swampy315 Posted February 19, 2016 Report Share Posted February 19, 2016 Hello all. Has anybody out there successfully put a dellorto VHST 26mm flatslide carb on a mont 315? If so do you know what jets and needle + clip, mixture and airscrew etc please? I have just brought one after struggling to get a keihin pwk to work properly over the last two years and need to get it set right. Cheers Quote Link to comment Share on other sites More sharing options...
mont 315r Posted February 20, 2016 Report Share Posted February 20, 2016 Hi I just bought a vhst for my montesa 315 I am half way through jetting I will post the settings when I am finished. Quote Link to comment Share on other sites More sharing options...
mont 315r Posted February 20, 2016 Report Share Posted February 20, 2016 I bought the carb with gas gas jetting, it is a 26mm vhst. 1 Quote Link to comment Share on other sites More sharing options...
nigel dabster Posted February 20, 2016 Report Share Posted February 20, 2016 where are you swampy? Quote Link to comment Share on other sites More sharing options...
swampy315 Posted February 20, 2016 Author Report Share Posted February 20, 2016 Hi all. I am in Kent. What cc gas gas was the carb off? if it was a 250 then I doubt it will be far out. Quote Link to comment Share on other sites More sharing options...
goudrons Posted February 20, 2016 Report Share Posted February 20, 2016 This might help with jetting http://www.dellorto.co.uk/shop/dellorto-motorcycle-carburettors-parts/complete-carburettors-dellorto-motorcycle-carburettors-parts/vhst-24-to-28mm/r9351-vhst-26bs/ Though I've found Eurocarbs pilot jetting always seem a bit lean for slow trials work, so it might be worth buying a 37S and perhaps a 38S as well. (38S works better in Rev3's) Also, 60 choke is a bit mean, in the past I've ran a 0.7mm drill through them to aid cold starting. As for fine tuning it. Start with centre needle clip and mixture 1 to 1+1/2 turns out as a base and screw in the fast running a bit to get it started and idling fast to warm up. Dial in the idle speed and mixture until you get it to idle smoothly at the desired speed. WOT should be right on that main jet. Adjust needle clip down or up to dial in throttle transition from idle to main (around 1/4 or 1/3 throttle opening). If it bogs or coughs opening the throttle and needle is fully lifted, move up an pilot size. Quote Link to comment Share on other sites More sharing options...
swampy315 Posted February 20, 2016 Author Report Share Posted February 20, 2016 Wow, the plot thickens........that is a good link, thanks goudrons, I have some of the spec listed on the link but not all of it. I have a 37 & 38 s idle but only up to a 96.02 main. my slide matches but my needle and floats dont!...............the whole experience with the keihin over the past couple of years has scarred me, so I may wait a bit and see if anybody who has one fitted on a 315 and fully dialled in shares there knowledge on here with me and everyone else, luckily I have (learnt) that patience with stuff like this can pay off. Quote Link to comment Share on other sites More sharing options...
goudrons Posted February 21, 2016 Report Share Posted February 21, 2016 Setting up a carb can be a bit frustrating and can take a bit of time and effort. It's driven me it up wall many a times, getting the bike running well in the garage only to drive out miles to an event and it run like a bag of spanners and the very last thing you want to be doing is opening up a carb in a muddy field! Then once you do get it somewhere that seems right, you're always wondering it it's good enough, could it be better, To add to the headache it's not uncommon for a different settings to work just as good as another, but you have to start somewhere! Eurocarb has sold 4 slightly different VHST kits for the Rev3 over the last few years, all with slightly different part numbers, jets and atomizers and they all seem to work, then again, anything is an improvement over the Mikunis fitted at the factory! I've set a couple of VHST's up on different 250cc bikes and to be honest, they all end up very near one another as I used the first as a starting point. D37 needle 50 or 55 Slide 200 to 250 inlet valve 60 or 70 choke 3.6gm floats There are a couple of different atomizers that work, 271HE and 272HH Pilot between 36 and 40 Mains tend to be somewhere between 100 and 110. If you have these and are riding in Kent, I might be able to help you set it up as I ride in the NKTC. Worth noting Dellorto's are prone to pilot clogging if the the slightest spec of grit or dirt gets in there, so make sure you've a clean fuel filter installed and keep the airbox and filter clean. Also drain the float bowl after every use, modern fuel goes stale very quickly and the green gunk it leaves behind will also clog it up pretty quickly. Quote Link to comment Share on other sites More sharing options...
swampy315 Posted February 22, 2016 Author Report Share Posted February 22, 2016 Thanks goudrons. well we probably know each other at least by face then, I dont ride so many nktc these days, normally the SEC and the odd Owls club trial. I should be doing cowden nktc in march though hopefully. Thanks for the help, I will get on it and order some more parts when I have some cash, my work is out of season at present so it may have to wait a bit. Cheers James Quote Link to comment Share on other sites More sharing options...
mont 315r Posted May 21, 2016 Report Share Posted May 21, 2016 Hi all, did any body have a list of jets for a bike that runs well on a vhst. I have tried 6 different idle jets 2 different needles. It has a weak bottom end power and a CR250 top end. Exactly what I didn't want . Quote Link to comment Share on other sites More sharing options...
mont 315r Posted May 21, 2016 Report Share Posted May 21, 2016 Hi all, did any body have a list of jets for a bike that runs well on a vhst. I have tried 6 different idle jets 2 different needles. It has a weak bottom end power and a CR250 top end. Exactly what I didn't want . Quote Link to comment Share on other sites More sharing options...
jonnyc21 Posted May 21, 2016 Report Share Posted May 21, 2016 Don't know enough about the 315 so this could be miss placed thinking. When I hear week on the bottom and strong at the top and I wonder if your ignition timing is a bit advanced. If the 315 can have the timing adjusted you might consider a slight shift back. Good luck. Quote Link to comment Share on other sites More sharing options...
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