Mikuni Questions Again

[Mickey Sergeant]

I have decided to get my 26mm mikuni board out.I thought there were poggers out there that can do this.Thanks again in advance

Mickey Sergeant
74 Berkshire

[john durrill]

Mickey,
Almost any Machinist could do the job. Forest would be a good one to check with . He has been in the business a while.
 I think a some time back several of us looked at doing that.
 Could you use a vernier caliper on the slide and get the OD. Then use the caliper to measure the thickness of the carb body and post those for us.
 The bore should be 26 mm . You need some sealing on the sides of the slide for the carb to work.
 You will loose .040 on each side of what you have now if you go out to 28 mm.
I would say try and keep at least .060 sealing on the sides of the slide to the carb bore from playing with porting a little.
  Maybe Ron or some of the other folks could give you a better measurement for the Min. needed for proper sealing.
 john d.

[Larry Perkins]

Would it not be cheaper and safer to just buy a 28mm Mikuni or used Bing?

Larry P

[firstturn]

Lisen to Larry.

Ron Carbaugh

[Mickey Sergeant]

I would love to find a 28mm bing.What I Understood was that the 28 is hard to come by.If someone has one let me know.Has to be in good shape,ready to go.Finishing up for Chahalis national next month.LG is building me a pipe.Had it out at a race last weekend.Ran pretty good.Had a hard time keeping up.Everyone in the 100int class had modified bikes.It was at the hammer and tongs event in riverdale raceway in Wa.He said he was going to try and put a picture of me on the websight.If anyones interested.

[Larry Perkins]

Mickey,

Always interested in cool race pics.  I have a 28mm Bing body & bowl but it would need all the innards from a Bing donor.  That is the best I can do for you.  Do you have a Motoplat or a PVL?  The PVL is probably the best instant mod for the Berkie. Rev, Rev, Rev!

Larry P

[Mickey Sergeant]

I have the motoplat.Dont have the funds for a pvl.Mabe by next year,If I cant find a bing I may just trade up my 26mikuni for a 28

[john durrill]

Mickey,
 Do you have someone you could borrow a good, stock 27 mm Bing from for a bit?
It will flow as much or maybe a bit more than a 28 mm Mikuni.
 I have jet specs that should get you within 1 or 2 main and pilot jet sizes. The stock 276 needle jet and the #4 needle should work fine even with your new pipe. The above jet info is with the 40-404 vaporizer installed.
If you lived a bit closer we could loan you a carb for a race or 2 till you find what you are looking for.
 john d.

[Mickey Sergeant]

I might be going down to LG place next week.I believe He has some bings that need some work.I will Have him look at my bing and get his opinion  if mines worth trying to repair

[Mickey Sergeant]

Looks like they took pictures of everyone but me at the hammer and tongs event in riverdale.thers even two pictures of my daughter on her xr75.Shes #3.Maybe next time.

[john durrill]

Mickey,
 Here is the jetting info we mentioned,





Here is the Jetting for Carl Cranke modified cylinder , head and his pips installed

These mods dyno out at

 You can get a #5 needle  (was used in the first 1972 CMF 100/125/6A Penton)for 27 mm carbs(that's one step richer)and a 278 or 280 needle jet( 1&2 sizes richer) if the reed kit , your pipe and porting likes the extra fuel.
john d.

[Mickey Sergeant]

Thanks for the info on bing carbs.That will come in handy.Going to see LG in a week.Will have him look at carb and see if he thinks its worth trying to repair.He's 5 hours away.Makes it hard when there's no other penton guys around.

[KJDonovan]

Mickey,

I just got 28MM Mikuni in this past weekend with a box of Yamaha parts I picked up.  It looks complete, let me clean it up a little tonight and get the numbers off it for you.  I am assuming you are looking for VM28 with the spigot, not flange.  I would be happy to trade it for something.  Send me an email it this is something you may be interested in.

Thanks,

KD

Kevin J. Donovan
Foster, Rhode Island
72 Jack Piner (My Ride)
72 Six Day (Wifes Ride)
71 Yamaha AT1 (Project)
73 Yamaha AT3 (Project)

[Mickey Sergeant]

Went to LG'S last weekend.We were able to put together a 27mm bing.Put it on The other night with a new pvl ignition.Man what a difference.Put the carb on first to see how it did first.Smoother througout powerband.Then installed pvl,More responsive off idle and more crisper.AT this point i'm satisfied  with what I have.THanks for everyones help

[Dwight Rudder]

They don't make a 28mm VM Mikuni anymore and you can't bore the 26mm out to a 28mm.  Not enough to properly seal around slide. You can bore out to a 27mm or maybe a 27.5mm.  Someone used to do this but for some reason quit.  A 26mm is good for a torquey 125 or a 100cc.
Dwight