Middle pot running rich

Well, last night I checked the chokes are seating and moved the suspect float needle from the middle to the right hand carb but the issue remains with the middle pot, so I think I have done all I can to eliminate the carbs as being the cause.

I took it for a quick spin round the block and the popping and banging seems worse if anything, but it was a short ride. I measure the downpipe temperature to determine which pot is playing up and the middle one has always been significantly cooler that the other two. After last nights short run it was 100?C cooler, which is much the same as it's always been. (150?C compared with 250)

Pretty sure the middle pot is misfiring due to something on the ignition side now so I will have a search on here and start a new thread on that subject if I can't find what I am after.
 
As John said. Popping on over-run is indicative of a lean mixture.
Check for cracks in the intake sleeve or the plastic insulator and O-rings between the intake spigot and the head.
While you're at it, check that the exhaust gasket is sealing OK. There's sometimes a tell-tale sooty mark between the head and clamp ring if it's leaking, but you may have to take the gasket out and have a closer look to be sure. Put in a new gasket anyway.

Also check compression and valve clearances, just to eliminate any possible mechanical cause.

PS: Are the carbs synchronised?
 
Ok, Now I am sucked in too.
A motor needs fuel, air, compression and ignition to run, right?
If the centre header is cold, it isn't burning fuel.
You say the manifold is intact, the choke not on, the float correct.
I assume the throttle slide is connected to the throttle rack and rising giving air.
That means there is poor ignition or poor compression.
Hope this helps.
Russ
 
Yogi said:
..and for those that find it hard to measure the float height accurately, here is a little tool you can buy that fits most carbies...  you can use verniers to measure, but this can make it a bit easier.

http://www.ebay.com/itm/Carburetor-Carb-Float-Level-Gauge-Motorcycle-Tool-fit-any-motorbike-/221394726969?pt=Motorcycles_Parts_Accessories&hash=item338c277039&vxp=mtr

Yogi
Click to expand...

Just set up the float heights on my Mirage using this little device: wow, what a difference it's made! So good to be able to know the heights are spot on rather than simply 'ish'. Followed it up with balancing the carbs and the bike is transformed once again into a smooth, responsive yet snarling beast!

BIG thanks to Yogi for this pointer: dunno how I ever managed without it..

AndyW
 
Hi , if you have 100c difference you have a major problem with combustion ,the middle should run the same if not a little higher. There is a theory that the middle needs to run a little on the rice sde due to shit fuel we have nowadays. I always run mine slightly rice on the middle seems to stop the need to shim all time. Lean is very bad unless you are tight fisted then you'll think your quids in.That's my findings anyway
Good luck
 
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