compression conversion???

[predator90]

Hi,

I have been looking for some type of comp. conversion calculator.

My son has a predator 90 and I had some problems w/the reeds breaking off and going into the cylinder. When we did the first compression check it was 60psi...I am hoping this was because the reeds were still in there. the manual states the compression is 7.7:1 can anyone convert that for me

Ty in advance.

justinsmom

[370banshee]

well teh reason that it read only 60psi is because you had a broken reed and your compression was going out the broke reed cage and probably back through the airbox. what kind of reeds are you using??? i'm guessign your compression shoudl be somewhere close to 110-115psi when it has good reeds. you best bet is to buy i nice set of reeds and they will last a very long time. oh yeah why are you worried about compression are you having some other problem other than the reeds???

[predator90]

The bike just died on us. So we checked the obvious and that all seemed to check out OK. Then when we got back that is when we did the compression test and it was really low. Then someone had mentioned the reeds. Took a look and one had broke off. Took the pieces out and it started up without any problems and seems to be running fine now. The reeds were aftermarket carbon fiber one's. We put the stockers back in for now until I can get another set.

We will run another comp. test tomorrow. How much damage do you think could this have caused??? It looks to be OK...I am just hoping everything holds up until winter when we can start doing some bigger mods.

TY for the response 370 banshee,

justinsmom

[go-blow-or roll]

i wouldn't think that a reed would do any thing to a motor, pretty soft stuff. i will try and get you a compression figure tomorrow at work! when you put the new reeds in did you have to change the rev. plates?

[suzuki LT250R]

The reeds shouldn't do anything. I have broke them before and the motor will chew up the pieces.

[370banshee]

yeah the reed won;t gop below teh piston. so it'll just break it up and push it out the exhaust. don;t worry bout it

[predator90]

WOW!!! You guys have really been a great help...and I feel alot better about this now.

We will run another comp test in the morning and see what we get. I will have to ask my other half about the rev. plates, go-blow-or roll.

I am just starting to get into the wrenching of these quads, so I am a work in progress. LOL

Mom's can do more than cook and clean... by the time winter gets here I will be giving u guys advice, I hope!


I will keep u posted and be visiting the forum alot.

TY again.

[go-blow-or roll]

no problem! i work for a polaris dealership, if there is anything i can help with let me know. you got a good wheeler to start out with to. thoes 90's can be made to go pretty fast for what they are. there is a guy that goes to the drags with his and he is only running about 2-2.5 sec. slower in 300ft. then the big gunns.

[go-blow-or roll]

sorry i didn't get time today to look up the figures on the 90, get them for you tomorrow.

[go-blow-or roll]

it should be 116psi but i don't know how to get the ratio out of that?