finally rebuilt gp800 over a year. just put engine back in. last time it had low compression on one cylinder due to pin that holds rings in place falling out then ring caught on power valve flap and ripped rings off rooting the whole bore and piston. got another single engine block, gave it slight hone, new piston and rings, gaskets etc. put all back together and now has 85 psi on replaced cylinder. is it possible that if the power valves between each cylinders are not in sync, that it could be changing static compression in the engine??? cheers
yeah you would get different compression readings if the power valve is open or closed......not sure how differnt.........could you manually open/ close them for testing??
The rings don't seal against the power valve, so it shouldn't make much difference to the static compression. You need to use a diamond tipped hone on nikasil cylinders so if you used a stone one you probably just wore down the hone a bit. were there any scores on the bore at all? 85psi is really low
I just checked both cylinders compression again with putting power valves fully extended and closed/ 5 psi difference between the 2 cylinders which means there is no difference between them. could reed valves effect the compression if one is faulty and it is just chance that the one on the cylinder i replaced is rooted????
i think its fully rooted. put oil in cylinder and did compression test and it went from 85psi to 115psi. i guess that would indicate the rings ant tight enough on piston...?
[i think its fully rooted. 3D really. The only thing wearth in 3 D is the latest porn. :lol: . Stupid question have you run it in yet. Compresion my go up if you give a good run. 800 power valve OHH yer.
it was at a old feller friend of mine who was a engine re builder for 50 years. no not run it in yet... thought i would compression test it first as was running roughly. nearly gave me a heart attack when compression tested it. should i run it in first?? how could that possibly make compression go up ? i realize that when running in that the different metals expand and contract and shave each other down slightly but could this really be the problem ??
and you may think my 3d is a piece of shit but i have never ever had a problem with it before !! it seems as reliable as my car !
Get it running and then try test with both valves down....then get a splash of gas and a lighter...splash the gas around that 3d and spark up the lighter...should fix all your problems... Ps...tell the russian we all miss him and his retarded posts
i think compression on stock gp800 motor is only like 120psi...is it turning over at a good speed? , got throttle wide open?, etc
If you have a broken reed valve it doesn't show up in a compression test If oil brings it up then its because it is sealing something up. Normally your rings What the compression on the other cylinder
one cylender has 130 psi and the otherreplaced cylnder 85psi - which increases to 115 with a wet compression test. did it on new battery,turning over fast, with WOT. yea i had in my mind the rings ant tight enough but got it done through an old guy i know who is engine re builder for many years and i was there when he measured everything, no need to light the 3d up, its never had a problem before and my insurance company already doesn't like me. The russian rides motor bikes as well now......
i did half the run in process today and compression raised from 85psi to 105psi. hopefull will go to 120psi by end of run in process. quiet interesting that it sorts its self out...
