Runs terrible
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Junior Member
Squid
Joined: Aug 2019
Posts: 22
From: Md
Runs terrible
I’m having issues with my bike where it acts like it wants to stall after 15-30 minutes of riding. This video shows it hesitating to rev up like the carbs are messed up.. any ideas what could cause these issues??
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Junior Member
Squid
Joined: Aug 2019
Posts: 22
From: Md
Bike history
The bike was supposed to be the lowest miles Superhawk in the country at 3,200 miles. It has a very low 4 digit serial number with a date of manufacture of 3/97. It doesn’t have a scratch on it. I test rode it home from Va to MD and after a while it starts to act like it runs out of fuel, or running on one cylinder and bucking like a bronco. The clutch had been replaced, tires as well as slip on delkevic exhausts. It ran just as poorly with the factory exhaust. The choke doesn’t want to stay out when you pull it. It also takes a very long time to get up to operating temperature and idles low. The revs hesitate when you give it a hand full of throttle. Those are some of the symptoms. It seems to be a fuel or carburetor issue...Those are the symptoms and any help is much obliged.
Senior Member
Superstock
Joined: Jul 2018
Posts: 277
From: Champaign, IL
Start simple. Fuel tank vent. Choke at that age probably needs replaced. Friction keeps it open. They are cold blooded. Mine is, even with the upgrades to the carb etc. Idle can be set simply. Is the hesitation while it is totally warmed up, or still on choke? Idle circuit cruddy my first guess. Clutch replaced at 3,200 miles, yikes. My dry clutch Ducati race bike did better miles than that!
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SuperBike
Joined: Sep 2008
Posts: 1,707
From: Essex, UK
Could be a few things - As mentioned you can adjust the choke cable tension by tightening up the adjuster ring. With the low milage fuel could have gone off and gummed up carbs. Also has it a standard or aftermarket air filter? Did PO do any carb tuning to compensate for the exhaust? Plus are the various tank hoses in fine fettle and correctly postioned esp the vacuum hose to the fuel tap.
Last edited by Wicky; Nov 1, 2020 at 05:10 AM.
Thread Starter
Junior Member
Squid
Joined: Aug 2019
Posts: 22
From: Md
It runs poorly whether cold or warm. When you rev it, you don’t get a smooth throttle response. It’s jerky at times and wants to wheelie at times and sometimes it doesn’t respond. No adjustments were made to the carb after the installation of the exhausts. They are Delkevic 8” slip on pipes. It was running the same way prior to the install of the pipes. My local Honda dealer won’t touch the bike. The dealer charged me for a long list of things he said he did to no avail and kept mother bike for months... I was able to fix the issue with not being able to keep the choke out though, thanks for that advice !! Any further help would be appreciated.
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Junior Member
Squid
Joined: Aug 2019
Posts: 22
From: Md
A local shop put the new clutch in but didn’t fix the carbs if anyone knows a pedi or shop in Md familiar with these carbs let me know I want to put a jet kit in to compensate for the slip on pipe
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SuperBike
Joined: Sep 2010
Posts: 1,987
From: Bisbee, AZ
I had a set done for an ‘84 Nighthawk by https://www.wgcarbs.com/ carbs looked like new.
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Junior Member
Squid
Joined: Aug 2019
Posts: 22
From: Md
Thanks for the reply
You don’t need a jet kit for the pipes. There’s a thread on jetting. One thing at a time. Get to baseline first.
I had a set done for an ‘84 Nighthawk by https://www.wgcarbs.com/ carbs looked like new.
I had a set done for an ‘84 Nighthawk by https://www.wgcarbs.com/ carbs looked like new.
$349 at wgcarbs. I’m going to also do oil and air filters, manual cam chain tensioners, radiator drain and refill, spark plugs for now to have a good baseline...
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SuperBike
Joined: Sep 2010
Posts: 1,987
From: Bisbee, AZ
Number 10 https://www.partzilla.com/catalog/ho...wk/air-cleaner
Thread Starter
Junior Member
Squid
Joined: Aug 2019
Posts: 22
From: Md
Thank you for that extra advice I have no idea what filter is in there and though I was told it wad low mileage it actually has over 15k miles on it... 5 times the mileage I was told it had...
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SuperBike
Joined: Sep 2008
Posts: 1,707
From: Essex, UK
Senior Member
SuperBike
Joined: Aug 2005
Posts: 1,864
From: Fort Wayne, IN
I'll bet that's the problem.
Clean out the tank cap really well. I suggest removing it from the tank first so you can blast it thoroughly with carb cleaner.
If you want to verify this is the problem, ride it until it has the problem then pop the cap to allow air to come in. Pretty easy to do especially if you have a spare key.
Clean out the tank cap really well. I suggest removing it from the tank first so you can blast it thoroughly with carb cleaner.
If you want to verify this is the problem, ride it until it has the problem then pop the cap to allow air to come in. Pretty easy to do especially if you have a spare key.
Thread Starter
Junior Member
Squid
Joined: Aug 2019
Posts: 22
From: Md
Question
When i removed the gas tank partially I see that of the 6 screws holding down the air box five are missing. Only the one at the top right is fastened. Will that cause an issue with the motorcycle or is that cosmetic(excuse my ignorance please )? i don’t know...
Senior Member
Superstock
Joined: Jul 2018
Posts: 277
From: Champaign, IL
VTR virgin
Superstock
Joined: Mar 2015
Posts: 447
From: Auckland, New Zealand
The missing screw in the airbox lid won't matter; it just helps to hold the filter in place and seal out dust from bypassing. Any self-tapping scew can be used there. The fuel tank breather is the smaller hose plugged into the bottom of the fuel tank (the bigger one goes to the overflow by the cap). Pull the small hose off and check that is open to atmosphere, and also blow through the spigot on the tank and make sure it is clear. There's no breather in the fuel caps (unless the US bike is different to the rest of the world), you can flip the tank over on its back and it won't leak. You can unbolt the fuel petcock and pull out the strainer in the tank for a check.
The other thing to check is the general condition of the small black rubber vacuum hose going to the fuel petcock (must have no cracks) as the engine vacuum is used to keep the vacuum fuel tap open to let fuel flow to the carbs. Any leak here can stop the fuel flow and give the poor running you describe. There is also a rubber diaphragm in the petcock that can perish and stop fuel flowing easily.
The other thing to check is the general condition of the small black rubber vacuum hose going to the fuel petcock (must have no cracks) as the engine vacuum is used to keep the vacuum fuel tap open to let fuel flow to the carbs. Any leak here can stop the fuel flow and give the poor running you describe. There is also a rubber diaphragm in the petcock that can perish and stop fuel flowing easily.
Thread Starter
Junior Member
Squid
Joined: Aug 2019
Posts: 22
From: Md
Thank you for your reply I will check the vacuum hose and most likely replace it. I just came from the dealer and I ordered a bunch of parts to include the air filter assembly, oil filter, sub filter, air box screws etc etc. I will get down to the bottom of the problems of this bike because it has a **** ton of character compared with my other bikes..
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