Previously, the bike could rev all the way to 14k RPM, but sometimes had hesitation. I removed carbs, cleaned them (they were FILTHY) & fitted them back without changing jetting or needle heights. Needle seated correctly- I double checked.
Bike will now not rev past 5000rpm, even with choke on however will rev to the limiter in neutral/not under load. Fuel & air filter & spark plugs are brand new.
What could I have possibly done wrong?
I have seen this before a few things to do too make sure. First take the air filter out and shine a light use your fingers to move the slides up and down I suspect the springs that go on the slide is not seated in center you can tell from the slide going halfway and hanging up. Next, the boots on the slides only go on 1 way there is a notch on the carbs for them. I would guess this would fix you up if not we can get deeper into it with air-fuel mix screw settings.good luck
Can you check for a vacuum leak?. Also you have a vacuum line coming from the tank to the carbs to check. It could be your ignition also you can check your coils 1 at a time with a multimeter I can help you with that if you need me to. Also the stator and cdi I have a book on your bike so if you need help let me know. I would start with the coils. When its cold start it up and feel the pipes to see if they are evenly hot.
On the bottom of the carbs can you see the screws for the air mixture? I believe your right about the problem being the carbs, do you have any aftermarket stuff done to it?? jetkit,pipe. I would start with the air mix screws out 1.5 turns I have a jetkit for my 1100 katana I will find it and have more info. If you have the carbs off go in and have them tanked overnight as the mains are hard to clean. Do you have a way to synchronize the carbs?
Yes you are right 2 1/4 out on the mix screws, will the bike idle ok if so that would not do it. On the needles you have a spacer - clip - washer? then a another spacer. with the clip in the 3rd groove from the top? You do need a tool to synchronize the carbs I can help you get it close first you need to set the carbs so they open all the same with no slack in the linkages I find it easy er to do this with the carbs out if you watch the butterflies and take your time and get them to all open and close all the way together you might get lucky and be %100% on. I know on some model carbs they ran a bigger main jet on the outer 2 carbs you might want to check the mains as that is the high rev circuit. Mid rev is needles. Low is air mix screws and pilot jet.
I am happy to here it. Good work and be safe.
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Hi i just purchased a 1988 gsxr slingshot 750,when i went to collect it the guy had trouble starting it but it fired up and sounded awesome trailed it home and now it wont start.It does try to fire but wont actually run,ive checked the fuel and it is coming out the pipes into the carbs,i have a spark at the plugs but still it wont run.It has been streetfigthered and the choke cable has been removed.It does seem to me that it could be flooding,please Help im at my wits end,cheers Andy
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Thanks for the reply CBRWAGS.
I did check to see if the slides were going all the way up & down properly & I've taken them out & put them back in twice already too.
Also looked to see if I had perhaps pinched the slide diaphragm, but not cracked or damaged.
On these carbs it's pretty much impossible to to put the slides in the wrong way- so we can rule that out too.
Stripped the fuel tap & the tank is spotless. More than enough fuel getting through.
If I use only 1/2 throttle, the bike can slowly creep up to 6200rpm.
EquinoxDark
Vacuum leak? Err, help me on this...
I can tell you that there are 2 fuel lines from the tap to the carbs plus 1 vacuum line from the tap to carb no.#3. Those were fine, but to make sure, I also removed the diaphragm in the fuel tap so fuel could "freeflow" to the carbs - didn't work either.
I don't have a multimeter, but all 4 plugs are definitely sparking. I replaced 1 plug cap as it was cracked, still no change. Not sure how to check if CDI or stator is functioning correctly, but it was working A-OK before I took the carbs out for cleaning?
I removed & stripped the carbs again yesterday, this time used some silicone on the slide diaphragm to make sure that its sealed when I put it back together. I'll fit them back in again tonight & I hope by some miracle it works properly! This bike is killing me!
The air mix screws are 2.3 turns out, which is where they were when I 1st took them out? I finally found the workshop manual on the net which says about 2.5 turns. I'll try everything from 1 turn to 3 turns & see what happens.
I got the bike with a Hindle pipe, not sure if the jets are stock- will compare to the bike manual. Still makes no sense to me as to why the bike doesnt run properly as nothing was changed when I removed the carbs - except filter & plugs.
Umm, what do you mean by "tanked:?"
I would need some sort of measuring device for syncronisation, right? If so, I'm sure I dont have it.
PROBLEM SOLVED. Seemed it must have been sucking in air through the diaphram. After using some silicone between the carbs top cover & the slide diaphragm the bike is going like a boeing!
Bike is revving all the way to 14K rpm with no hiccups/hesitation. The bad 3000rpm dead spot I used to have is gone too. I am so happy I could eat a hamster.
my 98 gsxr 750 does the same thing but at about eight thousand when im accelerating fast it cuts out a few times then if i pull the clutch in when its cutting out and keep on gas a little bit the tach bounces per say without even hitting the rev limit then ill just coast for a second or two and then get on it again and the problem repeats itself. it does it real bad at about 90mph it will not go past 115 in any gear it just cuts out real bad but when just sittin in netural it will rev all the way to red line everytime when doing a burnout the tach will bouce as though its hittin red line but only hits eight to ten thousand rpm could it also be an air leak i checked for vaccuum leaks, appeared to be none.
I don't know
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