Noise in head?

**GTO** · 08-13-2008, 12:16 PM

I have a 3 HP Briggs that runs great and doesn't smoke but under load and mid to high RPM I'm getting a tapping/knocking/peening noise coming from the top of the head.

I pulled the plug and it doesn't look like the piston is hitting it so could it be the valves? I adjusted the carb many times.

BTW, this engine had the air flap gov that was connected to the throttle that I removed.

jesse8931 · 08-13-2008, 12:21 PM

pull the head i bet the valve is smacking the head

**GTO** · 08-13-2008, 12:22 PM

Quote:

Originally Posted by jesse8931

pull the head i bet the valve is smacking the head

Yes but why?

jesse8931 · 08-13-2008, 12:25 PM

it could be a lot of things

**GTO** · 08-13-2008, 12:28 PM

The engine is stock and newer with few hours so maybe the air gov types were never intended for any real RPM ?

jesse8931 · 08-13-2008, 12:53 PM

maybe the springs are to weak to handle the rpm's you need on a mini bike

blownengine · 08-13-2008, 01:31 PM

I agree with Jesse. without the governer your springs are put under alot more stress

EZBORE · 08-14-2008, 09:14 AM

Measure the length of your stock exhaust spring and then call Dyno Cams 910-655-9035 ask for stock aftermarket springs for a 5hp the same length. These springs will be approx 3 to 5 lbs more pressure and should eliminate valve float. I do caution you because after installing these springs the engine will turn more rpm's and you will have a much greater chance of having a internal problem like a rod or piston failure. The better solution maybe to try and lower the gear ratio on your bike

**GTO** · 08-14-2008, 01:38 PM

Quote:

Originally Posted by EZBORE

Measure the length of your stock exhaust spring and then call Dyno Cams 910-655-9035 ask for stock aftermarket springs for a 5hp the same length. These springs will be approx 3 to 5 lbs more pressure and should eliminate valve float. I do caution you because after installing these springs the engine will turn more rpm's and you will have a much greater chance of having a internal problem like a rod or piston failure. The better solution maybe to try and lower the gear ratio on your bike

The gears won't matter becaue it does it at mid RPM under load so I guees I'll take the springs out and compair them with one of my parts engines 3 & 5HP. I wonder if a spacer washer would help.

EZBORE · 08-14-2008, 02:17 PM

Is it possible this motor has a rod knock ? -- Rod or piston noises are heard under load Valve float occurs normally at higher rpms -- Are you seeing metal particle when you drain the oil.