the chance of running oil longer rather than doing what EVERY (I do mean EVERY !) quality engine builder will say , go ahead , just don't recommend it too people that don't know about this stuff . Oh ya I know the oil looks clean , therefore it is :nono: ,

Also as for the miles on a motor(as your implying your miles are due to not needing to change oil early) , any motor that is run more or less street or long hours of steady miles and miles will last considerably longer than those that are short trip , commuter miles , start -stop , cold start-up over and over . As in the auto relm 80% of all wear in at startup . That's why I don't simply look at high miles meaning something was done right either when new or later , to me that means a lot of highway miles and not subject to as much wear as is standard.

I've sent samples to a lab to see what is actually in the oil ,have you ?

I really dont know what to say when you start comparing to tires and brake disc... You make it sound like you done this a hundred times and never any problem with particles in the filter after piston change, or is it like this you done it one time and thats your reference? Honestly why dont you change filter if its not a question about money?, we all know that it best for engines to have fresh oil and new filters!

So every enginebuilder says to change oil a couple hundred kilometers after only a pistonchange...? Were not talking complete engine teardown. I love the fact that you write "quality engine builder "
so anything I come up with that doesnt support your facts can be called a bad builder ect... I have a hard time figuring out why you are typing in a public forum, but refuse to hear other peoples experiences.

Anyway, back to it....I bet its still the better safe than sorry situation.... If they told somebody to not do it, and the custuomer had another unproblem with the engine dying and came back with it, he would blame the engineguy for sure. Its not hard science, you know how the oilsystems works, what are you trying to do by changing new oil that gets filtered by a fine papirfilter, which has no debrees in it?

No one on an mx track will do that, but i guess the ones servicing competition-bikes isnt a "quality" enginebuilders ? Theese guys do a LOT of service to keep their bikes up and running, and change stuff long before it breaks. You should see (and meassure) the stuff they take out of their engines and discard.

Fun fact: The Mx-guys run their enigines for more hours on the oil than it would take me to clock in a couple hundred kilometers on my xt600 just commuting... MX spec oil interval for a xt600... hmmm..

So youre saying oil with 1000km on it can look golden, but still be contamined to the point where it must be changed? really?

Oeh, not all cars come with dynoil for break in... Enginebuildermag even writes "Consequently, it should make no difference if a conventional oil or synthetic oil is used for the initial break-in. The deciding factor would be the cost of the oil itself." But I gues theyr're not quility engine builders aswell. They also mention that seating the rings can take as long as several thousand miles. So if you swear by dino oil, you should probably use that again on the following oilchange. (you didnt mention whatoil to use in the post i replied to, so you might wanna ad that, when its so important.)

A guy claiming to have rebuild over 300 bikes, recommends 1500miles before chainging oil, to proper seat the rings.

So theres lots of different oppinions outthere, even among the guys who build and maintain theese bikes

Theres oil made for break-in, some say not to go beyond 1000 miles, and thats not on your everyday dino oil, but oil specifically made for breaking in a completely new engine.

Its weird theres no word about assembly lube, priming the oilpump ect when you try to take so good care about the bike and initial startup after opening it up...

I'd be much interested in the result of you oil analysis. Especially if its oil with a couple hundred kilometers on it, on a bike simular to ours, with only a pistonchange. That would be awesome, but any other will do aswell. I've seen many results on advrider on blokes dualporting their ktm ecx's where they were able to stretch their oilinterval a couple hundred percent.

I'm not sure theres places which does that here. I've actually never felt the need for it, with the bike beeing so reliable.

I do change the oil more often on my wr250r, as it sees much heavier use, and frequent use of riding the clutch.

Oeh, and I actually didnt recommend og told anyone to do it my way, you might wanna read it again. I just posted my experience, so people can make up their own mind. I asked question about your experience, but you didnt answer most of them.

So lets just agree to dissagree, and people can make up their own mind.

That's the thing that kind of flung me for a loop and why I even said anything . I've just never heard of that way of thinking for such a little cost compared to what a person has stuck into the new topend.

Hei! Recently i rebuild my XT ,rebored,new ProX piston and rings.Also i rebuild and my cylinder head,new valve seals. But,when i start-up in the morning i have a white smoke for a 1minute and after that it's okay. Compression is about 140+psi.

Do you have some king of problem?

I have not completed the build as yet. How many miles do you have on the new engine since rebuilding. It may be that the rings are not fully broken in (seated in). 140 lbs of compression does not seem to be high enough for a new engine, again maybe it is not broken in yet. My 86 xt has about 15000 miles, never been apart and has 170 lbs compression on a new gauge. That is the top of expected compression range of 150 to 170 lbs.

