LCGB Forums

Troops -- apart from the obvious, what's the thoughts on the difference between a rubber and solid mounted 30mm carbs -- I have a rubber mount but thinking of going to a solid mount to take out the issue of carb rubber splits etc -- thoughts on pro's & cons? -- Cheers G

IMHO rubber mounting is preferable with the mobile vibrators we ride, but a lot of people seem to struggle to understand the importance of selecting the correct rubber sleeve (made for purpose with correct grooving & size) with the correct width ‘worm drive hose bands’ (not necessarily a ‘Jubilee clip’) or the fact that over-tightening will cause their premature demise.

There are riders that use radiator hose but I would not do so without grinding a suitable piece with an undersized bore to obtain the same features as a proper elastic mount.

I have successfully mounted ex-Rotax Ø38 – 39 mm VHSC’s with shortened spigots by grinding sleeves to fit, including grinding of the recess for the selected worm drive hose band.

Many riders also seem to be unable to grasp the concept that ‘isolation’ means no contact with any part of the carburettor ‘upstream’ of the rubber mount.

That is not just the carburettor, but also any hose or filter in the slightest part inflexible must not make contact with any other rigid component such as tank, toolbox, side panel et cetera during any point of the suspensions travel from unloaded @ tick-over on the stand to fully loaded with two average rally going scooterists with their luggage, wigs, grass skirts or whatever.

BTW. Rubber mounting the carburettor is preferable mainly in avoiding the components inside the carburettor wearing out quicker. It’s not just the slide & body but the needle & atomiser that get hammered by the vibration.

I hope my rather biased, cynical, grumpy view helps though!

On top of what WT1 said. Solid mounts can sometimes be a pig getting your carb off, especially by the side of the road, whilst rubber mount is easy. But the flip side is solid mounts mean your carb is far less likely to come off whilst riding, as once a rubber mounted carb can fall off and when they do it is almost impossible to keep on unless you have something like carb clean with you to remove the fuel and oil off the rubber before refitting.

I had the later problem riding the short distance home from 8 Balls rally, I had snapped a throttle cable and on replacing it managed to knock the carb off, had no carb clean on me so re-fitted with just a wipe clean with a rag, I then had to stop to put the carb back on another 4 times in only 16 miles :-/ Once home cleaned up the rubber and has been good as gold since.

Think the main reason motorsickles went rubber mount was to stop fuel frothing around the float chamber

Got a solid mount dellorto 30mm carb & manifold if you are interested?

spud wrote:Got a solid mount dellorto 30mm carb & manifold if you are interested?

Cheers Spud -- but going to have 1 more shot at the rubber mount -------------- now I have the correct manifold to match the rubber

hullygully wrote:Think the main reason motorsickles went rubber mount was to stop fuel frothing around the float chamber

That was my understanding too but have always wondered if that would really be a problem for the majority of scoots ridden on the road I agree with Burnside with the difficulty in getting solid mount carbs off when they are spigot mounted. I have often had to resort to drifting them off with a piece of wood and a hammer from the other side