loomesy Posted July 22, 2009 Report Share Posted July 22, 2009 Hello, I have a Beta tr35 with the dellorto carb, which I have recently stripped and cleaned, only to forget in the process, the number of turns out for the adjustment screws. So now I have a bike that idles too high and will rev its head off, which is mildy inconvenient, noisy and a bit scary. I realise the big one sticking out the side of the carb is idle speed adjustment, but not sure about the other one, and how they relate to each other, so would appreciate any possible advice regarding these. Also, whilst I'm here and all that, the bike has upside down forks, does anyone know the fork oil capacity. I know the tr34 which had normal way up forks has 200cc oil per leg, but would the tr35's legs have the same capacity Thanks for any help Loomesy Quote Link to comment Share on other sites More sharing options...
dan williams Posted July 22, 2009 Report Share Posted July 22, 2009 The screw sticking out the side is idle speed adjust. It determines where the slide stops at the bottom of it's travel. The other screw is the pilot mixture adjust screw. DelOrto's are different then Mikuni or Keihin in that this screw adjusts fuel where on the other carbs it is an air adjust. For the DelOrto, screw in (clockwise) equals leaner mixture. For the Mikuni/Keihin, screw in (clockwise) equals richer mixture. Typically 1.5 to 2 turns out from bottoming out is standard. This will affect how the bike responds off idle. Can't give you more then that as every bike is different so you just have to fiddle with it 'till it's good. Lean mixture will cause a "hunting" idle speed and a bog off idle when the throttle is pulled open quickly as well as pinging off idle or shutting down. Rich will run somewhat lethargic from idle to 1/4 throttle, will smoke a bit more but will start easier with the choke off when cold. Beta's also tend to run rich when pointed downhill because of the carb mounting angle which is made a bit worse with a misadjusted pilot circuit. Quote Link to comment Share on other sites More sharing options...
loomesy Posted July 27, 2009 Author Report Share Posted July 27, 2009 COOOOOOL Cheers for that, running like a dream now..I think Quote Link to comment Share on other sites More sharing options...
peterb Posted July 28, 2009 Report Share Posted July 28, 2009 Hello Loomesy, All what Dan said is fine though I must point out that your carb is a PHBH, not the later model PHBL that has an adjustment as per Dan's description. The PHBH carb uses air as the pilot circuit and the screw adjustment at the rear of the carb body, should be around 1 to 1.5 turns out as a starting point, from fully clock wise. Turning this adjustment out, counter clock wise, leans off the mixture at the low end. Ta ta, PeterB. Quote Link to comment Share on other sites More sharing options...
dan williams Posted July 29, 2009 Report Share Posted July 29, 2009 My apologies. Only bike I had with a DelOrto '95 Beta ran much better with a swap to a Mikuni. Quote Link to comment Share on other sites More sharing options...
wasntme Posted July 30, 2009 Report Share Posted July 30, 2009 Glad you sorted the carb. I've been messing around with mine over the last couple of trials. A good clean out and a few screws turned sorted mine too! It's still slightly rich I think. Some Fork info according to Beta UK FAQ on the TR35 if you still need it: Fork Oil - Quantity Left 300cc Right 280cc. Rich Quote Link to comment Share on other sites More sharing options...
loomesy Posted July 31, 2009 Author Report Share Posted July 31, 2009 Oh right, cool thanks for that. Especially the FAQ bit I'd imagine that this may explain why it doesnt feel as perky as a 260cc trials bike should. Compared to my mates 96 Techno, which I realise is a lot newer, water cooled, and more powerful, but still...my tr35 seems positively comatose by comparison. Ive found it bogs down a lot, so presumably its running far too rich, coupled with the fact that it running on 50:1 rather than 70:1 which is probably not helping things either...so much for 'running like a dream' Also whilst I'm here is there any reason why there is foamy, spongy stuff in the front brake reservior, my thought is that it prevents air getting into the hose if the bike goes upside down or something. Id imaging if you fill the reservoir to the top, there wouldnt be any need for that??? Apart from changing the fluid is there anything I can do to improve front brake performance? Ive got a braided hose on it bit its still shockingly bad, though Ive heard early disc brakes on trials bikes were pretty awful. By the way on the Beta FAQ it says engine oil (which presumably means gearbox oil rather than 2 stroke): 800 cc. Is that right?? Sorry about bringing up an old thread but thanks again for your help, Im learning stuff all the time. Its much appreciated!! Loomesy Quote Link to comment Share on other sites More sharing options...
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