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So, has anyone successfully jetted a set of VM34's for a 750? I'm having a devil of a time rounding out a lean flat spot at 1/4 to 1/2 throttle.
I've seen a set of VM's supposedly jetted for a 750 being sold on DCC and Niche Cycles and the jetting just doesn't make sense to me. I've got a set I bought from 650 Central, Michael Morse took his best guess but with his jetting I'm lean where I mentioned.
So here's what I've got in there now:
Pilot jet - 25
Cutaway - 2.5
Needle - 6F9 position 4
Needle Jet - 159 P-6
Main jet - 200
Float level is 23mm
The supposed 750 jetting I've seen advertised is:
Pilot jet - 25
Cutaway - 2.0 (doesn't seem right for a 750 engine)
Needle - 6FJ6 (much leaner than a 6F9)
Needle Jet - 159 P-8
Main jet - 200
I've been trying to work out this damned flat spot for a year now to no avail. Makes highway riding quite problematic. Really hoping someone has some experience.
Man, CX, that's way off from where I am.
I do agree I think the needle's wrong. The stuttering starts right at 1/4 throttle, but it does clear up at about 1/2 throttle with the no. 4 needle position, so that part of the needle is too lean. I'll look into 6DH4...
I've got a P-8 NJ I'm going to throw in there and try...let's see what happens.
I feel like my slide and pilot are ok. Everything from idle to 1/4 is really solid.
Mmmmm ok, so, I could not even get the bike to start with the 3.0 slides even with the enrichers on...or without.
The slides sit too high, even at the lowest position, idle,screw barely touching the slide. checked throttle cable at all points, all adjusted properly. Is it possible the 3.0's are simply too lean for the engine?
Here's what it's set up with now:
Pj 37.5
Slide 3.0
6DH4
NJ P-8
MJ 200
Didn't have a q2 yet and want to make sure I can get it running before springing for them.
These are the 3.0 slides at their lowest position, which after putting the 2.5's back in I realize is not much higher than them. For comparison, the 2.5's sit at about the height of a 5/32 drill bit, the 3.0's at an 11/64 drill bit. Which is what I would expect given the leaner cutaway.
Checked spark, all good there, don't know why it won't fire up unless it's just too lean. I tried to cover the intake bell with my hand (and one of an accomplice) and it fired once but didn't start.
Is the slide all the way down (closed) on the engine side? And if not, are the slides sitting on the adjusting screws or is there no slack in the throttle cables?
The slides are down as far as they can be, idle screws are not touching them, there's a little slack in the throttle cables, about 1-2mm, as is standard. The engine side of the slide is not completely closed off, in fact I can put a 5/32 drill bit into the space...hmmm...
I must be losing my mind. Ok, slides are sitting correctly, no obstructions and the front side is indeed closed. Left slide on the left, right on the right. Same jetting as above, mix screws 1 turn out.
It cranks and every once every three or four revolutions thinks about firing in one cylinder. Tested both plugs, spark is good to both.
Yeah, I can't take that dcc jetting seriously. I've read some threads from people who've put their other supposedly pre-jetted vm's on their bikes with horrid results. I'm sure the 3.0's will prove the answer...once I get them going.
My plugs are wet after cranking with the enrichers on. I can smell fuel in the afterburner, er , exhaust. Only thing I can figure now is I need a richer pilot? Maybe a 40? I tried raising the slides a little, about a millimeter. That didn't work.
Held the throttle wide open and cranked...no change.
Plugs are wet, checked again. I'm going to go get some spare plugs and try a new set, see what happens. Man, I've never not been able to get a bike started...frustrating. The air/fuel must be off somehow.
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