How do these look?

TopGunnSrx

TopGunnSrx

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May 27, 2003
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Livonia, Michigan
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www.tsufilmz.com
Did my took my powervalves out and popped heads off let me know what you think of my piston head and powervalve.....Pistons got over 6,000 miles on them original ones and original rings still running at 132 psi across all 3 cylinders for compression... is that what it should be? MY powevalves have over 2,000 miles on them running yamalube i dont see how ppl can say it sucks!
 

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Now that you have the head or heads off take a look at your cylinders around the exuast port and booster ports for shinny spots where the nicisol may be wore off
6000 miles is when i redid my top end and what a differance it made
 
throw new pistons and rings in it for piece of mind, then cut the heads alittle. and put her back together. the reason you want to do the pistons is, the skirts will start to fatigue and you wont know till its too late. like the old fram adds used to say, "you can pay me know, or pay me later" the pistons and rings may cost a few bux but it is cheap insurance. plus the sled will be good for another 6000+. ski
 
the piston wash looks pretty good, so its running good, but i think you should replace pistons too... just bore over a little .20 then youll be ready to break her in this year, with your reliability up and a little snappier.. and yes yamalube is the best.... half synthetic its the way to go :kw
 
Gees I hope we can go more than 6000 miles before replacing pistons.I say leave it alone. If your compression is good and were it should be then I think your good to go.If you beat on your sled then maybe replace them, but hell things look good.......
 
i believe yamahs service life on the pistons mostly due to skirts, is 7000-7500 miles. you guys need to realize these sleds are not automobiles and turn 2-3 times the normal operating rpms of autos. those skirts rattle and fatigue. and you cant tell till its too late. your there now, just buy the parts for piece of mind. especially the way you ride rich. no need to overbore the holes (they are nikasil anyway) just drop three new slugs, wristpins and brgs in. if the thing blows up mid jan or feb you'll lose almost the rest of the winter trying to get parts and fixing it. oh i forgot you have an unlimited budget to work with. :) ski
 
Every sled I've had,I replaced the piston and rings every 3500miles like clock work.No matter how they looked.just because of the skirts.Just my opinion.
 
My last 2 Yamahas were a 94 600VMax and a 98 700SX. Sold the 600 in the summer of 97 with over 16,000Kms. without ever opening the engine. My friend bought it and is still running that sled today with no problems. Put over 18,000kms. on the SX never opened the engine on that either. Just picked up another SX for my wife, this ones an 97 with over 18K, never rebuilt. The main reason I spend the extra money to own Yamahas is their incredible durability. At what point do you consider changing pistons as insurance a waste of money? 3k, 5k? Measure the skirt wear, compare it to the published wear tolerances and if it's within put it back together and don't open it back up until your ear tells you there's a clearance problem with the pistons. Just MO
 
piston and rings

Like skidooboy said the skirts shrink remember these things came lean from the factory when it real cold out and you w.o.t giving her hell thhats when it happens.once they have shrunk they don;t come back.Now the space between the skirt and the cylinder wall is greater and the piston starts to rock back and forth against the cylinder wall and this ends up being noticed at w.o.t under load you will start to loose rpm and power ive experianced this firt hand.and if you let it go to far well you know what the out come my be.one word of advise is when you do do the top end do it right if the cylinber need to be redone don't cheap out re nicasil them other wise your top end wont last that long and you have wasted you money,and use yamaha pistons and ring wiseco's will only last about 3000 miles not made to last.and last for 50 dollars canadian get the pistons coated ceramic on the top and poly moly on the skirts and the pistons will last longer then none coated ones
:rockon: :rockon:
 
I think yamaha pistons will last alot longer than 4000 miles.I would love to talk to a tech from Yamaha on that one.I think skidooboy would have them laughing in the isles.
Also it comes down to good lubrication
Here this is from Amsoil

"400,000 Miles of Severe Snowmobile Field testing With No Deposit Buildup, Power Valve Sticking, Ring Sticking or Engine Failures.
Subjected to adverse field testing conditions in the Rocky Mountains, including long trail rides, high RPM powder riding and steep hill climbs, AMSOIL INTERCEPTOR demonstrated superior wear protection and outstanding deposit control."
 
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sx7 why would i have them rolling in the isles? please enlighten us all knowing one. no where did any of us say 4000 miles was the service limit. and there is no way amsoil ran one sled for 400,000 miles thats all of the sleds combined mileages over a several year testing period. if you want to gamble go ahead. in this post top gunn (someone i know personally) is asking a question, what do these look like and what should i do? i gave my personal opinion and advice. nothing more, nothing less. i'm not saying i am gods gift to snowmobiling here. just giving advice on a subject i know of, considering i know tg and his riding style and the fact i happend to own the EXACT SLED! not sure where your trying to go with this. dont come on here asking for advice then when we all tell you what you dont want to hear start spewing about how we are all wrong. measure the skirts check the compression and leak down (yes that needs to be checked too) make sure the nikasil is good in the cyls. if they all check out, run em. i dont care. ski
 
I have seen may yammies with well over 8k and never been touched. That's why I'm over at camp yammie now. Hope my srx treats me as good.
 
Gees your sensitive take a pill, all Im saying is Yamaha would laugh (I think ) of people changing pistion at the interval you are SUGGESTING they Im sure would would say you can go a hell of alot longer than that.Please tell me were Im spewing,its just my opinion.
Oh and by the way ignore my 33 post as indicated on my post count,Ive been around alot longer.
 
All i wanted to know if how they looked they all check out so i am going to run them. I wouldn't doubt anything ski says seeing how he knows quite a bit about this kind of stuff nor most other peoples opinions. Didn't want to get anybody riled up
 
Top Im not upset I think he took my comments the wrong way.If someone wants to replace pistons thats fine but to me I think its total waste of money until things don't sound correct or you have tons of miles in the engine.
If something brakes then you fix it at that time.
Just my thoughts.
 
hmm so a venture 500 air cooled with 16000km should be torn down eh? i am not touchin it lol cause it runs too good to even think about doing that. thing is when its mild out it pulls easy. when it f***ing cold you can berak the pullcord starting it. ;)!
 
piston and rings

Maim
You don't understand
Your little 500 fan is totally different ,it's not reving 8500 rpm and not making neer the hp to cc of the 700 srx

Sorry for my opinion and things iv'e seen with my own eyes,guess that this thread has spiraled out of reality

:rockon: :rockon:
 
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