General Discussion Anything SuperHawk Related

Intermittent Issue

Old 05-05-2015, 06:51 AM
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Intermittent Issue

I did a quick search, found some similar issues but no conclusions.

A little about my bike.

All stock except Staintune Exhaust and dreaded K&N Air filter. New stock plugs, always ran 93, aftermarket fuel filters. About 21k miles.

The first winter it sat which was about 2 years ago, I started the bike and it ran good. Out of nowhere it started to stall out and run rough. Wouldn't hold an idle. Seemed like it was running on one cylinder. After warming up it ran fine. Didn't think much of it.

Then I ran out of gas last year. Had a buddy top me off and started it up and it did the exact same thing. Ran rough as if it were running on 1 cylinder ago. After getting aggravated I just rode it home. After hitting 2nd gear around 4-5k rmps it cleared up and ran perfect all summer.

Then, late last year it started doing the same thing out of nowhere. I was riding normal, cruising down the street and it started again. I parked it, changed the plugs, cleaned the air filter, changed the fuel filters and it ran good again for a few hundred miles until I parked it for winter. Always with a full tank with Stabile.

Yesterday I take it out for my first ride of the season. Running beautifully for about 10 miles then it began. I nursed it to where I was going and parked it. Went back out an hour later and the exact same thing. Couldn't get a ride home so I just rode it. After about 10 miles of stalling, back firing and people giving me weird looks I opened it up and went through the gears. Out of no where it cleared up and ran perfect for the next 5 miles until I got home.

I thought I fixed the issue with clean filters and new spark plugs but obviously not. This all happened over the course of a few thousand miles, since I got the bike. When it runs good its good.

Any ideas of where to begin with this issue? Intermittent issues are the ones that stump me.
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Old 05-05-2015, 08:48 AM
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I'd check fuel flow and the spark color to start. With exhaust and the K&N and no rejet, you are running lean.
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Old 05-05-2015, 08:54 AM
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I forgot to mention the jetting. I have no idea if it is jetted or not. I thought Staintune bragged that no tuning was necessary. There was one time that It was running rough and I pulled the tank, the one fuel filter was bone dry. I'm assuming a fuel issue as well. What would prevent fuel from flowing though? If the petcock was bad, would it prevent fuel from flowing to both fuel lines or possibly just one? Is it even possible that a K&N could cause an issue like this? I know everyone hates them, but I've had them in everything I've ever owned with the exception of my John Deere lol and never had a problem. Thank you for the reply.

Last edited by 996thehawk; 05-05-2015 at 08:58 AM.
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Old 05-05-2015, 09:21 AM
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As standard there's only a fuel filter in the tank attatched to the petcock. Or do you have in addition aftermarket inline fuel filters on both the fuel hoses?

With a K&N and freer flowing pipes you'll need dynoing and rejetting.

After storage / having the tank off - Have you switched the petcock back on and attached the vacuum hose correctly?

Re fuel filters. Were they primed to allow flow. checked that they aren't gummed up? I fitted a pair for a friend on her VTR as extra insurance after she had a respray and they could wet lock up preventing fuel flow unless primed.

Last edited by Wicky; 05-05-2015 at 09:28 AM.
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Old 05-05-2015, 09:36 AM
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My bet is crud in your tank. You should never let a bike sit & then just start it up. Condensation will cause water, then tank scale etc cause debris.

Save yourself a lot of labor and drain your tank to totally empty. Remove the petcock if possible or at least shake it upside down. You should also clean the carbs at this point but a clean fuel supply goes a long way to making your life better.

Another lifesaver is inline fuel filters. Its pretty easy for the heartache it saves. I posted a thread on here somewhere on doing mine.

You should for sure clean the carb jets as they are small & don't get cleaner on their own.

I don't see any possibility that you don't have crud in your jets. Even if it clogged then cleared up, its only a matter of time.

BUT, with an old cruddy tank, no amount of carb cleaning will help since more crud and water is on the way downstream.
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Old 05-05-2015, 10:44 AM
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agree - jetting and a K&N may cause poor or weak running, but not likely deathly stumbling one minute and decent running the next.


clean and dump the tank, clean the carbs. Use caution when cleaning the carbs to not intermix parts - the needles are different from front to rear, and sometimes they may have different needle height settings.


Check the float needles when you are in there too. A sticking float will make it run like crap for sure.
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Old 05-05-2015, 11:42 AM
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I'll be replacing the K&N either way. Seems it does more harm than good.

There are aftermarket NAPA fuel filters in each fuel line going to the carbs.

I never turned the petcock off or disconnected any of the fuel/vacuum lines during storage. So it is definitely not that.

I thought that the aftermarket fuel filters were possibly restricting fuel flow. Would anyone recommend going back to stock fuel lines w/o filters?

I guess I'm looking at a carb and tank clean. I will get to this asap and check back. Any other advice while I'm in there would be greatly appreciated. Thank you all for your help.
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Old 05-05-2015, 12:23 PM
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Originally Posted by 996thehawk View Post
I thought that the aftermarket fuel filters were possibly restricting fuel flow. Would anyone recommend going back to stock fuel lines w/o filters?
I would suggest removing them.

