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Carbs and Fuel System
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Thread: does my carbs needs to be tuned? Reply to Thread
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  Topic Review (Newest First)
11-18-2017 05:26 PM
eltiti21 put 1 shim, on each carb, they are around 0.8cm on size, bike seems to be responding better, less bugging now on those RPM but still hesitate a little, and runs now kind of rich i guess i will try to run it a little before checking the plugs and see where im at, still some back fires at low RPM 1-2k on front cylinder.
11-07-2017 02:56 PM
eltiti21
Quote:
Originally Posted by Spockster View Post
You're welcome, happy to help.

Not the air screws, the shim under the slide needles.
got it, i'll order a shims pack and put one to start by there on each carbs
11-07-2017 01:27 PM
Spockster
Quote:
Originally Posted by eltiti21 View Post
okie, i will turn it out a bit more see if it helps, thanks for your comments and knowledge, i highly appreciate it.
You're welcome, happy to help.

Not the air screws, the shim under the slide needles.
11-07-2017 12:22 PM
eltiti21
Quote:
Originally Posted by Spockster View Post
Could be the transition between pilot + main is a bit lean, the slide needle should help with that.
okie, i will turn it out a bit more see if it helps, thanks for your comments and knowledge, i highly appreciate it.
11-07-2017 11:28 AM
Spockster
Quote:
Originally Posted by eltiti21 View Post
took the spark plugs out and they have that brownish color, like cooper color on both cylinders. i think they are burning right. just dont know why i'm getting that hesitation at light throttle around 4-4.5K rpm
Could be the transition between pilot + main is a bit lean, the slide needle should help with that.
11-07-2017 09:33 AM
eltiti21 took the spark plugs out and they have that brownish color, like cooper color on both cylinders. i think they are burning right. just dont know why i'm getting that hesitation at light throttle around 4-4.5K rpm
11-06-2017 01:12 PM
Spockster The slide needle can make big changes in the fuel ratio. Some needles have multiple grooves so you can just move a clip into another groove, but on the VN we have to use shims.

On my 2-stroke, one notch on the slide needle takes it from burbling rich, to screaming wheelies at 10k rpm.

I haven't had to rejet my VN carbs or change anything except to get the dirt out. Stock pipes though. It might take some trial and error to get the shims right, but it's better than being too rich and not knowing it, that can lead to bad carbon buildup.

Keep an eye on the spark plug color, just pull the plugs that have no deep well, no need to check both on the same cylinder.
11-06-2017 12:31 PM
eltiti21 sounds good, will order a shim pack and start there i just i don't have to putt out the carbs again (5 times already) to install this
11-06-2017 11:39 AM
Spockster Could be it was so lean, no combustion or very little was able to occur, so adding fuel lit the fuse. Of course shorter pipes will be hotter just because of less surface for heat transfer.

I would start with one shim and go from that. Size, I'm not sure, but there's some info around here on that. The shim allows the slide needle to be higher, letting more fuel in, at a given throttle opening.
11-06-2017 11:31 AM
eltiti21
Quote:
Originally Posted by Spockster View Post
Well, a lean condition causes combustion temp to rise. Rich will make it cooler.
you are right, but i give it a bit more fue and got better and hotter, any idea why? and what size of shims should i use or how many?
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