How is your carb jetted for K&N and megaphone?

[mypvtidho]

If you are running the K&N cone filter and the megaphone muffler with the stock VM28 MICARB, what jets are you running and what notch on the jet needle?
PLEASE ONLY REPLY IF YOU ARE RUNNING THE ABOVE EQUIPMENT.

[jedaks]

I have used a K&N on a Mikcarb, and I do run a Goldstar straight-through. If that is any help to you....

First, you need some way to support the back of the carby so the rubber inlet tube isn't supporting the weight..you will get air leaks which will mess up your jetting and add confusion. The cone filter lets in lots of air so you need richer jetting to compensate or you WILL ruin a piston, which WILL put molten shards of metal all through your engine. I have experience with that.

Before I knew better, I ran a cone filter and free flow muffler with the stock jets of 25 pilot jet, P0 needle jet, clip on the 4th groove and a 120 main jet. That was too lean. An engine rebuild taught me the lesson the hard way.

I live at sea level so the jetting I use is a P2 needle jet, the needle clip in the lowest groove and a 127.5 main jet. The pilot jet is 27.5 That is appropriate for my situation. However I now use an Ace Canister, which I think is better than a cone filter. The carburetor is drawing from a supply of still air.

Anyway, I hope this is of some help to you.

[mypvtidho]

Yep. Thanks. I was looking for a comparison.
I also am at sea level, am using a 30 pilot, 135 main, and A5DH7 needle (bottom groove) on unknown needle jet.
Still having issues at around 1/8 throttle. All other areas runs good.

[ace.cafe]

Your main jet is too rich. Try a 130.
Problems at 1/8 throttle position are often related to the throttle slide or the needle jet needing to be richer, or both. This is a transition zone from the pilot circuit to the needle jet circuit, and the transition is helped by the throttle slide cutaway.
For sea level, a P2 needle jet is commonly needed.
The carb comes with a 4.0 slide. People sometimes need a 2.5 or a 3.0 throttle slide if the richer needle jet doesn't solve the problem. But the richer needle jet is needed anyway. The stock O8 needle jet is too lean for sea level operation with a free-flow system on the bike.

The needle jet is Mikarb-specific, and cannot use a Mikuni brand needle jet. You have to get it from NField Gear or Hitchcocks. The throttle slide can use a Mikuni brand slide from a VM28 with the proper cutaway specified.

These items are the most expensive parts in the Mikarb, and that's why the stock ones are often left in the carb, and why it is hard to tune unless you put the right ones in.

I would buy the P2 needle jet, and see if you can tune the problem away with that. If the problem persists, then you can get the throttle slide with the richer cutaway.

[greekxj]

I have the K+N also with a wide open Goldstar and 28 mm carb. I have a 130 main, 30 pilot, P2 needle jet, needle on bottom notch(stock slide btw), 1.5 out on the air screw if a remember right. Its been a while but that's what i got if i remember correctly. It took me a while to get it set but the thing that really helped alot was the P2 needle jet. Forget the stock one, and i even went to the P0 first with no luck. Runs great now though