melampus

:twelve
All right guys, here’s my current problem with some history. 1996 SRAD w/ 28,500 miles; piped & jetted. Had a high-speed stalling problem where every time I exceeded & sustained 125mph on the speedo after a few moments she would begin to stumble. Then if I stayed on the throttle, she will buck. Meaning from 125mph+ she would intermittently stall & then run poorly & then stall & then run poorly, creating a bucking affect. If I grabbed the clutch she would stall immediately. Either way she stalled, but then if I coasted to a stop, waited a minute, turned the ignition off & on then she started right up! I had tried starting on the fly in neutral as well, but she did not fire until stopped & rested momentarily. It felt very much like when you first start running out of fuel or lose spark, and it sounded like when you push start a bike. You know that split second before she fires... bblluuuuuuh. I had originally thought that maybe my fuel warning light was only working intermittently as on the first three occasions I was low on fuel, but then it happened again with a 3/4 full tank disproving that theory. It was very strange. The bike had given me no problems outside of that. I don't know if she is starving for fuel; like a clogged fuel filter or dirty carbs, but then why would it be intermittent; does she need a valve adjustment as she has 28,000 miles, but even if would it cause her to run that poorly?

Anyhow thinking there was a blockage somewhere a good friend and I removed & cleaned the in-tank fuel filter. We pulled the carbs, and blew out all the fuel lines that connect them. We shot compressed air through the jets, and checked the float levels. Then when re-installing the air-box we noticed that those foam seals that join the snorkels to the frame openings had deteriorated to the point that they were basically non-existent. We were thinking that maybe that gap was buffering the flow of air at high speed. We ran over to Home Depot, and found these 3” or 4” (I don’t remember which one) plumbing fittings. They are about 5” long cylinders made of really thick yet pliable rubber. We carefully split one straight down the center with a razor, and then fitted one of the halves to the airbox snorkel with the trimmed side out. We installed the airbox, and shaved the fitting with a razor to match the contour of the frame opening. Once we were satisfied with the joint, we had a mold for the opposing side to copy. This was the cheapest, and most effective replacement we could think of. When we test-drove her, she had LEANED OUT to the point where she was backfiring, and if riding behind her you could see flame in the canister from the rear. On the road when you put your hand over one of the air intakes she immediately came to life! I am figuring that these joints we fabricated maybe increased the intake charge to lean her out that much. At that point we recruited a friend of his who is a mechanic who then re-tuned the air/fuel mixtures. She ended up running pretty good, but still needs a little more fine-tuning as now she has a stumble between 4,000 & 5,200 rpm, but the high-speed stall has been eliminated. That was a month ago, now 1 month later she does the strangest f***in thing. After riding wheelies it will run like absolute dog **** basically everywhere through the rev-range, but worse in the low to mid-range. Exactly the way it used to run up top, but without the stalling. Just coughing & spitting & sounding deep like a twin, but still running through it. Then after a few minutes of driving she goes back to normal. I know you can fill your airbox with oil from riding wheelies, but it was just a month ago I had the airbox open & drained the small collection of oil I had so I doubt it could be that. Plus I can’t ride mile long wheelies or anything so again I doubt it. Also there have been a couple times I experienced hard starting, and on those occasions after she started and ran for 10 seconds, she stalled with a large loud flaming backfire. Then would restart like nothing ever happened. I am totally at a loss, and looking for help. My bike is my only transportation, and I work five days & seven nights a week so I can’t have a lot of down time. I’m hoping this is something that people have heard of before, and I can work on the most likely solution right off the bat. Any help is greatly appreciated!

DrinkWheelieMix

umm have u hooked a voltmeter on it??? (maybe its lacking charging power) i dont know alot about alot i just know a little bit about a little bit. or it could be the fuel pump isnt supplying the necassary fuel t needs. just my

melampus

Well, I thought that it was maybe a loss of spark from not getting juice like you suggest, but I never have a problem with battery power. I have never had a loss of lights or starter, you know? And why would it be intermittent? I haven't checked the generator's output though, but I do think that it will be on my list of things to check.

The thing is I just took the night off of work to pack my **** as I'm moving houses, and on the way home I ran into a friend on the road. He wanted to see some tricks, and after a long wheelie it started acting like **** again. He said that she was spitting blue flames ranging from 4-10 inches out the exhaust as I was experiencing the problem. So now I'm really thinking it is a lean condition again. I really want to know how the mixture could progressively get leaner & leaner over a months time though.

