Carb balancing problems

[chunkielad]

I've been getting an occassional 'spit back' from my right carb but once you put your finger on the whole where a meter would go, it stops.

I thought I'd get some meters, balance the carbs and get a new cap for the one that is missing from this hole.

I stuck the meters on and started the bike - the needles went hay wire and then I adjusted the valves on the meters and they settles to a steady 180 mm.Hg on both sides. Then I stopped the bike....

...the left hand needle stayed steady and slowly reduced in value but the right hand one (the one with the popping) dropped suddenly - does this mean I have a seal problem?
____________________
Mark Harrison R.I.P - 26th March 2003.
Remember you always and will ride in your honour.
Big revvs up for Mark!

[Kickstart]

Hi

The cap is VERY important. WIthout it the mixture at idle / low revs on that cylinder will be very lean.

I take it you are using the dial type vacuum gauges. You stop these bouncing round with an adjuster to restrict the "airflow" into the gauges. As such I suspect all that has happened is that you have one adjuster far tighter than the other.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[chunkielad]

What will happen if I haven't had the cap on for months? Could there be any damage?
____________________
Mark Harrison R.I.P - 26th March 2003.
Remember you always and will ride in your honour.
Big revvs up for Mark!

[Kickstart]

Hi

Air going in there has avoided the air filter so potentially some grit will have got in and damaged the bore, but that is probably quite unlikely. The lean mixture will cause that cylinder to run hot, possibly increasing wear, but without any catastrophic failures it is probably OK. It should be a lot easier to start and run far better once it is fixed. However is the cap missing or is the pipe for the vacuum fuel tap missing?

All the best

Keith
____________________
Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[chunkielad]

Just the cap for where the meter goes on - I'm just a bit worried about this 'spitting' noise - the whole right carb judders when it does it!

I thought it was just excess fuel at first and cos there was no cap, the pressure released through the vent.
____________________
Mark Harrison R.I.P - 26th March 2003.
Remember you always and will ride in your honour.
Big revvs up for Mark!

[Kickstart]

Hi

I would not worry about the spitting back. It is possible that the lean mixture has damaged the valve so it is not sealing but I think this is unlikely (especially as it is only going to have a noticeable effect on the idle mixture). Basically at idle the mixture was probably so weak on that cyinder that half the time it did not manage to ignite the mixture.

Where does the fuel tap connect its vacuum line? Just about every bike I have had which has had a vacuum fuel tap has connected it to one of the take off points for the vacuum gauges.

All the best

Keith
____________________
Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[chunkielad]

No that goes to another tap on the left carb.

I hsve made a cap for it and started the bike and no a single problem. Seems to run marginally better at idle - All I have to do now is ride it.

I can't play too much whilst still cos it's air cooled and gets hot quick.
____________________
Mark Harrison R.I.P - 26th March 2003.
Remember you always and will ride in your honour.
Big revvs up for Mark!