TOPIC:

Hi all,

This topic has been very helpful so far but I’m hoping the group here can offer some advice. I just bought an 81 kz440 project with what looks like the 2:1 manifold described here and a single Mikuni VM30 carb. The previous owner did the conversion (I think) but never got the bike back on the road.

The bike will start and run only with the choke on and dies immediately when the choke is shut off no matter how warm the engine is. The carb looks practically new inside and out, has a 26 main jet and a 55(?) pilot jet. 

*the only character I can make out on the pilot jet is a 5 followed by some other character so I’m inferring the 55.

My initial thought was the pilot jet was way too small or clogged if the bike wouldn't run without choke, but based on the setups mentioned here 55 sounds really large.

Alternatively, is a single VM30 even a reasonable setup for this motor? I see twin VM30 kits online for this bike and most of the posts here have referenced larger carbs.

Suggestions appreciated to help me get this thing running!

 

A 26 main jet is to lean (could be 260???) and a 55 pilot jet too fat. Are you sure your jet readings and positons are correct? Do you read all sites of the topic about the jet sizes?
 
 

For Jetting, I went with a #35 Pilot jet (it came with a 25), and a 170 main. It came with a 260 main but I purchased several jets ranging from 160-200. I knew a 260 would be too big.

 

 but it runs extremely rich, so i have went down to as low as a 17.5 pilot and a 140 main

 

I'm using a #30 pilot jet, #170 main jet , needle clip at 1st position ( the tip top), air screw 3 turns out and a K&N high flow air filter to top it off (helped a bunch for getting extra air) .

You’re right, main jet is a 260 and pilot jet turned out to be a 35 and a lot more clogged than I realized when I looked at it the other day. I went down to a 25 which is closer to correct. Thanks again.