31k carb swap

[davey]

What difference if any are the 31k carbs to the 4l0.
I have a set of 4lo carbs and a 31k with the american carb system on and was wondering if i could swap em as i dont like the us version as they have a lever system and not two separate tops.

Thanks guys

[rich]

So, let me get this right you want to fit a pair of UK 4L0 carbs to a US RZ350 to replace the linked carbs? Yes they will fit and work fine. You will need to fit bigger mains though, I suggest 240 as a start. Might need a UK throttle cable too.

Good luck

[davey]

Thanks rich for the info , just what i needed to know mare

[seahorse83]

just for info not all 31ks have the link on the VM26ss Mikuni carbs.
As far as I am aware the Aus delivered 31k carbs, are all NON Link, NON Power Jet Mikuni VM26ss carbs.

There is a difference, between the 4LO and the 31k carbs, particularly the Jet needles in the 31k which are a 5Ki needle and longer by about 3 mill, and not as sharp a taper.
I know this a s I was playing around with needles 2 days ago, took some 4lo needles and tried them in the 31k carbs, they work, but not very well, in-fact I found a fantastic flat spot. SO back to a 5ki needle that works best in the 31k carbs.

The 31k carbs have a vaccume take off on the right carb, the 4L0 does not. The float bowl drains are better on the 31ks for setting a clear line float level check, the 4lo just has a drain that's it.
Im sure the 4lo would work on the 31k bike, but it will be interesting to hear your thoughts on the swap. You may have to swap your fuel tap as you wont have a vac anymore to work the 31k fuel tap.

Food for thought