Baja mb200 with a predator engine on it

[Kirch76]

A buddy of mine has a Baja MB200 that he put a predator 212 on it. It runs great until you get to top speed which is about 25 mph. Once it hits max speed it seems like a rev limiter kicks in. So it kinda hits the limiter and slows down a bit then revs back up again and then slows down. I have 2 other bikes with predator engines on them but the gears are not as steep and they just sit at a constant rpm until I let off the throttle. Is this normal since it has a gear reduction set up and it hits max rpm so quick or is the governer not working correctly?

 

[minibikin']

It's surging against the governor. Pretty common. Is it stock? Try a slightly larger main jet...


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[Kirch76]

Yeah the engine is stock for now. He did not want to do anything to it until we found out if it was normal. I figured it was just bouncing off the governer since its geared so low. Do you think a torque converter would solve the problem? What would putting in a larger jet do?

 

[BikeWorm]

Yea, the low gearing is letting it hit the top quickly and the governor is kicking in. That is the surging, a TAV will let you get more top speed out of the stock motor without losing the low end

 

[gumpit]

What is a stock jet size?

 

[lawn-boy biker]

Surging indicates a lean condition. This should not happen at any time....load or no load, governed or otherwise.

 

[minibikin']

What is a stock jet size?

I believe it's .028"


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[Havasu Dave]

Surging indicates a lean condition. This should not happen at any time....load or no load, governed or otherwise.

I have had misadjusted governors do this on several engines, albeit flat heads. With the OP's description, he's already geared way low, which would exacerbate this condition.

Directing him to jetting due to a lean condition is premature IMO.

Get it geared to where you want to run it before doing anything.

 

[BikeWorm]

Surging indicates a lean condition. This should not happen at any time....load or no load, governed or otherwise.

What the op is describing is not an actual surge in the rpm's it is the fluctuation of throttle being imparted by the governor. Its most likely because those bikes are geared very low and it is topping out quickly.

 

[durandbagwell86]

What the op is describing is not an actual surge in the rpm's it is the fluctuation of throttle being imparted by the governor. Its most likely because those bikes are geared very low and it is topping out quickly.

Yep. I'm sure it's the governor. If you go in with the throttle stop screw so it can't turn as many rpms I bet the surging would stop. Jet won't help, gear change so it don't hit the governor or removal of it (with billet rod and flywheel) is the only way.