3AJ update, any ideas?
 

The last few attempts to start the bike have seen it backfire hard enough to blow the carbs off their rubbers!

It started and ran fine yesteday (under it's own battery power) but when we went to start it again, it wouldnt play ball. Valve timing? the chain was zip tied to the sprocket before the work started, and hasnt been moved. Could having a much less worn cam and head mean the valve timing should be re done? Its not getting the best spark, but getting sparks and petrol.

Any Ideas?

Thanks

Pete

Backfiring.
 

I had an XL500 not so long ago, after reboring and rebuilding I had the same problem. Sounded a bit like a shotgun going off. We diagnosed it in the end as a sticking valve because it was an intermittent fault. Head off, new valves, back together and problem solved.
Possibly the same problem for you?

Good luck

Thanks or that we'll have a look at the valves. Getting restless to get back on my XT!

Pete

Backfiring
 

Oh, forgot to mention that we changed the guides and seals at the same time for good measure. Might as well while you are in there and sometimes the guides can be contributing to the problem.