44mm 650 carb?

[chrisdoc0608]

I am trying to help out a guy that bought my 650 group k motor with an idea abt where to start with jetting since he has a 44mm carb and not the 46 i ran. I asked harry and was told that the 44mm carb on the 650 has a different circuit than the 44 on the 701 and it could not be rejetted to work with the porting on the 650....

Im a little confused though, the motor is ported not re sleaved to a bigger bore. anyone care to give some incite why a 650 carb would not work with just bigger jets on a ported 650 motor?

 

[INDebtSJ]

I have a 685 big bore from harry. The setting he sent me was
633/685 BN 44 Slpr
low .75 turns out
hi 1.75 turns out
pilot 110
main 125
seat 2.5
spring 65
pop-off 10

 

[SUPERTUNE]

Any aftermarket SBN 44/46 will work, as well as a 44mm off a 701 waverunner III only.
These carbs have a 4 hole fuel circuit in them. The stock 650 44 carb is a 3 hole circuit and no matter what jet you put in the 650 it will not jet right for a high performance engine.
Just like a set of stock 760cc OEM dual 44mm's, same problem with them, as well as a funny throttle plate in them for lean burn, fuel efficient, emissions friendly carbs. NOT for hi performance IMO, As just about every aftermarket race carb company uses new aftermarket carbs to start with for this reason.:deal:

 

[INDebtSJ]

I did send the carb origanally to harry with the motor way back when. He may have done some internal mods to it then.
The numbers that I used was when I put that motor in a different ski and asked Harry what the setting should be.

 

[chrisdoc0608]

chucky, althought this motor is ported, it will be used with a stock exhuast and stock every thing... its going in a mans vxr and he has no intentions of modding it (for his kids). since he is not after top preformance would it be feasable to use the 650 carb and still acheive a decent running ski in comparison to a stock motor without the porting?

thanks


btw, would you happen to have a picture of the difference in these carbs?

 

[SUPERTUNE]

No I don't have a pic, But easy to tell.
Hold carb upside down, open throttle plate all the way open, then look at the jet side of the throttle bore-under the bombsite and you will see a series of holes running top to bottom, 3 holes in the bore will be the 650 carb, 4 holes will be all other I talked about.
Size order of holes are: 3 hole carb=big,small,small 4 hole carb=small,big,small,small
There is also a much bigger hole over by the low speed adjuster, that is the idle/pilot circuit.
These holes control the midrange/partial throttle this is where the VXR will be running when riding lets say 2 up, pulling a tube...this is were the engine gets a very high load at partial throttle, this is the problem your facing that Harry is speaking of...
Just to be safe use a 4 hole carb.

 

[BruceSki]

chris that 44 i sent you is a 4 hole... it was off a vxr pro 701.

my buddy checked it out for me before i sent it out to you.

 

[chrisdoc0608]

No I don't have a pic, But easy to tell.
Hold carb upside down, open throttle plate all the way open, then look at the jet side of the throttle bore-under the bombsite and you will see a series of holes running top to bottom, 3 holes in the bore will be the 650 carb, 4 holes will be all other I talked about.
Size order of holes are: 3 hole carb=big,small,small 4 hole carb=small,big,small,small
There is also a much bigger hole over by the low speed adjuster, that is the idle/pilot circuit.
These holes control the midrange/partial throttle this is where the VXR will be running when riding lets say 2 up, pulling a tube...this is were the engine gets a very high load at partial throttle, this is the problem your facing that Harry is speaking of...
Just to be safe use a 4 hole carb.

Thanks alot Chucky that makes alot more sense to me now. :headbang:

chris that 44 i sent you is a 4 hole... it was off a vxr pro 701.

my buddy checked it out for me before i sent it out to you.

Thats great, that carb will be going on my spare ski when i build a motor for it after my build is done and i swap my motor from the spare ski.

I will just let the man man that purchased the motor know what he needs to do.


Thanks guys