trials lad Posted February 4, 2004 Report Share Posted February 4, 2004 Hi I have heard people saying the '99 montesa have poor carbretors What i want to know is what is wrong with '99 montesa carbs? Cheers dan Quote Link to comment Share on other sites More sharing options...
mark christopher Posted February 4, 2004 Report Share Posted February 4, 2004 there ok if there set up right dont worry! Quote Link to comment Share on other sites More sharing options...
subira Posted February 4, 2004 Report Share Posted February 4, 2004 I ran my '99 with the 2K jets and it was better than stock. In a straight comparison the Keihin PWK28 worked better for me on my '99. It seemed to take longer for me to get it run right, and would vary a lot over a day's riding. Never had that problem with the later PHBL. The Keihin and PHBL both worked well side by side, the Keihin giving a bit more top end whereas the PHBL was better suited to my lower rev riding. Tried the newer Dellorto VHST as well, but that seemed to be another sensitive carb, I'd like to know if they have mod'ed it much for the works bikes (i.e. over and above jetting). Until then its sitting in a drawer ! Quote Link to comment Share on other sites More sharing options...
monty-python Posted February 5, 2004 Report Share Posted February 5, 2004 The standard 99 carb is rubbish, I phoned the importer about the jet kit that they do for it (to order one) and the guy at sandifords told me that i would be better off ditching it and upgrading to a 2002 spec. When i asked the price i was more than pleasantly surprised (about Quote Link to comment Share on other sites More sharing options...
trials lad Posted February 5, 2004 Author Report Share Posted February 5, 2004 Thanks , but i want to know why they are rubbish? Quote Link to comment Share on other sites More sharing options...
subira Posted February 5, 2004 Report Share Posted February 5, 2004 (edited) OK so here's my take, ready to be shot down in flames. Mr Traynor is the expert on this stuff - but here goes anyway Two things. 1. The idle circuit. As the idle screw adjusts only the air on the old carb i.e. you always get the same amount of fuel and you adjust it with the air to fine tune it. The idle screw on the PHBL acts on the fuel flow so you can meter the fuel flow with a fixed amount of air. As its the fuel element in the air/fuel mix that is providing the bang! a bit further along the line, it sounds to me like it gives you greater control over the fuel/air mix and ultimately the resultant bang!. 2. The PHBL is a later development by Dellorto - the most noticable thing about the carb is that the body is much smaller than the previous. Still has the same diameter, but all together more compact. I read somewhere that this worked better with low revs and small capacity motors. The Carburetor Manual by Dellorto explains it all, I just can't find my copy at the moment. My final cop out is that the other manufacturers all ditched the PHBH(?) for the PHBL way before Montesa - the theory is the Monty factory had a job lot and kept fitting them until the stock ran out in 2001. GG & Sherco were using them before, Sherco didn't buy any, GG had plenty of bike to churn them out on. I had the same conversation with the importer in 2000 when I was trying to sort my '99 - I spent Edited February 5, 2004 by Subira Quote Link to comment Share on other sites More sharing options...
ianj Posted February 6, 2004 Report Share Posted February 6, 2004 sandifords told me that i would be better off ditching it and upgrading to a 2002 spec. When i asked the price i was more than pleasantly surprised (about Quote Link to comment Share on other sites More sharing options...
subira Posted February 6, 2004 Report Share Posted February 6, 2004 (edited) Don't want to be a pain but.. The inlet rubber and the air hose rubber might need changing as the carb is smaller and they're different parts on the later bikes. They may fit, don't know how monty-python got on ? Edited February 6, 2004 by Subira Quote Link to comment Share on other sites More sharing options...
munch Posted February 6, 2004 Report Share Posted February 6, 2004 ian i have a 2002 type carb jetted an right size inlets vgc ill sell for Quote Link to comment Share on other sites More sharing options...
monty-python Posted February 7, 2004 Report Share Posted February 7, 2004 OOPs , er yeah, i should have mentioned that you need to change the rubbers as well. I can't remember how much they were off hand but they won't bankrupt you, and if you still have the originals on,, they won't be far off needing replacement by now. I also needed a new clip (jubilee type thing) cos the old one wouldn't tighten up far enough, due to the smaller diameter. I found these things out the hard way, you know, order carb, it arrives, order inlet rubber, it arrives, try fitting airbox rubber, it splits, swear loudly, order new one etc etc, but it was worth it in the end. Quote Link to comment Share on other sites More sharing options...
redhubuk Posted February 7, 2004 Report Share Posted February 7, 2004 The old montesa carb dilema. I've tried various options on my '99 mont, and I dont think the original carb is rubbish enough to throw away, but i tried the later '02 PHBL by borrowing it and the airbox rubber, and making a sleeve for the inlet side to fit the larger '99 intake manifold. It worked fine, small tweak on the mixture screw, and all was well. Improved slow speed pick-up (smoother and more controlled) but by only 10% ish. Not really enough to warrant a change, so then I fitted a new VSHT Dellorto jetted for the mont. Had to modify an air cleaner side rubber hose to fit the large bellmouth on the dellorto, inlet manifold rubber fits straight in. Improved slow speed pick-up and response from original carb, but over half throttle she really goes but in a much more controlled fashion than either of the normal slide carbs. Flatslides have allways been prefered for higher revs, whereas normal carbs are better at slow speed stuff. So now my VSHT flatslide Dellorto up for sale, complete with air filter side rubber hose, 3 trials from new. It's cost me over Quote Link to comment Share on other sites More sharing options...
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