TeeCat, just dig into it.. once you pull the bowl off and take the slide out, you'll see how everything goes together. The hardest part is getting the cable end in the slot while trying hold the spring.
-
Enjoy XS650.com? Consider making a donation to help support the site.
XS650.com receives a small share of sales from some links on this page, but direct donations have a much greater impact on keeping this site going.
Urgently need Mikuni VM36 help please...
- Thread starter TeeCat
- Start date
TeeCat
One-Mik Wonder
Thanks, griz and Travis... just saw your posts. Hoping for cable and jets today or tomorrow. I think I have most other design/fitment issues solved now, including a filter setup, but will have to mod the left side cover after I get the bike running, dialed in.
TC
TC
TeeCat
One-Mik Wonder
I'm trying to get the bowl off this brand new 36mm VM, and it won't budge. I have the four screws out, but I don't want to pry or hit it. What am I doing wrong? There should be nothing but a gasket, so what's holding it on there? I don't want to ruin this carb or the gasket, so help appreciated.
Drain can stay in, right?
Drain can stay in, right?
You just have a little gasket sticktion, and you need to open that carb; a new carburetor should always be stripped and cleaned, you need to find out what's in it, and you can't install a viable pilot jet without dropping the float bowl. Tap gently with a screwdriver handle to loosen and gently pry any stuck spots on the gasket free with a small screwdriver or knife as you remove the bowl. If the gasket breaks, don't fret about it. It's a simple gasket and easy to make. In a pinch, cut one out of .040" cardboard, hose it down with Permatex copper Spray-a-Gasket, and let the stuff firm up over night. Grease it before installation. It'll seal and release just fine.
TeeCat
One-Mik Wonder
grz, thanks... the top is open, spring and slide are out. Got my jets and just need to get that bowl off. I'll keep trying... just don't to force or pry... or break.
TeeCat
One-Mik Wonder
Guys, I'm trying everything with this carb and the bowl will NOT come off. Rubber and plastic screwdriver handles. Wooden knife sharpener handles. Damned thing may as well have been glued on. Ridiculous. GOTTA get this bowl off or I can't jet or cable up. I just don't want to break the flange prying.
TeeCat
One-Mik Wonder
Finally!
I ended up wrapping the carb body in a cloth and very lightly cradling it by the mouth and the opposite surface in a wooden carpenter's vice. Then I tapped around the bowl with the end of a half-inch wooden dowel and the weight of a light hammer behind it. A few careful blows dislodged the bowl with the gasket fully intact.
I ended up wrapping the carb body in a cloth and very lightly cradling it by the mouth and the opposite surface in a wooden carpenter's vice. Then I tapped around the bowl with the end of a half-inch wooden dowel and the weight of a light hammer behind it. A few careful blows dislodged the bowl with the gasket fully intact.
I'm surprised it was that hard to remove.. I'm assuming it didn't really take all that much force and you were just being careful with it. Either way, glad you got it removed!
Tech7
XS650 Junkie
What we used to do to Holley float bowls was put some vaseline on the gasket when you reassemble to help it come off the next time. In case you have to remive it again.
TeeCat
One-Mik Wonder
Travis, I was surprised too. I was being really careful though. You don;t want to have to endure a "I ruined my new carb" lament.
Cable arrives tomorrow, I hope! Hope that works out okay. And maybe I'll get lucky and be okay with the 25 pilot and 200 main.
Cable arrives tomorrow, I hope! Hope that works out okay. And maybe I'll get lucky and be okay with the 25 pilot and 200 main.
TeeCat
One-Mik Wonder
Per Jasper's kind recommendation, I have been reading this document. It gives float specs, but does not describe how they are measured or how to set them correctly. The illustration on there is poorly annotated. Any Mikuni VM guys know?
