5 replies to this topic

[trialholic]

Hi guys

My beta 4T, when ride at medium speed and I shut off gas i can hear some "bangs" through the exhaust..

Is it that normal? or should I tune up the carb in some way?

Thanks mates.

[pindie]

---

Don't want these Ads? Why not help support TC and sign-up as a Trials Central Supporter

[pindie]

Air leak in an intake or exhaust joint.

[nzralphy]

Run the engine and spray some starter fluid around the carb. Wiggle the carb and see if the idle changes -- to find the air leak.

[jimg]

"Bang"? Like a loud popcorn popping sound? Perhaps several in a row? If so, this is a common sound when shutting down the throttle on the Evo 4t, especially when going down an incline. My only sugenstion is to ensure your jetting is set correct. I had to adjust my pilot and main jet as the bike was too lean and the popcorn sound diminished a fair amount. The air boots on the carb are "hard fitting" and the front boot can shimmy back causing an air leak. So, double check that fitting and don't over-tighten the boot clamp as it will cut through the boot in a short time if too tight.

[carl ekblom]

Needle in 4th or 5th groove and fuel mixture screw 3-4 turns out may help and check for air leaks in intake system.

[trialholic]

Thanks guys!

it was an air leak between the carb manifold and the carb union hose, the hose clamps were too loose and the carb was a little backwards. I pushed the carb in place, tighten the clamps a bit and... problem solved!

Edited by trialholic, 26 April 2012 - 06:02 PM.