Time will tell you if your rings are seated properly. Monitor oil consumption closely. My 84 continued to burn oil after the last re-ring. It would puff smoke at startup and on deceleration. This is why I pulled it down again and bored to 2nd oversize and new OEM piston and rings. Clearances are now factory spec. Hopefully I can get the rings to seat.

Once I get it together and running, I will take it on the road and not idle it in the shop. From what I understand you must start the break in process quickly while the cross hatch in the cylinder still has sharp edges.

There are lots of opinions about break in procedures. I will not go into that here.

I welcome anyone to jump in here with some wisdom. JJ, your experience here could benefit all of us since you have built many engines.

Steve

Side question

What are you guys doing to monitor engine temps? I'm looking to add a gauge.
ex:Gauge

JJ has just the ticket, he will jump in here with his solution and why. The spark plug gasket method is no good, will show a way too hot of an indication. JJ puts the sensor into the head so that the oil bath inside the rocker box helps determine the temp.

I'll have to wait till I get home to post a pic of the location I found for the most responsive spot for reading true head temp. I use those TTO's but am really thinking they're POS's . None of mine work below 40-45ºF, the screens just blank out. The Vapor unit is best but more $$ and more stuff than needed if a person already has stock gauges. If you don't worry about the cold issue, the TTO's work , but you need the one with the 6mm x 1.0mm threaded probe.

I have an oil temp gauge instead of the dipstick. I think it reads oil at its lovest temperature, and it meassures the return-oil.

The temp guage will just give you another thing to worry about, I know I dd at first...

Here's where I put my probe in my XT's , This location measure the oil temp right above the right side exhuast valve , the hottest part of the motor and it'll show the quickest if anything is going wrong . I just see what it reads normally and if it suddenly goes higher I'll know to check things out .

http://i1028.photobucket.com/albums/...psnfxzx4sq.jpg

Do you have pictures of the gauge?
You have it set up to monitor the bike while driving correct?

Thanks

I have both TTO gauges and Vapor unit for seeing the temps, depending on which bike . They're on the handlebars or dash to see while riding at anytime.

Trailtech TTO temp in eBay Motors | eBay

or the Vapor , trail tech vapor in eBay Motors | eBay

Which adaptor do you use? Seems they come in different variations ex: for spark plug or radiator.

I use the 6mm x 1.0mm probe exclusively . I had 2 of thoe ring style probes and placed them all over the motor and none came close to as consistant and accurate as the probe in the head. I had 2 TTO's on 2 bikes all summer a few years back to directly compare . Usually had 25-50ºF difference .

Thanks a lot

curious to what temp #'s it runs at and what is considered max temp for these motors.

I usually had 250-275F on my mostly stock motors @70F air temp with the probe inside the head. The other style of probes would vary 210F to 240F and fluctuate with wind and outside temps quite a bit , plus take 4-5 times longer to show changes(like stopped at a stoplight then to moving). Hotter the air temp temps went up a bit. This is the reason I like to use synthetic oils in the aircooled motor , standard dyno oil begins to breakdown at 250F , synthetics are designed to withstand the higher temps , but I imagine it takes quite a few miles for the oil to get bad enough to not be up to the task. My high
comp motor see 300F regularly on trips in the warm summer up to 330F.

Thanks JJ
Trail Tech 72 ES1 TTO Air Temp Meter M6x1 0 Screw | eBay

That's the one.

I haven't reused head gasket in the past but wondering what you guys thought of reusing one?
Its metal oem yamaha with about 400 miles on it.
This head gasket just got unlucky on this bike and had a crappy life.

Air cooled lowish compression.

You can reuse them and get lucky and you can re-use them and not. If it's been running in a bike them generally they're done in. Up to you...

Sent from my G7-L01 using Tapatalk

With all the trouble you had - Get a new one for sure.

I agree, replace it. It has been compressed once, will not compress more. Probably leak.... or not.... :funmeterno:

Cometic Gasket Top End Gasket Kit 97MM Bore Fits 88-96 Yamaha XT600 - Rakuten.com

Any thoughts? I need both gaskets.

Is that the same bolt pattern as your head ? Looks like it in your first photos, If so they'll work fine.

When putting the clutch assembly back in. Do I need the tool to hold clutch to torque down nut? Or can I use....
I don't have any old plates to make a tool with. Wondering if their was a way around this.

Get the tool. Its £20. There are other ways of jamming up the clutch basket but they often end up doing damage.

Sent from my G7-L01 using Tapatalk

Air/rattle-gun

Bought the tool at Cycle Gear (US motorcycle parts/gear store) for $21.
Took it off with air tool but figured it should be torqued down right for return.

