Blown Head Gasket XT600
 

Hello

89 XT 600

Looks like head gasket.

Can I take off the head by tilting the motor forward or is it more complex. Anything that i should be looking at or thinking preventively?

Thanks
Greghttps://www.dropbox.com/s/gv5vd806t1...80161.MOV?dl=0

Yes, tilting it forward will allow you to get the entire top end off. Don't forget to remove the rear bolt below the swing arm pivot. Also don't forget to remove the rocker box screws inside the valve setting cover area and the one on the top middle of the rocker box. The engine does tilt forward enough, been there done that....

Thanks Steve

Any opinions on shopping for gasket.
OEM is like $45 shipped

Always OEM on the head gasket. :thumbup1:

Mezo.

Pictures of head

1st time doing the replacement gasket so any advice would be great.

Thanks
Greghttps://www.dropbox.com/s/brxt3ji03s...-head.jpg?dl=0

I had to laser out my own copper head gaskets to keep my hi-comp motor sealed up so the oem must be on the edge. Yours is an '89 so it does have the extra bolts, which is why they added it , I made the mistake of grabbing the older head so it has less bolts so I believe that's the main issue. For the valve cover, clean the two surfaces really good, but not with a razer blade. Make sure there are no scratches.
I use Permatex Moto-seal which was original made specifically for split case aluminum motorcycle engines. Works good , super clean and oil free surfaces are key to proper sealing.

With the head off, now is a good time to drill & tap that little plug on the front righthand side for a temp sensor. It is right above the right exhaust valve so picks up the hottest spot in the motor and quickly to keep an eye on it.

There's no need to tilt the engine in order to get the top end off on my 86.

Sent from my SM-G900V using Tapatalk

humm, how'd you do that? Clearance needed to remove rocker box....

I played for quite a while to get one of mine off without moving the motor , never could get it so I took it out for full access. I've heard someone else saying of a very specific placement and way to do it but I never found it.



.

What temp sensor are you using?
Was very mildly driven and definitely never over revved.
I can't find any warp or crack which leaves me confused as to what happened.
The leak was coming from right exhaust corner. But there is a mark/indent on surface. This seems to be more interior to valve and would still give a good mating surface for head. But I'm not sure.

The 90mod you can remove covers with engine on bolts, just remove intake boots. What is the marks on the head, seems deep scratch or just dirt? think you gonna have trouble with the gasket on these scratches.

Those indents/deep scratches on the head are where the head gasket flame ring seals. You're going to have to get the head surface machined to fix the problem.
A good idea while the head is off is to lap the valves & renew the valve stem seals.

Bob

Question is how much is possible to machine on this? seem pretty deep.

If the scratches are to deep then what are my options. Ebay?

Any idea how that happened?

If it has to be milled down, will it change the engine characteristics (run worse)?

No longer avaible from partslist, 3TB is avaible and price 360dollars..So yes EBAY, i recon JJ have one for you? Hard to tell how its possible to make the scratches in that area, didnt happen when engine was on bike running. Yamaha 1988 XT600 XT 600 Engine Cylinder Jug Barrel Piston Set | eBay

I've milled off most of mine when I rebuild them. Most I just take 2-3thousanths, I have taken .015 off one(the head, not cylinder but can do the same). The timing is effected a little, it goes retarded some but not enough to have running issues. If you need/want to take more off getting a thicker copper gasket can bring back the height, I don't know what would be the limit , I use .043" copper as a oem replacement, I imagine .0625" would be my max thickness.

I actually do have 1 or 2 or 3 heads/covers here if you need a set ,plus a freshly bored cylinder and matching Wiseco piston. Need a complete running motor ?

Oh and for the temp sensors , I use 6mm x 1.o Trail Techs , either the individual TTO readouts or the Vapor computer,
http://www.ebay.com/itm/Trail-Tech-T...580acd&vxp=mtr

Do you think this is the reason behind the blown gasket?

Motor has new piston/jug/valves/chain from previous owner.

I ordered a new gasket yesterday, will it still be of use if head gets milled or would I need to not open in case a thicker gasket is needed.

This puts a tamper on things.....

