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Discussion Starter · #1 ·
Hello, I bought 2 mikuni 32vm carbs for my scrambler and I'm having a hell of a time getting the bike to run OK.
I bought the kit pre-jetted for the cl so I don't think the jetting is wrong.
Does anyone have any advice on getting this setup running decently?
As it is, the bike idles OK, but stalls immediately when I give it any gas at all.
I've scoured the net looking for any info about beginner installation of these carbs and I can't find any info...

HELP!!!

Todd.
 

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Two immediate possibilities.... The float level is set wrong, and it "runs out of gas when you open the throttle...... Second one... the main needle (in the slide) is too low allowing too much air before the liquid flow comes into play... Same result.... (lift the needles a notch or two in steps until it "cleans up")

Did you "throat" the intakes to "match" the larger venturi size so the incoming mixture flows smoothly (without obstacles)?
 

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Discussion Starter · #3 ·
Hey, thanks for the reply!
I'll check the float level tonight and see if that helps.
Also, I wonder about the pod/air filter setup that came with the kit.
I've heard about people wrapping duct tape around the pod to keep it from letting too much air in, but I don't know much about that...
I don't know what you mean about throating the intakes to match the venturi size...the mikunis fit perfectly where the old carbs pulled out.
Sounds like I'm in for some serious trial and error.
I'm still surprised no one has written a basic how-to online regarding installing mikunis...
 

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Just because the OD of the carb "fits" in the manifold, doesn't mean it can or will flow properly..... Throating is the process of making the " bore" of the carb match the intake portal size without "steps" ....... Measure the ID of the manifold right at the "lip" where the inserted carb stops.... measure the ID of the carb at the end of the spigot, where it will abut that lip... if they don't match in size, the incoming mixture will "hit" the step, reducing the flow rate...It must transition smoothly from the carb venturi to the intake valve portal to achieve maximum efficiency.... Think of it this way... A barrel will roll smothly down an inclined ramp, but not smoothly down a set of steps (stairs)....
Throating eliminates any "steps"...
 

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Todd, does your bike start OK. You say it idles OK, but dies when the throttle is advanced.
See if you can find what jets & needles are installed in the "pre-jetted" kit.
We gotta know where we are starting from.
Here's a recommendation from this webpage: http://www.postdiluvian.org/~mason/moto/jetting.html
Honda CB350 racing Mikuni VM32 Main:200 Pilot:30 Needle jet:p8 Needle:6F5 Air jet:2.0 Slide:2.5

A road machine will require more conservative main jet and needle jet.
Also, check this page: http://www.caferacer.net/forums/topic.asp?TOPIC_ID=6799

I suspect a 200 main to be way to big. Notice one guy on the caferacer forum is running 130's.
No intake leaks? Fer sure?
I've spent considerable time tuning the Suzuki T500 Mikunis on my 450. Few more things to iron out.....
Nate in PDX
 

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Discussion Starter · #6 ·
Hey, I'm in PDX too!!
Maybe when I get a little further along I'll bug you to help me in person...
I'll look into these things and then post again.
Thanks for the advice!
Todd in PDX too.
 

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Good to hear from a fellow P-towner. At least it's not spittin' snow today!!!!
After checking several webpages, looks like the VM32 may come with a 6F5 needle. I been dorkin' out on needle charts lately and looked at the 6F5 needle. Looks like it dumps a whole bunch fuel in just after the needle starts to rise out of the needle jet. This could be your problem....assuming the carbs have 6F5 needles. and assuming everything else is hunky-dory on your machine. I'm running 6DH7's right now and want to try the 6DH3. Looks like a shallower transition from idle to 1/2 throttle.
Blah blah blah
Nate in PDX
[attachment=0:24rcjpdn]Mikuni needles.JPG[/attachment:24rcjpdn]
 

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Discussion Starter · #8 ·
I feel like a real idiot, but I'm new to aftermarket carbs/pods and I didn't know I had to put oil in the air filter.
As you know, Nate, the weather has been rainy/sleeting in portland and I'm pretty sure that was the main culprit of my bike running like ****, because today a friend of mine casually asked "what oil did you use in the pods?", to which I replied "ummmm...".
Anyway, I bought the oil, oiled the pods, and the bike fired right up and rode nicely.
The funny thing is: now, after oiling the pods, the off idle acceleration is snappy but the mid range rpms are kind of choppy.
Would the oiling have changed my air intake that much?
Also, the stock airbox won't quite fit around the pods...will the oil seal out the rain, or does this mean I can only ride on dry days...???
Anyway, thanks for the info.
I'm sure as I keep riding it, I'll want to try different jetting, so the advice is much appreciated!
Todd.
 

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Discussion Starter · #9 ·
Got everything set up, seems to be running ok.
Carbs need more tweaking though.
Any advice on how many turns out to start for the mixture screws?
Thanks! TOdd.
 

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i am having problems with my mikuni vm32 carbs too. I go them from sudco and they came with some pods of unknown brand. should I have oiled the pods?
They look to be paper filters and I thought that you only oiled foam filters.

set me straight please, Dustin
 
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