I have an XVS 125 Dragstar which blew it's piston and rings at the beginning of December, replaced the piston and rings with brand new ones, but I have no compression on the front cylinder (this is the one that blew). Help!!!!!! I'm one step away from torching the sodding thing!

Did you check the bore before you replaced piston? What about the valve clearances/condition?

Sent from my E6553 using Tapatalk

Yup, I've had the engine apart twice. Got any white phosphorous? I'm just losing the will to live with it. Looks like third time is the charm 

How strange. What about the head gasket?

Sent from my E6553 using Tapatalk

Did you check the piston and rings inside the bore before bolting it back together to make sure it was correct? Sounds silly but had it before on an old Mercades, the rings where faulty (crap quality I thought) so they wasn't creating a solid seal ! 

I'm assuming you've had a compression tester on it? 

Valves, 

9 minutes ago, blackhat250 said:

Valves, 

I did this years ago on my auld Bonnie. Had the head off (fekkin push rod seals as usual) and when I put it together again the tappets seemed a wee bit noisy so when I retorqued the head after 10 miles I never bothered to reset the the valve clearances thinking the retorque would set them correctly. When I tried to start it it had very little compression, although it did start but ran like shit. Eventually ground to a halt. Once recovered to home I checked the valve clearances and I could actually see the valves closing as I loosened them off. Once set correctly the compression was back to normal 

Yup  it's valves, one valve had snapped. Taking my spare cylinder head to a garage to get the valves from one fitted in the other. I have a head which has buggered studs for the exhaust, which are f***ed and can't be removed. Yes I know drill em and pull em. I can't it's f***ed.

How bad are they cos I couldn't get original nuts back on and used some normal m6 nuts and went on and stayed on ok, so far