Hi

I have a 1600 xflow on bike carbs which I got from a guy who had it in a running car. I have managed to install it into my Locost and fire it up. But it is backfiring thru the carbs badly. And just not running right its not responding well to throttle either. What could be causing this?

Here is a video of the engine View My Video

Any help or advice would be much appreciated.

Check how tight the tappets are on #1, backfiring through that carb like it is (you can see it) could be a tight, sticky or burnt valve

Odds are it is running far too weak, however before you touch the carbs check the valve clearances and ignition timing contact points gap .

running to weak on idle,
are the carbs balanced?
also what carbs are they?
i carnt watch your vid as my laptop keeps crashing.

yep start with simple checks
Valve clearances, and timing
air leaks (inlet manifold, vac pipes, and carb)

If all those check out it could be the idle mixture twiddly has been twiddled!
or carbs need a clean (blocked jets or sticky fuel valve)

Regards
Rob

Just had another look at the vid, and carb number 1 looks like its slightly facing downwards compared to the rest?
(if it was at a slight downwards angle compared to the others it would suggest it has moved and maybe not sealing round the top and would be forcing the butterfly to a different opening)
----could be an optical illision in which case ignore :-)

[Edited on 31/8/09 by robocog]

Check also that the slide is lifting as you rev the engine, if not check the condition and seal on the diaphragm.

I thought it was running too rich because it was spitting fuel out of the carbs. Also before I was running a 1300 on webber 32 dgv. So I bought a sytec proflow fuel pressure regulator.

The carbs are from a Honda fireblade 900. The guy told me that they have been re-jettted and balanced and the engine was running fine in his escort.

I will check the valve clearance and timing with a timing gun.