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Motorcycle Repair/xl175 slows down


QUESTION: my xl starts and revs up fine,goes through first and second gear then starts slowing down choking it kills it.

ANSWER: Dave, any number of things can be happening with your XL175....
First check the compression to see if it is around 160-180 psi.
Adjust the valves to .002" on the intake valve and .003" on the exhaust valve (at T mark on the flywheel alignment with both valves closed).

Make sure the whole fuel system is clean ....  gas cap vent hole, petcock internal passages and screen, fuel line, carburetor float bowl, float valve with float level set at 22.5mm.

Gap points to .016" at the widest gap during rotation, then set the backing plate so the points just OPEN at the F mark indicator on the flywheel index marks.

Make sure your drive chain is not over-tightened and there is plenty of clean fresh oil in the crankcases.

Spark plug gap is about .025" Put in a new one if the old plug is oil/fuel fouled.

Check spark plug cap for 5K ohm resistance.

The standard main jet is #110, but if you change the air filter or exhaust system, you may need to jet it up one step.

Bill Silver

---------- FOLLOW-UP ----------

QUESTION: I've done everything but the jet change I noticed something you might have some experence with. My xl gets up to about 35 mph then the ground speed drops but the RPMs stay up, weird.

Dave, the clutch is slipping....

Either go over the adjustment procedure to ensure that you have some freeplay at the clutch lever or you will have to pull the clutch cover and replace worn/damaged clutch plates and/or clutch springs.

Bill Silver

Motorcycle Repair

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Bill Silver


Need help with vintage Hondas from the 1960s? I am an expert with 250-305cc bikes in particular and most all of the other pre-91 models, in general. I do NOT claim to have a great deal of experience on Gold Wings, Cruisers, ATC/ATVs and dirt bikes.


I have owned/ridden/maintained Honda motorcycles for 35 years. I have written five books on Honda repairs and collecting. I was a service manager for two Honda shops back in the 1980s.

VJMC (Vintage Japanese Motorcycle Club) of North America

VJMC newsletter, as editor for two years and as contributing editor currently.

3 years auto shop in high school, teacher's aide in Automotive Technology in Jr. College, Diesel mechanic course in college, self-taught mechanic and automotive writer.

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