Thanks Chris. The brass one isn't tapered, or if it is, it has a very light draft angle on it. The thing that concerns me though is that one is longer than the other. Oh well, off the bike they come and I'll put the stock ones back in. Bugger.
btw - only slightly off topic - chanced on this :- BikeBoy.org - Ducati 900SS Carb model with Keihin FCR 39 and 41mm carbs N.B. - if you want to make complete sense of them, make sure you read the notes when sober..
For the first time since I adjusted the mixture screws (putting back the originals), installed the mini dyna coils and finally got my new battery yesterday I went out for a run today. Just in case the seals were dodgy after my fidgeting I ran the bike on the drive till it ticked over fine, set up the tickover and it seemed good as gold. However parking up in the highstreet, stopping for a coffee with herself, I noticed that in traffic it was beginning to misbehave again. After coming out from the coffee place, I noticed that there was a big puddle under the bike, and yes my heart sank. Firing the bike up, it sounded to all the world like it was flooded, - firing on what sounded like one cylinder. Eventually I got it running much to the smug grin of a self righteous harley owner twat with an alice band - wtf!?! Getting it onto a nice bit of b road, I opened it up and after much popping and banging it seemed to clear its throat. Italian tune-up style. However, the revs needed to be kept high or else it bogged down. getting it back on the drive I could see that there was a trail of fuel following me down the road. :frown: On the drive, even with engine off, the fuel just kept running out of the carb overflow drain hose. Last time it was the horizontal cylinder carb pissing fuel, now it was the vertical cylinder on the left. I went to reset the mixture screws, thinking perhaps they had unwound again. Fuel ran down my screw driver, I then noticed that fuel was pouring out from the top of the carb as well, and also one of the joints in the exhaust underneath the swingarm. So, fuel tap off, and waited till all the dripping stopped before getting it back in the garage. This is truly fucking bollocks. I thought about a rebuild kit, but would it really solve anything ? Time to trawl ebay for a set of cv carbs, as I was stupid enough to sell mine all those years ago. :frown:
Do not want to be smug but I am only missing metal fuel tank with petrol pump .... and injection comes on.
Surely fuel p*ssing out of the overflow is sign that either the float needle is stuck; worn ; damaged; floats leaking, or the fuel level is at the wrong height................My SS did exactly the same thing as yours......found to be wrong fuel level and worn needle/seat..... ....and I'm not sure about the pump as to whether it is 'closed' when the ignition is off, but if 'open', I would imagine there is a 'head' behind the fuel down to the carbs if the tank is pretty full. AL
Indeed, it's not a fault with the carburettor design but something wrong with it's function; something that can be fixed. Probably a good idea to switch off fuel supply to any carb when the bike's standing though and if you want an automatic solution then fit something like this; PETROL Solenoid Shutoff Lock Off Valve for LPG Conversion - NEW! | eBay
When my filter finally needs changing or if my pump packs up; all that cr*p is getting junked and an external solid state pump and filters will be fitted...............plus and adaptor made for the tank fuel tap so I can fit a shut off version tap with a reserve faclity...... And that bl**dy fuel level sensor can go as well. AL
Thanks Duke and Al. The fuel filter is new so I know its not that. Like you duke I can only assume something within the carb is amiss. I looked at rebuild kits, but perhaps it's probably just worth getting a guy with a rolling road to come and collect it and do a proper set up on it. There's a guy in Great Bookham who is a suzuki specialist but I've read he's quite good. Fortunately my prehensile paws can get to the fuel tap to shut it off, and that's what I've done. I may well still get a set of mikuni's as a backup though.
could someone who's running these be kind enough to post their settings so I can compare when I take mine apart. Ta
With the ignition turned off the fuel still poured. Its only when I turned the fuel tap off that it finally stopped. I long dreamed of fitting an external fuel pump to bike instead of all that in tank shite. how would you deal with fuel level - go old school with a reserve tap? http://www.demon-tweeks.co.uk/motorsport/fuel-pumps/facet-solid-state-electronic-fuel-pump-kit
Sev, Its got to be float height, or float needle related. People seem to obsess about jets and mixture screws, but the first and most important thing is to get the float height spot on, and the float needles seating properly, otherwise any other tinkering is meaningless. Make sure that the spindles the floats turn on are spot on too, and that the floats pivot cleanly, without hanging up on the float chamber. Sometimes setting the float height can be tricky, because of the spring loaded float needle, so the way I do it is to put the carb into its normal operating orientation, then blow down the fuel feed pipe gently. then raise the float, till it shuts the float valve, then you can hold the float still, and measure the height. My guess is that your float height is too high, or that the float needle or float is sticking.
Chewy, thanks for your advice. I took them off the bike, and preliminary measuring, blowing down the fuel inlet would suggest my float height was around 15mm. Also I wondered why I'd never had this issue until recently and it occured to me that I don't think the fuel tap has ever been fully open all the way. I'm sure its only ever been half open so I don't know if this compensated for it at all? Anyway, today when I get home I'm going to make a basic angle plate to hold these things at a proper orientation and also a decent working height as yesterday I looked like I was trying to play a kettle like a trumpet! Measuring the angle the bottom of the float housing seems to sit slightly nose up from level, but that may be down to unevenness of my garage floor or my paddock stands (f+R). Would you recommend setting up so the housing split line is at 0 degrees (dead level) or try and emulate the exact angle? I don't really want to strip these things out again - but I will get it to a rolling road as I feel it deserves a proper setup!
Inside the FCRs And Keihin FCR FAQ If you are seeing 15mm float height, I wonder how you are measuring it. Chris Kelly suggests that it should be 9mm. Hmmm
I set the float bowl level and then blew down the pipe. I then measured the exposed float to the edge of the housing at the point when the needle stopped any air passing through.
Even though your float height is 15mm, as opposed to 9mm as suggested from the website, it would seem that the float is unable to close the float needle valve in this configuration. How about posting a pic of what the float needle tips look like too? Is there anything that could possibly be the cause of the floats hanging up? Are you sure that the fuel pump can deliver the fuel, and that the excess fuel is coming back into the tank without restriction, and the carbs aren't becoming pressurised?
Sure thing, I'll get some pics up this evening. I haven't tried measuring it as in the photo admittedly, as I had the carburettor body parked in a horizontal orientation. The float seems to move freely enough. The fuel pump can deliver the fuel I'm pretty sure of that, as fuelling hasn't been a problem given the rate it manages to piss out of the carbs and onto the floor. I only have the one hose running into the carb, both inlet and return hoses are linked with a Y piece and then go into the single feed hose for the carb, the top spigot on the carb is where the drain hose goes to allow a nice puddle to form on the floor.
Certainly got to be floats, heights, and float needles then. A 4 mm difference is massive when dealing with float heights, they have to be spot on. I bought my FCRs second hand on ebay, so I went through them totally before fitting, and set them to Chris Kelly's recommendations, apart from a 160 main jet, which was fitted when I bought them. Ive now raised the needle one notch in mind of the Spaghetti exhaust and the revised cam timing and JE pistons (but its still 904cc). All seems to be fine, but I haven't put it on a dyno yet. With no FCRs and stock header I was seeing 84bhp on a Dynojet dyno, and after fitting the FCRs on a fast tour of the lake district I saw 60+mpg, so figured it might be a little lean (but no flat spots, and the plug colour looked fine), so after fiddling with the cam timing and fitting a spaghetti header I thought that richening up the midrange a tad would be wise.
