Help XT600E big bore piston kit
 

hey guys...I'm about to get a new piston kit for my 1990 Yamaha XT600E...

I've searched and found Wiseco 2MM over bore (97MM) 11.5:1 compression ratio.... ain't that too much compression?

The rest of the engine is still stock besides the kickstart I've assembled..... The bike has only a little less than 17000KM so it's "NEW" considering it's age but since it has to have some work done because it ain't got any compression I'll put in a higher compression piston :cool4: althou 1mm might be what i need which I prefer than having to over bore 1mm more :cool4:

Help :rolleyes2:

I also found a JE PISTON KIT with the same specs...which one is better?

whoa there!
 

Dude, if you re-bore 2mm overbore your 'using up' the room for a re-bore, sureley?
and your not gonna notice any power difference as it will only increase the capacity by maybe 1 or 2 cc at the most ( I may be wrong at 1 or 2 but it wont be a LOT, OK? )

if its power difference your after i dont think your gonna notice much.

go for the WISECO

Hi,

I cannot answer your questions, sorry, but if you are worried about the compression then there are a number of alternatives offered by Wiseco.

Take a look at the last page on this link (page 10):-
http://www.wiseco.co.uk/_private/07/YamahaCycleDirt.pdf

One other aspect that you may want to checkout and consider with the higher compression is the engine oil and fuel needed. Do you need to upgrade from semi-synthetic to fully synthetic oil? Do you need to upgrade the octane of the fuel (e.g. use Shell Optimax instead of ordinary unleaded)? I think you may well have to do something to help the higher compression engine?

Hope this helps,
Geoff

Hi Geoffe...as a matter of the oil...I don't know if I'll have to put full synthetic or semi... I use 10W40 as it's mentioned on my user manual...
As for the fuel I use unleaded fuel..I know it has less octanes but it says it should use only unleaded fuel but their is a lil product to add octanes which has to be =) I think it says unleaded because of the cataly or whatever it's called in english, I think......

I'm thinking of going for the 11.5 : 1 ratio =) 1 mm overbore

Why
 

don't you just buy the Yamaha oversize, in steps of 0,5 mm. No fiddling with the compression, just oversize piston to match the bored and honed cilinder.

Auke

Hi =) because I can get something a tiddy better that will give me more power and performance and it'll cost a little less for the same as OEM parts..

they are lighter, stronger, give me more power even tho a lil more fuel might it need to run efficient =)

Which I think it'll make it even more fun to ride =)

Get the Yamaha Piston reliability quality and you can get 2mm oversize if you really want to.
how much lighter is the Yamaha piston compared to the Wiseco piston.
It is possible to put the XT660 piston into the 600 motor.

I have a ProX 97mm,same as a Yamaha piston but cheaper.The Wiseco is 100g lighter,and mine had a broken skirt,hence the ProX replacement.You can fit a 101mm,but need to use another sleeve.

Hi =)

Motu you said: "The Wiseco is 100g lighter,and mine had a broken skirt" was it the OEM that broke or you already had placed a Wiseco piston?
Is the piston you have stock compression? I'm probably going to that 96MM from Wiseco with 11.5 : 1 compression ratio

Brian E what is that piston reliability thing? I've never heard anything about it =)

The Wiseco broke - it was running well and there was no wear or marks on the bore.I replaced with the ProX,which is identical to OE,standard comp,the Wiseco was standard comp too.The Wiseco is a slipper type piston with a very small skirt,I don't think it's very strong.I didn't fit the Wiseco,but found the damage when I pulled the barrel to fit rings.

Slipper pistons are sensitive to worn barrels(sleeves) They start to "wobble" very easely and crack. I used them in a Husaberg I had some years ago,good stuff for competition or race purpuse.But don´t expect much milage out of them if you plan to use them in a daily comuter/travel bike.

Hi.

The barrel will be ovebored... so it won't be worn right?

The thing is I ride it strong most of the time...how much milage do they normally hold average of course? I ride it everyday when I'm back home and in 2 years of riding it I've done less than 6000 miles on it... now I'm away from home studyng in college and only go there for a week or two on holidays so it'll take alot more now to do 6000 miles again :cool4:

When I said I ride strong is I like the acceleration but I don't keep the high revs because there just aren't roads for that where I live, for speeding that is.. so I keep medium, medium-high revs........

I 90% of the time ride below 80mph but still mostly around 65mph..

If the Wiseco last 15000 miles that'll give me alot of years on it :D


What's the difference between Prox and Wiseco? :innocent:

Thanks:cool4:

ProX is a cast OE copy - Wiseco is a forged piston.The forged piston is supposed to be stronger....it is heavier than cast,and that is why the Wiseco is cut down to a slipper piston.They are also run with more clearance because they expand more with the thicker material.

