Re-jet absolutely necessary?

[FlyingSteve]

With just a stock style K&N replacement filter you could more than likely get away with out a rejetting. However, when you mess with the exhaust then you MUST re-jet. A better flowing exhaust system will allow the engine to take in more air, doesn't matter if you have the stock intake setup with a stock filter or pod filters.

[850 Combat]

So...

Got a nice stock exhaust you want to part with?

[GabrielGoes]

So...

Got a nice stock exhaust you want to part with?

lol that is a great comment

[BassCliff]

It came w/ K&N filter in stock air box which is why I thought it might have already been re-jetted. What sizes should I go up and who should I order them from.

Hi,

Mr. salty_monk mentioned that with his bike, a K&N filter in a stock airbox with 4n1 pipes, he went up 2.5 (one size) on his main jet and turned the idle mixture screw out another whole turn. But you might have to go up two sizes on your mains. To be sure, you have to perform plug chops and read the plugs at each throttle setting to be sure you have the right mixture for each carb circuit. There are notes about plug chops on my website and guides for carb tuning, such as:

For CV Carb jetting, see the very informative article at Factory Pro. Also see the carb jetting tips at Motorcyclecarbs.com, Inc.

Mikuni Motorcycle Carburetor Theory 101 - from Ian Williams Tuning

See the vendor list in the READ ME file for carb parts vendors.

Thank you for your indulgence,

BsssCliff

[TeamDar]

My new V&h 4-1 came with a sheet of paper with jetting recommendations to use with the pipe. It says for an 80-81 1000 to go to a 125 main and a 42.5 pilot.

You left off the important part about removing the stock air box lid. If you skip this part your bike will run too rich.

[twr1776]

I agree with the other opinions that you can do it yourself. Have you done the intake boots, o-rings, airbox to carb boots, and re-sealed your airbox? You will need to do this first IMHO to have a good baseline for tuning.

I have the same set up on my 1000 with CV's and went one over on pilots (42.5), two over on mains (120) and shimmed the needles with three washers. Use OEM Mikuni jets, they are available from many sources. You should do the plug chops but either Salty Monks set up or mine should get you close enough to fine tune from there.

[ZoSo750]

I have the same set up on my 1000 with CV's and went one over on pilots (42.5), two over on mains (120) and shimmed the needles with three washers. Use OEM Mikuni jets, they are available from many sources. You should do the plug chops but either Salty Monks set up or mine should get you close enough to fine tune from there.

I'm not trying to hijack or stray from the OP's post, but I did the same (42.5 pilots and 120 mains) to my 82 750 with V&H 4:1 and pod filters. Should I think about shimming the needles too while I'm in there? It didnt run when I bought it but the carbs were frozen solid for the most part so I'm confident that was my problem.

[gearhead13]

I'm not trying to hijack or stray from the OP's post, but I did the same (42.5 pilots and 120 mains) to my 82 750 with V&H 4:1 and pod filters. Should I think about shimming the needles too while I'm in there? It didnt run when I bought it but the carbs were frozen solid for the most part so I'm confident that was my problem.

You will need a MUCH bigger main with pods and 4-1 on that 750. The DJ kit comes with main air jet correctors which allow you to use a much smaller main to be used, and with the correctors you need to use a 130dj or about a 120 mikuni main.

http://www.dynojet.com/pdf/3315.pdf

[kng254]

OK so II think I'm going to jet them myself with 42.5 pilot and 120 mains and shim the needles. I went to the sudco website but I'm not sure about the carbs do I look for pilots and mains for a bs34ss or vm34,and where do I get and what size washers do I shim the needles with?

[gearhead13]

The jets need to be for a bs series carb. The pilots are bs30/96 and the mains are 'large round'
Radio shack is a good place for the washers.

[Steve]

Just be sure to shim the needles correctly.

The shims do NOT go below the clip.

They will replace the thick nylon spacer above the clip.

.