Street magic TR50 low compression problem. help please

[Psyko]

I have a Tr50 that won't start. I've replaced piston and rings (standard size) and done main gaskets etc. mechanic said it has low compression (90psi). Turns over fine but just won't fire.

I've pulled the engine apart again, cleaned carb, cleaned reed block, new plug, fresh fuel.

I have not looked at any crank seals or anything around that area yet. Anyone else struck this problem? Any suggestions?

Thank you!

[CookMySock]

It has low compression AFTER the rebuild? Did the cylinder need a hone? Did you set the ring gap correctly? Is the piston identical to the old one? Got spark? Tried tipping a bit of fuel down the carb? Tried new spark plug?

Steve

[Spearfish]

Squirt a bit of 2t oil down the plughole and see if the compression goes up at all, it could give you an indication of why the compression is low.

Did you use new gaskets?
Then just go through the list DB suggested.
Heaps of parts are available for these lil bikes.

[Psyko]

Thanks guys for your responses!

It was playing up before i pulled it apart. Would start and idle but any revs would splutter and carry on like an old man. I replaced the piston and rings provided by scootling. the old piston was an ART piston and I broke one of the rings trying to remove it from the piston for cleaning. I couldn't find anyone supplying ART rings so chose to get a whole new P&R from scootling (Meteor brand). The ring gaps apparently don't need adjusting. The bore looks smooth, the piston and rings fit in nicely and move smoothly. I have tried fresh fuel and plugs. Plug has a spark. Scootling are the ones who checked it and said it had low compression.
I haven't tried tipping fuel down the carb yet. The plug gets wet so definatley getting fuel thru! i have also tried Start Ya BAsterd with no success

I have read that crank seals leaking could cause low pressure so Im in the process of pulling out the crank to check them out.