Pressure on flywheel side?

[1601pete]

Afternoon all.

Got a low down running issue on my bike. Seems a bit lumpy on tick over and misses when blipping the throttle. Did the valve clearances as they were due and removed carbs and cleaned all jets etc and replaced needle jets (didn’t look that worn). I didn’t change needle although they had some discolouration on one side but were still smooth etc.

Anyway got it all together and it still lumpy down low.

Whilst messing about with it for some reason I decided to take the centre cap off on the flywheel cover casing whilst it was running on tickover. There was a significant amount of air pressure emitting from the centre hole? Is this normal. Got me wondering and then I noticed a film of oil on the centre nut and in and around the inside of the casing?

Any guidance would be appreciated

Thanks

[cobbadiggabuddyblooo]

Does it use oil or do you find not long after an oil change the oil has changed colour to a dark or black look from blow by?

[1601pete]

Don’t think it uses an excessive amount of oil. Just changed the oil but I’m a bit reluctant to ride it based on poor running so will be difficult to see if oil changes colour quickly.

Thanks for the reply btw. Should there be oil residue in the flywheel casing?

[cobbadiggabuddyblooo]

Yes, some have experimented by running an extra crankcase breather from the alternator case via one of the bungs so I wouldn’t stress too much on the pressure.
More than likely your problem would be carby related either a balance issue or idle/pilot curcuit and mixture screw.
Does the bike smell rich or fuelly when idling?
When placing the needle into the slide, it needs to locate and if either the original D shaped plastic spacer does seat correctly into the slide.
If an aftermarket fully curcular spacer is used under the clip this will create issues too with the needle not sitting concentric as I pointed out only last week on aftermarket kits.

[1601pete]

Thanks

Doesn’t smell rich when idling. The problem seems intermittent. Never had the carbs apart in 10 years and had the problem just start. Stripped them and cleaned everything and the problem is still there and is intermittent. I can start it sometimes, It will idle and I blip the throttle and it’s fine. Then I could come back to it 30 mins later. It will start miss and pop and backfire down low. But once above 3 rpm ish it clears. I can shit the throttle and it then dies.

[OzzieDave]

Have you checked for air leaks in the air box, around the connectors which go onto the carbies. The connectors may not be sealing completely either, I had to put some fabric duct tape on the inlets to seal the connectors, while sealing the air box with Selleys engineering silicon sealant, as it will stick to ABS.

[1601pete]

Seems like the right hand cylinder has the issue. I’ve recleaned the pilot circuit on that side. Pulled both carb / inlets rubbers and checked for cracks / splits. Both seem ok. I’ve shorten the spacers between the rubbers clamps to help them close a little bit more and seal. I’ve siliconed the air box rubbers on the underside of the air box. Just waiting for it to dry before I try it again

[dicky]

The air-cut valve cover may be cracked.
You can get replacements for them from Kedo.

[cobbadiggabuddyblooo]

Good point Dicky.
They are the 2 white plastic discs on the side of the carburettors.
They cut the air supply to the primary curcuit on over run to stop any popping and banging through the exhaust.

[1601pete]

I’ve visually checked these and they look ok. Should I remove completely to check? The inner one looks fun

[1601pete]

Started it this morning and all seems ok now, so was either an air leak or dirty pilot circuit on the RH cylinder

Thanks for all your advice