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

Man how frustrating!!!!
I mean it’s down to anything at this juncture… how about the choke circuit? Is it operating properly?
Reaching I know …..


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A backfire is a timing or fueling issue - too much or too little. If it's backfiring due to timing, it's due to something mechanical. Modern CDI's are pretty reliable. I have a call into my guys to see if they have any ideas, just waiting for a call back.

 

Cheers NB

I also cranked it over with the plugs out and got a 3' stream of fuel out of Cyl #1

clearly the needle and seat there are F'd. so much for new ones, the old ones will go back in.

 

Jesus christ.

 

Yea, I called his name a few times today

 

You can still buy the OE needle valves and seats, not cheap, but not hope for the best, either.

 

Well, this clearly changes the game. I will hold off talking to my guys until you feel you've got the carbs right and are still having issues.

 

Thanks NB.

Clearly the shyte needles and seats are causing the #1 cyl to flood, but....what the rest of the issue is IDK, as the rest of the symptoms are the same as before.

Ill put all 4 sets of needles and seats back in and see where I land. ill do the Valve check and cam timing too while im at it.

Ill be a few days (at least), ive got a pile of work to do at my cottage for the rest of the week so wont have much time to mess with the GIXXER

 

It needs a "Time Out" anyway.

 

It most certainly does.

 

Im not the patient kind...

Carbs are back off now.

Needle/Seat on #1 (new needles and seats) seems to have failed after only a week, I could blow down fuel line #1 (Feeds 1 and 2) and hear the air escaping the seat. I put the all the old needles back in now and all 4 are sealing up when I tilt the carbs back and forth.

Choke plungers all look good, no pressure on them when the choke is off there is free play between the bar and the plunger head as per spec.

So at this point, I think I have probably solved the fuel leak and fuel filled cylinder issue due to the needle/seat on carb #1, but not sure about why its still dropping cylinders. That investigation continues.

Valve cover coming off next to see if I have a cam timing issue or a valve clearance issue.

Be great to have a second set of carbs to try. But alas, no such luck

 

seems to be OK, it was fucked up initially, but I got that all adjusted ok before the last 2x I ran it.

 

That bike doesn’t have a fuel pump , right?


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no mention of carb float level settings ?

 

no fuel pump on it.

I did check the float levels when I rebuilt them. 3 were good, one was out of whack and I set that correctly (14.7mm).

Apparently these carbs are notoriously difficult and sensitive. one fellow on the GSXR forum considers himself exceptionally well versed in Carbs and Carb work and he said he had his in and out half a dozen times before he got them to run right.

 

OK, so Squirrelman's question on floats led me to re check ! Thanks Squirrel !

It seems my floats are sitting low on measurement (technically too high) and I may be flooding the intakes/cylinders. this is beyond the issue with the bad needle and seat, which I fixed.

I had noticed pools of fuel in all 4 intake manifolds when I pulled the carbs off yesterday too.

I'd measured the float heights with the callipers and it looked OK, but after Squirrel's question , I decided to make a gauge and check them that way.....well....theyr'e not right. so ill be sorting that.

see the pics below with the calliper and then with the gauge. in hind sight you can also see they're not quite parallel with the carb body......jeez im hoping this helps sort it out.



Hey Squirrel, anyone, is this orifice im pointing to with the pen, the overflow ?

 

^^ i don't think so.

 

I hope you're not checking float height with the carbs upside down on the bench. Like in 2 pictures now.

The weight of the float is depressing the spring loaded button in the valve.

 

yea, It just looks like they're upside down, and the angle of the tang covers the plunger and it appears that its pushing down on the plunger, but ....its not.

Carbs are tilted to the point where they just seat the viton tip and dont depress the plunger, no air will pass thru the fuel line.

if I tilt them upside down they depress the plunger and sit much lower.

look at the blue bins in the background of pic 2, gives you some better perspective. the angle I held the phone at just made it look like they're more upright.

Sound right ?

 

Absolutely it does. And I think we've covered this before. It's just something that is overlooked so many times my brain goes there instantly.

Full disclosure: I had 2 ciders while surfing waiting for my take out. (House made Roasted Chicken Ravioli and Greek salad.)