R75/5 choke stopped working

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MikeGeee
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R75/5 choke stopped working

Post by MikeGeee » Mon Feb 26, 2018 2:04 pm

Hey all,

So my R75/5 used to start right up when it choked (half or full), but now it will not. It will start up without the choke (thanks, probably, to the sunny Southern California weather), but it will die once I engage the choke (cold or warm). I can keep it alive by giving it some gas, but it's not supposed to work like that.

It used to work perfectly. Any suggestions as to what could be the problem/remedy?

I cleaned out the float bowls, including the little hole that I was told creates many gas-related problems in these bike. No difference.

Look forward to any answers.

Thanks a bunch!
1972 BMW R75/5 Toaster
1976 Honda CB200t
1948 Harley Davidson WL45

barryh
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Re: R75/5 choke stopped working

Post by barryh » Mon Feb 26, 2018 4:25 pm

There is not much that can go wrong with the enricher mechanism if it's correctly adjusted on the cables and hasn't been disassembled. The jet in the bottom of the float bowl is one but you have cleaned that. The other thing is the gasket on the enricher covers that can suck air in. New gaskets and lapping the covers flat will cure that plus new O rings on the shafts.
barry
Cheshire
England

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MikeGeee
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Re: R75/5 choke stopped working

Post by MikeGeee » Mon Feb 26, 2018 6:48 pm

Thanks for the response, but I don't understand where the enricher cover is. Can you explain?
1972 BMW R75/5 Toaster
1976 Honda CB200t
1948 Harley Davidson WL45

Rob
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Re: R75/5 choke stopped working

Post by Rob » Mon Feb 26, 2018 7:55 pm

MikeGeee wrote:
Mon Feb 26, 2018 6:48 pm
Thanks for the response, but I don't understand where the enricher cover is. Can you explain?
The enrichner cover is the one with 4 screws in this photo.

Image

source: http://pt-photos.com/carb_page.htm
Rob V

Kurt in S.A.
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Re: R75/5 choke stopped working

Post by Kurt in S.A. » Mon Feb 26, 2018 7:56 pm

Look on the backside of each carb. When you move the choke lever to engage the choke, do you see a small lever move up/down? That's how the enrichener is engaged. It's possible that the steel cable that moves that small lever has loosened up and doesn't move the lever.

Kurt in S.A.

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MikeGeee
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Re: R75/5 choke stopped working

Post by MikeGeee » Mon Feb 26, 2018 9:04 pm

Ahhh, thanks. I haven't taken these carbs off the bike yet, so had no idea what the reverse side looked like.

I don't know if I'll have time to get to it tonight, but I'll post an update when I know more.

Thanks again everyone!
1972 BMW R75/5 Toaster
1976 Honda CB200t
1948 Harley Davidson WL45

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Zombie Master
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Re: R75/5 choke stopped working

Post by Zombie Master » Tue Feb 27, 2018 2:43 am

Clean and lube. that's what we do.
Any and all disclaimers may apply

barryh
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Re: R75/5 choke stopped working

Post by barryh » Tue Feb 27, 2018 4:50 am

Further to whats already been said about checking the levers move and my earlier comments on the cables being correctly adjusted. In the picture you will see two cylindrical protrusions on the enricher covers at 12 o'clock and 6 o'clock. They are the stops so you need to check the lever hits the lower stop with the enricher off (as in the left hand pic) and the top stop with the enricher full on. You can do this by sight/feel without removing the carbs. Just put your finger on the lever and push to see if it's on the stop when it's supposed to be.



Image
barry
Cheshire
England

Wobbly
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Re: R75/5 choke stopped working

Post by Wobbly » Tue Feb 27, 2018 8:23 pm

barryh wrote:
Tue Feb 27, 2018 4:50 am
In the picture you will see two cylindrical protrusions on the enricher covers at 12 o'clock and 6 o'clock. They are the stops so you need to check the lever hits the lower stop with the enricher off (as in the left hand pic) and the top stop with the enricher full on. You can do this by sight/feel without removing the carbs. Just put your finger on the lever and push to see if it's on the stop when it's supposed to be.
Furthermore, the enrichener lever is operated by a solid steel wire (as opposed to a multi-strand type) push-pull cable. The adjustment is made by changing the position of the "barrel" on the cable. The barrel rides in the cylindrical hole in the end of the enrichener control arm, which is visible in the photos. The barrel is NOT soldered in place on the cable end, like the clutch cable. The barrel is provided with a set screw.

If that set screw came loose, then the enrichener lever on the side of the air box might be pushed and pulled all day with very little action resulting at the carburetor end. That's what you need to check.
After 20 years as a professional bike mechanic and 30 years as an engineer I know just enough to be dangerous !

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MikeGeee
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Re: R75/5 choke stopped working

Post by MikeGeee » Thu Mar 01, 2018 2:43 pm

Yeah, i've check that the control arms are swinging, and they are. That would have been a simple fix.

I still haven't had time to take the carbs off, but I will get to is ASAP and report back.
1972 BMW R75/5 Toaster
1976 Honda CB200t
1948 Harley Davidson WL45

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