It'll work as long as not much is milled off, that's a likely cause of the blown gasket. It's impossible to tell how deep those marks are with pictures. If it can be kept to less than .015" then there won't be issues with the oem gasket , it is tightening up the squish but still workable and timing won't be off too bad. Wait to open package till head is milled.

Just remember when reinstalling, the timing marks on the cam won't end up perfectly even, the chain is newish so that'll keep it within reason. If they need to take more off then you'll need a thicker head gasket, or a thicker base gasket and a bit turned off the piston top to get the proper squish back or pre-detonation can start easier.

Can you measure how far from the top of the cylinder does the piston come up to? In you picture the piston appears to be almost even with the cylinder top, it should be more in the .03" area ideally on these.

its a weiso piston in there would that change the measurement?

Clean the top off and get the number stamped on it. If it's a std comp piston it should still be close to .03", a higher comp will be closer but either way it shouldn't be less than .015" with .02" better.

What do you use to clean the piston top?

Got a wire brush ? Some degreaser or carb cleaner works but with it still on the motr you don't want a bunch of junk going down. Should be fairly easy to clean of with a wire brush, just don't get too aggressive.

The piston does appear to be a standard comp , being that it's a flat top.


EDIT, after looking at some pistons I have on hand for the XT, your does indeed look to be the standard comp due to only 2 valve reliefs on the exhaust side and the slight dish(far right). The 10.75:1 101mm(middle) that I have is completely flat and has all 4 valve cuts so will be only approx .015" below cylinder surface. The 11.5:1 102mm JE is quite different (Left) still will be .015" below cylinder at the edges,

http://imagizer.imageshack.us/v2/800...673/qwgT9j.jpg
http://imagizer.imageshack.us/v2/800...911/FuSKMZ.jpg

Any ideas on cost to mill a head?

For me zero ,I do my own machining, don't really know what some will charge, maybe $50, maybe be $100( shouldn't be, but some areas??). Get a quote first from a local machine shop . Make sure they'll do it for a set price up front so no surprises. Otherwise send it to me and I'll do it. Can't remember where your from.

NY

See if you can have someone local do for a decent price, shipping will still cost a bit may $30-$35 both ways, plus a bit of down time.

Thanks i'll look into it

I also feel I need to replace the rocker head because I've had rocket noise for last 2000 miles :(

We all have rocket noise :clap:

Speak for yourself, mine don't have noises , mine have rattles :innocent:
,



Ajax , depending what and how loud your rockers are it may just be one or 2 getting on the loose side and in need of adjusting. All theses motors have some rattling to an extent, it's the design. There is a limit but there have been that make just an awful rattle from new, but live a long life with no issues.

Also that Wiseco piston is a forged slug , it usually has another .001"-.0015 clearance in the bore for expansion, compared to oem, so can have a bit more noise. Depends who bored it out and what they used for tolerances.

I had a long thread on here awhile back regarding head noise.
In summary when motor starts warming up about 45-60 sec the rgt side exhaust lifter starts a strong tapping sound. I can mimic sound by hand with tappet. Lifters have been checked and adjusted routinely. Rocker head has been removed and inspected as well.

With that said it has over 2500 miles since i've got it back on the road and has proven very dependable :). Just noisy and industrial sounding.

But its in the back of my head that it will get worse and I don't know if its a good idea to just replace the suspected rocker arm or replace the whole rocker head.

I've been looking at some of my rocker covers and rockers and have noticed some of the shafts that the rockers pivot on are a little worn to one side from the rocker. I'm guessing those are the source of some of these rattling rockers. Doesn't have much danger in breaking or any unexpected issues, just noisy. May slowly get louder as they wear more . I'm having a couple complete shaft/rocker sets coated with a diamond based substrate that'll eliminate the wear plus reduce most friction . Also have a cam with them to get coated , it's supposed to eliminate 90% of the drag and not "need" lube , so if ever low on oil , there won't be any damage , at least not up there . I don't plan to test that part. Also have a set of valves being done with the coating on the shafts.

If you grab that rocker to check it, see if it'll wiggle on the shaft itself, that'll tell you if that is the cause of your noise. Otherwise with the cover off you can remove the shaft and inspect it, there should be less than .001" clearance between the rocker bore and shaft.

