Carb Questions

G

gomotomoto

Been Around the Block
Have been on the hunt for a set of carbs for my CL350. Just bought a set of sonic cleaned VM 28's. They came off of a yamaha banshee quad, which I think is a two stroke.

I should have checked here before the purchase, but I bought them for what I thought was a good price.

Here's are the Questions:

1. Is there only one Mikuni VM 28? Meaning are there variations for two and four stroke?

2. Are there specific Jets that I should buy in advance so I can get it jetted? Just looking for mid-level performance...nothing special -- just want reliability.
 
I believe a Banshee uses the same (kinda) motor as the rd350. So yes, they would be jetted for a 2 stroke.

Search around here and google for "cb350 vm30 jetting". A lot of people get vm30's that need re-jetted for the same reason. Usually CrazyPJ mentions what needs swapped out (should be very similar for your vm28's).
 
2 strokes usually use Primary type needle jets BUT most reed motors use bleed types. It's anyone;'s guess what's in those carbs. Are they two normal VM carbs or stock Banshee carbs?

Please post a picture of the carbs and list all the jets needles etc so we can try and get you a starting point. Picture of the needle jet might help too.

The two types of needle jets have different flow characteristics. A Primary type tends to flow more fuel than a Bleed type at higher engine speeds and less at low speeds - all other things being equal. That's to compensate for the fact that piston ported two strokes have a reversion problem at low revs ie the gas goes in and out through the carb several times and picks up a lot of fuel. A Primary type compensates for that. If a Primary type is ued ona 4 stroke it's a little harder to jet them correctly. But not impossible.
 
Ok, got the carbs in the mail today, here's the guts and the markings on them. What do you think? What would need swapping out?
 

Attachments

  • carbs.jpg
    carbs.jpg
    73.3 KB · Views: 244
182 is a "Primary" type but we can probably get you into the ballpark. O-0 is fairly small so that is most likely to need to be changed. If you haveto buy new ones try to get 176 series in a P-4 or 6 size.

all those jets will work as a starting point but by the time you finish some or all may need to be swapped out. That main jet must be wrong. #40 on a large hex is smaller than my pilot jets. Are you sure it's not 140 or 240?
 
yes, must be 140 -- was a bit dull and hard to read. I see a possible 1 in front of the 40. Do we have a good online Place to purchase jets?

Thanks Teazer
 
Google Mikuni Main jets and there should be a few places to compare prices including shipping. Main jets should be around 5 or 6 bucks each, Needle jets are expensive - like 15 bucks or more, pilot jets are cheap (or they should be). I may be low on those prices, I haven't checked for a while and when I buy a lot of jets I don't want to look at individual prices.

http://www.psep.biz/store/mikuni_main_jet.htm
http://www.pjmotorsports.com/mikuni-jets.html
http://www.sudco.com/mikunijets.html


There's a trick here though. You have to know which jets you need.

Main jets are Large Hex style 4/042
Pilot jets are VM22/210
 
Ok, here I go I guess... what a pain in the ass. I guess at the end of this, I'll gain a better working knowledge of the carburetor. Just kind of feels like I'm at the bottom of the hill with buckets of water that I gotta get to the top.

Fark it, I'm in.

Not looking for race performance. I just want average joe setup for now.

1. So for now the main jet (140) and Pilot jet (35) are ok?

2. Needle jet: so I'll buy this: http://www.jrgraham.com/itemdetail.do?action=prepare_detail&itm_id=48973 - does that look like the right one?

2. Fitting the carbs to the motor. The 28's leave a good bit of room. Is there a step-down part that I need to buy, or do most people just jury-rig this?

3. Pods - K&N make a difference, or go with the cheap ones?
 
Go,

You are the first that I know of. I would start with what you have and see how that works. The N/J you found is the one I would use, but it will probably need a new needle to match it. That's why I suggest you try what you have first and order new brass once you have some idea what it needs.

K&N are really good filters, copies are junk. Go with K&N.

Stock carbs are large bodies because they are CV style and a 28mm is small body so you will need an adapter of some sort. The neatest and simplest I have seen was a length of plastic water pipe nipple cut to length and fixed in place with JB weld. I was very skeptical, but it works if you can find the right size tube at your local hardware store.

Have you looked at stock Mikuni intakes from the SUDCO collection. They show all the dimensions on their web site. What about intakes from an SL350 - didn't it have 24mm Keihins?
 
Right on, I'll strap these carbs on and see If I can get her to run. I'll post results from there. Duly noted on the K&N. Great idea on stepping down the adapter.

I have a few silly things to get the tank back on the bike, then the carbs go on.

As far as a baseline for all these little bits, where should I start em? Screwed all the way in?

It's obvious that i am greener than green - but i'm goin' in regardless.... I'll post results as soon as I get some to post.
 
Not exactly. Normal air screw setting is 1 4/ - 1 13/4 turns out from fully seated and do not over tighten them. Throttle stop (idle speed) screws are turn them in until the touch the slides and then another 1 - 2 turns as a starting point.

Are you sure you want to do this? It couldbe a long rocky road. Do you have any pictures of the carbs you got?
 
That's funny actually. What I really want is a bolt on solution, but can't get my hands on factory carbs.

So - no, I don't want to do it, but want to get her goin already. Bought her in june and didn't ride her yet.

I'm pissed actually. Should have had the factory carbs from the builder by now...
 
I had forgotten that your bike came with huge carbs that would never have worked. The simplest solution would probably be to ask CrazyPJ to supply a apir of jetted stock carbs from his stash or from one of the guys on here.

I'm not trying to dissuade you from your direction or from learning - just trying to think of a quicker and potentially less frustrating solution as you fight with different jets etc getting it dialed in. I have no idea who has stock carbs or if PJ would be interested, but he seems to understand those carbs better than the rest of us.
 
That's a good idea. I actually just send PJ a PM. I know VonYinzer has a set that I'd buy, but think he's waiting on them as well.

My carb karma is bad, that's pretty clear. I think I've paid my dues to the carb gods and maybe they'll furnish me with a set of stock ones... soon.
 
I made alloy sleeves to fit on carbs and shrunk fitted them to fit my CJ250 (bored to 391cc)
 
Spec's for 30mm mikunis,,,,open carbs,free flow exhaust,no air filters, early style cam .165 mains,35 pilots,p5 needle jet(159)primary type,jet needle 6f5,throttle valve 2.5,main air jet 2.0 and the needle valve 3.3,,these are 2 stroke carbs supplied from Winners Circle.If your spigot measures 40mm, cb 360 carb insulators will work,spigots can be turned down to fit stock insulators if needed.Your carbs are smaller,velocity increases,jetting as mentioned might be rich for your carbs,,,,,,good luck keep us posted WT
 
What size are the stockers. I'd dig through my stash if I knew what you needed. I know I have a pair of a cb 400 twin, but I believe they're 32mm.
 
You must log in or register to reply here.

DTT Light or Dark

  • DTT Light

    • Spread the Love

    Back
    Top Bottom