Here is my mikuni vm 16 mounted . So far I am very happy with it , The bike runs good after a jet change. I am still going to try and dial it a little better .
mikuni vm 16
- Thread starter headtrama
- Start date
What would you say is the biggest change on how your motor runs with this carb?
Played with the jetting today got it running even better . Now I have to put some miles in it to fully break it in .
My carb came with a 70 jet in it and it wouldn't go past half throttle without bogging . I went to a 95 jet 100 % better with just a bit of a off idle stumble. Today I went down to a 92.5 jet adjusted the air screw to the highest ldle about 1 3/4 turns out from seated . Bike has never run better , smooth idle no four stroking anyware with a nice crisp exhaust note .
Hi Headtrauma, thanks for the info on jetting. Are you talking about the main or the needle jet being 92.5? I went to mikunioz webpage & they list main jets in this range as coming in increments of 5. Your motor appears to be mounted at roughly the same angle as mine, (mine mounted with SBP shift kit), which has the carb about 26 degrees from a level attitude. Does this affect it at all? I have read in someones else's post where a lean condition at WOT was caused by this, not jetting. Anyway, thanks. Cheers
The 92.5 jet is the main jet size I am running now . Everything else in the carb is how it came out of the box . My mikuni takes the round main jets I noticed the hex jets don't come in a .5 size . Does your carb use the hex jets , I mesured the angle of my carb it is at 23 degrees . I just pulled the plug and it is a light gray on the tip and looks like its tan around the base . I have not noticed it going lean on a full throttle run it pulls nice from mid range to the top end .
What manifold are you using , I made my own that fit this carb perfect . I got rid of the spacer and stepped the manifold on the end to fit into the rubber seal .It could be that they are going lean because of a leak around the manifold if using the spacer .
What manifold are you using , I made my own that fit this carb perfect . I got rid of the spacer and stepped the manifold on the end to fit into the rubber seal .It could be that they are going lean because of a leak around the manifold if using the spacer .
Hi Headtrauma,,, (great name). I read about the lean condition from the carb being so far from level on the motored bicycling forum, (I think). I didnt think it would affect it at that angle. My carb uses the hex main jet & is still in the box, not mounted due to not having a manifold. I have been waiting for manic mechanic products to come available again & use one of his large billet manifolds but its been a long wait. I asked at a local machinist but paying almost twice what the carb cost for a manifold isnt on & I dont have access to a lathe so,,,,. I would be more than happy to pay for time, effort, materials & freight to Australia if you could turn one like yours up. Anyway,,, cheers
Ask piston bikes if they have the manic mechanic manifold in stock. They list it on there web site , I don't have any aluminum stock left . If not ill see if I can scrounge up some aluminum.
One more thing is to use a good pet cock. The ones that come with the kit suck. Sick bike parts has a nice one that flows good .
Hi Headtrauma, thanks heaps mate,,, appreciated greatly. Piston Bikes & Bike Berry are both out of all stock of M M products & I've emailed M M a couple of times with no reply. I'm ordering a Rock Solid Hi Comp head next week, they have billet manifolds but nowhere near big enough O. D. for the mikuni. Well, I've just fitted a new shimano rear derailer & 8 speed revoshift shiftgrip & chain & threw a new BP6HS plug in so I'm off for a ride. Cheers mate
Headtrauma u rock. I would be eternally greatful. Oh, I already have SBP petcock, as well as the deluxe shift kit, nickel plated expansion chamber & heavy duty air cleaner. They do great products & they're extremely helpful. Nice people to deal with. Thanks. Cheers mate
Its just an old steel mountain bike but its getting there. Rebuilt the motor with quality bearings, seated countershaft bearings with loctite bearing retainer. Used a 10x14x15 small end bearing. Big end is stock. Widened ports a smidge, slightly 45 degree ramped top of piston & exhaust port & bottom of piston & inttake port for less turbulent flow & slight timing change. Port matched both in & out. Added front & rear disks. Built own cdi,,, modified kdx type. Front suspension with 2 triple clamps. I'd post pic if I knew how, posting from phone. Cheers
Sounds like you did a lot of work to it . I have messed with the internals some on my motors . I wish they made a better crank for these little engines. I was able to pick up some aluminum today so ill start on that intake for you .