View Full Version : Gsxr 600 srad surging at constant throttle
Ive had a problem on my 1999 gsxr 600 since ive been riding it, but fairly inconsistently until recently. Over the last few days its become a bit more common, the problem is that on constant throttle between 30-40mph the bike does what i can only describe as a surge. The throttle position is constant but the bike will get in a rhythm of dropping power for half a sec or so, then getting power back again for half a sec or so. If i accelerate slightly the problem will go instantly.
Ive bought some redex on the off chance itll save me some bother but ive read before now that its not much cop.
Im thinking its a fuelling issue, something to do with the carbs... Should i look at balancing at the first step , or is there any other ideas ?!
Wideboy
10-12-13, 09:49 PM
balancing is the easiest and cheapest thing to try first providing you have gauges. My thunderbus used to do it when cruising at 80-90 on the motorway, a coil was breaking down.
andrewsmith
10-12-13, 09:51 PM
Carb balance by the sounds of it. My SV does that when they drop balance
Yeah ive got a set of balancers and my dad knows how to do it so i think thats next port of call..will report back when ive done it, cheers guys
yorkie_chris
10-12-13, 10:34 PM
I'd suggest an intake air leak as a possibility or other sort of lean running. Or possibly some crap in the pilot circuit/low speed needles.
Ok, will invsetigate further for that if nessacery after i balance it.
johnnyrod
11-12-13, 01:23 PM
Yep worth checking the balance but as YC says it sounds a bit lean. How was it in the other recent cold weather? I think the carbs have a sort of plate heater to try to prevent icing but it's crap, so the cold air (especially when moist) coming in through the scoops can overpower it. If it hasn't packed up, of course. Redex, waste of time, fix the mechanical problem or if you suspect carb heat problems then try a bit of Silkolene FST (isopropanol) or equivalent.
Been fine in the other recent cold weather but thats mostly been above 30/40 where ive had the issue
yorkie_chris
11-12-13, 04:57 PM
Carb icing doesn't make it surge, IME, it makes it fall on it's backside when you open the taps to overtake or go up a hill or something.
Also presumably youd only get that at sub zero temps, which it defo wasnt the last 2 times ive had it
yorkie_chris
11-12-13, 09:06 PM
Surprisingly not, what you need is cold-ish and humid. The evaporating petrol causes quite a temperature drop.
andrewsmith
11-12-13, 09:21 PM
Pretty much what weather we've had this week.
Fair enough , i wondered whether there would be a scientific explanation to dismiss my naive thoughts :p
Had the carb balancer on and only one was out by a whisker so dont think it was that. However the rubbers where the airbox attaches to the carbs were on the looser side of things, so not sure if there was a leak there. Also pulled all plugs, they all looked the same and as expected.
Havent ridden it yet due to weather but il report back if my problem hasnt gone. Could it be the TPS?
yorkie_chris
15-12-13, 09:35 PM
Loose carb boots a definite possibility.
TPS unlikely on a carbed bike, they make a minimal difference.
Problem still there, same as before. Is next step to clean the carbs out?
so constant throttle at 30-40mph but in what gear and what revs?
Well since it got a bit more frequent, id say its usuallly between 30-50. Not sure what gear but when revs will usually be lowish, 4-5k from the few times ive looked when its doing it. Whenever it happns i usuualy pick up the revs and it goes. It also can be a bit sluggish pulling away for a second or two, as if the amount of throttle ive twisted hasnt done anything, then suddenly the revs pick up too much, as if its on a delay. Not sure if this is related..
Well since it got a bit more frequent, id say its usuallly between 30-50. Not sure what gear but when revs will usually be lowish, 4-5k from the few times ive looked when its doing it. Whenever it happns i usuualy pick up the revs and it goes. It also can be a bit sluggish pulling away for a second or two, as if the amount of throttle ive twisted hasnt done anything, then suddenly the revs pick up too much, as if its on a delay. Not sure if this is related..
Similar to my Zx then. Feels a little sluggish down low but once above 4k it's normally fine. Idle is pretty s*** at the moment as well, even after a carb synch which in my case all were out a fair bit but all that did was smooth out the pickup from idle. Still surges at constant speed. hmmm...
i'll go out on a limb and say the coils are breaking down or the plugs are on their way out.
have you checked your oil level lately?
johnnyrod
20-12-13, 10:25 AM
I'd clean the carbs and see how you go. Could just be a bit of something stuck in one of the jets.
yorkie_chris
20-12-13, 04:52 PM
I reckon some crap in the pilot circuits somewhere. Sounds lean.
