pipal1000 Posted July 23, 2011 Report Share Posted July 23, 2011 I hope sombody can help me as this probelm is driving me mad !! Have just bought a 2001 315R Cota. Ths bike starts and runs on choke and revs up and settles down fine. When I turn the choke off this seems to starve the bike of fuel (I think?). If I don't touch the throttle the bike runs for a about 15 seconds then the revs climb and it just dies. I reckon this is fuel starvation and the revs are rising as the mixture gets weaker. I have had the carb apart, blown carb cleaner through all the holes and jets that I can see, have taken all the jets out and cleaned them. I also thought it might be an air leak so took of the carb stub and reed valve block. Have visually looked it over and checked the gaskets and applied gasket sealent to the faces and re assembeld (again!!). The last owner tells me that the bike has had a rebore and new piston and compression on the kick start seems fine. You guys seems to have answers for all types of weird and wonderful probelms and I hope somebody can help me here. Have just read on another link that the bike must have a BR6ES spark plug some am off now to check that and take the bl**dy carb off again...aaarrrgggghhhhh. Quote Link to comment Share on other sites More sharing options...
jes42 Posted July 23, 2011 Report Share Posted July 23, 2011 Hi Mate. I had the same thing with my '04, it might sound obvious but have you made sure you're not kinking the fuel pipe when putting the tank back on ? Mine had been shortened a time or two over the years and so couldn't be routed properly, a longer pipe sorted it. I know it's basic but I fell for it!!!!! Good luck. Quote Link to comment Share on other sites More sharing options...
for artie Posted July 23, 2011 Report Share Posted July 23, 2011 Remove the choke slide. Clean it and the slide hole. Quote Link to comment Share on other sites More sharing options...
pipal1000 Posted July 23, 2011 Author Report Share Posted July 23, 2011 Fellas - Tks V much. Have checked for possible trapped fuel pipe (again and again!!), have stripped carb to single items, used almost a full tin of carb cleaner and a high pressure air line. Have blasted every hole in the carb. Have checked and adjusted float heights, have blasted the carb. Have cleaned air filter and the little additional air filter and re oiled, have blasted the carb. Have adjusted the air mixture screw and tick over screw and blasted the carb. ave put in a new spark plug. Finally I blasted the carb. No change!!!!!. The bike just won't seem to run at low revs or tick over. Its like the whole of the lower rev range is a massive flat spot. I can keep the bike running by keeping the revs up and mechanically it sounds fine. Did I mentioned I blasted the carb. Have given up for today........not beaten, just recharging the enthusiasam batteries for tomorrow. Any other thoughts or ideas would be much appreciated............ should I blast the carb again??? Quote Link to comment Share on other sites More sharing options...
copemech Posted July 23, 2011 Report Share Posted July 23, 2011 Fellas - Tks V much. Have checked for possible trapped fuel pipe (again and again!!), have stripped carb to single items, used almost a full tin of carb cleaner and a high pressure air line. Have blasted every hole in the carb. Have checked and adjusted float heights, have blasted the carb. Have cleaned air filter and the little additional air filter and re oiled, have blasted the carb. Have adjusted the air mixture screw and tick over screw and blasted the carb. ave put in a new spark plug. Finally I blasted the carb. No change!!!!!. The bike just won't seem to run at low revs or tick over. Its like the whole of the lower rev range is a massive flat spot. I can keep the bike running by keeping the revs up and mechanically it sounds fine. Did I mentioned I blasted the carb. Have given up for today........not beaten, just recharging the enthusiasam batteries for tomorrow. Any other thoughts or ideas would be much appreciated............ should I blast the carb again??? What carb is it? Can you find a fine wire to pass through the pilot jet? Quote Link to comment Share on other sites More sharing options...
pipal1000 Posted July 23, 2011 Author Report Share Posted July 23, 2011 It's the standard Delorto carb. I can see light through the pilot jet hole so assume it's OK. However, this is another job that will be done tomorrow. Thanks. I'm getting desperate so will try anything.......... well almost!! Quote Link to comment Share on other sites More sharing options...
wherry Posted July 23, 2011 Report Share Posted July 23, 2011 (edited) Fellas - Tks V much. Have checked for possible trapped fuel pipe (again and again!!), have stripped carb to single items, used almost a full tin of carb cleaner and a high pressure air line. Have blasted every hole in the carb. Have checked and adjusted float heights, have blasted the carb. Have cleaned air filter and the little additional air filter and re oiled, have blasted the carb. Have adjusted the air mixture screw and tick over screw and blasted the carb. ave put in a new spark plug. Finally I blasted the carb. No change!!!!!. The bike just won't seem to run at low revs or tick over. Its like the whole of the lower rev range is a massive flat spot. I can keep the bike running by keeping the revs up and mechanically it sounds fine. Did I mentioned I blasted the carb. Have given up for today........not beaten, just recharging the enthusiasam batteries for tomorrow. Any other thoughts or ideas would be much appreciated............ should I blast the carb again??? Additional air filter? Sounds like you may have a PHBH carb there. Seriously, what does it say on the side of the carb? Are you sure it's a 2001 bike? Got a picture of it? Edited July 23, 2011 by Wherry Quote Link to comment Share on other sites More sharing options...
