Dellorto VHST bs racing 28mm carb info.

[Rotund]

http://www.scooter-center.com/en/produc ... 34mm?meta=

Going up to a 28mm carb on my Mugello and have been offered one of these cheap.

Anyone used or using one? any problems or pitfalls?

I can get a brand new PHBH 28mm for sixty quid so im not that worried but on the other hand its red so it must make it go faster surely.

any advice appreciated.

[giankx]

Beware of them, many VHST out there are for 4 stroke engine.
Even if they are sold for both 2 or 4 stroke they are with a holed atomiser and are impossible to set well on a 2 stroke engine (the carburation is always lean).
Be sure that they have an AQ atomiser so you can use the D needles. The same combination is used on PHBL carbs, so is easy to find everywhere.

[SpanishSX200]

I agree, I had serious difficulties setting this carb. If you PM soosh on here I think he got his to work on a stage 4 RS setup!
Simon

[B-Race Tuning]

I would prefer the PHBH route at any cost over the VHST even if it was free. VHST a lovely carb, and works well if set up correctly with no real forthcoming issues over any other carb.
PHBH. Cheap. cheap parts. easy to set up at home. fairly easy to get hold of parts locally over VHST. No discernible performance difference between any comparative choked carb on a road lambretta, BUT, 40 years of tried, tested, reliable carburation. Got to get there, and back, to be a good trip.
Get some ethanol petrol resistant paint and paint it. You'll go faster then S

[Grumpy225]

This is an old one but has anyone else had luck with the VHST28 BS carb?

I’m running one on a deanspeed 190 with BGM big bore and am having a little trouble dialing it in.

Starts easy but it’s mad Smokey and revs a little weird on the down shift. At wide open the thing is quick with sharp throttle response. Kicks over easy and responds correctly with seal testing (no leaks).

Currently it’s running
115 main (100 starves out at 1/2 throttle, 120 starts to feel muddy)
S36 pilot
60 choke
50 slide

Not sure about the atomizer but will check that next.

Just curious to find out what others are running with this carb to see if I’m on the right track.

[Warkton Tornado No.1]

I have been using carburettors designed, or modified, specifically for two strokes for decades.

The guillotine slide favoured by the likes of racers, whether BSSO, Kart, Moto-Cross or 'serious' two stroke tuners are to be found in various manufacturers carburettors, including Dell'Orto. The VHBC is mandatory in the Rotax class of Karting & almost so in BSSO Lambretta racing.

My point is that any carburettor is tuneable. Even the PWK copies can be modified to work well. It's all down to which herd you follow.....

The thing I find with Dell'Orto's is that the slide & atomiser size will be very similar when using different types of their carburettors on the same engine.

Yes, needles vary, but charts exist to get a good guesstimate, so you can get very close to the optimum from the outset.

IMHO many Lambretta home tuners use too big an atomiser, which is best being 'just big enough' so that the needle size can be more finely tuned.

All of the above is just my opinion through experience. Much of my findings are through mistakes, failings but also some success & by reading what experts have to say.......

[Grumpy225]

My point is that any carburettor is tuneable.

Not if you don't have the jets

If it were a PHBH or Mikuni I could have had this thing jetted in quick. 9 Pounds a piece for the pilot jets plus shipping! Needless to say I did not choose this carb to use.

The good news is the customer has a good tuner local to him and will help him dial it in perfect.

[Warkton Tornado No.1]

My point is that any carburettor is tuneable.

Not if you don't have the jets

That's true of any carburettor, but I get your point!

I wouldn't choose the VHST, but the PH range is bottom of my list as far as Dell'Orto is concerned. My choice would be Keihin, a good PWK (such as Polini's new version, KOSO etc) or VHBC & its derivatives.

Having said that, a mate slung on a Chinese copy PWK 34 mm with power jet (& some spare jets) that was checked over for the flaws to look out for, & it had none. I was amazed @ how good it is for about £15.....

As for the VHST pilot jets, there may be sets available by the likes of Stage 6 etc, but individually, Scooter Attack sell them for £4.36 each, so worth shopping around.

[rosscla]

My point is that any carburettor is tuneable.

Not if you don't have the jets

That's true of any carburettor, but I get your point!

I wouldn't choose the VHST, but the PH range is bottom of my list as far as Dell'Orto is concerned. My choice would be Keihin, a good PWK (such as Polini's new version, KOSO etc) or VHBC & its derivatives.

Having said that, a mate slung on a Chinese copy PWK 34 mm with power jet (& some spare jets) that was checked over for the flaws to look out for, & it had none. I was amazed @ how good it is for about £15.....

As for the VHST pilot jets, there may be sets available by the likes of Stage 6 etc, but individually, Scooter Attack sell them for £4.36 each, so worth shopping around.

Anywhere in the Uk selling the Polini PWK?