The questionable rocker: the spring that holds it on shaft and creates tension is worn further then the other 4 rockers.
It has less resistance to up and down movement, no drag. It has more movement on shaft.
If I move and release it, it will fall with no resistance. The other 3 rockers have the resistance.

All else looks fine with it including contact area at tappet

With that bolt holding the rocker shaft in you unfortunately can't change the spring without the cover being removed. I know the cover I used on my present motor had some "free moving" rockers and it also clatters , will be fixed soon.

You'll just need that spring and maybe a new shaft, if not the rocker also to tighten it up.

What you mean here, he already have cover off?

doh:

:oops2:

:innocent:

:wheelchair:



Alzheimer is kicking in


then it will be no problem changing it .:thumbup1:

:)
cover is off and on the table

If the frame on the XT600 is the same as the E model then you can get the head off without tilting the engine. Rocker box cover is a pain but i've put a previous post here with details how to do it. Saves much time and hassle.

thread's a bit all over the place but lets give it a try :)

looks like PO was a bit of a butcher.....

would def try to mill the head surface to get rid of any grooves, specially where the metal ring of the gasket makes contact. at least here in milan a single resurface like that would be no more than 25 euros...

valve seats in the xt600 are kind of far from the surface so you could mill off quite a bit and compensate with two or a thicker DIY base gaskets.

whatever you do, use an MLS (multi layer steel) gasket rather than the stock old school klinger/metal (like in your pic) for the head. much more reliable and easy to get off if you need to re-open. Cometic or Athena or Prox shoudl make one like this

http://www.ebay.it/itm/KIT-GUARNIZIO...item234ac4d5b4


maybe post some pics of the rocker. if the sliding area is damaged then buy new or reweld and grind.

https://www.dropbox.com/s/vfj0e3815k...t600A.jpg?dl=0I called a bike shop that was recommended from my local shop. Guy at shop told me to just get some 200 grit emery cloth with a straight block and sand it down a bit. Then put it back together and ride....

He didn't see the picture of the head but didn't think it would be that big of a problem.

I'll try to find a machine shop to have someone actually see the head.

He obviously didn't see the pic, if he did he wouldn't have recommended sanding it with 200 grit on a block.
The head needs machining.

Bob

Or he was the previous owner that put it together that way :laugh:

With a normal head that would be fine, just not with gouges where they are.

I'm going to take it into a machine shop this week to see what can be done.
If I go with another head (different bike) do you think I will have any problems?
Another head with my rocker box.

If you go with another cyl head, you must get the head and rocker box & use them together as they are "matched". When they are manufactured they are bolted together & align-bored for the camshaft.

Bob

Yup , mixing those 2 isn't a good idea , I'm sure some can work, but many definitely won't.

Took to yamaha dealer.
Knowledge guys, they said to invest in head and rocker box. They also noticed that the valve springs were upside down.
Seems more problematic to mill this head and hope it doesn't get milled to far.

Jjrider
Let me know if you want to sell a head and rocker box.

Greg

Why?

I agree ^

From what I can see it can be salvaged. If you want send them to me and I'll fix it , not a problem. If the scratches are deeper than they look in the picture I can weld them up and then faced so minimum taken off.


Summers wasting, time to get back riding.

IMO I think welding the head will soften the aluminium in that area, increasing the chance of future head gasket leakage, especially where the flame ring seals.
Once the welded area has been softened, there is also the risk of the exhaust valve seat next to it coming loose.

Bob

It can be done.

Here's a sample of head/rocker box if I go that way.
Yamaha TT600 Cylinder Head Valve Cover Rocker Arms TT 600 83 86 | eBay

That head is cheap enough, good also that the rocker box is included. Some on eBay separate them to sell them individually. Bad idea...

Won't fit your '89 cylinder. "88 and '89 have a different hole pattern.

Plus the one cam bore is wobbled out, mostly on the rocker cover side. Side of the cam chain

So my options are for only an 88/89?

I know the rocker box had an extra bold but i didn't know there would be a problem bolting the head to jug. Thanks for that!!

http://www.ebay.com/itm/231637695366...witem=&vxp=mtr

If this is a good fix I would get this. But not the right years right....
Please let me know :)

best
Greg

Only the ones off an '88 or '89 will fit your jug, unless you get an older jug, they all fit on any year bottom.