Some folks like them but I have seen issues in the past by running them.

To me, the filters are designed to be run on a pressurized system (something with a fuel pump) and in a gravity feed application they might cause a flow issue.

I have only run the tank screen in my bike. Bought new 9\97 and have never experienced any issues with getting gunk in the carbs.

Of course this is just my opinion and YMMV.
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Old 05-05-2015, 04:52 PM
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I think that similar to saying "I never got a flat so you should be fine". Just sayin.
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Old 05-05-2015, 08:20 PM
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Originally Posted by 996thehawk View Post
I thought that the aftermarket fuel filters were possibly restricting fuel flow. Would anyone recommend going back to stock fuel lines w/o filters?
FYI, my tank has see through Mr. Gasket #9748. There is a thread about it here. Give it a read.

In that thread, I found the previous owner removed the stock (plastic & brass mesh) filter on my petcock. If you decide to remove those aftermarket fuel filters, make sure the P.O. of your bike didn't do the same thing as mine did.
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Old 05-07-2015, 11:16 AM
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I've decided to start with new fuel lines, new stock air filter, and I'm going to pull the petcock out and clean or replace the screen. I will check back if I come across a solution. Thanks again for all the help.
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Old 05-07-2015, 12:32 PM
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Originally Posted by smokinjoe73 View Post
I think that similar to saying "I never got a flat so you should be fine". Just sayin.
Using that reasoning you could say you guys are similar to saying "I'm so scared of getting a flat that I'm going to fill my tire with patches, just in case"....... just saying.

I gave my honest opinion that the filters could be causing an issue.

I have never heard of VTRs or Honda road bikes to have an issue with gunk coming from the tank.

So IMHO putting aux filters inline is fixing a problem that doesn't exist and adding extra places you can get a fuel leak.

When was the last time you had to clean one of those filters?


So do whatever makes you happy but I'll stick with the tank screen that has worked without fault.
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Old 05-11-2015, 03:12 PM
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Just a thought, but has this problem happened each time you have run the bike with a really full tank? The symptoms sound a little like vapour lock, which happens when you fill the tank a bit too much, stopping air getting back in as the level drops. This then stops the fuel flow to the carbs and you effectively run out of gas, usually on one cylinder first so the bike loses power and runs poorly. The fix is as easy as cracking the gas cap open and letting some air back in.

You could also have a partial blockage in the vent pipe leading back into the tank, this is the smaller of the two pipes to the right side of the fuel petcock under the tank.
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Old 05-04-2016, 08:41 AM
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So here's and update, only a year later... I installed a new petcock diaphragm, new fuel screen (which was no-existent), fresh carb sync, 2 new fuel lines WITHOUT the in-line fuel filters and a stock air filter. The bike started right up and ran perfect. Idled perfect and revved up perfect. No more stumbling or anything.

Went for a test ride and it ran 10 times better although I still have a noticeable loss in power. I checked the spark plugs, front cylinder looks lean. I pulled it apart and took the carbs apart. They both were pretty clean. First thing I noticed was a tear in the diaphragm for the rear carb. The other thing I noticed was that the pilot jets were an aftermarket #50 opposed to the stock #45. Both mains were the stock #175 and #178. The only thing I have done to my bike is a set of Staintune Pipes. Everything else is stock now. I will clean the carbs and replace both diaphragms and do another sync.

My questions is, should I put the stock #45's back in or keep the #50's for the mains?

Last edited by 996thehawk; 05-04-2016 at 09:08 AM.
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Old 05-04-2016, 01:55 PM
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Off the forum for awhile 996thehawk, but be sure to check the PVLR threads. Your bike seems to have similar issues that mine was having before finally placing the fuel lines in the correct locations. Good luck with your diagnosis.
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Old 05-04-2016, 02:07 PM
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Many seem to have good luck with 48 pilot jets.
(Sounds like a fishing tip or something).
You were wise to replace the petcock valve.

I have Staintunes and use 48 pilots, standard mains, stock filter and an extra washer under each diaphragm needle.
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Old 05-13-2016, 11:53 AM
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Thank you for the info guys. I decided to start with the stock 45 for now. Got it running today. Seems to be good but its raining real hard, so I'm going to wait on the road test. Will update...

Also, found that the diaphragm needles are adjustable... Are these factory or aftermarket?
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Old 05-13-2016, 04:31 PM
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Originally Posted by 996thehawk View Post
Thank you for the info guys. I decided to start with the stock 45 for now. Got it running today. Seems to be good but its raining real hard, so I'm going to wait on the road test. Will update...

Also, found that the diaphragm needles are adjustable... Are these factory or aftermarket?
Adjustable could be Dynojet or Factory Pro. I think (but not positive) HRC had adjustable needles as well.

EDIT: Do your needles look like one of these?
Name:  20150412_141944.jpg
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Last edited by CruxGNZ; 05-13-2016 at 04:34 PM.
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Old 05-14-2016, 10:52 AM
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Test rode the hawk today. Running better than ever! Thank you again for everyone's help and knowledge!
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