mikuni on 7 hp engine

#21
LOL...I remember commenting on this video. All he's doing there is over powering governor function with his throttle hand. He's just avoiding the work and expense of doing it properly like many others.

I'm sorry, but a lot these guys in videos like this think they are clever. I feel bad for people who are new to this and copy these rig jobs. I will say this...If it works for him then he should go for it. Not my engine.
really :) ! haha so anyway now i dont know what to do,‍♂️ noone can explain to me why engine should explode? because to big carb or the lack of guvernor or why i cant combine and still have guvernor and mikuni…:/
 

toomanytoys

Well-Known Member
#22
really :) ! haha so anyway now i dont know what to do,‍♂️ noone can explain to me why engine should explode? because to big carb or the lack of guvernor or why i cant combine and still have guvernor and mikuni…:/
Your motor is designed to run 3600 rpm. That is where your engine is set to run with the governor when it left the factory. You can possibly safely tweak a factory engine to 4000ish rpm safely. Beyond that the rod is going to fail and quite possibly the Chinesium flywheel is going to fail.

You cant combine the governor with the mikuni because there is no way to hook it up. Slide carb vs a butterfly carb. It's just not gonna work.

If you want to run that mikuni get a billet rod, billet flywheel, cam, heavy valve springs, and your mikuni. Then you can spin that thing to 8000 rpm and rip like a monster.

If you don't want to do all that then put your stock carb on and hook the governor back up and leave it alone.

There is no free horsepower. It all cost money. I'm not sure where you are from but if you want to save a lot of effort and time a tillotson or a ducar clone will run 5500ish rpm out of the box. Couple more horsepower than a stock clone.

The only reason I'm wasting my time trying to explain this is to try to save you a motor. I can't tell you how many times on here someone posts their engine won't run anymore. Then after wasting time trying to help them they say, oh i removed the governor from the engine. Well your engine has blown up and now you need a new one. Good way to waste 150 dollars. But at the end of the day its your engine and your safety. Do what you wish but no one here is going to tell you to send it that way.

watch this video


it will explain how the governor works and if you can envision trying to hook this up to a mikuni carb you can see why it will not work.
 
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#23
Your motor is designed to run 3600 rpm. That is where your engine is set to run with the governor when it left the factory. You can possibly safely tweak a factory engine to 4000ish rpm safely. Beyond that the rod is going to fail and quite possibly the Chinesium flywheel is going to fail.

You cant combine the governor with the mikuni because there is no way to hook it up. Slide carb vs a butterfly carb. It's just not gonna work.

If you want to run that mikuni get a billet rod, billet flywheel, cam, heavy valve springs, and your mikuni. Then you can spin that thing to 8000 rpm and rip like a monster.

If you don't want to do all that then put your stock carb on and hook the governor back up and leave it alone.

There is no free horsepower. It all cost money. I'm not sure where you are from but if you want to save a lot of effort and time a tillotson or a ducar clone will run 5500ish rpm out of the box. Couple more horsepower than a stock clone.

The only reason I'm wasting my time trying to explain this is to try to save you a motor. I can't tell you how many times on here someone posts their engine won't run anymore. Then after wasting time trying to help them they say, oh i removed the governor from the engine. Well your engine has blown up and now you need a new one. Good way to waste 150 dollars. But at the end of the day its your engine and your safety. Do what you wish but no one here is going to tell you to send it that way.

watch this video


it will explain how the governor works and if you can envision trying to hook this up to a mikuni carb you can see why it will not work.
i understand, can u link to the motors at 5500 rmp u said, im from sweden so would be great to buy something close buy or anything, and that i can put a toque converter 19 mm shaft..
 
#24
LOL...I remember commenting on this video. All he's doing there is over powering governor function with his throttle hand. He's just avoiding the work and expense of doing it properly like many others.

I'm sorry, but a lot these guys in videos like this think they are clever. I feel bad for people who are new to this and copy these rig jobs. I will say this...If it works for him then he should go for it. Not my engine.
It shows that I gave it a dislike when I watched it, not surprising. It has 11k likes, now, from people who don't know better.

There are so many idiots making YouTube tutorials. I wonder how many of them do a followup video when their shit blows up, I'm guessing not many. I'll give the C&C guys credit for their admission at the end of that particular video but I imagine that's pretty rare. I watched some C&C and RBG videos a few years ago, they seemed to be the popular channels at the time, I didn't like how either did many things, even simple things like driving an axle through frame and wheel with a BFH instead of taking time to finesse it through. I imagine there are some good tutorials on YouTube but you'd probably have to go through hundreds of bad ones before finding a good one, unless you know of a channel by someone who does things the right way, I don't know of such a channel.
 
#25
i understand, can u link to the motors at 5500 rmp u said, im from sweden so would be great to buy something close buy or anything, and that i can put a toque converter 19 mm shaft..
Here's the Ducar 212 which is governed at 5300 rpm, I have no idea whether it is available in Sweden. The governor would not function on it, either, if you replaced the OEM carburetor with a Mikuni.

https://www.dynocams.com/item/212-1000/ducar212/
 
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#26
really :) ! haha so anyway now i dont know what to do,‍♂️ noone can explain to me why engine should explode? because to big carb or the lack of guvernor or why i cant combine and still have guvernor and mikuni…:/
If the engine is ran at too high rpm, the connecting rod may break due to excessive stress and it may bust through the crankcase. If the engine is ran at too high rpm, the flywheel may explode due to excessive centrifugal force and flying pieces may injure you or others. Those parts are designed to work safely long-term at the goverened engine speed. If you're lucky, the valves may float before either of those things ocur. There are aftermarket billet parts designed to withstand higher rpm. The reason why you can't have the governor function with the Mikuni has been explained, a few times, the Mikuni uses no linkage that the governor could be connected to.

Here is an old thread, many pictures have disappeared over the years but some are still there.
https://oldminibikes.com/forum/inde...ur-engine-and-oldminibikes-please-read.35509/
 

Lizardking

Well-Known Member
#32
Lots of great information and time was given here, but all worth it if lessons were learned.

I would recommend putting this engine back to stock and on your bike and enjoy riding it. Research, buy and build an engine of your choice the correct way with no rush.
 
#34
Lots of great information and time was given here, but all worth it if lessons were learned.

I would recommend putting this engine back to stock and on your bike and enjoy riding it. Research, buy and build an engine of your choice the correct way with no rush.
yes o will send back to shop , the ducar 212 seems nice, and much better as stock motor for racing, its build better i saw a review .. so maybe go for that
 
#36
3/4 in (0.75") = 19.05 mm
To simplify things, I rounded to whole millimeters because 0.05 mm is next to nothing, less than 0.002" (2/1000"), 0.001968504" to be precise.
 
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