what can happen to a cylinder?

[jas250r]

I just got done with a compression check on my la sleeve 300 and i'am only getting 135 psi. cold motor just bored over. checked the gage for air leaks, weren't any. talked to a few people, the only thing i can think of is, when the guy i had was boring it he had to go from 40 over to 60 because he said there was a flaw in the cylinder at 50 over and when he went to 60 over it was all cleaned up. what are your opinions? my gauge is a cheap but new one from harbor freight. have done it wot and not wot have kicked over at least 15 times, ever test. runs good has been ported for mid and top, going to try to borrow a better gauge like snap on, etc.:confused:

get a guage you can be sure of and let us know....

[MR.BIG]

Wow you should be pushing 185# plus!

[250R Baja Rider]

That reading seems too low.

Did you use the right piston?
The 86 piston is different from the 87-89.

A guy once used the wrong piston with the spacer plate.
The wrong piston was about 5mm from reaching the top of the cylinder, therefore reducing the compression.

Remove the head and turn the motor by hand. The piston should be almost flat with the top of the cylinder.

[baker250r]

Originally posted by 250R Baja Rider

A guy once used the wrong piston with the spacer plate.
The wrong piston was about 5mm from reaching the top of the cylinder, therefore reducing the compression.



That guy was me! :D

[250R Baja Rider]

I guess you are not alone.

I've heard other people have done it too.
S&^* happens!!!

[jas250r]

pulled the head and gasket was leaking again, (the only problem that i've had with this 300)I'am thinking that one of the studs or two are being pulled out? I lapped the cylinder on a certified granet block at work less that a month ago. The cylinder still looks perfectly flat, checked with a straight edge with the studs in for now and can't fit a feeler gauge between. Now i was thinking about running a bottoming out tap in each stud hole and seeing if there is more depth so i can run a longer stud, and maybe use blue loctite. Everytime i have torqed the head done i have never notice that a head nut is not tightening (keeps turning) But maybe somone has been down this road before? The friend i bought this from a few years ago said with a stock head not recambered for the bigger piston i should be at least 185, and with the paul turner power head with the 22cc dome he said he remembered it being around 210?:confused:

[baker250r]

u can also helix coil the studs.....

[methyman]

The 300 resleeved cylinder has a bad problem with sealing the head. You will need to get a head with a o-ring in it . Give this guy a call. Kelsey is a great guy to deal with real knowledgeable.

RK Tek
1245 W. Industrial Park Rd.
Preston, ID 8326
208-852-3221

[jas250r]

I tried longer studs that go all the way down to the bottom of the hole. tried it with the duncan head with the old fiber head gasket. only got to 120. giving up for now have a trip planned for the sand dunes in two weeks, going to have the stock cylinder checked, either hone it or bore it, and get the piston to match, so i will be running a stock cylinder with a 38 carb and a fmf rev pipe with v-force reeds, and spacer