StrayCats GSXR 750 Problem - Only VRF Forum Guys seem to be helpful

I'm wondering what the integrity of the float itself is? Does it have a tiny hole somewhere?
I think you are close Cat.....

 

At this point anything is possible sixdog.

Close examination hasn't revealed anything, no fuel evident inside the float.....but we will see.

I looked, I shook it and listened, I shone a light thru it to see if I could detect any fuel, but no.

If the same carb leaks again from that carb throat, it would have to be a float issue of some sort, as ive now switched the needle and seats for 3&4

 

24 hours and no carb leaks, but the fuel bottle was getting a bit low because when I drained the carbs to swap parts around , it took more fuel (8oz or so) to fill em back up again.

I just refilled all 4 carbs and added more fuel to the bottle to create a bit more pressure and we will see how it goes today.

If I get a leak , we'll follow the next step. (if leak is Cyl 3 -- float assy may be Fk'd , if leak is Cyl 4 means new needle/seat is F'd)

If she's still dry at EOD today, then tomorrow ill put them back in the bike and give her another go.

I think we maybe on the right path here.

If floats/needles were all wrong, it would make sense that it could drop a cyl every day, as I added fuel and tried to run it, just got flooded out. It also makes sense why it would run fine after it had time left sitting (since I never left a fuel supply attached), once the bowl fuel level dropped enough, everything would dry out and it would start up fine after sitting for a while. then with fuel supplied again, it would drop a cyl one at a time once again.

I guess this theory will be put to the test once I get these carbs set up properly. Time will tell if it runs better. ill have everything crossed the next time I fire it up, it will be a tense moment. If it doesnt run right after this, you guys may hear some foul language emanating from the great white north.

 

Well.....

I put the carbs back on this morning after 3 day with no leaks or dripping. the bike fired up on choke on all 4 cyl, and was running well

Once it came off Choke, cyl 3 once again started to drop, the header pipe temperature gradually dropped.

Pulled the plug on cyl 3 and it was dry as a camel fart

I then setup a separate small feeder tube thru the air box to carb#3 and drip fed fuel to it with the bike running. cyl 3 came to life and got up to temperature.

So it seems im fuel starved on Cyl 3 for some odd reason. jets are clean, I guess I need to check the float level again, but I doubt floats being a tiny bit high would kill the cyl at idle or low revs would it ?

 

Does it do that just at idle? Does it come to life when throttle is applied? WE are getting there!!!!

 

Not to any great extent sixdog, Temp does creep up a tiny bit when rev'd, but not very quickly. Just lots of popping etc.

It does not seem like its a pilot jet thats plugged and it does not burst to life and not high/good temps when the main jet/needle jet take over with more throttle.

 

Hmmm, so it's safe to say it's the idle circuit. When the carbs are out can you see the idle jet hole in the intake tract? when you spray carb cleaner through the idle circuit does the spray come out strong or comparable to the other 3 carbs? ( hope I make sense )

 

OK, there are 2 jet holes on the intake side of the carb, im not sure whats what - one main air jet, one pilot air jet.

I guess if I remove the main jet and the pilot jet I should see the spray there ?

 

I believe so …


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pulled the carbs again.

Main air jet is clear
pilot air jet is clear
Main fuel jet clean and clear
Pilot Jet clean and clear
mix screw is correct

When I pulled the carbs I decided to measure the fuel that I drained out of each carb. #3 had a less fuel in it than the others, so I adjusted the float height a bit - incase they are "THAT" sensitive. I cant imagine this would matter but, you never know.

#3 and #4 are now on the fuel bottle again (since I took them apart) and ill wait to check for leaks again. I did have to swap out a seat O-Ring - as I was removing the float assy on #3 it popped out and wouldn't re seat due to the swelling of the o-ring, so I had some other new ones, I replaced it and that what im testing now. I pulled a bit on the seat for #4 too, to make sure it wasn't ready to push itself out, seemed fine.

 

Switch needles …


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By needle I mean mix screw …
The VF1000r I just bought had two mix screws missing the retaining washer that goes before the o ring … idled like crap! Now smooth


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OK, I did put new O-rings and washers in all 4 mix screws, I can swap the screws easy enough

 

I think its gotta be something more material, the fuel doesnt even seem to flow to that cylinder when I rev it, at least not enough to make a meaningful amount of heat in the pipe. so its gotta be a bigger fuel supply issue no?

Maybe the new float height will help, maybe I need to do a timed fuel supply test. 3 seconds and see how much fuel is in each bowl. Or run the fuel supply with the bowls off to see the flow.

 

Formula:
p = pressure (psi)
h = head (ft)
SG = specific gravity

so, 3' of head, with the product being gasoline (at a SG of 0.82) = 0.434 x 3 x 0.82 = 1.067 psi. Volume doesn't matter, all that matters is the height of the column of fuel. So what you want is a tall 1" column, i.e.: the longer the hose (height above the carbs), the higher the pressure.

A filled 1" diameter hose, 3' long, will have the same head pressure as a filled 12" diameter hose, 3' long.

 

I have no input. I am just a spectator on this episode of "it's a GSXR life". I am rootin for you stray.

 

fixed that for you

 

Cheers NB

 

sorry dude. bikes are a pain some times.

 

Slightly more so when they don't have a Wing on them.

Keep on keepin' on stray.