1983 R80ST Choke Trouble

[PhantomII]

:dunnoMy 1983 R80ST will run only when fully choked. After warmup, when I move the choke lever to the "off" position, the engine dies. Any thoughts as to what may be the problem? Thanks very much!

[henzilla]

Welcome PhantomII


I am sure a mod will move your question in a bit over to the Technical Forums under Airheads where a wealth of ideas and opinions will help with your issue


But welcome aboard again and tell us a bit about you and the bike...

[PhantomII]

Thanks for the warm welcome, Steve! I see you are a fellow Texan! I'm in Houston and the R80 is my first bike. Unfortunately, I don't have a lot of time to ride it. The bike has about 33K miles on it and this choke issue has just developed recently. Prior to that, it ran great. The previous owner had alot of work done on the bike prior to selling it to me. Unfortunately (again!), I am not very mechanically inclined, so I usually seek advice when it come to this sort of thing!

[PGlaves]

On that bike the "chokes" are actually separate fuel circuits that are enricheners. Running on the enricheners and dying without them tells me the carb's normal fuel circuits are clogged.

These are actually two or three circuits in each carb with the idle jets being one circuit and the needle and main jets being the other (or the other 2).

It sounds to me like something gummed up the main fuel circuits. I would start by pulling the fuel bowls, and then maybe a total carb cleaning.

If it only dies when at idle or slow RPM, then it might be only the idle jets but if it bogs without enrichment above 1500 rpm or so then the needle jets are probably involved too.

This is a "logical" diagnosis of a problem I haven't seen in years, but it sounds like the most likely. Look for globs of gell like varnish in the fuel and passages.

[tghsmith]

check to make sure the PO did not reverse the the choke shafts if he worked on the carbs as part of the work done before selling, the shaft ends on the carbs have a small punch mark to show direction . this mark should be located toward the bump in the casting of the plate that is held on by the four screws, also check the four screws for tightness....

[20774]

It's not clear in the context of your follow up post when the PO did the work and when the bike ran great before the current situation presented itself. Has the bike ever run good for you? If so, and the problem just presented itself, then it's likely something has plugged some holes in the carb, leading to a carb overhaul as Paul mentioned. If it's never run well for you and the PO did the work just prior to you getting the bike, then I would certainly check that the carb work was performed properly, especially the setting of the choke levers as well as how the levers are actuated. Make sure they're moving the proper directions and up against the stops when completely off.

[Manfred]

Phantom II,

Welcome, from another Houston rider! I'm between Willowbrook Mall and Tomball.

I'm also having what I think is a choke problem - only related to starting. My bike doesn't like to start with the choke engaged and it takes too long cranking without the choke to get started. All my cables are working fine - I am taking the carbs apart this week during my time off.

Drop me a PM - perhaps we can help one another.

[BubbaZanetti]

welcome from another ST owner (there aren't a whole lot of us, haha)

above suggestions sound good. i had an idle passageway with a bit of a clog, luckily these things aren't too difficult to dismantle a bit and clean.

[monsondm]

Take a look at the carb end of your cables for the choke. See if one is possibly broke and not releasing from the choke position. If one carb stayed choked, in theory the bike could die at idle. It is an easy check w/o any disassembly.

Dale Monson, Big Rapids, MI

[PhantomII]

Thanks to all for the good tips & suggestions. Looks like I have stumbled into a whole new bunch of friends and fellow BMW enthusiasts! I know what I'll be doing this weekend!

[jforgo]

Replace the fuel lines. The ethanol eats at them. Especially the pretty lines with the braided cloth covering. What the ethanol eats becomes goo in your carbs.
I found some gray stuff locally (Tridon?) which seems much less affected by the ethanol.

[donbmw]

Clean the carbs

[amiles]

Get a copy of the Bing Agency Carb manual. You will NOT regret it.

[wecm31]

If you are tackling a carb rebuild... in addition to:

"Get a copy of the Bing Agency Carb manual. You will NOT regret it."

For a mere ~$30, Bing will provide a DVD to walk you through it as well. Not really necessary, but depending on how much experience you have with carbs, its a step by step visual instruction. Makes the job that much easier. The real test of your domestic situation can be when you propose to run the carb bodies throught the dishwasher, just to clean em up that extra bit. Proposal rejected in my abode:fight

Not to hijack the thread too much...consensus on the throttle shaft oring? I sprayed with carb cleaner while still running and found no change, so I chickened out and avoided the removal of the throttle plate and peened screws. thoughts?

[kbasa]

If you are tackling a carb rebuild... in addition to:

"Get a copy of the Bing Agency Carb manual. You will NOT regret it."

For a mere ~$30, Bing will provide a DVD to walk you through it as well. Not really necessary, but depending on how much experience you have with carbs, its a step by step visual instruction. Makes the job that much easier. The real test of your domestic situation can be when you propose to run the carb bodies throught the dishwasher, just to clean em up that extra bit. Proposal rejected in my abode:fight

What he said and especially what Paul said.

Before you take them apart, make note of the number of turns, etc. on any adjustment screws you're removing. Screw them all the way in and count the turns until they lightly seat. Use these settings as a base when you put it all back together.



Not to hijack the thread too much...consensus on the throttle shaft oring? I sprayed with carb cleaner while still running and found no change, so I chickened out and avoided the removal of the throttle plate and peened screws. thoughts?

It's not hard to take them apart, just mark the inside with a Sharpie pen. Draw a little mark that marks the plate's inside facing surface. Getting the Oring on can be kind of a pain, so get your patience on.