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Long Engine Warm Up ‘55-‘69

chrishea
Posts: 68
Joined: Tue Aug 04, 2020 12:54 pm
Been thanked: 3 times

Re: Long Engine Warm Up ‘55-‘69

Post by chrishea »

First I have to ask what is meant by cold blooded? Hard starting? (How is your technique?) Failure to idle after initial startup on a colder day? (Probably normal.) Failure to idle after driving 2000 feet and stopping at a stop sign? (Probably normal.) “Hesitant/flat spot” when driving off (less than a mile)? (Probably normal.) “Popping/bucking” while accelerating? (Abnormal - overly lean - or potentially last season’s gasoline.)

First I think we need to remember that these bikes aren’t fuel injected. There will need to be interaction to keep the bike running after a cold initial startup. I would consider holding the throttle a little open 1/2 mile down the road at a stop sign as being normal.

Upon initial ride off when cold, there is some hesitation/flat spot feeling on my /2 and later Airheads, it’s the nature of any carbureted vehicle, but that quickly clears as the rpms rise and the vehicle warms up. I ride my Airheads year round and do take my /2 out for a New Years Day run it is dry.

If you have a bike that always seems hard starting or real slow in “warming up”, I would start looking at: How old is the gas? Do you have a clogged idle jet? Is your coil weak? Is the magneto rotor aligned properly? Are the nuts holding carburetors to the heads tight? Are the carburetor flanges warped? Are the gaskets between the heads and carbs good? Is the float level correct? Is there some other air leak causing a lean condition? What about a mouse nest in the air cleaner? There’s other things to look at, I’ve had the first seven of those nine listed above happen to me (no other air leaks and no mice!). The clogged idle jet was the hardest to figure out - the bike wouldn’t start reliably. I could see through the clogged jet! It can’t be clogged if I can see through it, right? Wrong. A clear piece of varnish popped out. Since my idle jet clogged up I’ve been more diligent in draining the fuel from the carburetors if I know the bike will sit for more than 2 to 3 weeks.

Check those items systemically. You may have more than one issue. Don’t take something too far apart because you may not know what you’ve changed. Try some fresh gasoline first.

My two cents.
Chris
Seattle

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