Float experiments - what would your bike do??

[bally123]

SOLVED!! - Float experiments - what would your bike do??

Testing the results of the head modifications I ran the following set up:

Pilot 45, DDL #4, 185 main, #7 slide, Air screw 3 turns out (EC250 - 2005)

Bike pulled like a train, throttle only wheelies in 3rd/4th gear no problem Seemed pretty rich based on smoke from pipe and amount of fuel used. Very sputtery at 0-1/8 throttle and would load up in slow sections taking a gear or to to clear out. Idle was non existent, even with idle screw wound in too far (spring bound) still no idle - it just didn't even try to idle

I thought I would go the the other extreme and throw a 38 pilot in when I got home to see if I could get some idle - I reckon this is a pretty lean set up with the large section needle (ddl) and a 38 pilot. I got it too idle (just) with air screw at 3 turns out but not that well and idle screw had to be really far in, any attempt to set it off coil bound and bike stalled. (air screw setting obviously didn't have any effect)

So i figure somethings not right - surely I don't need lower than 38 pilot, and or an even larger needle. So as an experiment i let it idle (1000rpm ish) and turned the fuel off. After a moment the revs rose, not a gradual rise but a definite step change - suddenly the bike was at 2300-2400 rpm and I could return the idle screw to more sensible settings. The 38 pilot was now way to lean with a bog response to snapping the throttle. However the bike idled really well like this for a good 3-4 mins before eventually emptying the float bowl and stalling. I reckon a larger pilot would put right that bogging and I would have idle screw setting that brought the air screw back into play - I will test this next time.

I am now thinking the fuel level in the float could be an issue - I have checked the float setting too many times and I am positive its right. Can the fuel level get to a height where it screws up the idle circuit?
Is it possible the fuel level is too high when running? Could it be caused by vibration, or does the valve simply need renewing?

Does anyone else's bike act this way when the fuel tap is knocked off?

I refuse to give up, I refuse to give up......

Cheers Andy

 

[Fred1956]

If your idle screw is at coil bind then you have already bypassed the pilot & air screw circuits. To get them back in play you need to back off the idle screw (drops the needle back down in the main)

 

[gg3]

Hi Bally123,I have a similar issue.Had the bike running excellent after setting the float level( float bowl bung & tube method) & spending time on the jetting-MJ180,JD Blue clip 2,PJ40.Bike-2010 ec300 Alt.-0 to 500m Temp.- 22-30 Deg. Very Happy.Just did the top end,cleaned power valves & changed the base gaskets from 3 x.3mm to 1x.5mm.The bike smoked terribly,wouldn't idle & ran like it was super rich off the bottom.Top end very good,slightly more compression noticible.Changed to a JD RED clip3 & 38 pilot.Much better but still not right.Float Level?Checked & reset it(it was a little high,must replace the fuel valve).At the same time read a brilliant post by skraMnoR on power valve actuator play & decided my 5mm of play was unacceptable.Put the base jetting back in JD Blue,PJ40 to check if the adjustments were the fix,still really rich.Back to JD red,PJ38-Oh yes,feeling the love!Could even be better with fine adjustment but will probably not get round to it & just ride it.
Theory- Has the small change in port timing made it richer?But your head work won't change port timing like mine,right?
Does higher compression give a more efficient burn so less fuel is required?
If the fuel is off it will scream it's nuts off just before it runs out.

 

[Jakobi]

The reduction in squish massively improves efficiency as the fuel you are putting into the engine is being put under the spark plug as opposed to just floating around somewhere above the piston. This may mean you need to lean it off some. An increase in compression may require fatter jetting. Not sure if port timing has a whole lot of effect on jetting itself, but just changing gaskets impacts on both squish, and compression. A reduction in one creating an increase in the other (and vice versa).

Float level wise, I have found Keihin stock figures just don't work on the gasser due to tha angle that the carb leans at coming from the air boot to the reed block. Its so tilted forward that you will get splash/overflow into the engine and it will run rich. Drop the fuel level another 2mm and bobs your uncle. I might take the time to post up a pic of the Lectron installed just to show you how off level it is. The clear float bowl is good for that.

 

[bally123]

Fred: I am sure your right, but simply backing off the idle screw won't cut it. I know its super rich due to smoke and the way it simply stops when the slide is set at a "proper" idle point. Something more has to be going on here...

GG3 your issues sound convincingly like mine, I wouldn't imagine a 0.4mm change in your gaskets would yield such a response, in fact I rather suspect we are suffering from a fuel level issue.

Jakobi - great call on the natural tilt on the carb, I will get carb on bench and try some tilt experiments.

It got me wondering if a high internal fuel level would simply splash / overflow internally or......

It then occurred to me that the pilot jet has several cross holes in the side, this I believe is to introduce air into to the pilot fuel stream to assist in emulsifying the fuel before it's introduced into the carbs air stream - so if the fuel level is too high could it reach the level of the holes? Effectively submerging an area that should be an air circuit and over fueling at low throttle openings.....

Or am I over thinking it again???

Andy

 

[bally123]

Ok did some tests (not that my neighbors appreciated my experiments!), the float level was set at factory height and got a high level see photo - adjusted the float and got an improvement. (see 2nd photo).

