Dellorto 34 VHSB

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Kevin noble
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Sun Jan 12, 2020 1:44 pm

I’ve a TS1 225 with a jl3 pipe and a 34VHSB Dellorto carb and a power jet fitted....I’ve had nothing but bother trying to set up the power jet..so have decided to remove it...any help with a starting point for jets and such would be helpful
Many thanks

gaz_powell
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Sun Jan 12, 2020 10:03 pm

pm sent

gaz_powell
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Tue Jan 14, 2020 2:18 pm

Main 158
Needle K6 – CLIP ??
Needle Seat 300
Slide STANDARD 40
Atomiser DQ267
Choke 60
Pilot/Idle B40
Air Screw 2.5 turns out

Kevin noble
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Thu Jan 16, 2020 11:35 am

Thanks gaz

Warkton Tornado No.1
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Thu Jan 16, 2020 1:45 pm

I have just built a TS1 (70 x 60) from a knackered engine (66 x 60) that came with the same carburettor. I expect the original jetting will not be far off when I fit it again, but the atomiser & needle are very worn.

I think the VHSB/C range are OKeh as they are a two stroke carb, but although very tuneable, component parts are expensive.

For now, I fitted one of my air filtered PWK copies (34) that I fully 'blueprinted' & added my own adjustable power jet. I kicked it over yesterday, as you do on a full, extensive rebuild, just to get 'the juices flowing'

Incredibly, it started on the very first half-hearted kick!

(Very under-rated carbs)

(Sorry for the pre-amble, but I'm still amazed @ the ease with which the engine started as the crankcase dictated extensive porting & the barrel (off eBay) had thrown a rod, so I used the the now slotted part of the barrel spigot as additional ports!)


The point is, that in our Lambretta World, we do not tend to operate power jets on reed valve engines. I'm not saying it cannot be done, as is the norm with other two strokes, but the power jet is a compensating device that finds favour with piston ported engines.

If you want the VHSB jetting specifications, I'll dig them out later.....

gaz_powell
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Thu Jan 16, 2020 9:38 pm

gaz_powell wrote:
Tue Jan 14, 2020 2:18 pm
Main 158
Needle K6 – CLIP ??
Needle Seat 300
Slide STANDARD 40
Atomiser DQ267
Choke 60
Pilot/Idle B40
Air Screw 2.5 turns out
Make sure you drill out the cast in restriction in the inlet.
Take out the bolt and filter under the petrol pipe connection. Look in the hole you will see a the hole is only flowing half the diameter due to restriction at the bottom. Strip the carb and run the correct dia drill down it (ped if you can but i have done it hand with slow cordless pistol drill)
I think there are pictures on scooterhelp site
Those setyings are a tad tich.

Warkton Tornado No.1
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Mon Jan 20, 2020 1:11 am

The atomisers that I unserstand find use in TS engines are DP, not DQ as used in piston ported barrels. DP266 would be a good starting point.

As for needle, K30 would be a good basis on which to start.

Kevin noble
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Mon Jan 20, 2020 7:20 am

Thank you warkton tornado.... I’m awaiting a new fuel bowl (after removing outlet on the bowl the casing had cracked)...eurocarb have a delivery time of 10+ days before they can despatch...I’ll let you know how I get on..thanks again

Warkton Tornado No.1
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Mon Jan 20, 2020 12:57 pm

Kevin noble wrote:
Mon Jan 20, 2020 7:20 am
Thank you warkton tornado.... I’m awaiting a new fuel bowl (after removing outlet on the bowl the casing had cracked)...eurocarb have a delivery time of 10+ days before they can despatch...I’ll let you know how I get on..thanks again
Dell'Orto components are not exactly cheap, especially when you are having to guesstimate requirements! There are two sizes of bowl, the bigger capacity one for flat out racing suits all applications. I know that I have @ least one smaller type spare as all my 36 - 39mm carbs were set up for racing.

(I will know in the next day or so whether I have a NOS DP266 & other near sizes spare, as the engine I have just built & am setting up may not need that size.......if that makes sense.

I'm happy to lend on a 'sale or return' basis, but I wouldn't expect to charge what the likes of the shops sell for!)


If you can, stick with the proper two stroke carb you have, though I would advise to go one further, if you can, & try to incorporate an air filter. A mate told me that he can acquire the panel type filters (like a foam 'sock' that the fitted panel deforms around the carb) for less than 20 quid. Money well spent IMO in preventing premature wear, which is the primary cause of carburettor settings drifting...... ;)

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