Compression Question?

[mdhc500]

I have a 2006 stock motor with 10 hours or so on it. It was broken in correctly, and it has

never been abused or overheated. I just installed a Cool Head with 19cc domes and my

elevation is 1,347ft MSL. Note that the bike ran great, like a champ before the install. I

did not get a compression check before I did the install. I know this was a bone head move,

but I was like a kid at Christmas, I just couldnt wait and forgot!!! The bike has not been started

in about 3-4 weeks, and I never did fire it up after I installed the head.

 

When I took the comression reading last night after the head install I was getting 122psi

for my max reading? I was expecting way more with 19cc domes...

 

Now, I know some things can factor, such as the compression tester itself. Its my father-

in-laws and its a few years old. Also the bike has not been started in a while so maybe

the pistons/rings are dry??? Also I did not have the pipes installed yet either??? Maybe

I'm doing something wrong. I did put the tank back on, turned on the fuel and held it

WOT and kicked the piss out of it???

 

I got pissed off and called it a night after I saw this??? I did not do all this crap for a

stock compression bike...

 

Any thoughts???

Edited August 1, 2008 by mdhc500

[dragbanshee]

I have a 2006 stock motor with 10 hours or so on it. It was broken in correctly, and it has

never been abused or overheated. I just installed a Cool Head with 19cc domes and my

elevation is 1,347ft MSL. Note that the bike ran great, like a champ before the install. I

did not get a compression check before I did the install. I know this was a bone head move,

but I was like a kid at Christmas, I just couldnt wait and forgot!!! The bike has not been started

in about 3-4 weeks, and I never did fire it up after I installed the head.

 

When I took the comression reading last night after the head install I was getting 122psi

for my max reading? I was expecting way more with 19cc domes...

 

Now, I know some things can factor, such as the compression tester itself. Its my father-

in-laws and its a few years old. Also the bike has not been started in a while so maybe

the pistons/rings are dry??? Also I did not have the pipes installed yet either??? Maybe

I'm doing something wrong. I did put the tank back on, turned on the fuel and held it

WOT and kicked the piss out of it???

 

I got pissed off and called it a night after I saw this??? I did not do all this crap for a

stock compression bike...

 

Any thoughts???

I would think you would need the pipes on, but what do I know.

[mdhc500]

I will try that, and probably buy my own compression tester... Can anyone confirm?

[sheefreak]

You don't need the pipes on, but one thing I have found to be true is more compression testers are bogus, than work right. It is unfortuneate that you didn't try it before hand. It may have registered 80 or 90 lbs w/the stock head if it is not working correctly.

[mdhc500]

hmmm... I guess I could rent/borrow a "few" from Autozone and compare the readings? It would

be nice to know if I was over 150 and needed to mix 93/race fuel... I dont want to harm the

engine... I know its prolly not over 150 being a 1300+ ft, but I still refuse to believe its 12?...

 

Thanx

Edited August 1, 2008 by mdhc500

[Tedder]

I suspect your guage is off. We're at 1300'. With stock jugs a Cool Head and 22cc domes we're just under 150psi.

[mdhc500]

I suspect your guage is off. We're at 1300'. With stock jugs a Cool Head and 22cc domes we're just under 150psi.

 

 

I hope its off...

[shanYE west]

I would have to chalk one up for a faulty tester.. 19cc domes with your elevation would put you in the 160ish for psi. Try some different testers like you said.. and if you still get 122lbs.. then maybe try a leakdown and check for a broken/pinched o-ring. But I dont see a o-ring being a problem.. being that you would get 2 different readings from ea. cylinder. Its gotta be a bad tester but it wouldnt hurt to check for a leak I guess if you can't find anything wrong and the testers check out.

[mdhc500]

I would have to chalk one up for a faulty tester.. 19cc domes with your elevation would put you in the 150ish for psi like you said. Try some different testers like you said.. and if you still get 122lbs.. then maybe try a leakdown and check for a broken/pinched o-ring.

 

I have two testers lined up that I will use tonight... I installed a new o-ring kit and used some grease

to hold them in place... They all looked to still be in place just before the head made touchdown with

the jugs so I hope its not an o-ring issue... I will report back after testing... Thanx

[shanYE west]

I have two testers lined up that I will use tonight... I installed a new o-ring kit and used some grease

to hold them in place... They all looked to still be in place just before the head made touchdown with

the jugs so I hope its not an o-ring issue... I will report back after testing... Thanx

 

sounds like you got your bases covered.. good luck. :thumbsup:

[TeamRealtreeHD]

Good luck... I will chalk that one up as a bad tester too. The ones at Auto Zone are pretty nice.

[mdhc500]

We shall see... I picked up 2 to try... I should just buy one to have in the shop.

[Wildcardracing]

Static compression is good to know for octane requirements. With those domes at your altitude as said you should be in the 160 range and require 100-105 octane depending on timing. I would also chock it up to a low reading guage. Even a cheap guage can be a good tool to check the health of your engine and variances between the cylinders. In the future you can use it to see if your compression has dropped. However, I would recommend checking it with an other guage...preferably a high quality one and possibly a leak down test to be sure you don't have other problems.

[spinnin]

I have a 2006 stock motor with 10 hours or so on it. It was broken in correctly, and it has

never been abused or overheated. I just installed a Cool Head with 19cc domes and my

elevation is 1,347ft MSL. Note that the bike ran great, like a champ before the install. I

did not get a compression check before I did the install. I know this was a bone head move,

but I was like a kid at Christmas, I just couldnt wait and forgot!!! The bike has not been started

in about 3-4 weeks, and I never did fire it up after I installed the head.

 

When I took the comression reading last night after the head install I was getting 122psi

for my max reading? I was expecting way more with 19cc domes...

 

Now, I know some things can factor, such as the compression tester itself. Its my father-

in-laws and its a few years old. Also the bike has not been started in a while so maybe

the pistons/rings are dry??? Also I did not have the pipes installed yet either??? Maybe

I'm doing something wrong. I did put the tank back on, turned on the fuel and held it

WOT and kicked the piss out of it???

 

I got pissed off and called it a night after I saw this??? I did not do all this crap for a

stock compression bike...

 

Any thoughts???

 

I sortof had The same problem, I bought my shee blown up, brother-in-law put it back together for me, I dont live in the states, but when I was in the states this summer The only way to start mine was to eather pull it with another quad, or squirt a little fuel in the carbs and than when it even did start it wouldnt idle and ran like crap, well after blowing it up and taking the maching apart and calling Pro Design, the guy told me that with 22cc domes you should run 93 octain, 21-20cc domes run a 50/50 mixture of race fuel/93octain but no less than 105 octain, anything less than 20cc domes run straigh race fuel. well after I put it back together, it took 3 kicks the first time to get it running, and everytime after that it was a 1/2 kick, it even idles perfect. So what I would do if I were you is drain all the fuel out of your tank, get a gallon of race fuel, mix it up, dump it in and see if that makes a difference at all.

[mdhc500]

It was the gauge... New gauge shows the Left Cylinder at 151psi and the Right Cylinder at 149psi...

 

Thanks for the input...