Mikuni T34 on stock motor, any good jetting start point?

[Slick _James187]

Hello all, I'm new to blaster forum.
I just got my cousin's 03 running again, been sitting 7 years.
He put this carb on way back, and he was running a vito's 240 kit.
I'm not even sure if he ever jetted this carb.
I put it all back together stock motor, VF3 reeds and a capped boost bottle spacer plate.
FMF Fatty and power core 2.
It runs descent but seems lean up top.
I'll pull it back down tomorrow and get the jet sizes.
Anyone got a good starting point?
I'd really appreciate any knowledge you guys can kick my way!

 

[Awk08]

so you're saying it still has the mikuni 34 now on a stock cylinder ?
if so, thats too large a carb and may always run lean due to the reduced air velocity pulling thru the carb and over the jets.
stock to mildly modded cylinders run best on the stock 26mm carb

 

[Blaaster]

You may very well be able to get the large carb to work reasonably well after a lot of time and effort but it is never going to be impressive in the low rev range due to the reason that Awk stated.

Your best bet is to use the stock 26 mm carby.

 

[Slick _James187]

Yep stock cylinder.
Thats what I was thinking, but my cousin lost most everything to this bike including the stock carb.
I'm not sure i'll be able to talk him into picking up a 26, but i'll try.
Thanks for the info guys!

 

[Wifesblaster]

What happened to the 240 kit he was running?

 

[Slick _James187]

He still has the 240 jug, it needs resleeved pretty bad.
He still had the stock jug and piston in almost new shape so we are trying to work with it.

I've poured alot of time into getting this turd going lol
I sure hope he decides to get the smaller carb!
If its too lean and he trashes the motor, I may cry!

 

[Blaaster]

At least if you cannot convince him into swapping back to a stock carby, try to convince him to plug chop at 1/2, 3/4 and WOT.

 

[Slick _James187]

Ok, so no stock carb.
He ordered another 240 kit.
Now thats over with...

Any good start point with all the above and a heavily ported 240 jug?

There is an extra intake port cut in above the original
The exhaust port has two smaller port holes coming in from the sides.
This pretty common porting?

Also forgot to mention we ride from 500ft elevation on up to 1500-2000
And summers are 115 here, would rather be a little on the rich side in the heat.
We run Motul 510 at 32:1

 

[Wifesblaster]

You might just have to play with the jetting some. I would put a 35 pilot in and see where your air screw is. Put a 330 main in and see how it feels for rough tuning. Leave it rich for break in and then plug chop for fine tuning. The needle selection will be he hard part.

What jets were in the carb when you took it apart? I have to assume the jetting would be close to what was in there before since he was running a 240.

 

[Slick _James187]

I still have not gotten around to pulling the carb.
He did say they played with a few sizes back then.
I may only end up having to play with the air screw and needle clip.
He only now told me the needle is all the way lean.
I'll let you guys know when I find out what jets are in it.
Thanks for the info!

 

[Blaaster]

For break in do not exceed 3/4 throttle for 2 tanks of fuel.

Put the needle on the middle clip if it is the stock needle, you cannot afford to be lean.