[QUOTE=jjrider;537064]Here's where I put my probe in my XT's , This location measure the oil temp right above the right side exhuast valve , the hottest part of the motor and it'll show the quickest if anything is going wrong . I just see what it reads normally and if it suddenly goes higher I'll know to check things out .

How did you attach the sensor bolt? I have no hole threaded or not there.
The sensor bolt is the same length as some rocker cover M6 bolts. But the sensor bolt is not threaded long enough to hit female thread.
Am I thinking this correct?

I drill that hole in the heads then tap for 6mm x 1.0 . As they are stock there's an aluminum plug there and the hole in the casting is around 3/8" diameter behind the plug so the temp probe reaches in to where the oil is being splashed around . You can't use these probes as a replacement for any bolt , they're not made for it and will break before torqued down to the amount a bolt should be .

If you don't want to drill the hole in that plug you can drill & tap a hole in the rear valve inspection port and put the probe there , it will be exposed to the oil up there but won't read quite as high or as fast as the other spot . Will still be plenty good and the cap can be cheaply replaced or a short 6mm bolt put in the hole if the probe is removed and not used anymore or swapping to another bike.

http://i1028.photobucket.com/albums/...psz2wy4txh.jpg
http://i1028.photobucket.com/albums/...psqeeqjhax.jpg

I was wondering about this spot, much more do able for most of us.
Thanks for info. :D:D

Is there enough metal thickness for the lid to run a tap?

I like the exhaust valve location but I all ready have the head assembled.

It's thin but will be enough to hold the probe .It only needs to be about 5-6inch/lbs torque max , I put some rvt or similar sealant on the threads and just snug them up .

Can someone please give me the head bolt torque number.
Clymer manual seems to low

Book says 18 lbs but that seems low

From factory service manual 1990 First Edition

Cyl Head
Flange bolt M8 x 1.25 = 21 ft/lb
Stud bolt M10 x 1.25 = 14 ft/lb

Bob

Never use a rattle gun to tighten any nut/bolt that has a specific torque setting.

This is basic mechanical engining.

True... One should NEVER rattle gun anything tight. Apart from perhaps a set of wheel nuts on a Transit Van :thumbup1:

However there are some very accurate (And expensive) air guns that you can use because they are limited to certain torques. On torque sensitive bolts I still wouldn't though.

In this case I think he meant use a rattle gun to remove the clutch nut which is totally acceptable.

I never use a torque wrench. But with just the slightest idea of what youre doing, I see no problem using an airgun to tighten big nuts like that. Most of the airguns (both of mine) them have different settings.

I know its not the proper way to do it, but I do what works for me, and give others the option of choosing for themselves :thumbup1:


My wr250r has something like 125Nm for the rear axle, making it just about impossible to remove with the tools provided by Yamaha. I cant figure out why they list it so high, and I've had no problem setting it way lower.

So again, for me, nothing beats real life experiences....Eventhough they are wrong if you go by the book.

Happy riding...

I couldn't disagree more with this....

There are so many torque critical components on a motorcycle that you dont know you're wrecking until many miles down the road. Theyre the kind of second hand bikes you dread buying.

Torque settings arent made up for the sake of selling manuals.

Fair enough, its pretty difficult to screw up a rear axel but if youre 'rattle gunning' engines back together then remind me never to buy a bike off you... :eek:

You are the best:thumbup1:

Put all back together and started up without drama.

Spent about 1/2 hour breaking the rings in etc, leisure driving.

Inspected bike and can hear a hiss from the head gasket doh.

Stripped down bike again
Head measured straight
jug measured straight

Cosmetic head gasket, which seems a whole lot less sturdy then OEM.

Head bolts were torqued to spec. But just didn't seem tight enough.

Gonna check threads and see if any debris in head bolt chambers etc.

Going to take head to machine shop to validate, should of done that 1st I know. Kicking myself now.

Am i missing something?
Head gasket was stock size
No copper/silver spray added on install

It doesnt make sence to me to go by yamaha specs, when nuts on the counterbalancer and crankshaft loosenes. Yamaha doesnt mentioning loctiting theese either, I did it anyway. Quite the hack job, huh? :oops2:

I havent "'rattle gunning' engines back together", I've used it on 3 nuts, 2 of them known to beeing prone to loosening up. :D

I didnt just fire up the compressor and airgunned it till the nut didnt moove anymore. I know how tight the bolts was to remove, and tightened them the same amount. I marked the nut/shaft with a marker before breaking them free, and tightened the 2 bolts proone to loosening up, just beyound that. The clutch to the same mark, as this isnt a problem. Still used threadlocker.

