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Discussion Starter #1
So I put VM32's on my CL360. Test rode it for the first time yesterday. Had to lower the needle to the leanest setting or else the bike would hardly run. It ran fine but when I came back and looked at the plugs, they were very white and very lean. So I upped the needle once. Very hard to keep the bike running and had to retune and readjust the idle etc. Am I in need of other than stock jets would you say?

Also, throttle issues. Very poppy throttle. The actual mechanism is very unfriendly. I cannot really ease into first gear off the clutch with out really pushing it because the throttle is so stiff.. I am speaking of the hand grip throttle mechanism, the lines are fine I've checked them without the grip on. I have messed with the wheel inside of the hand grip throttle that the line is carried by, did some good. But eventually was there again to pain in the ass.. Any good recommendations for a throttle plastic grip for these bikes other than the stock ones that come with the Mikunis?
 

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supplied information is not methodical nor is it referenced to throttle positions and loads

you don't even mention jetting, slide cutaways, or much of anything else

impossible to give any advice that isn't blind folded dart throwing

have you even made any attempt to study a mikuni tuning manual?


don't use any of the plastic twist throttles.... they are garbage

also make sure your cables are of proper length so as to allow nice flowing runs and confirm they do so from steering lock to steering lock

if they don't flow well, then you need to change their length and/or reroute

quote:Originally posted by Hamburg

So I put VM32's on my CL360. Test rode it for the first time yesterday. Had to lower the needle to the leanest setting or else the bike would hardly run. It ran fine but when I came back and looked at the plugs, they were very white and very lean. So I upped the needle once. Very hard to keep the bike running and had to retune and readjust the idle etc. Am I in need of other than stock jets would you say?

Also, throttle issues. Very poppy throttle. The actual mechanism is very unfriendly. I cannot really ease into first gear off the clutch with out really pushing it because the throttle is so stiff.. I am speaking of the hand grip throttle mechanism, the lines are fine I've checked them without the grip on. I have messed with the wheel inside of the hand grip throttle that the line is carried by, did some good. But eventually was there again to pain in the ass.. Any good recommendations for a throttle plastic grip for these bikes other than the stock ones that come with the Mikunis?
 

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Discussion Starter #4
quote:Originally posted by coreyjdl

needle controls between 1/4 and 3/4 throttle, if its lean on idle, you're looking at adjusting something completely different. study a manual.
No it's lean overall not just idle. It was lean after a 20 minute test run. I'll study my manual! Everything is completely stock on the VM32.
 

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quote:
No it's lean overall not just idle. It was lean after a 20 minute test run. I'll study my manual! Everything is completely stock on the VM32.
That means nothing. The VM32 is not the original carb for that bike, so the word "original" means nothing here. That just the jets they stuff in the carb in order to sell it.

Get yourself a Mikuni Tuning Manual from Sudco, or anyone else who sells them. Read it, know it, love it.

http://www.sudco.com/tool.html#002-999
 

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Here is a simple rule to start with on any carburetor jetting.
1. Get the main jet right.
2. Get the needle / position right
3. Get the pilot jet right
4. Get the air/fuel screw right
5. Get the idle screw/adjuster right

Do it in that order or you will not get it right very easily. Carbs are not plug and play. This does not even take into account slide cut away, needle profile, needle jet or float level.


Ken
 

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Your throttle quadrant should be fine for this carb, recheck how your cable is connected to the carb... Also check how the return spring is set on the carb - is there an adjustment to the return spring???

As far as your lean condition - that's all set up with the main jet. Return the needle to the middle position and go up one or two main jet size and give it another try. If it's still running lean, go up another main jet size. Setting the needle up or down is for fine tuning the carb for 1/4 to 3/4 operation.

Hacksaw- I'm looking for a new twist throttles for my CB - is a non plastic one available and where can one be ordered??? .
 

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quote:Originally posted by bmartin



As far as your lean condition - that's all set up with the main jet. Return the needle to the middle position and go up one or two main jet size and give it another try. If it's still running lean, go up another main jet size. Setting the needle up or down is for fine tuning the carb for 1/4 to 3/4 operation.

Hacksaw- I'm looking for a new twist throttles for my CB - is a non plastic one available and where can one be ordered??? .
as far as lean across the board being fixed with merely the main jet.... I don't think so

metal for a brit will work.... pretty sure

thinking the UJM ball ends are close enough to fit where the Brit barrel ends go

if not........ there are plenty of other vintage euro twist throttles that will do the deed
 

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Discussion Starter #9
quote:Originally posted by kenessex

Here is a simple rule to start with on any carburetor jetting.
1. Get the main jet right.
2. Get the needle / position right
3. Get the pilot jet right
4. Get the air/fuel screw right
5. Get the idle screw/adjuster right

Do it in that order or you will not get it right very easily. Carbs are not plug and play. This does not even take into account slide cut away, needle profile, needle jet or float level.


Ken
Thank you for your advice!!! I was looking for something along those lines, not someone telling me to read a manual which I already have. I've read bits of the manual. And I've had a tech look at the bike too... And I never said anything was "original" i said the VM32 is stock in it's sold form means no new jets!!

Think some of ya should read what I was writing before you jump on me! I just wanted some tips. Thanks
 

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Discussion Starter #10
quote:Originally posted by bmartin

Your throttle quadrant should be fine for this carb, recheck how your cable is connected to the carb... Also check how the return spring is set on the carb - is there an adjustment to the return spring???

As far as your lean condition - that's all set up with the main jet. Return the needle to the middle position and go up one or two main jet size and give it another try. If it's still running lean, go up another main jet size. Setting the needle up or down is for fine tuning the carb for 1/4 to 3/4 operation.

Hacksaw- I'm looking for a new twist throttles for my CB - is a non plastic one available and where can one be ordered??? .
Well like I said above, If I go above the lowest needle height, the bike will barely idle and stalls out easily. If I go one above that, it won't even start.. Which is why I was asking about jet size. I figured that was my issue here.
 

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VM Mikunis don't come with original anything. They are set up either for a 2 stroke or a 4 stroke. Who knows what you have except the guy that sold them to you, maybe. They could be entirely wrong.
Ken
 

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you might want to post the various jet sizes and float levels in here so it can be determined whether or not your in the ballpark to begin with..slide cutaway,needle#,needle jet size,pilot and main jet sizes..i can post some specs i found for using Mikunis on some various bikes if you like.Might give you a start/reference point.just my 2 cents worth.
 

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Here’s a link to a PDF file on VM carb tuning and theory. The very bottom of it shows the circuits and the affect they have on throttle positioning (carb circuits).

http://www.mikuni.com/pdf/vmmanual.pdf

Taken from here

http://www.mikuni.com/c-manuals.html

Here’s a link that tells you to put a pin in the hand grip to help with diagnosing where the problem is and how to figure out what circuit needs attention (under “It just ain’t running right”).

http://www.motorcyclecruiser.com/tech/motorcycle_jet_kits_carburetion/index.html

The VM carb is a very versatile carb and is used on many different bikes (2 stroke. 4 stroke, etc) and have different jets (fuel and air) for different applications. They also have different main fuel system (primary and bleed type- emulsion tubes) for different applications. Just because a carb fits on your manifolds, doesn’t mean it will be a bolt on and work easily.


Heres a better link that shows the pin the the hand grip
http://www.motorcyclecruiser.com/tech/find_carburetion_problems/index.html


DG
 
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