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Wayne S.
Wayne S., Motorcycle Mechanic
Category: Motorcycle
Satisfied Customers: 1255
Experience:  Experienced and Licensed Motorcycle Mechanic - all sizes and brands welcome.
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I have a sportster 1996 1200 and long pipes that have been

Customer Question

I have a sportster 1996 1200 and long pipes that have been on it for a number of years, it has recently started popping once I reach 100 KMPH. and over
Submitted: 1 year ago.
Category: Motorcycle
Expert:  kwiggins29059 replied 1 year ago.
It may be running lean at higher engine speed. Check the are around the intake and carb with some carburetor cleaner with the engine at idle. Id idle speed changes when an area is sprayed the seal is not good. If that passes you may have some trash in the carb clogging the jets causing a lean condition.
Customer: replied 1 year ago.
Sorry for the delay. I work away and will not be back home until Friday 29 May 2015. I will check this out when I get home, however I have this in the shop and the carburettor tuned. They could not work out what is happening. You would think this I one of the things they would check.

Will get back to you when I get home.

Regards

Radar
Expert:  kwiggins29059 replied 1 year ago.
They may have overlooked it. Look forward to hearing from you later in the week.
Customer: replied 1 year ago.

This has not worked.It has dropped to 90KPH when it starts to pop. I have had the carb stripped and cleaned.

Regards

Radar

Expert:  Wayne S. replied 1 year ago.
Welcome,

Hi,
Check your fuel valve on the gas tank.

The vacuum might be low at cruising speeds and
the valve diaphragm is not opening fully.

This restricts the fuel flow at higher speeds
and causes a lean fuel backfire or popping.

Check fuel tank cap is venting pressure
and check any other vacuum hoses for leaks
that attach to engine intake area.

Any exhaust leaks are not good either.

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