Finally Checked Compression

[AdrenalineJunky]

I finally got around to checking compression. The right side is 130psi and the left is 125. Would this call for a rebuild up top? What is the factory specs for a fresh topend?

Can't get the bike to run like I want. It is like 70 degrees out and I go out to start it and have to kick it forever and still can't get the pilot circuit tuned right so it don't sputter from 0 throttle.

[jbooker82]

Wrong pilot jet will make for hard starting. Bran new stock top end at sea level is supose to be 130/130. I would say your compression is fine if you dont have a cool head.

 

josh

[AdrenalineJunky]

I just dropped down to a 25 pilot. I do have a Pro Design cool head but don't know what domes. I'm assuming 20's. I did notice tonight there is a small crack in one of the intake boots coming off the air box going to carb. What should compression be for cool head?

[AdrenalineJunky]

NOTE: I did this check after bike was warmed up and 1 plug was in the other cylinder while doing check.

[jbooker82]

Well it depends on what your elevation is. Ethier way with 130 psi of compression it should start.

[AdrenalineJunky]

It does start but not like it should. I am at about 700asl. Looking on a chart I found compression should be higher w/ a cool head. So a top end would be feasible. I should be between 156 and 169 w/ a 20cc dome according to chart. Like I said it was very warm out today and it takes forever for that initial startup. Once it's warmed up its fine.

Been working forever it seems to get it tuned.

[AdrenalineJunky]

HOLY SHIT!!!!!!!!! I just now pulled the head and it has 18cc domes........................... WOW that's a shocker. So that means getting a reading of 125 and 130 psi that my rings are pretty much shot???? Wonder why it isn't smoking more if that's the case. Means it should probably be getting race fuel with new topend cuz compression is gonna go up a pretty good bit a? Correct me if i'm wrong. Bottoms of domes are pretty black.

[AdrenalineJunky]

Piston is 513MO6550 which I found out to be Wiseco. Looks like she definitely needs some rings a? Will I need to get cylinder honed or can I just put new rings in?

[AdrenalineJunky]

Do I need to get all new O rings for the cool head? Don't think there is anyone local I trust to set the pistons up right so i'll probably just send them out to one of the sponsors and order pistons from them and have them set the gap and all that good stuff.

[jbooker82]

Do I need to get all new O rings for the cool head? Don't think there is anyone local I trust to set the pistons up right so i'll probably just send them out to one of the sponsors and order pistons from them and have them set the gap and all that good stuff.

 

Yea that is going to be your best bet. You might need a bore or you might not. It is a good thing you pull the head and I would say a top end is in order. Thats why you never know. Make sure you run straight race fuel, and do a compression check after you break the top end in.

 

Record when you did it and how much it was. That way you have a base line and time line for future referances.

 

josh

[bansheesandrider]

NOTE: I did this check after bike was warmed up and 1 plug was in the other cylinder while doing check.

When you do a compression check, you should have both plugs out of the motor and hold the throttle wide open. Kick it until the gauge quits climbing. Also use a gauge that does not use an adapter to screw into the motor and it should have a check valve right at the end where it goes in the motor. Adapters and the check valve being anywhere else will give a false low reading.

[AdrenalineJunky]

Well I am not sure the type of gauge I have but it has the pressure relief up at the gauge. But I just checked the ring gap on one of the rings and it is past .025 (far as my feelers go). Looked in book and said service limit is .020. Looks like I will be running race fuel when I get it back together. I am doing some thorough cleaning and might paint frame. What is good to get the surface rust off pipes? Also what's good to clean the carbon out of the domes? I know Mother's takes alot of stuff off. I just noticed my cylinders have been polished. Never even realized it. Should look good when I get it back together.

[Coupelx]

Well I am not sure the type of gauge I have but it has the pressure relief up at the gauge. But I just checked the ring gap on one of the rings and it is past .025 (far as my feelers go). Looked in book and said service limit is .020. Looks like I will be running race fuel when I get it back together. I am doing some thorough cleaning and might paint frame. What is good to get the surface rust off pipes? Also what's good to clean the carbon out of the domes? I know Mother's takes alot of stuff off. I just noticed my cylinders have been polished. Never even realized it. Should look good when I get it back together.

soak the domes in gas. it probably works the best for getting the oily 2 stroke skank off stuff.

[AdrenalineJunky]

Makes sense. Well I decided i'm gonna pull the motor and paint the frame and clean it up real good. Gonna take my time since it'll be my first Banshee project. Gonna get all the parts I need as I go and can afford at the moment. Will try to get some pics as I go to document.

[AdrenalineJunky]

WOW keeps getting better and better. I'm pulling the motor apart and forgot about having to disconnect the stator? I pull the cover and I see an adjustable timing plate. I'm like sweet. I look at the timing and according where the mark you go by at the split between the cases? Well if that's it then it's +8. If it's the case mark above that it's +11. WTF was someone trying to do? God i'm glad I tore this thing apart. Dumb question though. Do I need to pull the flywheel and such to disconnect the stator to remove the engine? If so that sucks cuz it's the last thing I have to do, thought I was gonna get to pull it out. I don't have a flywheel puller.