More Carb Advice Needed

[Guzzi07]

Hi everyone:

 

I am still playing with the Keihin FCR carbs on my 1995 Sport 1100, and would like to describe the issues I am still having and any opinions whether it is due to a too rich / lean condition. I think I know what adjustment I should make but want a second opinion.

 

The issues are:

 

1. When the bike gets really hot in traffic (it is summer now in Aust) it develops a big flat spot off idle when the throttle is openned a little harder than normal, it misses / bogs down for a few seconds before taking off. This can be a little hairy when lane cutting in traffic!

2. The idle speed increases as the bike gets hotter. It goes from 1000 / 1100 up to 1500RPM.

3. On a trailing throttle just off idle, it misses sometimes.

 

Thanks,

 

Jason

[gstallons]

What do the spark plugs look like ? If they are super clean , you need a larger pilot jet ..... I don't know if Kehin #s go up in size vis-a-vis #s or not ?

[68C]

Hot air is less dense than cold air.  There is less oxygen in this less dense air. To maintain the correct fuel/air ratio you would need to reduce the amount of fuel. You will need smaller jets or lower the needle. Carbs with accelerator pumps can give problems in hot weather.

[luhbo]

Basically that's exactly my experience, too. In most cases the bikes are running too rich right from the factory, aftermarket exhausts or airbox mods very often make things even worse. Just try it out, go back to the OEM jet sizes or, in your case, try smaller ones, you definitely won't do any harm to your engine as long as you don't go to Daytona

Hubert