Z1OwnersClub GB

Whilst delighted with the way the top end rebuild has worked out and the bike seems to run well, I have noticed that the bike can be difficult to start when warm. When cold it starts at first prod with the choke on the first notch, just as I would have expected.

However when warm it will not fire at all in any throttle position unless again the first notch of choke is applied. However once it fires you have to move quickly to close the choke as it tends to bog down, and give it a few revs to keep it alive. Then it settles down into a even idle. I would have thought that once warm just a tickle on the starter and it should just fire up.

Any ideas?

Ummmmmmmmmmm, how long after leaving bike does this happen? If its a few minutes it could be fuel evaporation, assuming carbs are set up Ok, - balanced, clean, etc!

Pigford,
thanks for the reply!

Usually its after a bit of time. Its summer here and its now 18-23celsius, So your evaporation idea could be correct. If I put the petcock on prime that should fill the bowls without cranking the engine excessively to suck the fuel into the carbs?

I suppose there is no real problem in choking it to get it started but any throttle with the choke on usually provokes a cut out, so ita bit of ajuggel to get the choke off and the throttle on, but a few blips of the throttle and it seems right as rain.

Had the plugs out for a look. Look a bit sooty but I understand with this unleaded fuel the old plug looks are no longer relevant? Aso A lot of my running has been in the city and the engine seems to run well.

I think I will start with the simple things first like removing the air filter.

I also have one of those vacuum operated fuel taps. Are these known to give any fault as it will the the 25 year old original parts?

Carbs were thoroughly cleaned but I have not checked the sync yet.

I have the vaccum tap hose connected to the #2 carb. Does it matter which one?

sync the carbs and then see what happens. Have you checked the fuel hieghts?

Rich,
thanks for your reply.

No I have not checked the float heights. I assume one does that by connecting a clear piece of plastic hosing to the to the carb drain?

I looked at the two outer cylinders using a colortune plug. Both these seem rich at idle speed, moving to blue once engine speed builds. Suggests the pilot setting is too rich?