Hi guys (and gals?),does any one know what size amal concentric carb works best on a marcelle barrel (for trials).In the box of bits which it came with was a 930,with a 928/ 2 1/2 slide,is this in the right ball park? Thanks.

Personally i would use a 26mm Premier Amal concentric. 

Marcelle barrels were used for both scrambling and trials.If it came with those size carbs it stands a chance it may have been used for scrambling.

OTF is correct by saying that a 26mm is best for trials ,thats what we all use.The only way to tell is if someone who knows what there looking for to have

look at the port timing to see what you have on your barrel.

_{what's the difference between a premier amal & the standard?}

Edited March 24, 201610 yr by suzuki250

It's a lightweight, better made version of the standard carb

Edited March 24, 201610 yr by hulmie

_{what's the difference between a premier amal and the standard?}

 

Premier has a redesigned pilot circuit which uses a new type external pilot jet that is located on the opposite side from the airscrew

and is not acceptable to some clubs....

and is not acceptable to some clubs....

Which clubs then?

The two clubs with the 'fussiest' rules accept it, so which don't?

The two clubs with the 'fussiest' rules accept it, so which don't?

This sort of nonsense is or will be damaging to the sport we enjoy.

Now Amal/Burlen are making the premier concentric in 20mm which might be ok??? for the 199cc Triumph Cub clubs are saying no DelOrto or Mikuni carbs to be fitted so are the same clubs now saying the premier canot be used at all.

There is no club that I know of that doesn't accept it

Me neither.

Marcelle barrels were used for both scrambling and trials.If it came with those size carbs it stands a chance it may have been used for scrambling.

OTF is correct by saying that a 26mm is best for trials ,thats what we all use.The only way to tell is if someone who knows what there looking for to have

look at the port timing to see what you have on your barrel.

Even if you have a "scrambles" barrel i wouldnt worry too much because most of the square Greeves barrels in use are "scrambles" barrels. Mine is and i done find any problems in trials at all. 

I agree, 26mm works well.
As for barrels, I think the Marcelle (and probably Greeves) alloy 'scrambles' and trials barrels use the same porting and are essentially the same barrel.
The heads do differ, a higher compression for 'scrambles' , a lower for trials.

Edited March 26, 201610 yr by sparks2

Hi guys,i've now looked into the trailer load of bits and pieces i bought and i've now found a 932 concentric and what i believe is an old 'Jonny

burns' Motox develoments barrel and two heads (350/360 c.c.?).So it looks like i have a bunch of pre '70 scrambling gear.

Excuse my ignorance,but did i see in the press a fella trialing a big bore villiers? (was his first name Maurice?)

I think i might try and stick it on top of a 32a in an old '62 dot frame i've got, and see what happens.(Any ideas about carbs and jetting and exhaust bore for that.

Life's fun.many thanks.