I see this often on here and many other sites. Something to the effect of "I put a vm22 on and can't get it to run right". I've got roughly a dozen carbs in my shop including a so called vm22 clone carb and a real mikuni vm22. The so called clone carb is less like a real mikuni than most others. The clone vm22 is really a 26mm carb and too big for other than very modified engines. The real vm22 is round all the way through while the clone is oval shaped in the venturi. The real vm22 has the a/f screw on the side of the carb next to the air filter. The clone is underneath near the engine. The real vm22 has a short, fat slide. The clone is skinny and long. I've started using nothing but nibbi and real mikuni and I'll never go back to the cheap crap. Tune either one of the good carbs and your done. Don't have to constantly mess with them.
THE CLONE VM22 LIE
- Thread starter johnott69
- Start date
I've noticed the circular/oval difference in venturi passage, but an oval slide? And if the manifold opening is enlarging to 26mm, it would seem best mated to an intake port of the same size, no? Further, it would seem counter-productive to enlarge the manifold passage to 26mm after a 22mm venturi because I expect pressure and velocity should then drop — and this, just before reaching the open valve.
Finally, does anybody else recognize that a short wide slide (as with Nibbis) also invites a dramatic loss of intake pressure at early throttling? Your low end power range becomes a hurdle more than a help.
Finally, does anybody else recognize that a short wide slide (as with Nibbis) also invites a dramatic loss of intake pressure at early throttling? Your low end power range becomes a hurdle more than a help.
It's not a 22-area wise more like a 24mm. You are correct that pressure and velocity will drop after the venturi but that is the case for a lot of carbs like a Tillotson or a clone carb where the venturi is smaller than the rest of the carb to raise the velocity over the fuel pickup for a stronger signal. I have never seen a short wide slide so I cannot comment on that.
No, while I do not use them anymore, I still have them on a few mini's from Tecumseh's to modded clones. I started using them a long time ago when there were no copy flatslides or other options. Never had an issue other that when using a fuel pump which overpowered the needle and seat. They all use mikuni jets and allowed a lot more power having double the flow of a stock clone carb. Back then they all used mikuni jets and were the same, never had a tuning issue. Years later someone on here was asking for help and his jet sizes were all different so we compared pictures on here of his main and pilot jets. He had a mikuni main jet and a Kehin pilot. Then GPS started selling some with all Kehin jets. The numbering system is different and now folks will recommend say a 15 pilot and 130 main and the person with Kehin jets cant figure out why the numbers are so different and why the mikuni jets do not fit. I can't say for sure but I figure that is why a lot of folks have issues.
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Yea...sort of what I was thinking. When you buy the random ones of Ebay or Amazon they're built for engines nearly 1/2 the size and need to be seriously jetted up in size. Like to a 120 main and 15 or 17.5 pilot for a 212. That's not even getting into needle shapes like Minimichael has been playing with for a Briggs model 13. My own Briggs 13 is running a Chikuni VM22 on a 17.5 pilot and 120 main but it came with like a 90 main and 10 pilot since it was sold advertised for a Tao Tao 125cc bike.
I dunno, seems like the ones you get off mini bike/karting sites come pre-jetted for a 212/224 though. Would probably make it easier on the average person to go that route if further research and trial/error wasn't desired. I guess that if it were me and modding out a 212 I'd likely go with something like a Holy Moses bored stock appearing carb or a Tillotson if I was feeling fancy. It's just one of those things where the community as a whole seems to think you need the Mikuni/Chikuni carb for a modded engine. Sort of like how the majority go with DynoCams even though there is other options for camshafts out there from BSP, EC, Isky, etc...
I dunno, seems like the ones you get off mini bike/karting sites come pre-jetted for a 212/224 though. Would probably make it easier on the average person to go that route if further research and trial/error wasn't desired. I guess that if it were me and modding out a 212 I'd likely go with something like a Holy Moses bored stock appearing carb or a Tillotson if I was feeling fancy. It's just one of those things where the community as a whole seems to think you need the Mikuni/Chikuni carb for a modded engine. Sort of like how the majority go with DynoCams even though there is other options for camshafts out there from BSP, EC, Isky, etc...
I’ve generally had decent luck with the Chinese versions, but like many others said, you will have to rejet. Just plan ahead and have some on hand. I’ve got a bunch of Mikuni jets, but have ordered some of the Chinese ones as well. That way, I can be prepared for whatever carb I may happen to get in the eBay or Amazon lottery. 
the only thing I can comment on about a fake mikuni is out of the box you take the stock 8-16hp kohler carburetor off and use the two bolts to just bolt the fake mikuni back up... stock idle 90main one clip down on two 304cc k181 engines. We ride them around the back roads like cars. The torque is unbelievable still with the 14t 60t gearing on both torque converters. When they wind out you really really have to hang on. A fake mikuni on a 5hp had me doing a ton of pulling on the starter rope and not much riding. When it did run the washer intake always loosened and took out the block threads. FRUSTRATING