Can't get it running right!
Thread Starter
Junior Member
Squid
Joined: Jul 2012
Posts: 9
From: Nashville
Can't get it running right!
I bought this Superhawk after it wasn't started for 3 years. I brought it home cleaned the carbs, replaced the fuel, replaced the spark plugs and installed a new battery. It fired right up. But, when I ride it, it pulls to about 4500 rpm and then runs like crap to redline. If I accelerate slowly it is better, but not right. Also it backfires a lot during deceleration and between gear changes. I went back and did the carb set up like suggested here and it idles perfectly smooth now, but still has the other problems. The bike is stock with a slip on muffler and I have worked on bikes for decades, but I can't figure this out. Help!
Senior Member
SuperBike
Joined: Sep 2008
Posts: 1,707
From: Essex, UK
Have you looked to see if the airfilter needs replacing / cleaning if aftermarket.
Check for air leaks in exhaust/header system and carb intake.
is the timing right? (can easily be set 180 out, esp after head rebuild if CCTs have failed)
Are the vacuum hoses correctly fitted, not kinked and intact.
Check for air leaks in exhaust/header system and carb intake.
is the timing right? (can easily be set 180 out, esp after head rebuild if CCTs have failed)
Are the vacuum hoses correctly fitted, not kinked and intact.
Last edited by Wicky; Jul 18, 2012 at 07:13 AM.
Thread Starter
Junior Member
Squid
Joined: Jul 2012
Posts: 9
From: Nashville
Everything you guys mentioned I have checked except the timing. If it was 180 degrees off I wouldn't think it would even run. The air filter is clean and oem. It only has 10k miles, so I would think it couldn't be something major. It realley fells like a needle problem, but the bike is pretty much stock and I've never had a slip-on cause a bike to run this poorly.
Senior Member
SuperBike
Joined: Sep 2008
Posts: 1,707
From: Essex, UK
If it was 180 degrees off I wouldn't think it would even run
If you're convinced the carbs are responsible, and eliminated the usual suspects, then take a gander at these threads:
https://www.superhawkforum.com/forum...leaning-27529/
https://www.superhawkforum.com/forum...-set-up-24769/
Last edited by Wicky; Jul 18, 2012 at 08:52 AM.
Banned
MotoGP
Joined: Aug 2007
Posts: 5,942
From: Lake View Terrace, CA
Are the diaphragms seated properly in the carbs?
If they are I would then check the filter screen in the tank and the petcock to make sure the diaphragm is not damaged and that it is in the full "open" position
If they are I would then check the filter screen in the tank and the petcock to make sure the diaphragm is not damaged and that it is in the full "open" position
Banned
MotoGP
Joined: Aug 2007
Posts: 5,942
From: Lake View Terrace, CA
What about the carb diaphragms? It sounds like you know how to check if they are seated properly but did you check to see if one of them possibly has a pin hole in it?
Of course the other obvious question, that still has to be asked, did you sync the carbs?
Of course the other obvious question, that still has to be asked, did you sync the carbs?
Senior Member
SuperBike
Joined: Sep 2008
Posts: 1,707
From: Essex, UK
If it was a CCT gone wrong you'd know about! Add that on the list of items to replace pronto with manual CCTs along with R/R (if you have an early unfinned one)
Are you sure the carbs are back on securely and the seals aren't hardened/perished, causing leaks?
Are you sure the carbs are back on securely and the seals aren't hardened/perished, causing leaks?
Slacker
Superstock
Superstock
Joined: Jun 2005
Posts: 489
From: San Antonio, TX
Check for blockage in the float bowl vents, and make sure the slide vents are not obstructed where they plug into the airbox.
You have twice mentioned the slip-on. This bike has dual mufflers. Has someone done a poor job at converting the exhaust to single?
You have twice mentioned the slip-on. This bike has dual mufflers. Has someone done a poor job at converting the exhaust to single?
Senior Member
Superstock
Joined: Oct 2011
Posts: 344
I hack-jobbed mine into a single when the clamp on one side broke, and with some tuning it still hauls *** (and the bike is lighter than before).
Senior Member
Back Marker
Joined: Jan 2009
Posts: 224
From: Hills of Kentucky
It happens all too often.
When in doubt, C4
Squid
Joined: Apr 2012
Posts: 72
From: Venice, FL
Wanted to add about the Emulsion tubes and mains to check they were in the correct carbs as well. I dunno how far apart the carbs when the OP cleaned them, but it's something else to consider looking into if it wasn't already mentioned.
Thread Starter
Junior Member
Squid
Joined: Jul 2012
Posts: 9
From: Nashville
Everything in the carbs is correct. I checked the numbers on the needles and made sure the emulsion tubes were in the right place. The carb boots are good too. I do have a single exhaust, but I have hand made plenty of custom undertail exhaust with no problems. Also the idiot I bought it from was running with no mufflers at all and he had no complaints about it.
Banned
MotoGP
Joined: Aug 2007
Posts: 5,942
From: Lake View Terrace, CA
Have you pulled the plugs and checked them?
If you say everything in the carbs and fuel system is fine then the only other thing is the ignition system, which would mean bad plugs or an issue with the coils or plug wires.
Are the wires push firmly in the boots? You possibly could pull the wires out of the boots to see if there is corrosion at the end of the wire also.
If you say everything in the carbs and fuel system is fine then the only other thing is the ignition system, which would mean bad plugs or an issue with the coils or plug wires.
Are the wires push firmly in the boots? You possibly could pull the wires out of the boots to see if there is corrosion at the end of the wire also.
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