HighLUX Posted June 15, 2013 Share Posted June 15, 2013 Use a cable tie on the rubber part of the return line to slowly constrict it down to provide suitable pressure to the carbs but enough to relive the pressure when at ilde etc. DISCLAIMER: Im drunk but my mind seems to think this is an excellent idea Quote Link to comment Share on other sites More sharing options...
Raizer Posted June 15, 2013 Share Posted June 15, 2013 Even a T piece inline, or a filter with two outlets woudl work yeh? T the reg return back into the supply line before the pump, sounds a bit rough, but it works Quote Link to comment Share on other sites More sharing options...
Beaver Posted June 15, 2013 Author Share Posted June 15, 2013 OK, if you say so. I just suggested changing angle because I had the exact same issue and changing the angle if the carb fixed it, but that's cool. Its easier to change the angle of your carbs than pulling them to bits to change the float level, just to try and see what happens. it takes me 5mins to change the floats. I don't see how I could change the angle of the carbs without hacking up the manifold. Quote Link to comment Share on other sites More sharing options...
Escorto. Posted June 15, 2013 Share Posted June 15, 2013 Try putting the whole car on an angle then.? /spam Quote Link to comment Share on other sites More sharing options...
Spencer Posted June 15, 2013 Share Posted June 15, 2013 You don't need to change the angles, neds in dream land. Changing angles may have fixed his problem but these carbs are made work work on a range of angles and not drop fuel, at the factory angle they are just designed to have optimum fuel in the bowl. Did you vacuum test the needles? I have had plenty of new needles fail a vacuum test when rebuilding a carb, if they don't hold vacuum they don't stop fuel. Quote Link to comment Share on other sites More sharing options...
Beaver Posted June 15, 2013 Author Share Posted June 15, 2013 Please explain vacuum test? I changed needles between carbs but the same carb was still leaking the worse so discounted that as the cause Quote Link to comment Share on other sites More sharing options...
Ned Posted June 15, 2013 Share Posted June 15, 2013 Sorry, mine have silicone joiners so was piss easy for me. I know you won't do it because apparently its wrong, but you could jack up a side of the car for a quick check. T section is something in saw come up countless times when in was looking online for my carbs, so worth a shot I guess Quote Link to comment Share on other sites More sharing options...
Spencer Posted June 15, 2013 Share Posted June 15, 2013 Changing needles isn't a good idea. Sit the carb so the needle is seated then use a vacuum pump to apply a small amount of vacuum and see if it holds. Quote Link to comment Share on other sites More sharing options...
Ned Posted June 15, 2013 Share Posted June 15, 2013 And re: needles, swapping like you did is a good idea, but if there's crap or something on the seat, it obviously won't get fixed by swapping needles, though you probably checked that when you swapped them over. Quote Link to comment Share on other sites More sharing options...
Spencer Posted June 15, 2013 Share Posted June 15, 2013 Needles and seats wear, swapping them could make your problem worse. They are replacement items, get new ones vacuum test and go from there? There's no voodoo angle, if you set the floats right and the seats are legit they should hold a couple PSI easy. But yes the correct angle of the carb will give you the right bowl volume. T piece is legit as well if you want to give it a burn. 1 Quote Link to comment Share on other sites More sharing options...
Beaver Posted June 15, 2013 Author Share Posted June 15, 2013 ah yep, although vacuum test seems a bit odd as they rely on the float holding them shut against pressure, not vacuum so why is that a good test? (Just thinking out loud) I'll track down some new ones to start with anyway. Will also try a return line with t piece just to see if it works Quote Link to comment Share on other sites More sharing options...
Beaver Posted June 15, 2013 Author Share Posted June 15, 2013 And re: needles, swapping like you did is a good idea, but if there's crap or something on the seat, it obviously won't get fixed by swapping needles, though you probably checked that when you swapped them over. yes ned, I'm aware of that, hence stripping them down and cleaning everything. Quote Link to comment Share on other sites More sharing options...
Spencer Posted June 15, 2013 Share Posted June 15, 2013 The vacuum pulls the needle hard on the seat and also tests if they seal properly, doesn't matter if you push or pull it they still have to seat properly to hold fuel. I was shown it by a dude at a carb shop, he reckons 1 out 10 new needles he installed would fail. UJ or someone has a one man brake bleeder/vacuum pump maybe? Quote Link to comment Share on other sites More sharing options...
Beaver Posted June 16, 2013 Author Share Posted June 16, 2013 Ah yep I see what you are getting at. Makes sense although if the float system isnt designed to handle much more than say 100mm of head (ie the level of the tank above carbs) then even if the valves sealed perfectly they could still be pushed open by say the pressure of the fuel pump? Also the other strange thing is that everything has been sweet (albeit one of the carbs flowing out the overflow) for about a week and then all of a sudden it wont idle when the pump is connected and you can hear it fucking out (ie car will start and idle perfectly and rev freely without the pump connected, ten hook it up and after about 15seconds it will gradually turn to shit and not run on all cylinders. Fuck this is driving me crazy Quote Link to comment Share on other sites More sharing options...
Spencer Posted June 16, 2013 Share Posted June 16, 2013 Yes even if they seal perfect pressure will still push them open past a point. Depends on the float setup how hard they close the needle. Strange indeed that it just fucked out! Dunno man test the needles and try the tee piece? Get a GC off here to help, Internet diagnosis is hard/ jack your car up lol 1 Quote Link to comment Share on other sites More sharing options...
Beaver Posted June 16, 2013 Author Share Posted June 16, 2013 haha yeh man really appreciate the thoughts. I rigged up a couple of t-pieces today, sorta worked but had trouble priming the system. Ive hit up the jokers at fuelflow who do the low pressure self regulating pumps so will see if they can offer any advice. Pumps are only ~$100 so not the end of the world if it doesnt work. Sick of trying little gay things haha Quote Link to comment Share on other sites More sharing options...
peteretep Posted June 16, 2013 Share Posted June 16, 2013 i reckon it will be some o-rings somewhere have perished, they fit them in unusual places on bike carbs. Stephen ended up fitting a fuel reg but it just masked the problem for a while. I think in his case it ended up being a gallery was so blocked it had to be drilled out Quote Link to comment Share on other sites More sharing options...
Beaver Posted June 16, 2013 Author Share Posted June 16, 2013 hmm interesting. I have had the carbs apart and it looks like they have recently been overhauled/cleaned out. That said, I will grab some rebuild kits for them any chuck those at it (well at least replace the float valves and idle mixture thingy) The idle mixture screws looked a bit suspect (some were bent) so yeh worth discounting anything silly like that. anyway the car is back running with the standard carb so will give them a onceover again and tripple check nothing is wrong with the carbs themselves. will also look a bit more at pumps I think. Im still convinced part of the problem is the carbs not being designed to seal against anything other then gravity supply. Quote Link to comment Share on other sites More sharing options...
peteretep Posted June 16, 2013 Share Posted June 16, 2013 if you are concerned about it, you can buy a low pressure gauge for around $30. just take off the feed and put the gauge in the end of it and you can see whats up. If possible find the bike manual and check exactly what the pressure should be. I used a pressure gauge to set my regulator and its set to about 2.8psi Quote Link to comment Share on other sites More sharing options...
Beaver Posted June 16, 2013 Author Share Posted June 16, 2013 Yeh that might be the best way. The a12 pump is ~2.6psi from factory so not outrageous but my judgement, its too much! aha Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.