Stupid Questions about Mikuni vm22 26mm

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Pitsterpits

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Got a lifan 125cc, a few extra holes in the exhaust and a uni airfilter(oiled)
I installed a Mikuni VM22 26mm(copy), and it didnt seem to give the bike much more grunt than stock carb.
I have been running with the choke lever down....which I now believe is choke ON.
Can anyone tell me excact position of the choke lever, is it up for off or vise versa?
The reason for me thinking that lever down was choke off is because it ran nice there, when I pull lever up the rpms invrease a lot, and it wouldnt run nice.
But when I check thr plug it seems its been running rich.

I've fiddled with the screw in the bottom, tried from 1 turn out to 3 turns out.
Theres also a screw in the right side, is it a fuel screw? It drops rpms when turned out, not in. The carb has stock jets, 15 pilot and 95 main. Needle in 4th position from the top.
The stock carb was eaaaasy to tune and dial in, this mikuni carb seems to be troblesome :(

I would like to know everything about this carb, its very little written about it on the internet.

Thanks
 
The lifan 125 is not exactly a powerhouse, so dont expect huge results with the carb swap. A 17.5 pilot usually makes them happier than the stock 15. Pull the filter off and check where the choke flap is sitting, vertical is choke on, horizontal is choke off. The side screw is the idle screw, bottom screw under carb bowl is the air fuel mixture screw. You can make a tool for tuning while running by pushing a ratchet drive flathead piece into a short length of fuel hose. Lots of threads on here explaing carby tuning as well if your not sure on the correct method.

Sent from my SM-T110 using Tapatalk
 
There is no choke flap, otherwise it would be very easy to spot which position its in.
The lever is connected to a plunger which goes up and down.
Lever down and the plunger goes down sealing the hole.
Lever up and the hole is open. Just noticed this, due to a small hole in the side of the carb I havent seen before.
Think I got my answer, thanks :)
 
Yeah down is off, up is on if thats the case. Sorry for the wrong info there, all the mikunis i have seen were flap style choke :/

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Yea this is a mikuni copy(well made though), they are not the same :)

Ehmm..wouldnt choke on be when the plunger is down and sealing the hole?
And choke off when the hole is open letting more air in, and lever in up position?
If you search Mikuni Vm22 Pz26 on ebay, you can see some pictures of it.
I have been running with it down, closing the hole inside the carb. When looking at the plug it has been running rich, but no plug fouling.
It has been starting on first try everytime too, the difference has been when lever is up, hole open. The revs wiuld stay high.
 
If it works the same as the keihin plunger chokes then up is on, it is an enriching ciruit that allows more fuel through instead of the flap cutting airflow..

Sent from my SM-T110 using Tapatalk
 

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