Jetting with VH4-1 and KNfilter

Was running my kz1000 csr with a vance hines 4-1 on the stock jets (122.5 main), and everything was fine. Now I put in a KN air filter and I suspect its on the lean end...

would bumping it up to a 125 main be an appropriate adjustment to bring things back to normal.

Is any other carb adjustment needed?

The bigger jets would be the quickest and easiest way to go. They are cheap. Roy

I using #140 main jets and #40 pilot jets with the V&H megaphone and k&n's on my 82 1000LTD. Runs good.
hope that helps you.
Tom

Ah, the fun of jetting... this will probly take a while to get right, but if your patient, its not too difficult.

Well, theres no way to just guess the correct jets.

Your speaking of the K&N insert filter I'm assuming?
If it was ok before, but now its lost power, then its lean.

Get some mains like 130, 135, 140.
A size up on the pilot should be fine if it idled ok before.

Start with the main by doing some wot pulls with the 140. Then go down to the 135. If it improves, great. Try the 130's. If it doesnt inprove then put the 140 back in. Lots of guys have had good success with that one, and it should be rich enough.

Do the needle next with half throttle pulls. Then move the needle clip up a slot and see if it improves... You get my drift.

Setting the pilot mixture/air screws: My method is to have the bike idling, then give it a 1/4 throttle blip. If the rpms fall below the idle rpm, lean the screw a 1/4 turn then repeat. If it hangs obove the idle then rich the screw.
I find this gives the best off-idle feel while riding.

Good Luck and patience...

Cheers.

yeah its a drop in filter (stock air box)

its idleing fine, is it still nessary to change to pilot jet?

wow, a 140 main, a KN really makes that much difference?

btw, wishful thinking here, but is there some secret way to change jets without removing the entire stinkin carb rack?:laugh:

I thought you had pods, my set up is with pods so wouldnt be right for you. :blush:
Tom

squints wrote:

btw, wishful thinking here, but is there some secret way to change jets without removing the entire stinkin carb rack?:laugh:

I replaced my carb bowl screws with allen head screws. I bought a bag of them from McMaster-Carr, along with lock washers to fit them, and installed the allen screws the last time I had my carbs off. I then took the right sized key off of one of those folding multi-size hex key sets, they have a loop bent in the end where they fold into the holder, I stick a stubby screwdriver in the hole and use it to get enough twisting force to loosen/tighten the bowl screws while they're on the bike. With the allen screws I can be sure of how tight I'm getting the screws, as opposed to slipping with a phillips and hoping.

If you're lucky you can get the phillips screws removed from the carbs while they're installed, then replace with allen bolts if you desire. Once the bowls are off, I just use an 8mm (or 5/16") box end wrench to remove the intermediate jet which has the main jet screwed into it, then hold the intermediate in the wrench while using a screwdriver to get the main jet out of it. The main jet is too close to the top of the transmission to fit a stubby screwdriver in there, so removing the intermediate/main together is the way to go.

to be honest everything appears to be runnin ok as of today. I just thought that the exhaust+KN filter would result in running lean.. what should be an expected jump, one or two main jet sizes up? any adjustment on the needle??


thanks

My bike ran ok before the jets were changed but after the carb work I found out what I was missing. Way more power
like night and day. :woohoo:
Tom

So I checked the plugs and the tips were a little carbon fouled and white. That means I am definately Lean... will bumping up the main correct this, or will I have to play with the needle as well?? Thanks

This should be all the information that you need:

scootrs.com/tech.cfm?tip=tunecarb

Jetting can be easy if you have patience and time. Seat of the pants tuning is the best.

Just remember, 1 change at a time!

Cheers, goodluck!

that is perfect, thanks