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fire from throttle bodies...:///

3K views 14 replies 5 participants last post by  Zippysport 
#1 ·
PROBLEM:
engine has been running rich and haven't had a good map, was getting a custom tune on Tuesday but now I think I have a bigger problem that I think I should address before tuning it. let me know if you think I should still tune.

My 05 750 wasn't turning on and when it did it was a really bad rhythmic low idle. I fixed that by agdjusting the fast idle to 2k rpm. after that when the engine started there was a thumping sound coming from the center of the block. seemed centered around the crank shaft, a neighbor said it sounded as if it wasn't running on all cylinders.

took the airbox off and checked the brand new spark plugs I put in. Cylinder 1 and 2 were clean while 3 and 4 were starting to accumulate carbon build up.

I tried starting the bike, I zeroed the pcv so no map was installed and I noticed smoke coming from the throttle bodies and at one point I saw an orange flame from cylinder 2. is this from excess fuel?

is my problem the fuel management? and what the fuck could the thumping be(not like rapid hammering like rods, but a deep rhythmic thump every beat on a four count). I have a video on my phone im going to try and post but its a shitty phone but you get an idea of what the thumping sounds like. it is not the gixxer ticking, rod chattering, and I checked to make sure engine is tightly fastened. I need help. haha:suicide
 
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#2 ·
Impossible to tell with what you posted honestly.

My first instinct says cam jumped time. Hard to say though.
 
#3 ·
my bad there was a lot of info i just threw on here. hopefully this is a little clearer.
the problem(s):
1.enigine wont turn on (turns over but wont catch) and when it does theres a deep thumping
*recently installed pcV but no map yet. running as if it didnt have pcv installed.
2.cylinder 2 shot out a flame and smoke would come out of the throttle bodies when i was trying to turn it on. didnt see which cylinder but once i saw it, i quickly turned the power off.
3.pulled out spark plugs, cylinder 1 was clean as if it was just opened, nothing on it at all and the rest had carbon residue. does that mean cylinder one isnt firing? I think i need to run a compression test to see.



I checked the timing just incase it wasnt timed right, but at TDC the notches were in the right spot and there were14 points under the cam chain cover. So that knocks timing off the list right?
 
#4 ·
also im not sure, but is the tension on the cam tension bolt suppose to be uniformly the same amount of force when turning it? because when i was turning it to tdc, a quater was real easy to turn and the rest required some force to spin back to tdc
 
#9 ·
If the plugs are in, what you are feeling is compression. If the plugs are out it is not completely smooth as each piston passes TDC there is a change in resistance.

Check compression again. It still sounds like it is out of time to me. Maybe even bent something.
 
#10 ·
Yes. Resistance variations based on piston position and relative angle of the crank shaft. Combine that with the load on the cams as they engage the valves.

Checked compression, but you're still worried about a broken rod? Dude... I'm not being a dick. Get some help before you make things worse.

Tell you what, have you checked your throttle body sync? Have you checked the cam timing? Have you checked the IAP vacuum lines?
 
#11 ·
took it to my local shop, and compression is good, cam timing is good. everything I checked he double checked and said it was good; compression and spark. but when he cleaned the spark plugs and reinstalled , the bike would turn on but cylinder one wasn't working. after a min of idling it died and wouldn't turn on again, just forcing the starter. he didn't know what to do after this. I am going to the dealer tomorrow to check the throttle body sync and see if they can diagnose the problem.
 
#13 ·
So I got the problem fixed: it ended up being a bad vacuum sensor.

but now another problem arose, when you start the bike the bike revs it self to about 8k.
it wasn't as bad, before it would rev up to 5k and then down to 2k. I turned the idle screws and it idled down to 1k. rode it for a while but now it revs up to 8k on start up and the only way to stop it is to push the throttle closed. was about to cruise it into the garage because I didn't want to ride it anymore at least until this was fixed and then it died and doesn't turn on anymore. :hammer
 
#15 ·
I agree. You'll need to take care of that as a starting point. It should snap back cleanly, and all the way, even when the bars are at full left and full right lock.

Did you perhaps add an R6 throttle to the bike at some point? I fear some people may have done that mod without doing the other needed work to make sure the there was enough slack left in the throttle cable.
 
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