Project Suzuki Across Engine Rebuild

Ok, so with a temporary fix on the fuel tank, i have got no rust/dirt entering the carbs anymore.

But for the guru's out there on the Mikuni BSW27 carbs, The problem i have now is richness, i can't lean the bike out to run, it wants to run rich, and the choke won't work cold, it kills the engine, but with a partly warmed up or fully warm bike i can use the choke.

I'm suspecting possible air leaks, one area im thinking is the throttle shafts. Is there any other areas that i can be leaking from air wise ??

I checked the boots but dont seem to have any leaks on them, i got have a spare set i'll put under vacuum load to double check.

 

cleaned my other set of carbs, no new seals or such and it seems better, the only new things in it is the float needles and seats and they leak also, so i'm going to try the originals and see.

 

So this is the point im at, i swapped the rebuilt carbs over to the old carbs that were simply cleaned, using the old sliders and needles from rebuilt carbs, using LK's green bowl gasket and bowl screw o ring.
Using old float need and seats, (tried the new keyster ones as well), new choke springs. Used both LK's o-rings on float seats and other new o rings.
I got it to run pretty good i think overall.

Problem i just can't fix. When i let the bike sit for about 1 or 2 hours, fuel tap in on, i get two 20c piece fuel puddles where my drain hoses are (i have isolated the hoses so i can tell left and right carb), both carbs do it.
I've tried both sets of float needles and seats, tested floats and they float good, cant make them sink. I've adjusted float heights anywhere from 20mm to 21.50mm (20.50mm manual spec), i've rechecked if the float heights changed after being used for a bit and no changes.

When the bike is running no leaks, initial key to on, fuel pump primes and stops when bowls are full. No fuel is going into the crankcase.

I simply just can't work out why they are leaking still. At this point i think i simply just gotta turn the tap off every time i stop :-(

 

i also measured the bodies of the float seats.

Oem OD : 9.96mm
Keyster OD : 9.97mm

Oem OD O-Ring Groove : 7.59mm
Keyster OD O-Ring Groove : 7.65mm

So NFI how its leaking, unless its something defective with all 4 bowls i have.

 

They are i'm pretty sure, they aint metal exposed tips, they are coated.

Again after 2 hours or so of sitting tap off, no leaks.
So no idea why its leaking with the tap on.

Other wierd thing i get is if i hold the rpm at say 7.5k for about 30secs - 1 minute, when you let go the idle is really low, then picks up again.

Just at point where i want it reliable for the most part which it now is, seems to start easy and if i leave the tap off it doesn't leak.
With these second set of carbs, mixture screws are 2 turns out, seems to like that spot. With standard 30 pilots / 90 mains.

I'll leave it like so for a bit , see if it fixes itself with any teething issues or whatever else develops in time.
Other things to move onto.

 

Float bowls arnt flooding, float heights set at 20.87mm , manual says set at 20.50mm
Fuel tap is off, there is fuel in the line still, no leaks.
I've had it set lower at almost 22mm, no difference.

 

what would be the safest height you could go too ?? 25mm ??

 

Having thought about it, suppose another thing i can do, is with the spare bowls i have, measure the height of that stand pipe for the overflow from the top of the bowls, then measure gasket thickness and work out what that is one the carb itself to see how high/low it is compared to the standard float height ??

 

I had previously 21.95mm set on both and it was still the same :-(

Also when the bike is running, no fuel out the overflow tube.
When the bike isnt running and on the side stand, the angle it leans at should help the overflow tube cause the tube is on the rhs and most of the fuel should slosh to the left.

 

Also just checked it now, the overflow of the tubes sits well above the floats in the carb, there is no way it should be leaking.
Bike also started fairly well, cold morning with choke.

 

Thats what im thinking, give it a fair few runs on the good days in winter and see if she breaks in or heals herself

Went for a ride before, it was partly strange at the start, one section of road not too far where i left, i couldnt go past 80 with full throttle. Wasn't bogging , just no power. Then after that go into town, fanged it around upto 60k's going up and down in the revs between first and second. Was a blast, need more corners in town tho lol.
Anyway had a bit of an open straight on the way back, middle of nowhere, had no issues doing 145k.

Overall idle was spot on everytime i was stopped, started super easy, turned tap off no leaks when i went places, going through the rpms was super smooth, no flat spots or anything.

Will just see how it goes from here on in .

 

nope, the hose i got on the drain tubes are clear and you can see it leak through, more evaporate.