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VHSA, VHSB, VHSH

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VHSA, VHSB, VHSH

Postby Ballspeed65 » Wed Apr 01, 2020 12:36 pm

What are the differences between these carbs?
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Re: VHSA, VHSB, VHSH

Postby Sticky » Wed Apr 01, 2020 1:39 pm

The last two letters.
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Re: VHSA, VHSB, VHSH

Postby Ballspeed65 » Wed Apr 01, 2020 1:59 pm

:D Apart from the last ONE letter are there any more differences?
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Re: VHSA, VHSB, VHSH

Postby Sticky » Wed Apr 01, 2020 3:49 pm

Ballspeed65 wrote::D Apart from the last ONE letter are there any more differences?


Doh!
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Re: VHSA, VHSB, VHSH

Postby Knowledge » Wed Apr 01, 2020 5:17 pm

I know that there are differences in slides between the them. I think the VHSA and VHSB have squarish slides, and the VHSH has an oval slide.

The VHSH has a smaller body that the other two, and therefore comes in smaller choke sizes (26-28-30). There are lots of internal differences too, including atomisers and needles

To be honest, you will probably get many answers by Googling images of the three and then coming back with more detailed questions.

Don't worry, and expert will be along shortly.
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Re: VHSA, VHSB, VHSH

Postby Ballspeed65 » Wed Apr 01, 2020 5:29 pm

Thanks.
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Re: VHSA, VHSB, VHSH

Postby Dazts1 » Sun Jul 19, 2020 7:31 pm

Think vhsa and vhsb have the fuel inlet on opposite sides of the bellmouth. Also airmixture screw is on different sides of the bellmouth too.
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Re: VHSA, VHSB, VHSH

Postby Adam_Winstone » Wed Jul 22, 2020 12:04 am

Knowledge is on the right track, with these being different models, being different sizes and with different parts for each. They are the same design family but are not the same.

The VHSA was basically a smaller version of the VHSB, with smaller body and smaller choke/venturi sizes; VHSA going up to 32mm, then the VHSB continuing from 34mm upwards. It is much like comparing PHBL and PHBH carbs, same design family but different sizes and few parts being interchangeable.

The VHSA range was discontinued and replaced by the VHSH range, again being smaller than the VHSB range and ranging up to 30mm.
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Re: VHSA, VHSB, VHSH

Postby Warkton Tornado No.1 » Wed Jul 22, 2020 3:42 pm

All of those carburettor's are tailored toward modern engine requirements, which with respect to two strokes, are notable by their 'guillotine' slides, being very narrow in the cross section of the carburettor. Main body materials, tops, body inserts (Venturi shape) are just the basic variations.

An exploded diagram for all to see is available on websites, including Eurocarb.

IMO the range of VHS are very adaptable, capable carburettors that are designed toward gaining the sort of performance you would anticipate @ the top end of the range of carburettors available to buy.

The Dell'Orto's homologated to Rotax karting are often available to buy in very good, used condition & worth looking into. Similarly, engines in Aprilias & Cagivas use the VHSB 34 LD which can be a good set-up on TS's. One I have to hand, has the one-piece screw on cap with the darker grey (magnesium?) body. BTW, the '34' has a shaped Venturi insert, more like 37 mm in places, but don't let that put you off.

I suspect that carburettor's from Keihin, Mikuni & the PWK's such as KOSO, OKO may be as good & the physical size may well be a deciding factor in choice, especially if air filtration is a factor. Another significant factor might be choice, & currently my belief is that a 'good' PWK clone offers supreme value for money (& they operate extremely well with an air filter!)

ALL of the PWK's like ANY carburettor should be stripped down & checked/blueprinted prior to use IMHO.
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