carl ekblom Posted May 10, 2006 Report Share Posted May 10, 2006 Interesting information . For my Beta-06 270 the VHST was so far a great improvement over the stock Mikuni. The light throttle spring offers good engine control and overall performance and throttle response is much better than with stock carb. However, for cold starting it needs a few kicks more. I guess that the choke jet(size 60) need to be slightly larger. The right hand carbs is called BD and the left hand is called BS. Now, I have to check the size of the fuel valve. I think I have the brass fork so it is probably 200. carl Quote Link to comment Share on other sites More sharing options...
ilovetrials Posted May 11, 2006 Report Share Posted May 11, 2006 (edited) One more comment.. you will need a larger filter rubber hose (38-40 mms diameter), there are some guys in spain that took the stock sherco filter hose rubber out and fitted it backwards (just reverse it..) in order for the rear of the carb to fit in the air filter, ie. the larger diameter faces the carb and the small one fits in the air filter. I had a keihin so I had a previosly rubber that I got from a local car parts warehouse, that fitted perfect.. Yes, at sea level pilots should be between 30-34, mains between 120-125 pilot jets are special for the VHST (are longer like keihin type) make sure to order a couple of those..., but the other VHST parts are interchangeable with the PHBL.. ie. mains, needle, diffusors, bowl, floats etc... One last advice... Try it first as it comes from the box... just try it, one step at a time.. first change piltos jets, then mains and if it runs ok, you dont need to change the valve, if you are noticing some strange behaviors at idle, (sometimes rich, sometimes poor), then think in trying swaping the 200 stock valve.. be patient, that way you Edited May 13, 2006 by ILoveTrials Quote Link to comment Share on other sites More sharing options...
ilovetrials Posted May 11, 2006 Report Share Posted May 11, 2006 (edited) Sherco and montesa have tested this carb under heavy competition... back in 2002-2003, and 2004 so its realiability is proven... this is a picture of a 2002 sherco with the VHST (Freixas Sherco)... this pic was extracted from Jose Maria Blanco web page... http://www.terra.es/personal9/marlintec/taller/ ....this page is for us, "the bible" of the VHST, check it out... without this page and Jose Ma advice through todotrial forums, I wouldnt dare to try the VHST on my sherco.... Thanks a lot Jose Maria!!!. This is Fuligas 315r bike(Dougies also fitted one of those..), take a look at the DellOrto sticker in the air filter box... this carb was champion of the world 2 or 3 times..!! Regards... Edited May 12, 2006 by ILoveTrials Quote Link to comment Share on other sites More sharing options...
carl ekblom Posted May 11, 2006 Report Share Posted May 11, 2006 Great! Is cold starting a common problem with the VHST? The chocke jet and passages is clean and the lever mechanism and piston is in perfect condition. Otherwise the carb is perfectly working exept from a slight pinging after a short full throttle run (fuel valve size to small?). Carl Quote Link to comment Share on other sites More sharing options...
ilovetrials Posted May 11, 2006 Report Share Posted May 11, 2006 (edited) Great! Is cold starting a common problem with the VHST? The chocke jet and passages is clean and the lever mechanism and piston is in perfect condition. Otherwise the carb is perfectly working exept from a slight pinging after a short full throttle run (fuel valve size to small?). Carl <{POST_SNAPBACK}> In my sherco it starts oK... I havent heard problemsa with that... maybe changing to a larger starter jet or drilling i guess... regarding pinging after a full throttle,..yes that seems due to a small valve... try changing for a 270 or 300m and problem solved... regards Edited May 11, 2006 by ILoveTrials Quote Link to comment Share on other sites More sharing options...
pedronicman Posted May 12, 2006 Author Report Share Posted May 12, 2006 'i love trials' please tell me what jets you are running in your vhst. got my vhst today and will hope to fit it this weekend. i have had it fitted with - 126 main 34 pilot 300 fuel valve. what are you using? ta. Quote Link to comment Share on other sites More sharing options...
