Pilot mixture screws- to do or not to do

Information and questions on GL1200 Goldwings (1984-1987)
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Posts: 4
Joined: Thu Sep 28, 2017 8:17 pm
Location: Fenelon Falls, Ontario, Canada
Motorcycle: 1986 GL1200A Aspencade, 1970 BSA Lightning, 1972 Honda CB350, 1969 Yamaha DT-1, 1982 Yamaha XJ650RJ Seca, 1950 Velocette LE

Pilot mixture screws- to do or not to do

Post by EngFarmer »

I am looking for some advice on whether to remove the capped pilot mixture screws in doing a carb overhaul to try to remedy a hard cold start problem that I believe is related to the enrichment valve system. The bike starts fine when the weather is warm (60's F and up) but only fires on one cylinder when it needs the choke (enrichment). With increasing revs the other cylinders start firing and with some extra throttle the engine warms up without incident. Aside from starting I have not noticed any other problems with the bikes performance.
This bike, a 1986 GL1200A (without the reed box on the intake manifold), had sat for 7 years without running and, with the carbs not having been drained they were pretty gummed up.....enrichment valves and float valves stuck, float bowls with green crud etc. To get the bike running I did as much carb cleaning as I could without taking the carbs off the manifold.....I was reluctant to do too much disassembly due to the apparent complexity of the carb/manifold assembly. After the cleanup I used SeaFoam in the fuel in the hope that it might loosen any areas that I had not been able to clean. The carb set was vacuum balanced and, except for the hard starting, the engine runs very well. I subsequently replaced the air cut off valve thinking that this might be part of the problem.
Now I am doing a more thorough carb teardown with a Randakks kit on order, and an ultrasonic cleaning bath available to try to assure the enrichment passages are clean. Previously I did not actually remove the enrichment valves because this involved disassembly of the linkages.
My dilemma is whether to remove the sealing caps and the pilot mixture screws to do a thorough job, or leave well enough alone given the possibility of the screws being truly stuck and having to boil the carb bodies to try to get them loose (as per the guidance in Howard Halasz's manual). I am generally inclined to the "if it ain't broke, don't fix it" philosophy but would appreciate any insight or experience that others might have in doing this job.
Thanks in advance!

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Location: Euless, Texas
Motorcycle: 1986 GL1200A original owner

Re: Pilot mixture screws- to do or not to do

Post by julimike54 »

I had my carbs done by a professional and he removed and re-set them along with floats and everything inside. I've had no issues since it was done, about 4 years ago.
Riding anything is a good day!
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