Carb leaking Fuel and Low Idle

redapple · Post by **redapple** » Mon Apr 09, 2018 9:00 pm

Hi

hoping desperately someone might be able to help with my carb troubles.
I took my carbs off my bike this weekend and gave them a good clean and even got them ultra sonic cleaned.
Everything looked good and put it back together. I then attempted to adjust the float height to the magic 14mm that I have read in previous posts that everyone seems to set theirs to.

Put the carb back on the bike and when I went to prime it with fuel the fuel pump kept on priming and then eventually fuel started to leak out of one of the vent hoses.

I took the carb and gave the float needles an inspection , took all the floats apart and re-seated everything and knocked the float height down a bit and put the carbs back on the bike.

This time the fuel pumped primed as per normal and once the carbs were full the pump stopped priming and I had no leaks, so i am presuming the float needles are doing the job.

Anyway I started the bike up after it had been sitting for 3-4 weeks, fired up but to keep it idling I had to put the choke on half way, even still after a while the bike stalled. I am not sure if I need to adjust the idle knob and she was idling quite low
I then started her up again and went for a short spin 5min and she rode ok but when I slowed down she would stall, like she didn't want to idle.
Then when I got home I noticed that she was leaking fuel again. It was too dark for me to investigate

My question is

a. with the idling being low and the choke on would this cause the above problem, do I need to adjust the idle.?
b. Are the float heights still set too high and this causing the problem.?
c. Does both the Idle and Float heights need to be adjusted
d. Am I wrong and my float needles are knackered?
e. is their something else that might be causing this.?

Any help would be much appreciated

thank you

Graham Crayon · Post by **Graham Crayon** » Mon Apr 09, 2018 10:03 pm

It does sound like you've got the float height wrong somehow so assuming you can get this right next time you take carbs off I would then adjust all air screws so they are set the same, I think 2.5 turns out from seated but you should check that. Also balance the carbs once they are back on. This will make a huge difference to how smooth it runs, especially on tick over. You don't need to spend loads on Mercury or vacuum gauges either. I bought a really simple bit of kit that consists of a clear length of tube with a few coils wound in the middle & a ball bearing in 2 of the coils. Each end of the tube goes on the vacuum port of the inlet stub for the 2 carbs you're syncing so one end on carb 1 port, other on carb 2. When both bearings line up (engine running obviously) the carbs are synced. Adjust tick over once you've done all 4 carbs. Choke out or on when the engine is warm is not good.

Post by **nuggitt** » Tue Apr 10, 2018 10:00 am

When you set the float bowls did you clamp them down as in photo before you set the height? Also did you rock the carbs forward till the floats went forward then rock them back gently so they were resting on the tang? Did I send you that video of how to do that?

matzxr · Post by **matzxr** » Tue Apr 10, 2018 10:48 am

Float Valves worn.
I had this exact problem.
New valves no leaky !!!!!

redapple · Post by **redapple** » Tue Apr 10, 2018 6:06 pm

thank you for the responses.

No Nuggit did not get that video, it would be much appreciated. Actually setting the float at a constant float height is harder than I thought it would be.

Took the carbs off and before ordering a new carb kit, I decided to give it another try.

I did notice that the far right carb had fuel leaking from the other side, like it was over filling.
I reset all the idle screws to 2.5 turns and then reset the float heights to the same level but knocked it down a little bit, no idea what height just went from the far left carb height.

I also clamped the float seal down as suggested. I actually think that might be the culprit and the far right carb one was not as tight as the others. But it could have been the float height as well

Put the carb back on the bike and started her up and blipped the throttle a few times and no leaks. I had to set the idle by ear as my tachometer doesn't have numbers on it just a bar. let it run for about 20mins still no leaks.

So I took her out for a spin and she runs well, I will still probably have to balance everything at some stage so its smooth.

I have a set of four gauges but I was not sure how to connect them up, I have only really done balancing with a laptop on EFI fuel systems to be honest.

Graham Crayon when said to connnect the hoses from the guages to the vacuum port of the inlet stub. did you mean this (Picture below)
So you have one hose connected to each one and on each hose a t piece with two hoses attached, which go to two gauges?

Graham Crayon · Post by **Graham Crayon** » Tue Apr 10, 2018 6:16 pm

No mate aren't they fuel supply in?
The individual manifolds that each carb bolts to via the rubber boots all have (or should have) a hole in them with a small bolt plugging it. You remove the bolts from the holes, replace with an adaptor that allows you to push a vacuum hose over it. if you've got 4 gauges then you can do them all at once as long as you have 4 adaptors.
I will try to find pics if that's not clear enough.

Graham Crayon · Post by **Graham Crayon** » Tue Apr 10, 2018 6:18 pm

Sorry I didn't study your pic very well. Those stubs you've circled are overflow I think.

redapple · Post by **redapple** » Tue Apr 10, 2018 6:24 pm

you are right those are overflow. If you have some pictures that would be great and also the type of adapters you need. Thank you

when doing it, is the process to get the bike to run smooth

- set your fuel/air screw correctly to get the fuel/air mixture right
- balance the carbs
- then set your idle

Graham Crayon · Post by **Graham Crayon** » Tue Apr 10, 2018 6:30 pm

Yes smooth as a babies bum when all 4 are synced. I can take pics of an old FZ 750 engine I've just removed. No carbs on it but will show inlet stubs with bolts that need to be removed.

Graham Crayon · Post by **Graham Crayon** » Tue Apr 10, 2018 6:59 pm

Jesus I'm losing the will to live trying to post actual images using imageshat so these links will have to do.

First one is of the 2 different sized adaptors. 5mm & 6mm which I think should cover just about most bikes.

https://imageshack.com/a/img923/480/ounytu.jpg

Second one is FZ750 engine removed with bolts shown where adaptors go. Cross/philips/pozi whatever heads.

https://imageshack.com/a/img923/6616/W5c098.jpg

Third one is FZR1000 Genesis engine (very black, removed from rat bike) showing hex head bolts. Better for removing with engine in place.

Well done for making any sense of this!

https://imageshack.com/a/img922/6494/dXvRdK.jpg

Graham Crayon · Post by **Graham Crayon** » Tue Apr 10, 2018 7:06 pm

Sorry for all the separate replies but I can't find an edit option.
You can & apparently should balance the carbs with tickover set slightly high. 1750rpm or something with engine warm. As you have said, set air screws, balance carbs, set tickover. smoooooooooooth.

redapple · Post by **redapple** » Tue Apr 10, 2018 7:17 pm

Sorry Mis-read your previous answer when you said inlet manifold. I think I know what bolt you are talking about now. I have attached a picture just to make sure

. Is it a 5mm or 6mm adapter you need to screw inside?

Graham Crayon · Post by **Graham Crayon** » Tue Apr 10, 2018 7:22 pm

That's them. Im back in the house now so can't be sure which adaptors you'll need but you'll soon see with a bolt out.

Graham Crayon · Post by **Graham Crayon** » Tue Apr 10, 2018 7:26 pm

Must say those vacuum take offs look to be on a crap angle regards fitting adaptors. They will be angled towards the block when screwed in?

redapple · Post by **redapple** » Tue Apr 10, 2018 7:33 pm

No worries they are not mine, I just got a picture off the net just for confirmation.