nelly1 Posted July 23, 2011 Report Share Posted July 23, 2011 id try giving the carb a blast mate sorry couldnt resist Quote Link to comment Share on other sites More sharing options...
pipal1000 Posted July 23, 2011 Author Report Share Posted July 23, 2011 I'm sure it's a delorto and have checked the owners manual and this small air filter is called a sub filter. It connects to a small spigot on the r/h side of the carb. Its about the same size circle as a 2p piece and about 25mm thick. It mounts to the frame on a rubber bush just next to the rear brake fluid reservoir. Ihave washed and oiled this and it seems to be clear. I do appreciate your help so will get the carb off again tomorrow and check the names/numbers on it. As you can image, I can now get the carb off in the dark with one hand tied behind my back. Whilst the carbs off I might even give it another blast. Cheers guys, keep the ideas coming. Quote Link to comment Share on other sites More sharing options...
wherry Posted July 23, 2011 Report Share Posted July 23, 2011 I'm sure it's a delorto and have checked the owners manual and this small air filter is called a sub filter. It connects to a small spigot on the r/h side of the carb. Its about the same size circle as a 2p piece and about 25mm thick. It mounts to the frame on a rubber bush just next to the rear brake fluid reservoir. Ihave washed and oiled this and it seems to be clear. I do appreciate your help so will get the carb off again tomorrow and check the names/numbers on it. As you can image, I can now get the carb off in the dark with one hand tied behind my back. Whilst the carbs off I might even give it another blast. Cheers guys, keep the ideas coming. If it's got the sub air filter it's the Dellorto PHBH carb and the bike has got the wrong carb or it's a 1999 or earlier bike. I've recently had my 1999 315R stolen so you'll forgive me if I don't offer any more advice on here publically. PM me if you want my advice. Quote Link to comment Share on other sites More sharing options...
copemech Posted July 24, 2011 Report Share Posted July 24, 2011 Seems I recall they switched about on the carbs in that timeframe, which brought my initial question of the type, yet I have not owned a PHBH, and recall they had a separate air circuit(thus filter) and fuel circuit. Yet still similar overall to the PHBL, and same basic principals apply, as you gotta get some fuel up from the primary circuit which should exit the small hole in the carb bore on the engine side and probably also a transition hole just behind the slide. No idea about screw settings on these, possibly others may chime in, but a couple things to keep in mind, the pilot jet is soo small it can fool you with a bit of clear sand chrystal when looking through, and you need to remove the screws and find airflow(or cleaner) through the passages blowing from inside back. I suppose bike could be sucking air in elsewhere, or even crank seals, as it would not be the first ones ruined with the alcohol laced fuel! Might just ck after to see if you got a vacume on your crankcase vent tube or remove mag cover and spray a bit of cleaner in there to see if there is a noticable change. Quote Link to comment Share on other sites More sharing options...
pipal1000 Posted July 24, 2011 Author Report Share Posted July 24, 2011 HOORAY IT NOW RUNS FINE !!! You guys are right on the button, it is a Delorto PHBH carb. Spent a pleasant afternoon on the patio furniture methodically stripping the carb .Had to argue this with the wife and explained I needed good light to do this work and the garage just isn't bright enough, that worked so I sat in the sun and got down to business. Unbeknown to me, seems this carb has 2 pilot jets. One is easily seen and unscrews, the other is behind this one right up inside the carb. The previous owner has obviously had a go at getting it this jet out and broke one half of the screw head off. So my only option was, in one way or another, to get it out. I opted to bang a sharpened flat blade screwdriver into it and with use of WD40 and by being very careful I got it out. Guess what I did then...... yeah... I gave it a blast. This little pilot jet seems to feed straight up into the main venturi and also branches off to a 'sloping' hole in the main venturi. I'm guessing but I bet there was a bit of swarf caught up and I've now got it out. Anyway after a most enjoyable carb blast I used a needle file to cut a slot into the wrecked jet and screwed it back in gently. I reassembled the carb and hey presto one running Cota 315R. I will order a new jet and replace it. My thanks to all you guys and I feel I have now joined the ranks of Delorto PHBH experts. By the way if you got a carb problem.... give it a blast. Quote Link to comment Share on other sites More sharing options...
copemech Posted July 25, 2011 Report Share Posted July 25, 2011 That is good to hear! Fact is , many times you may never actually see the culprit! Good job then, now giv'er another just to be sure! Quote Link to comment Share on other sites More sharing options...
rich delaney Posted July 25, 2011 Report Share Posted July 25, 2011 That carb works better without that secondary pilot jet. I believe it's intended to be something like a difuser but is prone to clogging. After having these symptoms numerous times I finally pitched the little bugger and the bike runs fine with no problems... Quote Link to comment Share on other sites More sharing options...
martin belair Posted July 26, 2011 Report Share Posted July 26, 2011 (edited) That carb works better without that secondary pilot jet. I believe it's intended to be something like a difuser but is prone to clogging. After having these symptoms numerous times I finally pitched the little bugger and the bike runs fine with no problems... Richard, you are a genius! When I think of all the grief that stupid diffuser gave us over the years..... I never thought of pitching it. What a simple solution. I love it. Edited July 26, 2011 by Martin Belair Quote Link to comment Share on other sites More sharing options...
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