Carb float height

[Rich74]

I have tried to set the float height using the tube method and there was no way I could get near the 4.5mm above the mating service. I have tried setting the floats using a ruler to 14.00mm with the floats on the resting position and the bike run worse than it was before. I will try setting them to 11.00mm tomorrow to see what happens. So while I am taking the carbs off again for about the tenth time, do any of you guy's know what height measurement has worked for you?


Your help will be much appreciated.


Richard

[Gnasher]

Float height or the need for adjustment in my experience is something hardly ever required.  Most issues with fuel levels within the float bowls is due to worn and/or blocked metering valve assemblies.

I've never had to reset a float, on a Fazer.     

[Rich74]

The bike wasn't getting hot on cylinder 3 and I checked for a good spark, all ok there. Have taken the carbs apart and cleaned and put in new seals.
I checked float heights and they were all over the place. Someone had previously mucked around with them. I have reset them so before they seat to the float valve closing, they position inline with the mating service evenly, in other words parallel.
Cylinder 3 is now hotter than it was but not as hot as the other cylinders.
Has got me thinking what is causing the problem with no 3 cylinder.

[Gnasher]

The bike wasn't getting hot on cylinder 3 and I checked for a good spark, all ok there. Have taken the carbs apart and cleaned and put in new seals.
I checked float heights and they were all over the place. Someone had previously mucked around with them. I have reset them so before they seat to the float valve closing, they position inline with the mating service evenly, in other words parallel.
Cylinder 3 is now hotter than it was but not as hot as the other cylinders.
Has got me thinking what is causing the problem with no 3 cylinder.

Pilot jet is more than likely the issue.   

[Rich74]

Thanks for your help here, I very much appreciate it. I will take it out and have another look at it. I am sure when I looked at it with my magnifying glass it looked clear and I cleared all the circuits out with a good blow of the airline.

[Gnasher]

Just checking you've not confused the main jet and emulsion tube with the pilot jet, handy thread here http://foc-u.co.uk/index.php?topic=23023.0 thanks to BBrown1664  .   Also check the pilot air screw jet, it sits right at the front of the carb mouth engine side and at a right angle to the pilot screw, they get blocked/restricted by gum.  Use a long strand of nylon from a dust pan brush or broom or any non metallic rod to clear the hole and the air bleed circuit, back into the carb body, it will pop out of the small hole in the main air flow camber.             

[Rich74]

Solved the no 3 cylinder problem of not getting hot. I balanced the carbs and that solved the problem. I now have another problem of the engine stuttering at 6-7000 revs. I have ordered a fuel filter, as I don't know when that was last changed and I am thinking that the air mixture screws may need a little tweaking. Aftermarket downpipes and exhaust can have been fitted. I have them at 2 turns out, so will try them at another 1/8 -1/4 of a turn out and see how that goes. I am pretty sure this is a fuel problem on the pilot side.

[Gnasher]

Solved the no 3 cylinder problem of not getting hot. I balanced the carbs and that solved the problem. I now have another problem of the engine stuttering at 6-7000 revs. I have ordered a fuel filter, as I don't know when that was last changed and I am thinking that the air mixture screws may need a little tweaking. Aftermarket downpipes and exhaust can have been fitted. I have them at 2 turns out, so will try them at another 1/8 -1/4 of a turn out and see how that goes. I am pretty sure this is a fuel problem on the pilot side.

The pilot circuit stops operating at about 3k, spluttering 6-7k is main jet circuit.  Firstly check you don't have a cracked plug, pop up the tank in a darken garage or out side at night, start the bike and look for arching in the plug wells, leads and caps.  You mention AM downtubes and end can, some owners make the mistake of playing with carb needle height and main jets and removing air filters.  Fazers need nothing doing to the fuelling when adding the above mentioned even a high flow filter, but there must be a filter,  fitting all the above cleans up throttle response low/mid range.  Check there is an air filter and it's clean, also check all the needle heights and jets are standard.


We can go from there if you find all of the above is fine. 

[Rich74]

I have checked everything you have mentioned and all looks good. The items I have replaced are coils, plugs and NGK caps. Carb balancing is correct at 230-250 and plugs have a nice biscuit colour.
The needles were in the correct groove and all washers present.
Only question I have, is when I replaced the main jet o'ring, I did it up finger tight, as not to distort the o'ring. I presume that would be the correct way of tightening of the jet.

[Gnasher]

When you say main jet do you mean emulsion tube (long with tiny holes) as it has an O ring, the main jet doesn't and screws into the bottom of the emulsion tube?  They should both be nipped up with a small oring spanner and a bladed screw driver, if the emulsion tube is lose it will allow too/much air into the mixture at mid to high range, which would explain your problem.

It could also be an air leak at the manifold rubber, check the carb is seated correctly (pushed all the way in) and the clip is sufficiently tight.  Let me know how you get on, there's still a few other things to try. 

[Rich74]

Emulsion tube is what I was supposed to say. I will nip them up tomorrow. I have checked to make sure the carbs are seated properly and the clips are tight.
I will update tomorrow.
Cheers for your help and time.

[Rich74]

Well my problem is now solved and many thanks for all the help.
I tightened the emulsion tubes with a small spanner and put a new fuel filter in and she pulls really well through the rev range.
This is my 3rd fazer now, as I have tried other bikes, but the fazer is probably one of the best bikes I have owned and I have had quite a few bikes over the years, Ducati's, other Yamaha's, Kawasaki's etc.
The only small thing I would like to sort out is I have to give it a little throttle to start the bike.The air mixture screws are 2 turns out and carbs are balanced at the right readings. Plugs are new, so I am trying to think if there is anything I could do to improve starting the bike on the button without throttle and it maybe a couple or so attempts to start.


Cheers for your help, it is very much appreciated.

[Gnasher]

Carb Fazer 600's have always been tricky starters, it's a balancing act of choke and throttle, many of the last crab bikes where/are my XJR for one.

The choke isn't a choke in the sense of the word as it doesn't add any fuel just cut the air which has the effect of enriching the mixture. It's an enricher circuit.   

Fazers run rich slightly rich at the low end as standard which is why they respond well to a high flow filter and end can without jetting.  With a standard can/filter I've had some success with setting the air mixture screws at 1 3/4 and 1 1/2 turns out but you need to test to ensure you'r not leaning off too much.  Most often than not you don't need any throttle or choke to start the bike unless it's cold, it's really a matter of getting used to what works for your bike.  Mine is about 5mm of choke and no throttle, let it run until the rev start to rise and back off the choke slightly.

I suspect the issue of starting lies in the ignition, something like a 4* advance would help, it certainly does with the XJR, but I don't know of a advancer plate made for a Fazer.  That said it's possible someone makes one, if they do you could try it.   

Without a plate it would be a real fuff for very little gain, IMHO just learn what works to start yours. 

[Rich74]

Thanks again for all your help and quick replies.
You have been a great help.


Cheers,


Rich