So I got my '80 motobecane running good, all cleaned up and healthy, then put the 15.15 SHA with 15mm intake. I have the 25mph model with stock cylinder. I have a 58 jet. It runs great up to 35 mph or so but won't idle at all, and starts a little hard (lots of pedaling needed). I tried higher jet (61) and it helped the idle a bit but was too rich. Any suggestions? My cable is slack enough to let the slide go down far enough.
did you screw in the idle screw at all? i just put one on a few different moby's and they idle perf! check for air leaks. are you using the air filter?
Yes, I have adjusted the idle screw. I think that if I put it in all the way, it idles but too high (engaging wheel). I am using the metal screen filter that came with the carb.
Where did you get the carb? If it was a used one perhaps some old fuel was left in it and it needs to be cleaned.
Check the little idle air passage on the bottom of the bellmouth.
Other than that you could have an air leak at the manifold joint?
I just installed a 15.15 on my 78 mobylette and it idles nicely with a 60 jet. The intake that I got from treats did not fit properly so I had to do some grining on it so it would seal. You may have a leak?
did you buy both the carb & intake from treats??? I'm about to embark on installing an intake & dellorto on my moby both purchased from treats. He assures me they will fit thought I haven't tried yet. I'll find out this evening, or this weekend if the rain holds out.
If the bike will not idle but will run smooth after you rev it up then you have an air leak. Get the bike running and spray carb cleaner or something else at every visible gasket the bike has. Watch for it to change the motor speed (kill it, rev up). If that doesn't work then you should take the clutch and stator plate off and check the crank seals. Put soapy water where the crank goes into the case and roll the motor over. If the soap bubbles or gets sucked in then the seal is bad and needs to be replaced. Which sucks but has to be done if you are ever going to get it to idle. Good luck.
I did get the carb and intake from Treats, I believe. It was definately brand new and clean. I will check the idle port hole as well as the crank seals. Hopefully its not the crank.
Thanks for the help, will keep you posted
Success!! Thanks for the help. The problem was that my 15mm intake was hitting on the fin above it, and was not sealing against the cylinder. I filed the intake down and now it idles perfectly.
Good to hear.
Was this a treats intake??? I too had to file the top of the intake to get it to seat properly.
Chas
Yes, it was a Treats intake, says "Malossi" on it. A bit of filing did the trick.
JRC
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