SPI piston for Ptek

[mxcollector]

At 3800km i think it's time to do my top end in my 08 summit....

Anybody has experience with after market SPI piston in 800R Ptek engine ?

How about SPI piston with 2 rings vs single ring like OEM ....

Tks

 

[Summitric]

Did you do a compression test? Seen many ptek with 7000 km on original Pistons/rings


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[Summitric]

Otherwise spi works good...


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[slededjr]

SPI work good. CV Tech has a set too. Phone Tom at Mots Machining. They carry them in stock.

 

[tex78]

Also mcb sells pistons sets with all u need

I'd use them before spi

 

[tiger666]

X2 on compression test I have around the same kms and I thought it was time to do the top end but the test showed 130psi per side so im going to run it for another year and check again.

 

[Fast Ent Inc]

hello
I have PROX on the shelf ready to go, they are a dual ring piston , they also come with the needle bearing.

 

[banditpowdercoat]

I personally only use RK Tek Wossner 2 ring Pistons. Less heat fade in long pulls and I had a N02 issue last spring, which totally destroyed the top ring, Yet the bottom still held enough to let me ride out

 

[Billy Boy]

Used SPI piston on a 600 HO rebuild and the motor is still going strong

 

[mxcollector]

Thanks guys for all the inputs !

Sounds like no big isue using 2 rings piston in these engine.

I will do a comp test before for sure , as I read that some get 7000km before isue .

.....so many told me that those PTek blow up at 3000 km mark , I was a bit scared to wait ....

Am a exYammy 2 smoke guy ,so rebuilding engine wasn't much needed back in the days

 

[Bnorth]

Check crank runout before you tear it down.

 

[101110101101]

X2 on compression test I have around the same kms and I thought it was time to do the top end but the test showed 130psi per side so im going to run it for another year and check again.

For those that don't know (me)... what would be the top mark or psi when brand new? I assume 130 is "fine" based on your comment, but I don't know if that is 130/200 or 130/135?

 

[mxcollector]

Check crank runout before you tear it down.

I will checked clutch side but should mag side also be check on PTek ?

 

[Bnorth]

I will checked clutch side but should mag side also be check on PTek ?

Only ever heard of guys doing the pto end. Not really sure how to check the mag end or if it really matters...

 

[DRD]

There is always low compression when the skirt breaks and the rod opens up a fist sized hole in your cases. Pistons are cheap


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[mxcollector]

There is always low compression when the skirt breaks and the rod opens up a fist sized hole in your cases. Pistons are cheap


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Thanks for pointing that out , much appreciated !

Is their any sign or way to know if a piston has a crack skirt ?
Am thinking , clacking noise or looking thru the exhaust or reeds opening ....

 

[Bnorth]

Thanks for pointing that out , much appreciated !

Is their any sign or way to know if a piston has a crack skirt ?
Am thinking , clacking noise or looking thru the exhaust or reeds opening ....

Pretty rare that a skirt will crack and survive long enough to see said crack usually it has windowed your case already. One way to check is to measure the skirt on the piston and see how much it has collapsed. A collapsed skirt will often eventually lead to failure. Especially with a cast piston.

 

[mxcollector]

So , I will simply play safe and get piston then ....

One more question , usually is it possible to replace piston in the chassis or best to remove engine ?

 

[tex78]

U can do it in there, but it's a pain in the azz to get both pistons - rings lined up and mono cylinder back on

Two people job

 

[Bnorth]

I like to use zap straps as ring compressors and then just cut them off the rod once the cylinder is part way on.