wanted; mikuni carb

[tomale]

I am thinking about replacing my bing with a mikuni carb on my 250 I think I need a VM36 I will do it if I can find on for 50 bucks or less, I know I am cheap

Thom Green,I own and ride a 76 250 MC5 MX which I bought new.

[Rocket]

Thom
I will dig through my tub of carbs tonight and let you know if I have one, I think I do.
Rocket

 

[sachsmx]

Thom, you might be money ahead to buy a prejetted carb from Pro-Flo that is set up for your bike. By the time you purchase the correct slide and jetting for a used carb, you'll probably have more money invested than if you would have bought a new prejetted carb, unless your used carb is free. New VM-36 Mikunis sell for around a hundred bucks.

 

[tomale]

thanks sachmx, do you they have a web address or do you have a telephone number? I am still finding my self trying to get back up to speed, I have been out of the game for 25 years.

Thom Green,I own and ride a 76 250 MC5 MX which I bought new.

[tomale]

Thanks Rocket, good to talk to you again.

Thom Green,I own and ride a 76 250 MC5 MX which I bought new.

[[email protected]]

The advice on a prejetted carb is accurate in that slides alone are about 30 bucks,having said that, Pro-Flow are great guys,but I have always had to rejet the carbs I have purchased,you'll need an assortment of mains and pilots anyway and they are less than 3 bucks each.Make sure any carb you buy has a 2.5 slide and you'll be safe.Frank

 

[deek]

Thom
Here's a source. If fact my 28 Mikuni, bought
it back in the 70's. I'm adapting to my 125
is from Sudco.
http://www.sudco.com/

Dale

Dale

 

[Cathump]

Thom, I buy my new carbs from Pro-Flo myself. Their web address is //www.pro-flo.com What I use on my '78 MC5 is a 34mm bored to 35.7mm. It gives much more bottom end and flows like a 36mm.



Rick Terry

[john durrill]

Rick,Dale , Frank, sachsmx
 could you look at your carb and post for us what you are useing for jetting?
the  size and model
the main jet
the pilot jet
the air jet
the needle jet #
the needle #
the slide cutaway
if it has a starter jet what the # on it is.
 what year and any mods you have done from stock to your engine.
 we have folks ask all the time on what to get if the go to a Mikuni. if they have to figure out all that from scratch it will cost them a lot of money over the price of the carb unless the are very lucky and get the right needle, needle jet, slide cutaway and air jet when the buy the carb.
 i will save the info to disk and post it in the library.
 I would greatly apprecieate it if you could.
 anyone else that can give us their info on the Mikuni they are useing will really help the folks in POG that want to go with another carb over the Bing.
 The pre jetted carbs i have gotten from Sudco have only had a main and pilot jet changed over the one you buy over the counter.
 The heart of your jetting is the middle the slide cut away, the needle jet , the needle , and the air jet. if you have those close to start with its not hard or expensive to get the main and pilot right.
 if you look at the specs for the un-pre-jetted carb on Pro Flows web site i bet its the same thing as Sudco.

 John D.
 


 

[Cathump]

On my '78 MC5 250, I ended up with a 260 main, 40 pilot, a 2.5 slide cut away, and I will have to look to see what the needle and needle jet are.

Rick Terry

[john durrill]

Thanks Rick,
 if you can get the air jet out, whats its #?
 it fine tunes the needle , needle jet combo.
 you are a Blessing
John

 

[tomale]

Rick, why go to all the trouble to bore out the 34? why not just use a 36? does it have something to do with the size of the carb and how it fits between the manifold and the aircleaner box? Is that for your bultaco's?

Thom Green,I own and ride a 76 250 MC5 MX which I bought new.

[[email protected]]

As follows: by the way I have a butt load of 34's and they jet the same.Email me.2.5 slide,Q-2 needle jet #159 type,DP-1 needle in the middle position.35 or 40 pilot depending on temperature larger is richer.270 to 330 main depending on the motor.My primary experience is with the range of Bul Astro's and this has worked on them all.I have always taken out the airjet in the bellmouth on a twostroke and found it ran better without it.The air screw should be at 1.5 turns if you have to turn it more than a half turn either way change the pilot.On the mid you should be able to whack the throttle open from idle without hesitation.If it hesitates raise the needle all the way if that improves it change the needle jet one size richer,if it''s worse go one size smaller.It should be optimum with the needle in the middle allowing you roon to work for atmospheric change.The main is just a matter of finding one that runs clean and then doing plug chops,look for a rather dark chocolate brown on a racebike as opposed to the cinnamon color normally prefered.Start big on the main and go down.Plugs are cheap.By the way hook up your airbox when doing all this>I just wasted a bunch of time and energy trying to get my 125 to right with an open carb.Works on 4 strokes and my Buls but the Sachs would not run right open.I am not recommending skipping the airjet,just making a statement that that's what I have always done.The Mikuni tuners manual from Sudco is really worth the pittance it costs if you enjoy tuning.Frank

 

[[email protected]]

While I was typing the posting appeared about boring out the 34 and it occured to me you might want to try the 34 the way it comes, if bottom end is your desire.Less venturi usually produces better low end response.The 360 Buls come with a 38 Amal and I always run a 36 mikuni.Let me see what I can put together on  one of these 34's.Frank

 

[deek]

Mine is: VM28-116 round slide (ran on a 100CC, early 70's, Belive it's off a Kawasaki)
Slide--------2.5
Pilot--------35
Main---------180
Needle-------501 Set on center grove
Needle Valve-- 2.5
Pilot Jet---- will have to persuade to come out, hehe.

Dale