The brand new 36mm on my single carb conversion seems to be flooding. The bike will start right up from cold, run for about a minute on the choke, and then die. Subsequent attempts to start it fail, and raw fuel is evident at the mouth of the carb. So I may have to yank the carb and drop the bowl, but I can't find any description of how to check/set the floats. Flooding seems like a good guess to me, though, and floats seem like a possible cause. New carb though, so that kinda sucks.
Thanks.
The brand new 36mm on my single carb conversion seems to be flooding. The bike will start right up from cold, run for about a minute on the choke, and then die. Subsequent attempts to start it fail, and raw fuel is evident at the mouth of the carb. So I may have to yank the carb and drop the bowl, but I can't find any description of how to check/set the floats. Flooding seems like a good guess to me, though, and floats seem like a possible cause. New carb though, so that kinda sucks.
Thanks.
So you start it with the choke, let it warm up a little bit, then when you remove the choke it dies? Can you do half choke? What do you have the air screw set to, did you mess with the idle adjuster (slide stop)?
TC, your floats are separate from the yoke, as I'm sure you've noticed. Height is measured from the gasket surface of the carb body to the float arm, at the point where the float arm contacts the horizontal pin on the float. If the gasket is stuck to the carb body and can't be removed without damage, measure from the gasket and reduce the spec measurement by 1 mm. Adjustment is made by bending the float arms, not by bending the tang. Each arm of the yoke must be measured and adjusted separately, and the arms must be even.
The enricher (choke) on a VM is a very aggressive item; you can't leave it in startup position very long without fouling a plug.
The enricher (choke) on a VM is a very aggressive item; you can't leave it in startup position very long without fouling a plug.
TeeCat
One-Mik Wonder
Travis - No, it would die before I would start to pull it off the choke, and then would be difficult to restart until I let it sit. Then it would fire up right away. The air screw was at 1 1/4 turn out when I started. Now it's about 1. I have read that the range is from 1 to three turns, correct? Or even less than one?
I have the idle screw set so that a 5/16 drill bit will friction fit under the slide.
griz, thanks... noted. I might try it with half choke before I pull the carb again to go to the floats. Might cut my grass and stuff and take a break from this for a bit.
TC
I have the idle screw set so that a 5/16 drill bit will friction fit under the slide.
griz, thanks... noted. I might try it with half choke before I pull the carb again to go to the floats. Might cut my grass and stuff and take a break from this for a bit.
TC
You can go in as far as 1/2 turn on the mix screw, but if you have to restrict the air that much I'd recommend going up a step on the pilot jet. Those plugs are probably fouled (they won't clean themselves). It's usually a good idea to have a few fresh ones on hand when you're dialing in new carbies.
TeeCat
One-Mik Wonder
griz, actually, if I understand you correctly on how the air screw works, wouldn't I want to try to lean the mix out by going out toward the 3-turn limit to start, and then coming in? Cause it seems like I'd want to add air vs restrict it.
I have Iridiums in there now, but I might go to Advance Auto after I cut my grass and try to grab a handful of cheap stockers for this.
I have Iridiums in there now, but I might go to Advance Auto after I cut my grass and try to grab a handful of cheap stockers for this.
Nope. Your scoot currently won't idle off the choke--an indication of a lean pilot mix. Play with the throttle stop and air screw and see if you can get a steady idle. If you have to turn the air screw in out of range to achieve that, step up the pilot jet and increase the air feed. When you get the idle steady, check off-idle transition under load. Bear in mind that every change you make in settings and brass has heavy upstream and downstream effects. Changing needle position, for example, often forces a change of pilot jets. Jetting isn't a straight-line process, no matter how the component-and-range charts look; it's a series of cycles of change and compensation. You run in circles, but they tighten.
I haven't any idea what brass is in your carbs apart from main and pilot jets. For a baseline that works in twin-carb applications, have a look at www.amckayltd.com/VM34-36.pdf . I have no experience setting up VM's on the XS650 as a single carburetor, but if the generic Q2 needle jet is in your carb it's probably going to be too fat. My guess would be that you'll need a P6 or at most a P8.