ilovetrials Posted May 12, 2006 Report Share Posted May 12, 2006 (edited) I Edited May 12, 2006 by ILoveTrials Quote Link to comment Share on other sites More sharing options...
carl ekblom Posted May 12, 2006 Report Share Posted May 12, 2006 My current jetting for Beta 270-06 altitude 50-300 meter Main 120 Pilot S37 Needle D47 Needle Jet 272H Throttle 50 Float valve 250 Choke 60 Carl Quote Link to comment Share on other sites More sharing options...
pedronicman Posted May 12, 2006 Author Report Share Posted May 12, 2006 have fitted the vhst today. the inlet into the manifold is 36mm in diameter as opposed to 31mm of the std phbh carb.it does fit but is very hard to push in and is a pain to take on and off each time to make adjustments to the setup. so as i lovetrials suggeted i am going to get it machined down to 31mm next week. when this is done then i can set up the jetting properly.have used an inlet manifold rubber i found that fits the larger back of the carb which is a similar size to the airbox fitting on the sherco, works a treat.the cable fits straight in so no probs there. will ride it at my local trial this weekend as it is. i have run it and ridden round garden and have since swapped the 34 pilot for a 33, it is the new type carb with the silver float tabs. first impressions are much more responsive and more initial grunt at the bottom. will see how it performs on sunday............. Quote Link to comment Share on other sites More sharing options...
ilovetrials Posted May 12, 2006 Report Share Posted May 12, 2006 keep us informed how it performs... Quote Link to comment Share on other sites More sharing options...
pedronicman Posted May 15, 2006 Author Report Share Posted May 15, 2006 rode the trial yesterday with the new vhst.- stronger power right through from bottom,not necessarily more bhp but stronger engine all round.better throttle response- comes in a little sooner. runs cleaner and the carburation doesn't 'wander' around like the old phbh. very pleased with initial first proper ride,very good trial with testing sections. the jetting seemed spot on- 126 main 33 pilot 300 fuel valve needle clip 2nd from bottom (this needle has 5 grooves instead of 4) getting the inlet michined down to 31mm this week to fit same as std carb. worth getting anf fairly easy to fit apart from getting someone you know to machine the carb!. i have not ridden an 05 or 06 290, so not sure how this would compare. Quote Link to comment Share on other sites More sharing options...
ham2 Posted May 27, 2006 Report Share Posted May 27, 2006 Pedronicman? It's been a few weeks ( and a few rides?)since your mod... progress report? Quote Link to comment Share on other sites More sharing options...
neo Posted December 8, 2010 Report Share Posted December 8, 2010 Has anyone else ventured this way? Can you share your experience's? ILoveTrials, is the Atomiser bush easy to change? ... Does it just pressed in? My VHST came with a 5mm Atomiser bush and an "S" Type Atomiser (pilot) jet too. Best of balance. Neo Quote Link to comment Share on other sites More sharing options...
copemech Posted December 8, 2010 Report Share Posted December 8, 2010 Neo, I will you my basic thoughts here. I would not expect much difference between the VHST 26 and a 26 OKO, as the basics are the same. One could spend a lot of time and money to achieve the same basic result. Seems for a long time,the Dellortos 26 were compared to the 28mm Kiehins, which is just different in dynamics, due to the bore. as I understand the new VHST carbs are coming in 28mm config. This may be good for top end, but I think they will still have the biting points of the 28 K carbs. Although overall the Dells seem more steady and less finicky, not as precise, and that is a trade. I should add that I am still on the 24 OKO on the 2.9, just cannot get off it! Yet I hav had fits getting it right. It is on the edge in this aplication, yet still smooth, quick, and more power than I need. Quote Link to comment Share on other sites More sharing options...
trialsnutterman Posted December 8, 2010 Report Share Posted December 8, 2010 Has anyone else ventured this way? Can you share your experience's? ILoveTrials, is the Atomiser bush easy to change? ... Does it just pressed in? My VHST came with a 5mm Atomiser bush and an "S" Type Atomiser (pilot) jet too. Best of balance. Neo 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. Quote Link to comment Share on other sites More sharing options...
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