So should be VERY close. :thumbup1:

What difference would a couple Nm be? Its like under 10% difference. Theres probably a bigger difference in torqing the threads oiled vs not. :innocent:

I did it about 1,5 year ago, just wanted to know how much time you give me before the engine grenades. I really dont think my nuts care which tool was used to tighten them op tho'. :mchappy:

Rebuilding an engine isn't as 'back shed' as many would like.

You need those mating surfaces SPOTLESS. Or at least so smooth that you can run your thumb over it and not feel any raises or notches.

Also it sounds like your head threads are tight or damaged. You can't accurately torque down a head unless the bolts are moving freely.

Tighten down the head from opposing corners turning each bolt a few turns at a time. You can count full turns of identical size bolts and see if they are winding down similar amounts when they 'Click' on your torque wrench (book procedure is best though).

I don't mean to sound patronising but are you sure your torque wrench is set correctly ? $10 torque wrenches don't cut it on engine work either.

That's assuming everything else is straight and lined up.. Are the dowel pins seated straight etc ?

Thanks Ted

I'm going to really go over this tomorrow.
I had done a previous head gasket on this bike without problems as well as my truck.
I did something wrong obviously.
I will do a leak down test as well this time to make sure of leaks.

Pictures are cylinder after like 10 miles or 30 mins.
Front part of cylinder seems to have some wear? I can't feel anything but its smooth with no honing marks at little over 1/2 way down.

Does this look like abnormal wear?

Is it a new piston ? Was the cylinder measured ??

Those score marks arenr what you want. If everything wasnt clean in there it could be contamination. Did it smoke ??

Sent from my G7-L01 using Tapatalk

New piston, slightly larger
cylinder bored to piston size

Was taken to bike shop for machining and fit
I installed rings and piston

I had this exact problem with one of my bikes. (XR650L). They cut the bore incorrectly. Slightly oval and with too much clearance. Did you supply them with the piston to cylinder clearance from the manual ?

My piston, rings and bore were all wrecked within 20 miles. It started smoking oil and had scores just like yours.

Its now getting re-done at another place. Another £400 worth of work.

Well thats's just for crap

I gave them 2 different cylinders I had.
One had some rust but was undamaged,
The other was my recent cooked up cylinder with aluminum stuck to walls.

They bore the latter one as they couldn't chemical peel the aluminum off.

It was fitted at shop.
I put the rings on then put piston in.

Any advise on what could/should be done at this point.

That's not a Wiseco piston , so I have to ask , was the end gaps verified ? Wiseco is really the only brand that is pretty reliable to have the correct endgap , other s can be good , but can be to tight . Also did you install the rings with the ends in the orientation as in the manual ? They do move around when running but it is needed to start out right.

I have taken a motor apart with only the few miles like yours has and saw similar marks (mostly "scuffs" front and rear where the push is toward in a running motor),everything felt smooth and seemed ok so I put it back together without changing anything, that motor is running fine to this day and had 190psi compression when tested later. It was the only topend I've ever taken apart with so little run time so I can't say it's normal for sure but I think it is how they tend to look till fulling seated and run-in.

When you put it back together clean good , very light oil in the cylinder then take it down the road briskly on the throttle and use the motor to slow the bike down , repeat 10 times going through the gears mixed with slowing down by the motor , not the brakes.

Picture of new piston box

All you can do is take it back to the place who cut it and ask their advice.

I presume you put the rings in the right order and the right way up.

Sent from my G7-L01 using Tapatalk

38k Miles time for new main bearings
 

Hi guys! Great thread!

My mike was redden by a friend of mine for 38K miles... it was never in the dirt and oil was changed every 2K miles or so. The bike is VERY clean inside the cases. I have seen bikes with 2K miles with a black coating inside. Cam is perfect with little to no wear, cam chain is still in great shape as adjuster was only out half way. The piston was very clean and rings are about 70% worn by measuring at the ring gap per the manual. The main crank bearings are worn as you can rock the crank in the case. The rod has no up and down play as well as the piston pin.

My plan is to:

1) New OEM piston rings with a hone job... the bike did not smoke at all before I took it down. You also can still see all the factory hatch marks on the cylinder wall!! That shocked me!

2) Lap valves with new seals

Piston looks great with little wear on it. I can feel a little play when it is in the cylinder but very little.

Any other ideas while she is all torn down?

I'm lucky this is the 1989 bike so it has the updated head bold pattern.

Thanks SO Much guys!

Eric

Hi Eric,
I would suggest starting a new thread.
But while you're splitting the cases to renew the crank bearings, I would check 5th gear for wear since this is a common problem, and renew as required.

Bob

hi what are the black marks running around the bore ? ,maybe marks from the piston rings where it has been left for a long time and left a very slight rust mark or indent ? also if you split the cases fit a new bearing for behind the sprocket as this can get a hard life due to maybe over tightening the chain ,steve