stepped spray tube on a 750?

hi there , what could be the effect if fitting a pair of amal 32mm with stepped spray tube , 4 rings needle and 3 1/2 valve cutaway on a 750........? if I ask it's because we have them (new in their boxes) and we need a pair of carb for my friend's 750 Cdo, yes I could fit and try and then report the feedback , but if someone had allready done it , it could save some time and some money too (replace the valve , spray tube and needle ).....we are cheap on this one.

Not done it to a 750 but have to a B44 Victor, runs well with no issues.

I had a seasoned Nortoneer tell me fitting slotted, angled or notched
spray tube was his secret weapon to get accelerator like response
off idle and above.

I plan to try this on factory Combat, filing a slot till I either notice
more response or it stumbles and stalls and put back normal tube.
Don't know if needle or jet will need fine tuning too with extra flow.

hobot

Unless you have a Combat head, a hot cam and a big exhaust, the 32's may be just too big. There simply is not enough venturi effect present to allow those 32's to function properly, not to mention being able to take advantage of the stepped spray tubes.
You may not ever get a steady idle or a smooth throttle through out the range, no matter what jet, slide or needle settings you use. Bigger is not always better.
There is also the step to concider. The 750 head has 30mm ports. Even if you are using 32mm adapter, you will have that lip either at the manifold or at the head, that will most definately mess with the mixture flow.

Its a secret mod to Tiger Cub Trial bikes (well not secret now :shock: ), fills in a mid range flat spot.

The stepped spray tube is usually used on two strokes, it helps to reduce the size of the main jet .
Cash

The 750 head has 30mm ports. Even if you are using 32mm adapter, you will have that lip either at the manifold or at the head, that will most definately mess with the mixture flow.

Click to expand...

Actually the 750 heads have 28.5 mm ports with the exception of the Combat and RH5 & RH6 head which are 32mm. Only the RH10 850 head actually has 30 mm ports.

Ron L said:

The 750 head has 30mm ports. Even if you are using 32mm adapter, you will have that lip either at the manifold or at the head, that will most definately mess with the mixture flow.

Click to expand...

Actually the 750 heads have 28.5 mm ports with the exception of the Combat and RH5 & RH6 head which are 32mm. Only the RH10 850 head actually has 30 mm ports.

Click to expand...

Causing an even larger surface to disrupt flow.

MARINATLAS,
This is not to say you cannot give it a go, I probably would.