I haven't any idea what brass is in your carbs apart from main and pilot jets. For a baseline that works in twin-carb applications, have a look at www.amckayltd.com/VM34-36.pdf . I have no experience setting up VM's on the XS650 as a single carburetor, but if the generic Q2 needle jet is in your carb it's probably going to be too fat. My guess would be that you'll need a P6 or at most a P8.
TeeCat
One-Mik Wonder
griz...
I'm reading this with interest. May I refer you to my conversion thread? I had some luck this morning that I reported in there, but it involved going all the way out to three turns out on the air screw, starting the bike on the choke, using the idle screw to keep the bike running as I de-choked (over about a minute) and then winding up with about a 1200 rpm (rough) idle as the bike warmed. I detail what I did in there.
My apologies... I shall try to do all my updating there, but there seem to be conflicting schools of thought as to whether I am rich or lean. Please see video.
Off to look at your link.
TC
I'm reading this with interest. May I refer you to my conversion thread? I had some luck this morning that I reported in there, but it involved going all the way out to three turns out on the air screw, starting the bike on the choke, using the idle screw to keep the bike running as I de-choked (over about a minute) and then winding up with about a 1200 rpm (rough) idle as the bike warmed. I detail what I did in there.
My apologies... I shall try to do all my updating there, but there seem to be conflicting schools of thought as to whether I am rich or lean. Please see video.
Off to look at your link.
TC
The procedure you used sounds fine to start with. Now with the motor warm, back the idle down to the lowest rpm it'll pull and tweak the air screw 1/4 turn one way, pause to let the motor respond, and turn it 1/4 turn the other way, looking for the position that yields higher rpm. Back down the idle again and repeat the procedure until you find the air screw setting that yields highest steady idle, and reset your throttle stop for 1200 rpm. If you find the idle spiking after a brisk ride to full warm-up, richen slightly--1/8 turn or so. Let your motor tell you where the "sweet spot" is. As to whether you're rich or lean, let the motor tell you that when you try to take a ride. If the motor falls on its face in off-idle transition, step up the pilot.
TeeCat
One-Mik Wonder
griz, I'll have to try your air screw suggestion at my earliest, but we may have a few days rain moving in.
Also, I'm quite sure I'm not ready to try to ride the bike yet, as evidenced by the off-idle (hard throttle crack) stumble in the video in the other thread; the motor definitely stumbles... this is all with the air screw at about 2.5 turns out, now.
Here's where I'm getting confused: twins is surmising that I'm rich and need to either drop a pilot or drop the needle in order to smooth out that stumble and maybe clean up the idle. And you seem to be suggesting that my pilot/off idle functions are already lean. So I suppose I'm not sure whose suggestions to try first. Seems like I'm coming at the same goal, but from opposite directions.
Just trying to sort the theory out in my head, and wanting to decide what to do next. Your suggestion does not involve any parts alterations or "labor", so should I do this before I move the needle?
And if you feel that posting in the conversion thread would make for more continuity, please feel welcome.
Also, I'm quite sure I'm not ready to try to ride the bike yet, as evidenced by the off-idle (hard throttle crack) stumble in the video in the other thread; the motor definitely stumbles... this is all with the air screw at about 2.5 turns out, now.
Here's where I'm getting confused: twins is surmising that I'm rich and need to either drop a pilot or drop the needle in order to smooth out that stumble and maybe clean up the idle. And you seem to be suggesting that my pilot/off idle functions are already lean. So I suppose I'm not sure whose suggestions to try first. Seems like I'm coming at the same goal, but from opposite directions.
Just trying to sort the theory out in my head, and wanting to decide what to do next. Your suggestion does not involve any parts alterations or "labor", so should I do this before I move the needle?
And if you feel that posting in the conversion thread would make for more continuity, please feel welcome.
