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Motorcycle Repair/Issues with a 1971 CL175


I recently purchased a 71 CL175.  It had been restored by the previous owner last year and he had the receipts to show for it.  He told me the throttle cable was sticking so the bike wasn't rideable because it would stick open.  No big deal.  I got it for a steal so I was ok with it.  Well, from what I can tell the throttle cable works fine.  Here's the issue.  I press the start button, and literally one press and it starts right up, but they it goes to full throttle without even touching the throttle.  I have broken into the carbs yet but what would I be looking for?  It's not dumbing fuel out, the left plug does look a bit wet, but the right seems fine.  

The guy I bought it from said he was riding it around last summer until this issue popped up and then he stopped riding it.

I'm just looking for a few things to check before I start digging in the wrong places.

Thanks for your time.

Hi Nathan,

Check if the throttle slides are dropping all the way to the idle screw.
The cutaway part on the bottom of the throttle slides faces the rear
of the bike, if they are not then the slides have been reversed
and you will have to swap them so the cutaway is at the rear.

Another thing that can cause high idle is air leaks around the carb
mounts or intake tubes. This can sometimes be checked by
spraying some carb cleaner aroung the flanges and see
if the engine speed changes.

Check you idle screws are not turned in too far as they
raise the slides up.

Another remote possibility is that a jet dropped out inside the carb
or the auto timing cam behind the contact points is stuck
in full advance or the ignition timing is just set wrong.


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Wayne S.


Licensed Motorcycle Mechanic, Knowledge of motorcycles from 1960 up, Japanese, British and most other brand motorcycle repairs.


Worked for Yamaha, Honda, Suzuki, Kawasaki British: Triumph, Norton, BSA Other: Most Scooters and Mo-Peds

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