Honda Rebel Forum banner
1 - 20 of 25 Posts

·
Registered
Joined
·
2,266 Posts
Discussion Starter · #1 ·
I have been experimenting with a set of 30mm VM round slide Mikuni carburetors along with a set of 32mm VM round slide Mikuni carbs and I really can not tell any difference between the two sets. I am also well pleased with them as they keep the fuel ratio the same from one ride to the next and from one day to the next and from one week to the next. Both sets have be turned or machined to fit the Rebels stock insulators (carburetor mounts) and stock air box. I am not trying to convince anyone that these carbs are the answer to all your prays for they are not. These cars do not have an accelerator pump so the throttle needs to be rolled open rather than snapped open, the enricher (the choke) is an on – off affair which has not bothered me at all but can't be run in any part choke position but can be cable operated from the original choke lever. If you can live with these attributes then you will most likely enjoy any of these carburetors for they start well, idle well, have good throttle response, and are much lighter on the insulators. I will defiantly be running a set of Mikuni carbs on my Rebel 450 as I have been doing for over 2,000 miles now, because I just had to gave up on trying to get the stock carburetors to have any kind of consistency even after having three sets of the stock carbs. So either set of these Mikuni carbs are for sale. Pm (personal message) if interested
 

Attachments

  • Like
Reactions: mporciani

·
Registered
Joined
·
2,266 Posts
Discussion Starter · #2 ·
If you are planing on running the VM round slide 30mm Mikuni carburetors on the stock 450 Rebel insulator (intake manifold) the intake end of the carburetor needs to be turned or machined down to 1.495 so it will go inside the intake manifold. If the stock air box and boots are to be used then the bell end of the carburetor needs to be turned or machined down to 2.177 to except an extension sleeve that needs to be made. This extension sleeve will need to be 2.130 O.D. 2.075 I.D. and .700 long. A rubber coupler will go over the bell end of the carb and the extension sleeve.


Jetting for the VM 30mm - jetting is for 100 ft. above sea level - The 30mm will come in Left hand idle only.


120 –----- Main Jet
25 –-------Pilot Jet
6F4 –------Needle (e-ring clip set in #2 notch)
2.0 –------Air Jet
159 0-2 --Needle Jet (emulsion tube)
2.5 –------Throttle Valve (slide) 33 –-------Needle and seat
air screw 1 ½ turns out from lightly seated


Do yourself a big favor – Sudco.com or Dime City Cycle.com can send you carburetors with this jetting and so can I. I can also do all the machine work, extension sleeves, and rubber couplers.
 

Attachments

·
Registered
Joined
·
2,266 Posts
Discussion Starter · #3 ·
Installing the VM 32mm is the same as installing the 30mm except the extension sleeve is a step sleeve and the large end of the carb will only be turned down to 2.200 and then shortened .350


Jetting for the VM 32mm - jetting is for 100 ft. above sea level - The 32mm can come in both Left hand and Right hand idle.


125 –----- Main Jet
25 –-------Pilot Jet
6F4 –------Needle (e-ring clip set in #2 notch)
2.0 –------Air Jet
159 0-2 --Needle Jet (emulsion tube)
2.5 –------Throttle Valve (slide)
33---------Needle and seat
air screw 1 ½ turns out from lightly seated
 

Attachments

·
Registered
Joined
·
35 Posts
Question is there any top end difference with the 32mm, and what is the mileage like with 30mm and 32mm VMs verses the stock CV carbs?
 

·
Registered
Joined
·
2,266 Posts
Discussion Starter · #5 ·
Question is there any top end difference with the 32mm, and what is the mileage like with 30mm and 32mm VMs verses the stock CV carbs?
As I have said before, I can not tell any difference between the 30mm and the 32mm and if there is any it is so small I can not tell and I can extend that to no difference between the Mikuni and the stock carburetors. I find no top end difference and gas mileage has not change with any of the carbs.
 

·
Registered
Joined
·
2,266 Posts
Discussion Starter · #6 ·
Making a set of intake manifolds for the 450 to accept the Mikuni carbs, this will get rid of a very tight bend in the stock insulators (intake) and the stock insulators are getting hard to find.
Did not want a weld where the tube met up with the flange so these are cut from solid stock with 0-ring seal.
 

Attachments

·
Premium Member
Joined
·
1,755 Posts
Old School, You are a very talented machinist.
I have done some machine work on a lathe at work when I needed to make something for the kitchen or roof machines but I just can do the very basic type of machine work on a lathe or mill.
But nothing like you have made for the mikuni carburetors to work. The intake manifolds would be great, instead of the stock ones which are hard to find if you need one.
have you made a rubber adapter to attach the front of the carburetor to the intake manifold like you did for the rear of the carburetor?
The mukini carburetors I have on my 450 get about 55 mpg the same as the stock ones, but the difference in the power is really amazing.
 

·
Registered
Joined
·
2,266 Posts
Discussion Starter · #8 ·
Thank you jax for the complement!
I seriously thought about making a rubber coupler to connect the carb to the manifold and then decided to go with this -- Moto Guzzi V50III Monza 1 7 16" 40mm ID Spigot Carburator 06937 A Mount Sleeve | eBay
I have not noticed any difference in gas mileage either between the stock carbs and the 32mm Mikuni's for some reason the bike is getting 58 mpg, could be because of the flat roads around here. I am hoping for a little more power with the bent intake straitened out but it will most likely be so small it won't be noticed
 

·
Premium Member
Joined
·
1,755 Posts
All the roads around where I live go up and down hills. Just to go to town I have 2 hills and one long downhill. When I go to San Luis Obispo CA. the hill I have to go down goes from 1500 ft to 440 feet.
My property sits at about 900 ft above sea level.
Lots of small hills to go up and down.
 

·
Registered
Joined
·
2,266 Posts
Discussion Starter · #10 ·
Even with all the hills your still getting fair gas mileage I think. Living in the country as I do all I have to do is get into 6th gear and let it roll. I am also about 90feet above sea level so that helps with gas mileage.
 

·
Registered
Joined
·
2,266 Posts
Discussion Starter · #12 ·
Thank you for the complement ChefVodka, in reality I am a much better mechanic than I am a machinist but I get by.
 

·
Registered
Joined
·
221 Posts
Considering the only machine work I can do is blacksmithing which is more about moving the metal than making it to exact specification the first time. A beautiful piece like you made is a work of skill that I appreciate greatly.
 

·
Registered
Joined
·
2,266 Posts
Discussion Starter · #16 ·
Finally got the new intake manifolds on from post #6 and tested them for a few hundred miles as for as more power goes well maybe but not enough to really mention but I can say it surely did not hurt anything. The gas mileage did go up from 58 mpg to 63.2 mpg and that was a surprise because I was not at any time trying to see how high I could get the gas mileage all the runs were driving 55 to 70mph most of the time around 65mph with a little heavy traffic and a few traffic lights thrown in.
 

·
Premium Member
Joined
·
1,755 Posts
Old School, That is a great gain in MPG. Just by putting straight intake manifolds on the carbs. Must of sped up the air and fuel mixture to get better combustion/more power.
 

·
Registered
Joined
·
2,266 Posts
Discussion Starter · #18 ·
Old School, That is a great gain in MPG. Just by putting straight intake manifolds on the carbs. Must of sped up the air and fuel mixture to get better combustion/more power.
That is exactly what I am thinking. Just always thought that stupid dog leg in the intake could not be helping anything but what ever it is "I'm loven it"
 
1 - 20 of 25 Posts
Top