Urgently need Mikuni VM36 help please...

[TeeCat]

Guys, looking for a Mikuni god.

I have a VM36-4 on the way... should be here tomorrow. Per this chart, it ships with a 310 main (4/042) and a 35 pilot (VM22/210). I need a 200 and a 25, respectively. Can't find them... ANYWHERE around here. Even if I get the carb tomorrow, I can't move another step til get these jets.

I bought the wrong extra mains too... I need the 45/402s.

Can anyone tell me where I can find what I'm looking for and hopefully have it in my grubby little mits in under six years? God, this is reportedly the most popular performance carb on the market, and not a shop within 100 miles has jets!

Thanks muchly...

TC

 

[grizld1]

The mains and pilots aren't all you need; the only generic items in those carbs that you can use are the slides, and unless your engine is in something close to full race tune that 200 main is gonna be too fat. You'll need 159-P5 or 159-P6 needle jets, 6F9 needles, most likely 180 MJ's and either 22.5 or 25 PJ's. If the air correction jet is present in the intake bell, remove it. Get a range of mains from 175-190. You'll need to order that stuff--the VM series is a popular performance carb only on vintage machines, and that's a pretty narrow niche. While you're ordering stuff, add a copy of the Sudco Mikuni Tuning Manual to the list.

 

[TeeCat]

griz...

I might not should have started a new thread for this. This is for a conversion from two BS38s to one VM36 with a 2-to-1 intake. Sorry for any confusion. joe-wiseguy, the maker of the intake, tells me that for my stock motor and shorty reverse cones, most folks in my position are starting with a 25 pilot and a 200 main and doing well with that combo. That said, I just need the parts to get started.

I think I may have mislead you into thinking that I was going from BSs to VMs in a two-carb application. Sorry about that.

TC

 

[TeeCat]

Well, I ended up having to go back to Niche Cycle in Florida for the jets... same place I got the carb from. I likely won't have then til Monday, but meanwhile, I'll be able to get the intake mounted, test fit the carb, and see whether an existing cable will work or not. I'll also have to modify my left side cover... hate to do that... but...

TC

 

[grizld1]

Oops--the fault is mine. You wrote "a VM36-4," not a pair. I'd still recommend a 6F9 needle over the generic 6DP1 and a reduction in NJ size--the generic Q2 is too fat for anything but a full-race engine. If I were trying to dial in that setup I'd start with a P-6 NJ and step it up to a P-8 if things look lean in the cruising range with PJ's, MJ's, and needle settings optimized. Re. the MJ recommendation from joe-wiseguy: sounds good, but take it as a baseline, not a recipe. I'll check my stash of jets in the morning and send you a PM on what I've turned up; I'm pretty sure I can fix you up with everything you'll need except needles.

 

[TeeCat]

griz, thank you very much. I may take you up on that in time. Meantime I hope I can get the bike rideable when the jets come. The carb should show up today, but the jets not likely til Monday. So my plan in the meantime is to mount the intake from joe-wiseguy (no wonder they're $250... how many times have you held a lump of metal in your hand and stared at it because it's beautiful?), which I have loosely mocked up already, mock up the carb to see if one of my two stock throttle cables will work (not sure about length or ferule fit to the carb), and decide what to do about modding my stock left side cover *cries*.

Thanks for the additional info, griz!

TC

 

[Tz250racer]

$250.00 for 2 36 vm carbs?.Wow.There is place on the web that has them for $102.94 each and free shipping.
http://www.oemcycle.com/Item/product/3238/

If you need carb parts then the second link is the place.

http://www.motorcyclecarbs.com/index.cfm

 

[TeeCat]

Tz, no... that's the cost for the handmade, ceramic chrome-coated intake manifold.

 

[grizld1]

Tz, the price in that link is for the carbs as they come from Mikuni, and that's about the middle of the range on pricing. To dial in that carb pair on an XS650, you'd need the following (prices cited are about middle of the road, some vendors are a little higher or lower; for high altitude adjust recommended MJ sizes down, recommendations don't apply to full-race engines).

MJ, 3 pr., 175, 180, 185: $21
NJ, 1 pr., P5 or P6: 32
Needles, 1 pr., 6F9: 32
PJ, 2 pr., 22.5 and 25: 14
____________________________
Total: $99

That's just for the brass to dial in with; then you have carb boots, air filters, and cables to buy. BTW, Rob Reil's prices on jets at motorcyclecarbs.com are the highest out there. In my book he's the source of last resort.

TC, glad you have the brass covered; if you need them I have good used 190 and 210 mains and a new P8 NJ, but you'll want to test what you've ordered first.

 

[TeeCat]

griz, speaking of cables...