Any ideas anyone?

Lb3

well, I was going to say at first that you might be floating your valves, but after reading the whole thing it sounds more like a fuel problem. Have you had your valve clearances checked though?

LongShot

May sound stupid....but once before on my EX500...I had sort of a problem with not getting enuff fuel to the carbs. Turned out...it was two problems in the same area. The Petcock valve for the ON/ Reserve/Off of the gas tank had crap in it...and the vacume line for the petcock valve from the carb had a leak.

Cleaned the valve and replaced the hose...and it was fixed.

I dont know if this could be your problem....but its a simple thing to check.

standy

check the vent hose form the fuel tank...sometimes when the tank is lifted, the hose gets pinched, causing a lack of fuel flow. (ever poured gas out of a can without opening the vent? the gas doesn't flow smoothly and consistently) I have seen this cause the same problem you are having many times. Good luck!

cstmgsxr

i think standy is right, that has happened to my 98 gixxer all the same, but i also had vacume lines and a oil line had a leak

melampus

I have owned this bike for 9,000 miles now, and have not had the valves adjusted yet. I do not know when/if the previous owner had them adjusted as well. I have asked this question many times before w/o a decisive answer, "Can valves at incorrect clearances cause problems like this."

Lb3

They can if the clearances are too tight and you have bent a valve. But this is only likely to happen if you did the job recently or had it done by somebody that didnt know what they were doing. In your case, if the problems were your valves, you would be hearing alot of vavle noise. It would be ticking alot. Its probably a fule/air/vacuum problem.

melampus

Thank you for your response, and Oh how I wish that is the problem. I'm assuming you are saying that the vent line gets pinched when lifting the tank, and stays pinched somehow after lowering. I wil take another look ASAP, but the thing is though that she is spitting half foot flames; mostly blue but some orange, too. It just keeps me thinking that the the guy who tuned the carbs, screwed it up. Then I think how it was running just OK when I got it back from him, and now it has progressively got worse. I'm just so frustrated at this point. It sputters so badly now, hard-starting, stalling, flames out the canister. I mean you would simply think it's running lean, right? I tried blocking the intake plenums, and it made no difference.

verticaljay

I had the same prob wit my 97...... My prob was a very very very small pin hole in one of the gas lines running to the carbs... check them look for any mark on your line that could possibly be a hole... change it if you find one.

I looked at mine and said no that couldn't be the problem but as soon as I changed it, it fixed the problem.

I think its something with the faster you go the more fule is need and more vacuum is applied to the lines and then the small hole will cause a prob.

Let me know if this helps.

Jay

melampus

I just want to let you all know that I appreciate your responses, and will be using your suggestions as a checklist for my troubleshooting. I will be updating this post as well, but I want to add that with three jobs & being in the middle of a move that I only have time to complete in the middle of the night my time is beyond limited. A major cause of my frustrations, not being able to spend time on my baby! So if it takes me some time update, please don't be offended or assume that your advice fell on deaf ears.

melampus

Well, that's it. Now she won't even fire.

standy

I just thought of something......was the update ever performed on your fuel pump/tank???? Do this- go to the bike, open the filler cap on the tank and take the key out of the cap. Just put pressure on the sealing surface of the cap to get the key out...it'll click. Listen at the filler opening as you turn the key on. The fuel pump will cycle. (make sure the bike is in neutral with the kickstand down and the kill switch in the on position) It usually makes a whistling sound. If you hear a spray sound, I have the answer to your problem. Some of the older gsx-r's had a problem with a fuel line coming off the pump INSIDE the tank. You also may be able to see if it is spraying by looking inside the tank while turning the ignition on. Let me know what you find.

melampus

For all that were helping out, THANK YOU.

This is what it was. So after she wouldn't fire at all I pull the tank & airbox to check all the fuel & vacuum lines for anything obvious. Compression tests read: 175psi, 175psi, 173 psi & 175psi. Then for the f**k off it I touch the slides, and notice that carbs 2 & 4 were sticking. So I pushed them up & down a couple of times. Put it all back, and she started & ran for a few days. Then she started doing everything she used to all over again. I pulled everything again, and the slides were stuck again. Looks like the guy who my buddy referred me to reinstalled the springs that operate the slides incorrectly. Got them back in correctly, and she runs like a champ again!

Got her dynoed as well. She walked in as was @120.4hp, and after leaning her out by two grooves she walked out of there @124hp.

It feels so strange having a bike that is not giving me any problems!