Hey Carb Wizards re: VM28 on CB360

C

Comestolife

New Member
I have a couple VM28 carb bodies lying around. No slides tops or jets. I want to throw them on my cl360 project, anyone have some jumping off points for slide and jet sizes? Thanks.
 
I haven't messed with Mikuni's before. Just the Keihin units on my cx500 and triumph. Thanks again for any help and if anyone is holding any parts they wanna let go, I would probably be interested in picking them up from you, as well.
 
i have some vm28s on my 360. they came extra from my RD350 bike.

this will not help too much given that i am at almost 7000ft altitude but my setup currently...

Mikuni VM28mm Carbs-
20mm float,
30 pilots,
180 mains, this will be affected the most due to your elevation, if at or near sea level try 200s
175-P2 Needle jet (Bleed),
5DP7 needle 2nd notch down,
1.6mm adjustable air jets,
2.5 Slides

i have found that bleed type needle jets require a bigger pilot, hence my 30, even though they are effectively unused at idle.
i also am going to put in 2.0 air jets to compensate for my richness at WOT, smaller mains arent helping.
if anything id say go with the 5DP7 needles in the 2nd clip down as this has worked very well up until WOT.
1st clip was too lean all around, may try a shim.
its very tedious and a lot of trial and error. wish i had access to a dyno.

let us know how it goes for you as i will one day be returning to normal elevations and would like some baseline to start.
 
Comestolife said:
Thanks, I will put an order in for some parts, soon and post up how it goes.
Click to expand...

did you ever get jetted? im finally at sea level and wanted a main and pilot jet size rec.
 
raptormeat said:
i have some vm28s on my 360. they came extra from my RD350 bike.

this will not help too much given that i am at almost 7000ft altitude but my setup currently...

Mikuni VM28mm Carbs-
20mm float,
30 pilots,
180 mains, this will be affected the most due to your elevation, if at or near sea level try 200s
175-P2 Needle jet (Bleed),
5DP7 needle 2nd notch down,
1.6mm adjustable air jets,
2.5 Slides

i have found that bleed type needle jets require a bigger pilot, hence my 30, even though they are effectively unused at idle.
i also am going to put in 2.0 air jets to compensate for my richness at WOT, smaller mains arent helping.
if anything id say go with the 5DP7 needles in the 2nd clip down as this has worked very well up until WOT.
1st clip was too lean all around, may try a shim.
its very tedious and a lot of trial and error. wish i had access to a dyno.

let us know how it goes for you as i will one day be returning to normal elevations and would like some baseline to start.
Click to expand...

You don't mention how you used carbs set up for a two stroke on a four stroke...
 
VonYinzer said:
You don't mention how you used carbs set up for a two stroke on a four stroke...
Click to expand...

The 175 needle jet is the conversion for four strokes. From the factory, the VMs come with 159 needle jets, which are for the two strokes.
 
You shure it's not the other way around? I thought that the RD had the 4 banger setup and the earlier R5 had the 2T setup? That's why the RD guys do the Dave f mod to make the RD carbs like the older version. Primary needle vs. Bleed.

Sent from my SAMSUNG-SM-G920A using DO THE TON mobile app
 
Pretty sure.

The bleed type is definitely for the four strokes since the two strokes get pretty good atomization due to the fuel passing through the crank case.
 
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