Hi. What do you mean by it runs with more clearance? [it's more "loose" in the cylinder] ??

One Solved!!
 

Hi there! my bike is at my local mechanic workshop....

One problem is already known...the chain that is inside the engine, on the cylinder, broke!

Tomorrow the engine will be split to see if any more damage has happened........ Hope nothing too serious :cool4: still, new piston is almost certainly go in.... +0,50 and 11,5 : 1 compression ration:cool4:

Did you get in the piston yet? I'm curious about the power increase. I've been thinking about putting an 11.5/1 compression piston in my bike.

Hi Micah...noup, haven't put it yet... I'll only do that when I have to rebuild the engine... which I'll probably include a stage-2 cam :innocent:

Vando

Keep us posted on that. If my engine blows, I'll probably be looking to do something similar.:thumbup1:

Well.. I just had to get new: two intake valves, the camshaft chain and all the necessary gaskets (all from Yamaha)....

It's gonna be a few years before I do have to rebuild the engine I HOPE! :innocent:

Have fun!

Vando :cool4:

Oh man, i'm sorry to hear about your engine damage...hope it will never happen to anyone. You should also take a new cam sprocket, as it should be changed with the new cam chain.

On the topic:

The higher compression piston, with the increased bore, will give some real power gain.

I'm using a Wossner 12.4:1 95mm piston, with an regrind camshaft (about 1st stage) and it worked fine.
Now i'm going to put a 282o/10.8mm cam, Ti retainers and uprated springs. I hope i will be soon ready to post my opinion on this stage of tune.

Digging up an old thread...
 

I've been thinking about getting another XT and tuning it out like this, any opinions on the high compression piston and performance cams? How good is the power gain? Are we talking 50hp+ at this point?

I've recently seen a XT600, with 101mm piston, 11.5:1 compression, Stage 3 cam, double keihin FCRs.
The "thing" pushes 63hp at wheel!


My engine, never had a problem due to hi-compression, the 282o cam let ti idle at 1700rpms and there is a lot of power, at all rpms. (i go up to 9k sometimes...)

Holy crap! :eek3:

So are we talking roll on wheelies in second gear if I do the high comp piston and maybe the cam?

I'm really resurrecting this thread now....
 

It's been about 8 years and ~40000 km now since I sported for the 96mm 11.5:1 piston.

Here's my thoughts:

That's way more compression than it needs. It's an XT600, and it's beauty is in it's simple ability to keep running. There is more at play though: as a big single it's weakest point is it's top end so by increasing the compression we weaken it's weakest point. Also, higher compression makes more heat which is not good for air cooled, and the premium fuel it needs isn't always easy to come by.

There's significant piston slap on startup till it fully warms up. Forged Wiseco piston (forged expands more than cast pistons, so piston/bore tolerances are looser) + air cooled (air cooled makes more heat, so piston/bore tolerances are looser) = a clacky bike. A loud exhaust helps solve this problem.

I've blown two head gaskets with the high comp piston. Last time it blew I had the head decked, ported, and valves seated. Now it's seeping a bit of oil at the head gasket again. She's a durable beast though, so she'll keep running till I buy the next oversize. :mchappy:

When I do it over, 9.5:1 compression will be with my next oversize. The XT is an "all around motorcycle", capable of trails, touring, cruising, or sport, a master of none of them, but well suited at them all. With that said, my next horsepower upgrade would probably be an extra cylinder or three. :scooter:

Well said, reliability is the name of the game. If horsepower is what you want, get another bike. I prefer my 86 with 15Kmiles and still has 170 psi compression on a new gauge. Solid as a rock, stock as new save a Zeeltronic CDI to replace the dead OEM one.

If horsepower gains are not done right, you waste your money.

My opinion only...

Thanks for the info, mine as still on the shelf and will be there..I bought another bike for the extra power ;)

mmm, got to disagree with many of the comments here, first, +2mm means +20 cc, not 1-2 cc... but most of your gain will come from the increased compression which in thermodynamics terms, means better efficiency, i.e. getting more power form the same amount of fuel. it's a big subject, do some reading on thermodynamics of internal combustion engines.

the improved motor response with higher compression starts already from low revs and you will certainly notice it. the main reason high comps can run hot is because people often install these pistons without checking squish height. this is hugely important to avoid detonation which overheats the engine. bring squish down to around 1mm, not more and youll be pretty safe. agree that this doable only if you can get decent gas, not a good idea if you are planning to go to remote places.