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rough gixxer

2K views 24 replies 11 participants last post by  gixxstar 
#1 · (Edited)
rough gixxer *update*

My '97 gixxer has always had a light backfire on off throttle decelleration from high RPM. This problem was very pronounced at the T&T at Mission. It also sometimes has a slight missfire from 2-3k RPM. It's got 24000km and I run normal 87 pump gas. I put new plugs in (schedualled anyway) and it smoothed out slightly but it not perfect. It's due for a carb sinc and valve adjustment but I haven't done that yet (could that be it?) I've also noticed that off idle response isn't as good as some of the other gixxers I've seen. Would this be part of the problem? I can get a carb sinc tool and do that job for now but the valve job will have to wait until next season as money is getting very tight (I just got into the pharmacy program at UBC). I appreciate any and all feedback. Thank you.
 
#4 ·
Just an aftermarket can. It's not very well packed though. It also has a K&N. I bought the bike with 17K on it and it had all of the add ons with it, it might have a jet kit as well but I haven't been able to verify that. There's a few jobs that I have done on a bike but carb tuning isn't one of them so I have no idea what's going on in there. I might learn soon enough. I used to run higher grade gas but tried the lower grade and there was no difference. It did the same thing before I went to garbage gas.
 
#6 ·
R6 Jono said:
try running a tank of 91 octane from chevron.

heck, go for a tank of 94 and drop down to 91 after

i even run 91 octane on my gix. and its a 1985!
WERD!

could be a super cheap fix.

who puts 87 in their sportbike ????!?!? :confused .... honestly :rolleyes
 
#10 ·
Kerker. Got to be the loudest aftermarket can availible. I'll balance the carbs and switch back to my yosh and give an update. Keep the ideas coming. Pete, where did you get your old bike tuned up and what did they do? I think that yours was the gold standard to what the old gixxer can run like.
 
#14 ·
Most people use the term "backfiring" improperly. Backfire is a snort back through the carbs caused by leaky intake valves, messed cam or ignition timing or some such. Carb problems usually don't lead to this.

What I bet Gixx means is afterfiring, where you get pops out of the exhaust pipe on decel. This could be the aforementioned causes, 'cept it'll be an exhaust valve. It could also be messed carb settings/adjustments. If it is carb, more often than not, afterfiring is too rich rather than too lean. You have unburned mixture entering the headpipes and igniting there.

This richness would explain the pronounced softness Gixx reports and the 2-3 k hole could be the bike starting to come on the needle, fattening it up worse.

Turn up the octane and see if it helps. It might but, I expect there's other issues here.

Crotch
 
#15 ·
Thanks for the advice Ken. It's the afterfiring problem that you described. I have suspected that the bike might be running ritch as well. The power is quite flat off idle compared to other bikes but is totally on par in the top ranges of the power band. The afterfiring is most pronounced when decellerating from high RPM off the gas, like I said anyone could hear me coming up behind them at Mission off the front staight by the terrible popping noises closing in on them. The bike smells like it's running ritch when I start it up but I'm getting the feeling that I'll need to consult some more experienced help to pin this down. It's not a pronounced miss at the bottom RPMs and I only notice it when I am cruising along in a high gear at fairly low RPM with only a little throttle applied. If I give it more gas, it smoothes out immediatly and accellerates smoothely. Again, thanks for the advise, it all makes a lot of sense. Keep any more coming.
 
#16 ·
I would like to make half the T&T this September or the race in October but money is very tight with school starting so I'll have to decide after I see what scholarship/bursary money is coming before I can make a decision.
 
#17 ·
I just did the carb sync. today. It was a fairly tough job (gets a little hot under there too, I should add). There was a lot of trial and error involved but we managed to get the job done. There is more to the problem but that but it made a huge difference. The low-midrange is MUCH smoother and the constant speed 'miss' has all but disappeared. The engine also feels like it has a bit more punch down low. It still does afterfire on decelleration a bit but much less than before. I'm very happy with the results.
 
#19 ·
Good old Pete said:
The bike was looked after by me, but I owe thanks to Bomax as well. At a 114 hp it was running kinda good,eh?
not sure I understand Pete , he's got the gixxer that got stolen ? they found it ?
 
#20 ·
Nutcracker, I met Pete a while ago before his bike was stolen. Nicest running carburated SRAD I'd ever seen.....
I don't know the model of sync. tool it was. It's my neighbors. He had to order it from Europe and it has little pins that are pulled up be the vacuum rather than Mercury or steel balls. It worked very well anyway. Interesting piece of equipment.
 
#22 · (Edited)
That's the one. He just got it and is very proud of it. Hehe, I can only imagine what a pain in the ass it would be if I made a mistake and sucked mercury up into the engine. You're right, the gauge worked great, I am thinking of buying my own now. I did have one problem. When I got all the carbs very close, I would try to make very fine adjustments and often the engine would race. I eventually got it all to a point where I could call it 'close enough' but still wonder if we were doing something wrong.
 
#25 ·
Took us a few hours. There's a few things that I have to add since you have a gixxer as well. It might save you some of the hassle that I went through to find this stuff out. The vacuum nipples are on the fronts of the carbs. I couldn't get at them without removing the carbs first. Those holes on each side of your frame with the white rubber covers DO serve a purpose, pull the covers off and slide a screwdriver through there to get at the clamps that hold the botton of the carbs to the cylender head. The adjustment screws are in between each carb and are accessed from underneath on the back side (phillips head). If I had to do it again it might take an hour to an hour and a half.
 
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