slice Posted March 11, 2015 Share Posted March 11, 2015 Ok folks time to ask for some help, I have had the carbs off of the FJ 3 times now, first time to change the float needle and seats/filters cos they were old and a bit worn out & dripped a bit, now the frigging things leak like anything, it's a right pain in the arse to take them off and so I'm trying to find out what I'm doing wrong. Bought new filters and seats plus needles and installed them as usual, checked the float height and finally figured out how to adjust them (thanks Mc) but now the damned things leak, I can't see what is wrong, checked the floats to see if they are tight, they are, no leaks. It has a fuel pump so it runs under pressure not a vacuum fuel tap like my old XJ. So my question is, WHAT am I missing? & why is the pigging thing leaking out through the overflow on carb number 4 and the central overflow pipe as well. Any advise is welcome at this moment up to and including setting fire to the bastard thing !!! Link to comment Share on other sites More sharing options...
Moderator DirtyDT Posted March 11, 2015 Moderator Share Posted March 11, 2015 Do the floats, float? Or does one, or more, have a hole in them so not pushing the valve up. The floats have to float, the valve needs to close and close before the overflow fills.............................simples in practice however................................... Link to comment Share on other sites More sharing options...
Moderator drewpy Posted March 11, 2015 Moderator Share Posted March 11, 2015 submerge them to see any bubbles, use turps or fuel as it has less density than water. does the pump not shut off when it "feels" the resistance as it can't keep pumping continuously ! 1 Link to comment Share on other sites More sharing options...
slice Posted March 11, 2015 Author Share Posted March 11, 2015 Yeah thanks both, tried the float test but did use water so will try the test in fuel. I think it's the needle not seating correctly but for the life of me can't see how to test that till it's all back together in the bike. The pump does start when you turn the ign on and then stops as the float bowls fill but when it's running it obviously keeps the fuel in the bowls topped off, so when it's on tick over it leaks but when you wring it's neck it don't? Link to comment Share on other sites More sharing options...
YPVS TONE Posted March 11, 2015 Share Posted March 11, 2015 If you have to take the carbs off again it maybe worth checking the little tang on the float that stops the floats dropping too much (NOT the tang that adjusts the float height) as here : http://www.xs1100.co.uk/float.htm Had this on my 350 YPVS if left for a few weeks the carbs would flood even after renewing the float valves and seats and found the small tang needed tweaking to stop the floats dropping to far and putting the float valves out of line. Tony 1 Link to comment Share on other sites More sharing options...
Moderator mervin Posted March 11, 2015 Moderator Share Posted March 11, 2015 Pattern needles and seats ? or gen yam/mikuni . i have heard of pattern needles and seats that leak from new Link to comment Share on other sites More sharing options...
slice Posted March 11, 2015 Author Share Posted March 11, 2015 Genuine Yammie ones, oh my wallet!, hadn't thought abut the tang thingy will have a closer look tomorrow. Thanks lads. Link to comment Share on other sites More sharing options...
blackhat250 Posted March 11, 2015 Share Posted March 11, 2015 The fuel pipe is on the correct fitting, and not on a overflow of vac nipple,, Link to comment Share on other sites More sharing options...
slice Posted March 11, 2015 Author Share Posted March 11, 2015 No checked that twice already just to make sure I wasn't being a tit! But a good idea never the less, thanks lads this, believe it or not, is really helpful. Link to comment Share on other sites More sharing options...
YPVS TONE Posted March 11, 2015 Share Posted March 11, 2015 Got mine from these chaps for the 350 http://www.allensperformance.com/fj1200.html Got them them a few years back for £14 each and Genuine Mikuni. Yamaha dealer wanted £90 for the pair . Link to comment Share on other sites More sharing options...
slice Posted March 12, 2015 Author Share Posted March 12, 2015 Thanks TONE, yes these ones were from Yammie UK so know they are the right thing. Paid £22 per carb X4 for the set inc gaskets and seals plus the needles and seat/filter. Link to comment Share on other sites More sharing options...
Moderator DirtyDT Posted March 12, 2015 Moderator Share Posted March 12, 2015 Allens is where I get my carb bits from. Not cheap but genuine and a good service. Not too far from where I work too. Some good points here. The floats need to work and not jam when the carb is reassembled. Earlier you said that the fuel was pumped. Is the return on the fuel pump clear - ie: the pump pressure is too much for the floats. This would only be identified when the pump was on however, you may still get some leaky fuel that is left over in the carbs at stationary. Link to comment Share on other sites More sharing options...
slice Posted March 12, 2015 Author Share Posted March 12, 2015 Now that's a good thought, will have to ask the owners club how to test for that but not something that had occured to me, thanks. Link to comment Share on other sites More sharing options...
slice Posted March 14, 2015 Author Share Posted March 14, 2015 Just to let you kind people know I fixed the bastard !!! Took 4 more removals to find out what the hell was going on but finally got there. It seems that if your a complete tit and you DON'T look at what your doing you can trap the float with the float bowl and bend the tang that holds the float in position then when you try to start the bike it spits fuel out all over your boots, still I now have clean boots and a clean floor in the garage. Thanks again for your suggestions and of course it helps if the dumb arse your talking to isn't an idiot !!! 2 Link to comment Share on other sites More sharing options...
Moderator drewpy Posted March 14, 2015 Moderator Share Posted March 14, 2015 never mind, we've all been there at some time 1 Link to comment Share on other sites More sharing options...
mcferreira100 Posted March 14, 2015 Share Posted March 14, 2015 Glad to know you came right Slice..I will remind everyone of a weird carb issue I had on the one DT175 with bowl continuously overfilling. After checking float levels about 4 times, a hairline crack on a brass tube in the bowl was the culprit. The only way you will find it is with a series of blow/suck tests on the carb..damn near impossible to trace unless you`re a carb expert. 1 Link to comment Share on other sites More sharing options...
Recommended Posts