Motorcycle Repair: 1970 honda sl 350, honda sl350, vent hole


Question
Just finished restoration. Bike idles well,& runs well on the road for about 1-2 minutes and then looses power. I can tell it is the right side carb.(which was rebuilt)is either not getting enough or too much fuel. When this occurs, I stop and let it idle for a minute and it clears up, only to occur again once on the road for 1-2 minutes.??

Answer
John, be sure to take a small drill bit to all the passageways inside the petcock to ensure that there is equal flow to both carburetors.

The other thing that is often overlooked is that the gas caps have a tiny vent hole that can get clogged up, causing a vapor lock in the fuel tank, which stops/restricts the fuel delivery.

I am assuming that you full disassembled the carburetors, removing the float valve seats and cleaning out the passageways behind the seats. Also, the air bleed passages in the carb throat need to be checked for blockages, which can cause metering problems. ALL o-rings in the carburetor need to be replaced when renewing each unit.

The CV carbs have an emulsion tube up above the primary main jet that is often overlooked and can cause performance issues.
http://www.cmsnl.com/honda-sl350-motosport-350-k0-us_model732/partslist/E++18.ht...  #9

After you have run in the engine for a hundred miles or so, recheck the ignition timing and valve clearances, when you change the oil.

Bill Silver