It also picks up to about 4k revs on the choke as soon as you apply the throttle but not sure if thats normal for this bike. Im thinking carbs probs next logical step...Yup i check the oil frequently-ish. Ive just done an oil and filter change too so its all fresh. How can i test the coils if they are intermittent?
yorkie_chris
20-12-13, 06:10 PM
You can't test them for that. Make sure carbs are spot on first as that could explain surge. Coils cannot explain surge but they could cause hesitation on pickup.
Fair enough, i was thinking it was fuel related and it seems more likely. Would it be worth looking into getting them ultrasonically cleaned or a diy job? If the pro cleaning is worth it, what sorta £ am i looking at?
yorkie_chris
20-12-13, 06:51 PM
DIY job. Carb cleaner and an air line.
check the vacuum hosing for cracks, engine breather for blockages and tank for rust. how old are the plugs?
i always check to carbs is working first then i do carb clean. no point in cleaning carbs if something else is wrong before carbs.
Tank wont be rusty as it was fine when fitted in august. Plugs not too old and their iridium. Dont think breathers blocked as i get a bit of oil in the airbox
Which is the vacuum hosing, the vacuum from the tank to the carbs?
yorkie_chris
24-12-13, 02:16 PM
Other way around but yeah, if that's got an air leak it won't help at all.
Ill have a look after xmas when i take another look at the bike but as far as i remeber its in fine condition..
Still havent had time to check the carbs/hoses but the saga continues with two other problems
Heated grips have started playing up
Today the speedo needle kept jumping up, sometimes a few mph sometime like 15mph more than i was doing!
Im unsure if these are related to the surging issue and that my whole problem is electrical, or if i just have a variety of problems. Any advice? I need to ask my dad to check the grips with the multimeter, theyre oxford ones which were working fine until on one ride they stopped working. Now when i try to turn them on i get the power light come on, the 30% heat light flash a few times then it all turns off. This is a different sequence to the smart 'no power' light sequence which keeps the power light on and just flashs the 30% light until the revs pick up and it registers sufficient charge
Ive got round to looking at the bike recently as after my off in May i haven't ridden until late october.
Need some more help with this. Ive taken the carbs off and cleaned them, checked the vacuum hoses whilst there are all is well. Problem is still no better. I also have electrical issues, so i cant be sure the running issue is fuel or electrical. Any help?!?
Corny Gizmo
25-11-14, 12:09 PM
Start simple, are the battery connections clean and tight?
If you cleaned the carbs out you may well need to get them balanced,I had the same problem some years ago with my honda cb 750!!!
Battery connections sound. Ive had this issue well over a year so any silly things like that should have been eliminated over time by other maintenance. The carbs were balanced before the cleaning a while back and im pretty sure it isnt a balancing issue.
wideguy
26-11-14, 08:08 PM
Is there water in the gas? Sorry if somebody already asked, and you've checked.
yup petrol tank has been emptied after the issue started and still remains.
Any more for anymore? feel like im flogging a dead srad right now! Trouble is I wont/wouldnt want to sell the bike as it is now without solving the issue
Carb set up. Has it got an open pipe/ air filter? Gsxrs are also prone to wearing out carb parts so might need a rebuild whats the mileage?
Jayneflakes
11-12-14, 11:49 AM
Have a look at plugs, caps, leads and the like. You could also try checking your connectors, some of the plugs can corrode which can lead to a poor connection.
Sounds like you are going to be checking a lot of stuff.
A mate here has a learner bike and he complained that since he had it, it was always a bit gutless even for a 125. While chatting away as he as getting ready to go recently I noticed that it was arcing from the plug cap to earth. Anyway, after fitting a new plug cap it runs really sweet. This has taught me to check the simple obvious things first, even new plugs can fail and a dodgy HT lead can give you trouble.
Good luck finding your gremlin, I am sure that you will in the end.
No its got a standard airkit setup, just k+n filter. mileage approx 32k.
Ive had a look at that stuff before, but tbh unless it looks broken hard to know you havent got something dodgy going on. Need to get out and try more things but just dont know where to start.
just fixed the last thing i knew was wrong with the bike, the fact it wasnt sealed properly between end can and exhaust manifold. A quick ride wasnt quite enough to say whether thats fixed it but i think not..
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