Compression test

[powpounder]

what should a compression test be on a 888r? My buddy did his today and it was 110 and 120. What should it read? Is the engine getting tired? Time for new top end?

 

[dcturbo]

Compression will vary depending on your elevation. So it depends on were you live on what is good or bad.

 

[powpounder]

we are at around 3300 feet and the engine has about 900 miles on it! Is it time for a new top end?

 

[MJay]

That seems kinda low to me. Have you used the tester on other sleds to verify its accurate?

 

[99RMKGUY]

that seems low but dont quote me on that. my 600 has 120 at 1000 feet with 3500 miles on stock motor

 

[x-5]

It has to be low, i'm at 3316 feet and my 860r with over 1000 miles is 170 with my snapon and 168 with a carquest tester

 

[muttrmk]

170 seems abnormally high

 

[Comp 670]

Really the only way to know would either be to do it when it was new and then compare or find a engine that is built EXACTLY the same.So many things affect comp,domes,pistons and mainly port timing.You can have two engines the same size and both can have way different comp with the same domes and pistons because they are ported different.When the ports open and close has a big effect on comp.

 

[x-5]

170 seems abnormally high

May be but it runs dam good...was 172 new

 

[PCDOC]

what should a compression test be on a 888r? My buddy did his today and it was 110 and 120. What should it read? Is the engine getting tired? Time for new top end?

How are you testing it? Throttle should be wide open and then pull 4-5 times or until the gauge stops going up.

I would try another gauge before you tear the motor apart.

 

[bigcat_ak]

Most sleds will not start with a true 100-110 comp.

 

[M7 man]

its a little low 135-145 would be where ya want to have it

 

[diamonddave]

what should a compression test be on a 888r? My buddy did his today and it was 110 and 120. What should it read? Is the engine getting tired? Time for new top end?

You could just have a gauge that isn't real accurate.Try performing with a warm and cold engine and see what you get. What is an 888R?

 

[powpounder]

Compression Test

Thanks for all the input guys! We have tried a few different gauges, warm engine, wide open throttle, all with the same results. The 888r is a big bore from Turbo Al in Revy, (Sled Shed). Al is a super guy, and would drop anything to help a fellow sledder out, but its to bad that he could never get this engine dialed in! I have the same sled, stock engine (other than an aftermarket head) and I highmark it all DAY long, right from day one. My buddy may have to call Al for more input.