misfire only running on centre pot

[beefos]

Still not running right after the rebuild.
starts easily now but misfiring.
Took the lt lead off coil 2 and the engine stopped.
lt lead off coil 1 and still runs same....pot 1 not working.
But coil 3 the same and surprisingly with the lt lead off coil 1 and 3 at the same time it runs the same with the original misfire.   So it seems it is only running on pot 2...

swapped the coils on 2 and 3 and the misfire stays with the pot so not the coil.

fuel comes out of the bowls on both carbs 1 and 3 when I unscrew the drain plug so it seems fuel is getting though.

Reading through the forum I found lt coil leads should be red on the left, they weren't all so corrected that. Still misfiring.

Any suggestions what to try next?

[Bixxer Bob]

Is the inlet of 1 and 3 wet?  ie getting fuel??  And is are the plugs wet?  I'm assuming you have sparks, so I'm thinking valve clearance but  not knowing what's already been done that's just a wild guess.   

[beefos]

The plugs in 1 and 3 were fairly dry hence why I tried the float bowl to see if fuel was getting into the carbs.
There was fuel in the carbs but maybe not enough? I don't remember any fuel filter between the carbs so wondering if I missed that and they are allowing some but not enough fuel through.
I have done the valve clearances so unless I did something wrong they should be ok.
I'm amazed how easy it starts and runs on only one pot!

[JayDub]

have you checked the inlet rubbers for cracks/splits? or the carb diaphragms.
fuel filters are (1) fuel tap, inside the tank. (2) inside the t-piece between carbs 2 & 3, most people bin them and fit an inline filter.

[beefos]

The inlet rubbers look good. I cleaned the 2 filters in the tank, they look a bit flimsy and the reserve filter was not intact but was letting fuel through ok.  Didn't notice the filters between the carbs so maybe I will have to take the carbs off and check. The inline filter sounds a good idea. I checked the diaphragm on carb 3 and it looks good.

[beefos]

Carbs are off. The cone filter at the inlet had some crud in it but not a lot.
noticed that on carb 2, the good one, the diaphragm seems stuck to the carb. Gently pulling does not remove it like the other 2 carbs...
I did notice the float chamber gaskets are old and compressed. Carb 2 is the best of the 3 so maybe why it was the only one working? I'll order some new gaskets and try again.

[JayDub]

Carbs are off. The cone filter at the inlet had some crud in it but not a lot.
noticed that on carb 2, the good one, the diaphragm seems stuck to the carb. Gently pulling does not remove it like the other 2 carbs...
I did notice the float chamber gaskets are old and compressed. Carb 2 is the best of the 3 so maybe why it was the only one working? I'll order some new gaskets and try again.

(Assuming they're Mikunis) You would be better getting the full 'O' ring kit too, it will save any anguish later as the ones in there now have probably hardened.

[beefos]

They are Mikuni.

I peeled off the diapraghm of carb 2 and it was stuck down with some silicone. I can't see any mention of using this in the manual although this was the carb that worked so I'm wondering if I should use some?

I also noticed the o ring at the vacuum nozzle was missing on carb 3 so I will be replacing the o rings as well. 

[threepot]

I would do s Jaydub recommends,and put a new set of o rings in whilst the carbs are off? Think they're available on eBay for about £13 per carb?

[beefos]

Carbs all done with new o rings and seals.

fired the bike up and still the same 

I'm still amazed at how well it runs on only one pot! But pulling off the LT wires from the coils 1 and 3 it continues running the same so they must be missing.

left it running to get up to temperature and no better so leaving it to cool then I'll take out the plugs.

[threepot]

Try a plug in each cap..up against the engine to see if it sparks when you turn it over? Remove all the plugs so the engine spins quicker.

[JayDub]

 ... check the coils, and if that's not the issue then it maybe time to re-check the valve clearances.  Its uncommon but another possibility is the ECU.

[beefos]

I did try swapping the coils and it stays with the pot rather than the coil so I think the electrics are ok.
Just took the plugs out and tried it anyway and all spark ok.
number 3 plug was wet but not petrol or at least I couldn't smell petrol on it.
The rebuild was sprag so didn't take the head off, although I did do the valve clearances. Some were a bit tight so I changed a few shims but only minor adjustments.

[threepot]

Did you take cams out? Just thinking maybe timing out? Or re check gaps?

[beefos]

I didn't take the cams out. I kept a note of the new gaps and shims and they were at top limit when finished, so .15mm for the inlets. Is it better to have them at bottom limit of .10mm?
I have shims so could change them. The shims I have are steps of .05 so the whole range in one shim!