37 replies to this topic

[Neo]

trialsnutterman, on 08 December 2010 - 12:44 PM, said:

The atomiser bush isn't that easy to change, yeah it is just pressed in but it is a tight fit and it is a pain to get at.

I don't think the height is that critical as I've got 2 VHST one with a 1.5mm and the other with a 7mm 1/4 cutaway version, I've got them running very similar but I have had to use very different needles to achieve the same response.

The S type pilot jet is more suitable for the 2 stroke but you may have to us the U type if you can't get a leak enough mixture as the the pilot jets start at size 32 which is what I'm currently using in the UK.

Great information ... thanks man.
Would you mind sharing your current VHST setup details with me?...And what altitude you're at?

Cope, I suspect you are right but I have to try this out because the PWK's are not as smooth as I'd like on the lows once the bike is well warmed up (on some days!). I can tell the VHST does not have that characteristic but at the moment it's not that smooth when it's revved up and lacks the midrange power I'm used to. But I'm assuming it's running a touch rich and needs more setting up.

Thanks again Gents.

Best of Christmas balance to you.
Neo

Edited by Neo, 09 December 2010 - 01:23 AM.

[trialsnutterman]

It's a 28mm version on mine so not much use really.

The carb is a standard on the 2011 Sherco 290, remeber this bike runs a fuel pump so you will possibly need a even larger fuel valve.

Main 126
Pilot 33
Needle D48
Clip 3rd
Slide 50
Mixture Screw 3 turns out
Fuel valve 250 (200 as standard)
Atomiser jet 270K
Choke 60
Atomiser height 1.5mm

Oh and it has a anti slosh plate installed around the main jet and a 2.6mm restricter in the fuel inlet.

[HAM2]

trialsnutterman, on 09 December 2010 - 10:15 AM, said:

It's a 28mm version on mine so not much use really.

The carb is a standard on the 2011 Sherco 290, remeber this bike runs a fuel pump so you will possibly need a even larger fuel valve.

Main 126
Pilot 33
Needle D48
Clip 3rd
Slide 50
Mixture Screw 3 turns out
Fuel valve 250 (200 as standard)
Atomiser jet 270K
Choke 60
Atomiser height 1.5mm

Oh and it has a anti slosh plate installed around the main jet and a 2.6mm restricter in the fuel inlet.

I'm trying to keep up (honestly )but a larger fuel valve and a 2.6mmm restrictor in the fuel inlet...is that not a contradiction?

Please type your reply s-l-o-w-l-y and in words of one syllable so I can understand .
Ta.

Edited by HAM2, 09 December 2010 - 02:34 PM.

[trialsnutterman]

The restricter comes as standard on the new 2011 Sherco I guess it is to reduce the fuel pressure from the pump.

Also the restricter is 2.60mm and the float valve I upped from a 200 to a 250 which is 2.5mm so it's still smaller than the restricter.

[copemech]

As in the 2010 application, the restricter would be used to dampen the pulses a bit, as combined with the smaller fuel valve to limit potentially overpowering the valve as you are now pushing fuel into it as compared to gravity feed. All based upon the pressures and flow.

In the conventional application, the higher fuel valve is needed and no need for a restrictor, yet as long as it is larger than the fuel valve should be no issue.

[Neo]

Thanks again trialsnutterman.... At this rate Santa is bound to bring you something good this year

Amazing... this what my VHST came with (off of a Gas Gas)

Main Jet: 122
pilot Jet: 34 (S Type jets)
Needle: D48
Slide 50
SPRAYING conical needle seat (Atomiser jet) 270K
Float valve 300

I have Boyseen Reeds so from what Boyseen writes I need to lean the pilot and richen the main a bit. But whats your thoughts Gents on that Float valve ... is 300 too big?

"Atomiser height 1.5mm" is that the Atomiser bush we're talking about?


Best of balance.
Neo

[trialsnutterman]

("Atomiser height 1.5mm" is that the Atomiser bush we're talking about?)
Yeah the bit that protrudes into the main bore of the carb

A 300 float jet might be fine with yours been gravity feed, you'll have to experiment.

[Neo]

Ok Dellorto parts on order.

They're a bit hard to find and quite expensive too ... hope it's all worth it?.... time will tell

Best of Xmas balance.
Neo