Beta rev 4 is regularly misfiring and whenever i do a step no matter what size runs really bad with black smoke out of the exhaust any one got any ideas for a solution PLEASE

Hi

Have you checked in the base of the air box, oil can collect within the air box after a big off.

Then when you hit a step some of the oil can be pulled into the carb and cause poor running.

We had this problem and found the above, once cleaned out it was sorted, you may need to clean the carb as well.

Edited March 11, 201214 yr by JFC

I had a similar problem with my evo 4T. It turned out to be dirt in the carb. I found it very difficult to clean the carb so I guess an ultrasonic cleaner would help.

Anyone have an idea of an alternative carb for the rev 4 or has anyone tried anything else Was told by Acklams the carb isn't brilliant for an off road bike

Clean the carb out. I am not familiar with this carb but asume it has a cold start enrichment system. Make sure this is closing off properly when not in use. Float level? dirt on or damaged float valve seat?

Occasionally faulty HT coil gives same symptoms.

Run the bike with the fuel turned off and see if problem goes as the carb empties - if it does you know flooding or similar is problem.

Cheers

I too have a problem with my recently purchsaed 4t.

It Starts ok idles ok but has a really annoying flat spot on about 1/6 throttle. Past this point

everyting is sweet again.

New plug fitted carb drained but not stripped.

Any suggestion?

DO NOT change the carb. Beta spent years testing and setting it up....you will fail. All the other Betas are fine. Find the fault with yours.

Remove and check the carb rubber bellows.