I was hoping to remove one of my two cables and use the other for the single Mikuni if it's long enough. Even if it is, without having seen a Mikini throttle cable fitting, it appears from pictures on the web that the carb end of a Mikuni-type cable has a little "barrel" ferule as opposed to a "disc" like our stock ones. Can I file the disc down to a ferule in a pinch to try to get the bike running/dialed? You would not believe how hard it is to get things like universal cables locally in a big city like Baltimore. Ridiculous.

 

[grizld1]

TC, in cable talk a "ferrule" is the metal end cap on the end of the conduit (cable housing). I don't recommend trying to file down the OEM cable end; the end that slips into the VM slide is very small and I doubt that the material in the cast end of the OEM cable is up to the job. Bicycle shops often fabricate cables and would be a likely source for the brass end you need, but before you have any soldering done, get the carb mounted and figure out the free length you'll need between the end of the conduit and the cable end.

If you want to make a cable from scratch, the go-to place is www.flandersco.com . Soldering is easy; get a bottle of Ruby Fluid or other tinner's flux, a roll of 60/40 solid core solder or a chunk of Flanders' 50/50 bar solder, melt it in a small vessel in a well-ventilated place, and heat just until the surface flashes. Clean the wire and cable end with acetone, slip the end on the cable, spread the wires to form a block when solder adheres to them, and slip the end back against the spread-out wires. Dip in flux then in melted solder and hold for 20 sec. or so. Clean up with a fine file if needed.

 

[TeeCat]

griz, this is very helpful, thank you! Thanks for taking the time to write up these suggestions!

I'll go ahead and mock things up when the carb comes... I can't even tell from pics how the carb end of the cable slips into the slide. I'm surprised how little info I have been able to find on this. But I hope I can at least get the cable situation sorted out before the jets arrive.

TC

 

[TeeCat]

Well, I have the Mikuni VM36, but there is no literature with it. I'm finding parts breakdowns, but no instructions for replacing jets or installing a cable. I don't have a suitable cable or the tuning jets yet, but can someone point me in the direction of the info I need? I suspect that the jets are accessible by dropping the bowl, but I have no idea how I'll install a prospective cable.

Thanks...

TC

 

[grizld1]

In the slide you'll see a metal plate and, beside the central hole filled by the needle, a slot with a wide spot in the outer end, a narrow channel, and a recessed seat at the inner end. Remove the clip. Compress the spring into the carb top and thread the cable through the carb top and spring, then insert the cable end in the wide end of the slot in the slide and slip the wire across the slot until the cable end seats in the recess. Drop the plate into position so that its bent edge drops into the cable slot.

 

[TeeCat]

This might seem obvious, but do I need to unscrew the top to access these parts? I do NOT want to mess up this carb before I even get the bike running with it. Sorry for the hyper-caution.

 

[Travis]

Yes, unscrew the top... there will be some spring pressure but nothing to worry about.. Nothing should go flying. What grizld just said will make much more sense when you're looking at it.

 

[TeeCat]

Guys, I'm at work now, but this morning before I left, I unscrewed the top and took a peek. In this diagram, I see everything you're describing down to the plate, but mine looks a bit different from what you're describing and from the drawing; I thought I saw TWO plates... one partial and one full, whose slots or apertures seem to coincide, but one seems to rotate/pivot on the other. Guess the piston valve has a top? Not clear in the drawing.

Also, you mention a "clip". The only clip I see in the drawing is the actual needle retaining clip (god, I hate e-clips), but that's not accessible/visible from the top of the carb. Seems unlikely I'd have to mess with that, so I'm afraid I'm still a bit confuddled. Seriously hoping I don't have to mess with that needle/clip every time I want to attach/detach a cable. griz, it seems like you're working from the bottom of the carb with the bowl off. (?)

Cable-wise, what I'll need is one that works with my cafe bars and stock throttle, but with a nipple that will fit the VM. I have a feeling I'll be spending my Saturday looking for that before I can do anything else.

 

[grizld1]

Sorry for the confusion, TC--where I wrote "clip" I should have written "plate," I was referring to the same part--will edit. Pull out the slide, thread the cable through the bits as described from the top down, and reassemble. The plate is there to retain the needle and keep the cable in position. The spring holds the plate in position.

 

[TeeCat]

Thanks, griz. Okay, so it sounds like you're working from the top then... bowl still on (though I'll have to pull that eventually to get to the pilot/main jets)?

Just preparing in my head... all of this is technically moot til I find a cable, though. Will be trying tomorrow.

 

[grizld1]

You have to drop the bowls to access the pilots, but the mains can be unscrewed through the float bowl plugs with a 6 mm. socket in 1/4" drive. Switching mains at roadside while doing full-throttle runs for jet selection is quick and easy.

When inserting the cable into the slide you need to pull the slide onto the cable while forcing the slide back to compress the spring until the cable end clears the bottom of the slide, enabling you to move the cable laterally through the narrow part of the slot to align the end with its seat.