New member with a jetting question

[Turbo]

Hi folks,
I have just purchased a 2004 blaster, it has many upgrades not all I am familiar with, however this I have been looking into, it has a vito's 240 bbk fitted by the previous owner, after he installed it he couldn't get it to run and gave up on it, he had no jetting knowledge ect, it's running a stock carb with k&n filter, I have installed a 35 pilot, & 280 main, it is still too lean, the needle is a 5n7, my question, is the needle stock? If so what needle would be good with stock carb?

I am planning on getting a bigger better carb in the near future.
I am in the United Kingdom.

 

[Awk08]

list all mods....pipe, airbox lid on/off ?

not going to find much info here on a stock carb feeding a 240bbk cylinder, most everyone upgrades the carb when going to a 240

your pipe, filter and airbox lid on/off will make more of a difference in jetting than an unported 240 cylinder.

 

[Turbo]

It has a Paul turner expansion chamber, FMf rear silencer, k&n filter, no lid, no tors, pyramid reeds, I thought the vito's bbk kit was ported?

 

[Blaaster]

#310 - #320 upward.

#32.5 pilot

Plug chop to confirm.

 

[Turbo]

This is what is happening, my throttle slide is fully closed, I have a 35 pilot installed, the air screw is 1/4 out from closed, any further out with the air screw & it won't start, and its hard to start now, when warm the bike idles with the throttle slide in the fully closed position this can not be right????

Jetting specs are
Std carb
Pilot 35
Air screw 1/4 out
Needle 5n7
Needle clip 5th (richest)
Main 280

 

[bummer981]

#310 - #320 upward.

#32.5 pilot

Plug chop to confirm.

Welcome to the forum.

You asked for help got it and ignored it. Your pilot is too big for the carb run the 32.5, as stated above. Your main is too small as stated above.

With your mods and the 240 you need a larger main to feed the beast when running. But the large pilot may be flooding it when idling.

 

[PRChrist]

welcome to forum... and buy a bigger carb like a 34 or 35!

 

[Herpderplol]

welcome to forum... and buy a bigger carb like a 34 or 35!

Yeh, all big bore kits should have a larger carb...

If you are interested, I have a 35mm mikuni carb, just pm me if you are I:I

 

[jus_me]

^^^^^^^ as stated. Plus herp has a bigger carb.. Not sure what your looking for though but with a 240 bbk most if not all upgrade to a bigger carb.

 

[Turbo]

Welcome to the forum.

You asked for help got it and ignored it. Your pilot is too big for the carb run the 32.5, as stated above. Your main is too small as stated above.

With your mods and the 240 you need a larger main to feed the beast when running. But the large pilot may be flooding it when idling.

I haven't ignored it at all, I know my main & needle are to small, however my pilot is too small not to big, my fastest idle is at 1/4 out with a 35 pilot, therefore the pilot is still too small also, I have taken the advice of the forum members and ordered myself a air striker 35mm carb, I am assuming I will need a larger intake manifold & modified air box ect

 

[Turbo]

Yeh, all big bore kits should have a larger carb...

If you are interested, I have a 35mm mikuni carb, just pm me if you are I:I

Thanks for the offer buddy, I have ordered a new 35mm.

 

[Blaaster]

This is what is happening, my throttle slide is fully closed, I have a 35 pilot installed, the air screw is 1/4 out from closed, any further out with the air screw & it won't start, and its hard to start now, when warm the bike idles with the throttle slide in the fully closed position this can not be right????

Dead right here it should not run or even start with the slide completely closed.

There must be an air leak somewhere.

Leak test and set the float height.

I have never yet known a stock carb working correctly with anything than a 32.5 pilot jet, there must be unwanted air entering the system.

 

[Turbo]

Dead right here it should not run or even start with the slide completely closed.

There must be an air leak somewhere.

Leak test and set the float height.

I have never yet known a stock carb working correctly with anything than a 32.5 pilot jet, there must be unwanted air entering the system.

Ok I see what your saying, how do I performed the leak down test?
Where are the known places that leak air???
Thanks for your input it is appreciated & very helpfull

 

[Turbo]

I have checked the float height as per the manual, it's spot on, I also checked the float needle and that is also ok

 

[Turbo]

I have just checked my altitude, I am 275m above sea level, higher the alt the richer it will run I guess due to there being less air, so jet leaner the higher you ride at and opposite if you ride closer to sea level.

 

[Blaaster]

 

[Turbo]

How To Perform a Leak Down Test – YouTube

Demonstrating a Leak Down Test performed on a Yamaha Blaster – YouTube

Spot on thanks, vety informative, will check & report.

 

[Turbo]

I have had a specialist to do the leak down test as I didn't have the equipment, they have confirmed its as tight as a ducks arse, I have now re jetted to these specs

Main 330
Needle clip bottom notch
Pilot 40
Air screw 1 1/2 turns out

It's now near perfect, starts first kick from cold ect ect
Just got to do plug chop, I figure the 240 bbk is just pulling masses of air through the 28mm carb & that's why it needs to be as above!!!!!

 

[Blaaster]

Running a #40 pilot has me worried.

Is the oil injection nipple on the carb blocked off?

I will say again I have never experienced a stock carb needing anything but a #32.5 pilot jet, air must be getting in somewhere.

 

[Turbo]

Running a #40 pilot has me worried.

Is the oil injection nipple on the carb blocked off?

I will say again I have never experienced a stock carb needing anything but a #32.5 pilot jet, air must be getting in somewhere.

I will check the carb and see, I haven't seen any nipple on carb????