VM26SS main jet sizing in thousands of an inch?

Has fuel level been confirmed within specs by performing the clear tube test?

Too low fuel levels could result in running lean in all throttle positions.

Good Fortune!

Patton wrote: Has fuel level been confirmed within specs by performing the clear tube test?

Too low fuel levels could result in running lean in all throttle positions.

Good Fortune!

Sure has....one of the first things I did with the help of this site. When I got the bike the PO was leaving the fuel tank empty because it would leak all the fuel out of the overflow tubes on the carbs.

Besides the petcock not shutting the fuel off, the bowl levels were way out of spec. The PO told me he had adjusted the floats to all be even, and they were. However I dont think he knew they are supposed to be adjusted to not only all be even but also to be at a certain level. When I first tested with the clear tube method the level in all four carbs was actually over the bowl gasket.

I think this excessively high fuel level was masking how lean the bike was jetted. The PO only owned the bike for 3 months and only put 300 miles on it.

The short of it is that the PO purchased the bike from the original owner. The bike had not run in years so he did just enough to get it kinda running. He then either decided he didnt feel like messing with it or figured it had major problems (because he couldn't get it running right) so he sold it.

Since I bought it I have had to undo alot of the stuff he did and fix a few minor things here and there and now its starting to run great again!

BTW.....just got the Kawasaki service manual for it yesterday! That book is going to be a major help!

Here's a very good jet cross reference post :

www.hondaatvforums.net/forums/repair-mai...-dynojet-mikuni.html

I found that thread but didn't trust it. Because before I drilled out my 115 mains I could only get a #58 (.042) drill thru it, according to that post I should have been able to get a 3/64 (.0469) thru it but couldn't. But my mains are not OEM, they are aftermarket from Z1E. So I dunno, maybe the aftermarket ones are not the same size as the originals.

I drilled mine with a #55 (.052) drill and its still a touch lean at WOT. Next size up is a #54 (.0550), I might try that.

So I'm not sure exactly what size mains I am going to need. I'm thinking about 125ish now.

A #55 bit would work out to a 132.1 jet - I would think that would be a bit too large, but you are there and I am not so you have to go with what is working for you.

IIRC once upon a time Z1 had a drill to jet cross reference up on their site, but I just did a search on their new site and came up empty. I would link you to it but can not find it. I have in the past pulled the chart down to my pc but an not sure it is kosher to post it here with out Z1's approval.

I will point you to this location home.comcast.net/~loudgpz/GPZweb/TK22mai...22jetsAndDrills.html Where member loudhvx has a couple of tables on jet to drill sizes - look at the bottom of the page in the link.

gd4now wrote: A #55 bit would work out to a 132.1 jet - I would think that would be a bit too large, but you are there and I am not so you have to go with what is working for you.

A #55 (.052) drill would equal a 132 jet if the sizes really are in MM, but now I'm not so sure. Because like you I believe that would be WAY too rich and I still seem to be a touch lean at WOT.

Plus before I drilled my 115 mains I could get a #58 drill (.042) thru them but no larger. A #58 drill = 1.07MM = 107 main, but my mains were marked 115.

Now we could assume that a hand drilled bore in the jet will not flow fuel as well as a machined bore from the factory. But that still doesn't explain why my original 115 main was really only 1.07MM if they are really sized in MM.

My plan is to give Z1E a shout when I figure out what size drill makes it run the best. Hopefully they will be able to cross that over to the main size.

Or probably not because I have a line on an original airbox and I would rather just go back to that setup. I know the original jetting, 105 main, 15 pilot and 3rd notch on the needle.

But I might try staying with the 17.5 pilot I have in there now and see how it runs. I have read threads saying some bikes were jetted lean from the factory. Was that the 1977 models or the later early 80's bikes?

Any markings on the main jet to indicate who made them.

There are differences between the different makers in how they lable sizes. See attached table. Maybe the jet you have is not a Mikuni but rather a Dynojet or Keihin.

gd4now wrote: Any markings on the main jet to indicate who made them.

There are differences between the different makers in how they lable sizes. See attached table. Maybe the jet you have is not a Mikuni but rather a Dynojet or Keihin.

I dont remember seeing anything other than the 115 on them. Do the different brand jets all fit the VM26SS carb? If so then it they could very well be a different brand. The PO changed the jets after he put on the pods.

Now I have to wonder if the pilot is different also. I have no idea where he got the jets. Or how he decided on the sizes he used, because they were WAY too lean.