What way to set up 4L1 carbs on 4L0 barrels

[soccersmyth]

A mate has a std 4L1 and has a 4L0 top end ready to go on.

The carbs he has are 4L1 00.

Indending to use the 4L1 std pipes and air box to if he can,
but ram air pods and large can alspeeds available if they need to be used.

Any pointers to what the jetting, needle position and air screw set up should be


Thanks in advance if you can help.

[Delbert]

I am using 4L1-00 carbs on mine , 4L0-01 top end ,, after much playing about I ended up with 25 pilots 180 mains 5k1 needles on the second notch from the BOTTOM , air screw one turn out , std pipes & air box & fibre reeds . Runs really well , no flat spots or the like , obviously all bikes will differ but may help

[Delbert]

Just to add , I couldnt go larger on the main with out it bogging down ,,, strange you may think , I put it down to the limited air flow through the 250 carbs as they have a smaller pre drilled air passage ,so they are limited as to how much air the larger top end is trying to suck through so it becomes too rich , hope that gargle made some sense

[soccersmyth]

So it's do-able.

Your setting could be used as a start point then,
and see how it goes.

Thanks for the reply

[Delbert]

I cant seem to edit my post fir some reason ..
I made an error with the needle clip position , I have it set second notch from the top not bottom , sorry for confusion

[flames]

mine runs 250 carbs,but the internals have been changed to 350 internals.mine are set up as per 350 carbs.carbs were like this when i bought it 21 yrs ago,so cant say how they run compared to standard,coz its all ive ever known.always pulled well tho.

[Delbert]

I have heard of people drilling the air passage to that of 350 carbs ,,, interested to learn more

[arrow]

Has your mate got the correct 350 oil pump and the course worm to go with it? The 250 pump cannot shift enough oil for the "bigger" motor.