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Discussion Starter · #1 ·
Hello everyone, I'm looking into getting some more top speed out of my Coleman CC100X mini bike without any governor mods. I have seen on YouTube that some people have put a 19mm mikuni carburetor and performance air filter on their mini bikes and have had some success with them. I'm also aware that installing a header pipe on the engine would help too, but I don't want to make the neighbors any more annoyed with the noise then they are now... 馃槀

Any thoughts on what I should get? Also, what about gearing ratios, I know those are also something I could take advantage of for top speed.

Thanks!
 

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General rule for gearing, more speed, either bigger front sprocket or smaller rear sprocket, do 1 tooth at the front or 10Teeth at the rear. Then test.
Torque is the opposite. Smaller front bigger rear. But only do one change at a time. A different chain length would be needed if the rear sprocket is changed.
An engine is a large air pump. The more in and out the more power. But there can be too much. I haven't done the small motors but for an 80-100cc I could see 19mm carb working. A header is great, just put a lawn mower muffler on the end. It won't be too loud
 

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Discussion Starter · #3 ·
General rule for gearing, more speed, either bigger front sprocket or smaller rear sprocket, do 1 tooth at the front or 10Teeth at the rear. Then test.
Torque is the opposite. Smaller front bigger rear. But only do one change at a time. A different chain length would be needed if the rear sprocket is changed.
An engine is a large air pump. The more in and out the more power. But there can be too much. I haven't done the small motors but for an 80-100cc I could see 19mm carb working. A header is great, just put a lawn mower muffler on the end. It won't be too loud
That's a good idea, I think I've seen some header pipe kits that have a muffler on the end, which would probably be a good thing to put on there since in theory there would be more air and fuel going into the engine with the 19mm carb.
 

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Changing the carburetor is one very effective way to completely eliminate the governor.

If you are trying to put a motorcycle carburetor on a lawn mower engine make sure you get the jet kits ARC racing makes the adjustable timing flywheel that you are going to need to advance the timing to make the motorcycle carburetor work! Without adding additional timing advance the engine will bog down when you snap the throttle open and die.
 

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Discussion Starter · #5 ·
Changing the carburetor is one very effective way to completely eliminate the governor.

If you are trying to put a motorcycle carburetor on a lawn mower engine make sure you get the jet kits ARC racing makes the adjustable timing flywheel that you are going to need to advance the timing to make the motorcycle carburetor work! Without adding additional timing advance the engine will bog down when you snap the throttle open and die.
Thanks for the info, I probably never would have though of that...
 

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Changing the carburetor is one very effective way to completely eliminate the governor.

If you are trying to put a motorcycle carburetor on a lawn mower engine make sure you get the jet kits ARC racing makes the adjustable timing flywheel that you are going to need to advance the timing to make the motorcycle carburetor work! Without adding additional timing advance the engine will bog down when you snap the throttle open and die.
I am curious what engines you have had to do this on?
I have upgraded carbs on dozens of minibike engines and never had to adjust timing. Flattops, both predators, other clones.
I am not saying that sometimes it might not be needed but I have never needed to do that.
 

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Discussion Starter · #7 ·
I am curious what engines you have had to do this on?
I have upgraded carbs on dozens of minibike engines and never had to adjust timing. Flattops, both predators, other clones.
I am not saying that sometimes it might not be needed but I have never needed to do that.
Just so you know on a few of the videos that I saw of people changing the carb out they never had to adjust the timing so I think I am going to buy the new carb, put it on there, see if it runs good and if it doesn't then I'll adjust the timing.


Here is the video I saw:
 

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I am curious what engines you have had to do this on?
I have upgraded carbs on dozens of minibike engines and never had to adjust timing. Flattops, both predators, other clones.
I am not saying that sometimes it might not be needed but I have never needed to do that.
We have 3 mowers on our race team one is a opposed twin one is a 6.5 the other one is a brig's 420 our race club requires a replacement of the flywheel over the years they have had a couple of them grenade and some close calls.

With that said they all run a lot better with the timing set advanced...

One thing to know is competitive drag racing is completely different than regular rideing.








Make sure you take pictures and Mark and notes on everything when you take the original carburetor off this way you can return it back to stock if need be
 

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Discussion Starter · #9 ·
We have 3 mowers on our race team one is a opposed twin one is a 6.5 the other one is a brig's 420 our race club requires a replacement of the flywheel over the years they have had a couple of them grenade and some close calls.

With that said they all run a lot better with the timing set advanced...

One thing to know is competitive drag racing is completely different than regular rideing.








Make sure you take pictures and Mark and notes on everything when you take the original carburetor off this way you can return it back to stock if need be
Will do! I'll let you guys know when I get that new carb and hopefully it works out good.
 

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We have 3 mowers on our race team one is a opposed twin one is a 6.5 the other one is a brig's 420 our race club requires a replacement of the flywheel over the years they have had a couple of them grenade and some close calls.

With that said they all run a lot better with the timing set advanced...

One thing to know is competitive drag racing is completely different than regular rideing.








Make sure you take pictures and Mark and notes on everything when you take the original carburetor off this way you can return it back to stock if need be
Yeah I get that. Predator flywheels should definitely be replaced after governor deletes and stage 2 and above. The plastic can disintegrate. And definitely timing advace is alway a good thing.
Just a carb swap and exhaust, basically a stage 1, it isn't needed, could you, for sure.
Lawn mower racing would be cool.
 
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