Hi,

I would like kindly to ask an advise. I have VM22 round slide carburettor in my garage. It is bolt on type.I wonder if somebody has an experience in using Mikuni VM 22 round slide bolt on carburettor in B40 trial version engine. My engine has compression rate around 6:1 or a little bid less and one inch long inlet spacer. I am trying to find the proper jetting for this Mikuni VM22 carburettor for using that in my Bsa. Can anybody help with jetting information?

Best regards

Erkki

Not the same animal but I ran a Beta VM26 on an early model C15. Selecting a needle was the hard part. I ended up with a 5F3 needle one step from full lean, 35 pilot and 130 main. The engine had road bike cam with compression around 9:1. This produced a strong idle, smooth mid range and good HP when wound up. By contrast, I could never get a TLR200 carb to run properly. Idle was always rich and felt weak. This bike felt like it had very heavy flywheels so response was much slower that a TLR200 regardless of carb.

Thanks mcman56,

Yes, these jetting istues are intresting. My vm22-133 Mikuni has now now main jet 100 and needle n8. Maybe the main jet is a little bid too small allthough it is the low compression ratio engine and for trial, where running and torque in low rews are the main thing. I know that these carburettors have been used for bsa b40 trials but so far nobody has put any info for internet about the jetting. Let us se, if there are still coming opinios. Thank you one more and have a really nice Christmas and Happy new year 2015,

Br Erkki

Many trials here insist on (small spell checker ) amal carbs, so no experience of other makes.

Edited December 18, 201411 yr by b40rt

Thank you, yes, many insists small carbs. why not Mikuni instead of Amal. Amal 7/8 is ok for trial bsa b40. Maybe someone has some experience concerning Mikuni with certain jetting.

Best regards

Erkki

I don't know if this is any help, but have used a vm22 on a Honda TL125 for over 20 years. As a stock engine size (125)used 110 mainjet, 25 pilot, 2.0 slide cutaway, don't have needle written down.

As a 200cc in the same bike, same carb, used 120 mainjet.

Using a 100 main jet with your 350cc engine would seem to be very small.

Many trials here insist on (small spell checker ) amal carbs, so no experience of other makes.

i was wondering what you meant as i have never come across a size stipulation. Amal yes Mk 1 yes , unless you have a Cub in Yorkshire of course , but not a size restriction.

i was wondering what you meant as i have never come across a size stipulation. Amal yes Mk 1 yes , unless you have a Cub in Yorkshire of course , but not a size restriction.

Spell checker changes the word amal to small, or a typo??? (could be wrong)

I know in ms word it tries to change it to anal!

Edited December 19, 201411 yr by suzuki250

Thank you tirmark concerning your reply,

Yes, I believe so too, that the main jet for B40 should be 140-160. I will try these. I also believe, that the needle type do dot effect so much in this situation. Let's see

Have a Nice Christmas,

As I am from Finland, the Santa Claus is pretty near, so we have also started to wait that white breard man.

BR Erkki

i have 145 main 27.5 pilot jet

What's wrong with an Amal?

Just finished putting an Enfield(Pacco-Mikuni copy) carb. on my C15.Its 24mm

so made a tapered mount/spacer for it.Switched the petrol on pulled up the choke

and it started first kick after a few seconds let the choke off and turned both air screw

and idle screw and gave it a go round the garden,pulls cleanly from idle.Still to try

it at a trial next weekend.The carb(new)cost less than £20 incl. postage.The last couple of

years I have been running an Amal(the one with all the improvements) and wanted to

keep it good .Will let you know how it goes.

cheers the noo Brian

Edited February 21, 201511 yr by broony

^{Out on the bike today at my first trial of the year at Cochno,Clydebank the bike ran well}

^{with the Pacco carb,pulled cleanly from idle(no cough like the Amal sometimes has).Braw}

^{cheers the noo Brian}

where did you find the carb Broony and has it still got the Enfield jets in there?

Edited March 9, 201511 yr by bashplate

From eBay,just search Enfield carb,it came from Mickey Spares ,the jetting is as came with the carb.

All in including postage just under £20(and that's from India).To be honest can't notice much difference

between the22mm and the bigger 24mm,I had to make up a spacer/manifold(with a taper).

Cheers the noo Brian