Misfire/Rich Running No power.
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Joined: Jul 2004
Posts: 150
From: Los Angeles, California
Misfire/Rich Running No power.
Okay, I need some help here, I'm at my wits end.
My 98 hawk was running great. I put it up on a trailer to take it to a track weekend, and when I fired it up at the track weekend, it was running HORRIBLY rich. Any attempt at reving the motor would result in engine misses and backfires.
I initially figured it was just cold and needed to get warmed up. It was the same even after warming up.
The track was up at 2500 Ft, and I'm at sea level, so we were thinking, maybe, just maybe it was the altitude. We tried switching to 120 octane race gas (with oxygenate), but it made no difference.
Even once I got the bike back home to sea level same problem. (even with the race gas still in the tank)
I was initally thinking it was something electrial or plug related. We replaced the plugs, no luck. I have a FLUKE 88 Multimeter that has the ability to sense spark, and it showed that each coil/plug is firing as it should (for a DIS system, 2 spark events per 720 of crank rotation).
The plugs show that they ARE firing, but it seems like the engine is just running HORRIBLY rich.
Is is possible something in my carbs went south on the 4 hour ride on the trailer? Where in the carbs should I start to look?
My 98 hawk was running great. I put it up on a trailer to take it to a track weekend, and when I fired it up at the track weekend, it was running HORRIBLY rich. Any attempt at reving the motor would result in engine misses and backfires.
I initially figured it was just cold and needed to get warmed up. It was the same even after warming up.
The track was up at 2500 Ft, and I'm at sea level, so we were thinking, maybe, just maybe it was the altitude. We tried switching to 120 octane race gas (with oxygenate), but it made no difference.
Even once I got the bike back home to sea level same problem. (even with the race gas still in the tank)
I was initally thinking it was something electrial or plug related. We replaced the plugs, no luck. I have a FLUKE 88 Multimeter that has the ability to sense spark, and it showed that each coil/plug is firing as it should (for a DIS system, 2 spark events per 720 of crank rotation).
The plugs show that they ARE firing, but it seems like the engine is just running HORRIBLY rich.
Is is possible something in my carbs went south on the 4 hour ride on the trailer? Where in the carbs should I start to look?
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Superstock
Joined: Jul 2004
Posts: 318
From: San Jose, CA
Is your bike a CA model with charcoal canister? did you overfill the tank by any chance, hence filling up the canister? I have done that before, and it made the bike totally useless. I had to undo the whole thing to get rid of the extra gas fumes.
Also, could this be a simple choke cable thing? or may be the internal passage that the choke opens is stuck open?
Also, could this be a simple choke cable thing? or may be the internal passage that the choke opens is stuck open?
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Posts: 150
From: Los Angeles, California
Re: Misfire/Rich Running No power.
I've verified that the slides operate properly, that the choke is operating right.
It's a 49 state bike imported into Californica, so it doesn't have the evap emissions system. Tried messing with the gas tank to see if gas tank pressure messed things up, but nope. When we switched to race gas, I dumped out a full tank of premium to go with the 120 octane race gas. (for those that dont know, the 120 octane race gas with oxygen requires you to jet richer than normal pump gas). The only thing the race gas did was allow me to shoot flames 3' from each of the pipes. Looked cool as hell, sounded like ***, but looked cool!
The weird thing is, it idles fine, runs great to 3500 RPM. That's when the misfires/rich/bog condition happens. IN 1st gear you can get past that by at about 5000 RPM. Then the bike lunges forward like there's a rocket strapped to it till 7000 RPM, then it bogs again till about 9000 RPM Then launches again.
In second gear, it doesn't have enough power to get above 5000 RPM, so you're stuck in the "bog/rich/misfire" hole.
The bike "sounds" normal, but I'm wondering if one of the cam chain tensioners didn't let go.
I'm going to do a compression and leakdown test on it this week to see if that is the case.
It's a 49 state bike imported into Californica, so it doesn't have the evap emissions system. Tried messing with the gas tank to see if gas tank pressure messed things up, but nope. When we switched to race gas, I dumped out a full tank of premium to go with the 120 octane race gas. (for those that dont know, the 120 octane race gas with oxygen requires you to jet richer than normal pump gas). The only thing the race gas did was allow me to shoot flames 3' from each of the pipes. Looked cool as hell, sounded like ***, but looked cool!
The weird thing is, it idles fine, runs great to 3500 RPM. That's when the misfires/rich/bog condition happens. IN 1st gear you can get past that by at about 5000 RPM. Then the bike lunges forward like there's a rocket strapped to it till 7000 RPM, then it bogs again till about 9000 RPM Then launches again.
In second gear, it doesn't have enough power to get above 5000 RPM, so you're stuck in the "bog/rich/misfire" hole.
The bike "sounds" normal, but I'm wondering if one of the cam chain tensioners didn't let go.
I'm going to do a compression and leakdown test on it this week to see if that is the case.
Senior Member
Superstock
Joined: Jul 2004
Posts: 318
From: San Jose, CA
another obvious check that I am sure you have done... air filter/passage. try taking the air filter out and run it without it in place, and see how that works.
you probably know more than I do about all this. I am just helping brain storm a little.
you probably know more than I do about all this. I am just helping brain storm a little.
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Senior Member
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Joined: Jul 2004
Posts: 150
From: Los Angeles, California
Re: Misfire/Rich Running No power.
Found the problem. One of the foam air filter elements from the valve train breathers had become wedged in the forward carb. It was between the flat slide and the butterfly. Needless to say, it was significantly affecting airflow to the front cylinder...
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