MrZoloDolo Posted March 6 Share Posted March 6 Could anyone throw out an idea on what's wrong with my Fz07? - Bike started bogging at speed. Got progressive worse over a ride. -While slowing down the throttle "ran away", revving without me touching throttle. -Shut bike off and it wouldnt start for ~15 minutes (fuel pump was priming...it just cranked without firing) -Finally started and throttle ran away again immediately to red line. -Started again 10min later opening and closing throttle and got it to idle down. (Limped it a mile home, sounded bad. Throttle acted like it was sticking) -Found it was running on one cylinder (one header was almost cool to the touch...other was hot) -Took tank off and pulled spark plugs and both sparked in air -Swapped the good cylinder ingnition coil to bad cylinder plug and vice-versa. Had spark with both. -Started bike with plugs/coils swapped around and still ran on one cylinder but only intermittently now. Both headers got hot(one was more hot) but bike was backfiring/sounded better but not great. RPM still sort of hangs like throttle is sticking. -Took EJK tuner off and still same problems. Any ideas? Motor sounds healthy at idle. Maybe something in throttle bodies or injectors? Link to comment Share on other sites More sharing options...
M. Hausknecht Posted March 7 Share Posted March 7 Symptoms suggest an air leak in the intake tract, especially the runaway throttle, backfiring, and good sparks unless, of course, the throttle on one or both throttle-bodies was actually hung open. Make sure the injectors are fully seated, and that the cap and hose are on their respective throttle-bodies. 1 Link to comment Share on other sites More sharing options...
MrZoloDolo Posted March 8 Author Share Posted March 8 Pretty sure injectors are seated. If by cap you mean couplers, they are on correct injector. I'm only seeing one hose connected to the throttle body on the left side. The right side has a rubber "nipple" over the metal fitting. (Picture of hoses). Tried spraying wd40 around throttle body and listening to idle to see if I could find any kind of leak but no dice. Link to comment Share on other sites More sharing options...
MrZoloDolo Posted March 8 Author Share Posted March 8 (edited) Might need to pull injectors/look into the throttle body sticking because that makes sense. Although I can't shake the feeling it has something to do with ignition coils because the symptoms slightly change when I swap them. (Rev hang and backfiring is way worse with them configured one way). Is it possible something with the spark plugs/coils can cause runaway throttle/backfiring? Edited March 8 by MrZoloDolo Link to comment Share on other sites More sharing options...
M. Hausknecht Posted March 8 Share Posted March 8 12 hours ago, MrZoloDolo said: Might need to pull injectors/look into the throttle body sticking because that makes sense. Although I can't shake the feeling it has something to do with ignition coils because the symptoms slightly change when I swap them. (Rev hang and backfiring is way worse with them configured one way). Is it possible something with the spark plugs/coils can cause runaway throttle/backfiring? Coils either generate a strong spark, a weak spark, or no spark. Yours (one or both) are generating at least a weak spark. A weak spark from a bad coil would explain the running on a single cylinder and the missing, but not the runaway throttle. The latter symptom requires that air enter one or both cylinders, with some fuel. Since you didn't find an air leak, I wonder if a throttle butterfly is sticking open some amount, but not consistently. Of course, it is possible that your symptoms are caused by two or more different conditions that just happen to coincide in time. 1 Link to comment Share on other sites More sharing options...
MrZoloDolo Posted March 8 Author Share Posted March 8 I appreciate you taking the time to reply. Will I hurt anything by disconnecting the airbox and trying to look in the throttle body while the bike is running to see if the butterfly valve is sticking? I'm not the most mechanically gifted. Link to comment Share on other sites More sharing options...
tomlichu Posted March 8 Share Posted March 8 (edited) That cap on the right is used to check the vacuum in your throttle bodies for balancing. Did you also check the connection from the airbox to the throttle body, and the throttle body to the engine? I had rev hang with a sudden increase in engine rpm when I gave the bike a little gas because I didn't properly seat my throttle body to the engine. When the bike is stationary, is your idle between 1100-1400 rpm. The bike can run without your airbox, but it will be very lean. Taking the airbox and throttle body off is not hard; it just takes time the first time you do it. If you take the airbox off (the most annoying step), you can see visually the butterfly valve opening and closing. You can also check your throttle position sensor (TPS, right side on the throttle body) and see if the connector is in good shape (no rust, seated properly). Edited March 8 by tomlichu Link to comment Share on other sites More sharing options...
M. Hausknecht Posted March 9 Share Posted March 9 You're safe removing the airbox and running the engine in neutral. With no load, the lean mixture won't matter at all. Check that the clamps and boots holding the TBs to the cylinder head are properly located, snug, and not damaged in any respect. Link to comment Share on other sites More sharing options...
MrZoloDolo Posted March 17 Author Share Posted March 17 Sorry for no updates. Got the issue solved for anyone coming acrossed this in the future. Pulled throttle body and one of the butterfly valves had sucked up part of my air filter! So you guys were spot on with the assumption it wasn't fully closing. Pulled the throttle body, cleaned out the foam/residue reinstalled and the bike has been running perfect since! Guess I got lucky nothing sucked into the engine, or if it did it didn't harm anything. 3 Link to comment Share on other sites More sharing options...
sweetscience Posted March 17 Share Posted March 17 What intake you running so we could avoid? Link to comment Share on other sites More sharing options...
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