Thunderbird 900 Carb Problem

david pratt · May 2, 2023

Hi all, been a while since visited the site..
I have a 99 thunderbird 900 which just had recently recommissioned after several years sitting idile..
Had a company remove and refurb carbs costing over £400..
It still won't start so contacted them their reply was to empty the carbs of fuel after using the bike by turning off fuel tap if not the floats would become stuck !!
Seems a little of hassle everything l use the bike , has anyone had this problem ?

sprintdave · May 3, 2023

Never heard that before. Use E5 petrol with an additive, ie Wynns, Miller's, Lucas and you should be fine. If I recall correctly the T bird 900 doesn't have a vacuum fuel tap so it is best to turn the tap to off position in case the floats jam up and cause fuel to leak into the engine.

wiredgeorge · May 9, 2023

That Thunderbird has Keihin CVK carburetors. If it won't start there can be a number of reasons not having to do with the fuel system; spark, timing, etc. There is no need to drain the carburetors but if you park on side stand, do turn the petcock to OFF as bikes tend to have dripping on the downhill side. If the carburetors are at fault, ensure the float level is set to 14.5mm above the gasket mating line. A general starting point is to set the mixture screws to 1 1/2 turns out from LIGHTLY seated as they control the air/fuel mixture at idle to about 2500 rpm and ensure the slow (pilot) jets are clear. Always use a fuel filter. Last, when starting the bike, keep your hand off the throttle if the choke is engaged (enrichener system). Opening the throttle mucks up starting at th is point.