The tell tail difference is that second bolt on the end of the cam chain tunnel. The newer ones have a bolt on each end, the '87 and older only have the bolt on one end. The 2 studs around the bore are spaced different also.


I was eyeing that last one for a while, looks in good shape, waiting to see if he comes down a bit .Don't really need it but if cheap enough. I'd prefer the newer style.

Don't know if my jug is original. Here's pics
https://www.dropbox.com/s/6xm6d02o7w...94518.jpg?dl=0

https://www.dropbox.com/s/hb8ffkh0ds...81%29.jpg?dl=0

That's a '84-'85 jug.


Didn't you post about the valves being new or reworked on your current head ?

So I should be able to use 83-89 heads?

'83 to '87,

I just can't comprehend why you'd buy another head.

Before I got it, it had a cylinder,jug and timing chain replaced. I don't know if the valves were just cleaned up or there were replacements as well.

I just can't comprehend why you'd buy another head.[/QUOTE]

Just want to get it running right. I've got 2 other bikes but look the must forward to driving the XT :)

JJRider let me know if I can send it to you? And what you need.

Or tell me what years I should look for on the head.

Best
Greg

Hi Greg
regarding the above, & no offence to jjrider who is kind enough to offer you an option to fix your problem.

I'm an automotive mechanic, not an engine machinist.
But recently I asked a local very experienced & reputable engine machinist who does weld aluminium cylinder heads, if he could weld the gasket side/surface of an aluminium Honda 130HP outboard motor cyl head for me. And the above is what he told me. He said welding the head will reduce the hardness from 100 Brinell to approx 70 Brinell.

He didn't mention anything about the potential for valve seats coming loose, but that would depend on how hot the area around the valve seat gets & whether it gets softened/annealed when welding. Keep in mind the valve seats are an interference fit in the head.
And when a valve seat comes loose & falls out the result will usually cause serious damage to the piston, valve, & cyl head.

Bob

I really dont see the point shipping this, using hours of work when you can buy used one cheap and put it straight in. Then you never have to worry about new leak or valve seat problems.

I get it, and really appreciate the input.
I'm just trying to confirm what head to get as the motor has been put back together with what years?
This is causing the delay as I probably let a good head with rocker box go last night (ebay) when it might of been a good head.

if someone could please look at previous picture from yesterday and confirm a jug to head combination I should be looking for.

Previous head was 1JK00
Jug on bike 34K00 Y1

What are the chances a used head off Ebay will have good valves ? That was my point when asking about the valves in his current head, if they are good, why buy another head only to have questionable valves and seats. Now if his are bad/poor , different story. I've had to fix every used head I have gotten off Ebay, usually a reason the bike is being parted out, plus add in high miles with poor maintenance ect....

As to the welding, well everybody "knows it all " .I've done a few myself and know of quite a few that have been extensively reworked, all doing fine. People would be surprised at what is done to race engines to gain hp and they hold up. That said it would be a last option of course, if not needed no reason to. And yes, I HAVE been to college and went through metallurgy and welding . Did he ever say about the alloy used and the differences when welding?

I could have had this done and had 500 miles on the bike already, just frustrating trying to help and having the equipment and knowhow to do it and a lot of squibbling. I wasn't even considering charging for it other than return shipping.

Ok i understand, if this is done free of charge its no problem. I was thinking hours of work and shipping cost, it get pretty fast expensive even in your country i would assume. Give it a try, not many people left that helps out like you do JJ:thumbup1:

I think its great to be able to get various opinions and advise.
I appreciate this very much :)
You guys are a wealth of knowledge and keep guys like me riding or at least dreaming it will be soon

I'm going to keep an eye out for a head on ebay.
Can I use a TT head from the same years? Any issues? Any differences?

Thanks
Ex: Yamaha TT600 TT 600 Cylinder Head Assembly Camshaft Rocker Box Valve Cover | eBay

Anyone know where I can get the gasket/o ring for the middle dowel on the head? Mine needs replacing.
I can order part but want to see if I might get an alternate gasket locally?
lYamaha 90430 08178 00 90430 08178 00 Gasket | eBay