So started bike and ran it with level tube still fitted. The fuel level went up really high! Certainly as high as in the first picture. Adjusted float some more - way off factory height now. Ran the bike and sure enough the float level again was too high! (No external overflow from carb)

So i turn fuel off and emptied the float level a little so the level sat at the carb to float bowl joint. Started bike and after a short while it idled, adjusted air screw with a 42 pilot to 2 3/4 turns. Bike was bogging on sharp throttle snaps but idle was great (idle screw was no where near coil bound). As it used fuel I just kept topping up float level to the joint. Swapped out the DDL needle for a JD blue - throttle response was way better and idle was great. Finally !!!I have been trying to run this combo for weeks. So as a final test turn on fuel tap, level rises bike loads up and stalls.

I had checked float function statically and for shut off by blowing through the fuel inlet, float was certainly set to correct height. It simply seems that when running the level was rising - maybe vibration causing the valve to leak through?? (Not that it leaked externally)

Can't wait to try my new shut off when it arrives. Hope it cures it...

GG3 I suggest you try a similar experiment....

Andy

 

[Jakobi]

When I jet I start with the float height, and then the slide height. I then change pilots looking for the right one which will idle with the AS at 1.5 turns (can use the AS to dial in or know when you are getting close). From there I use the needle clip position to get best response at 1/4 throttle to 1/2 throttle, and then change needle diameters and pilots again to maintain idle and get the desired delivery between idle and 1/4 throttle with most effect at 1/8th. Last circuit is the main. This has worked very well for me in the past.

As promised, heres the picture of the fuel level in the lectron

 

[n_green]

How old is your bike/carb. Sounds to me like the float needle and or seat is worn hence your float height adjustments go out the window when the fuel tap is on and bike is running.
Also based on those photos I think your level is still to high. If you are running an ASII carb the fuel level (when the carb is level) should be 6.5mm below the carb/float bowl join stock. This is usually altered to about 8-9mm below the join as mentioned by Jake above.

 

[n_green]

Have you taken the carb off the bike and given it a good clean/blow out with compressed air? Could also be grit in there preventing float needle from seating properly?

 

[Jakobi]

Nath.. The carb above is an AS1. From memory I think the float height is 16mm.

 

[n_green]

Nath.. The carb above is an AS1. From memory I think the float height is 16mm.

Well disregard then

 

[bally123]

Well its conclusive, the new valve arrived today but did not work. More tests including bending the float to a ridiculous extreme showed the seat must be worn. The level does not change when I adjust the float, it pretty much rises back to the joint every time and certainly it overfills further when bike is running - in turn causing it to over fuel and stall. In desperation I tried to dress the seat and got an improvement, the fuel level rises more slowly now, but ultimately it still ends up too high.

Jakobi, I am so envious of that float bowl, That would have made my life over the last week or so much easier. Great to get an idea of the level and angle though, thanks for posting...

So I need to renew the brass seat. I am not about to go and buy a new (or 2nd hand) carb just yet - I know all will be fine if I can just cure the sealing issue.

Seriously contemplating making one - but unsure about seat angle and I am concerned that surface finish is gonna have to be really good. (in that respect would a sharp edge help to seal better than a cone?)

Whatever happens I am gonna pull the old one tonight and get measuring!!

Or is there an available replacement or donor part from another carb?

Greatly appreciate anyone's experience or advice....

Andy

 

[Jakobi]

With all these Lectrons and Smart Carbs coming out it shouldn't be hard to pickup a second hand PWK for cheaps! Otherwise if you have a few coins..

 

[bally123]

Otherwise if you have a few coins..

Please, the last thing I need is temptation!! I suspect I'll get it to a point where I am happy with the PWK and then I will be bored and it will be time to find something else to try. At least I will have the advantage of all your threads to guide me...


Andy

 

[(F5)]

When we have drilled float jets cleaning them up can be an issue (+ the float jet protrudes further in).


anyhoo an old trick to reseat the float valve is to drop a small ball bearing down there & give it a smart tap with a punch to create a decent surface. Won't always work, but worth a try. I have the right size BB, but not sure what I have to pull apart to get it.

 

[swazi_matt]

Slightly off topic, but what is the best way to leave your bike after a ride to prevent seat wear damage?

I have heard some guys drain the fuel so the carb is fuel free, others say to leave the fuel tap on so there is pressure on the valve.
and also which is best when the bie is being transported? I gues with fuel on to prevent the float bouncing around

 

[Jakobi]

I've got no idea, but I never bother draining the carb, and never leave the fuel on. Once I accidently left the fuel tap on during transport and got some spilt fuel from it splashing around.

 

[bally123]

Well I am getting annoyed now. Made up a new seat and fitted it. Made some adjustments to ensure the valve is being operated nice and square by the float tang. The new seat seals well and to test it I did the following:

I hang the carb without float bowl in a bowl of water, blow through the inlet whilst I raise the water level, I am now watching the valve shutting off cleanly, no air bubbles at all (the valve requires only a small amount of depression on the plunger to seal). I do this countless times without problem. Here is the weird thing the water level is way below the joint line - I estimate maybe 5mm. (I appreciate water is heavier so float may close earlier)

On the bike the fuel just fills straight over the joint line, start it up and its the same story. Won't idle unless I drop fuel level down using the shut off tap.

I have checked the floats for fowling countless times, but given the overflow does not leak then I figure it has to be sealing on the valve. So maybe the valve is ok, so why on earth does the bike choke up and overfuel??? and why does dropping the fuel level slightly cure these symptoms???


Arrgggggggg, Maybe its time for a gallon of petrol and a box of matches !!!

 

[hannesd]

have you checked if you don't have a leaky float bowl (1 of the 2)?

 

[swazi_matt]

Does the float still move freely once you have fitted the bowl to the carb? Maybe it is catching on something (just brainstorming here)