Viper compression #s?

[8alltheway]

I bought a used motor for my 02 viper, seems to be in good shape, an the guy i bought it from seemed to be legit. Anyway, the #s i got mag to pto was 100, 115, an 123. is this ok? i thought that the cylinders all had different comp. ratios, but not sure? also i did this a couple weeks ago with the motor on the shop table (my memory may be off as there was involved), so i realize the #'s should be higher if it was a true warmed up motor reading. i need to know what they should be....

 

[MTN_VIPER]

With fresh rings PTO 110-115, center and mag 120-125psi. Center and Mag have the same compression ratio. PTO has a slightly larger combustion chamber, for a lower compression ratio.
If you test it with the engine warm, your readings will be slightly lower. Normal for most 2 strokes.
Judging by your numbers, (if the guage is acurate) it could probably use a fresh set of rings. Not a bad idea to re-ring a 2 stroke about every 3000-3500 miles or so, for optimum performance.

 

[8alltheway]

Ya i suppose it wouldn't hurt to do a re-ring as the motor has near 3k on it. that mag # kinda worries me tho..., but ill get some new rings in her an see how she likes that. btw, im not to familiar with the yami's, what do you guys recommend for rings, factory, or is there a better route? an thanks for the info ^, mucho appreciated

 

[MTN_VIPER]

Yamaha engine parts are good, usually better then aftermarket. So I just use the factory stuff. If you tear into it, measure the pistons for proper piston to bore clearance. I think the max clearance is .010", if the pistons are close to max spec not a bad idea to throw some new ones in while your there. With pistons OEM units are far better then aftermarket.

 

[skidooboy]

with 3000 miles might as well put wrist pins, wrist pin bearings, pistions and rings, head gasket. install an srx base gasket (better cooling) as well. look up mr viper700 on www.totallyamaha.com he knows alot about the vipers and srxs. no sense in risking a piston skirt breaking and taking out a cylinder, or worse. also, keep those powervalves clean. clean them every 500-750 miles and you shouldnt have any issues with cable pull through. a well tuned viper with megapower heads and slp triple pipes is a awesome set up. ski

 

[8alltheway]

I did notice that the power valves were really dirty, an these are the original ones on this sled an it had less than 1k of easy miles on it. my summer "to do" list keeps getting longer an longer with each post. thanks for keeping me busy guys...

 

[MTN_VIPER]

I have mr viper's port work on mine. Very pleased with the performance! Its the one thing I'm going to miss,,,,,,,the power/sound of that ported/piped 7 hundy, when I switch over to a Nytro next season.

 

[mopar1rules]

a better head setup for the viper, is to use 00-02 srx heads. you have to cut them though, to get the right comp ratio and use a aftermarket water rail. i used to think mrviper700 (on totallyamaha.com) was the shiznit too. i talked to a guy that nows alot, and he told me a few things about mrviper. now i don't think very highly of him. not to mention, he told my buddy a particular clutch setup....we tried it....and it worked for ****. mrviper wouldn't help us trouble shoot it, and my buddy spent $200 for nothing. mrviper never used to build his own motors, or do his own porting. he had race logic out of michigan do it for him. his porting job is nothing special. all he does is use one of race logics port templates and just ports your cylinders to what the template says. its not some aggressive or custom port job that he thought of.

now for the guy that wants to know about freshining up his vipers top end. just use the factory parts. new pistons, rings, gaskets, wristpins, and wristpin bearings.

yeah, the slp pipes do work very well. i have aaens on mine, and love the smooth power curve that they have to them.