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98 VTR1000 sputters above 4k in any gear

Old 06-16-2011, 11:08 AM
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98 VTR1000 sputters above 4k in any gear

Hi,

I just picked up a 98 VTR1000 with under 18k on the clocks. I wan't able to test drive very much. What I did was ride around, engage all the gears, rev it out to red line in N, and hold RPM at various numbers in N. Of course I'm aware I should have ridden it more, but it looked great and 17xxx on the clocks was low I thought. Also original owner.

While riding home, I noted the bike "sputters" in any gear above 4k RPM. Grab the clutch and it revs freely, no issues.
It shifts fine and holds any gear I select. ( dont think bent shifter fork)
The bike is stock and has not been altered in any way.

Could it be the clutch? Something in the gearbox?
Fueling under load? I put a tank of fresh 93 octane and same issue. (I doubt because it always revs freely and smooth in N or with the clutch engaged).

Please offer any help as it is greatly appreciated. My local Honda shop is 3 weeks out from taking anything in.
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Old 06-16-2011, 11:12 AM
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Well it sounds like a fuel delivery problem.

So either the petcock is damaged and needs a rebuild kit or the carbs need to be pulled and cleaned.
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Old 06-16-2011, 11:17 AM
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That doesn't sound at all like a clutch or gear issue.

I'm sure smarter people than me will chime in shortly, but that sounds like a carb issue to me. The main jets take over around 4K RPM, any RPM below that is pilot jets. I think you have clogged/dirty main jets.
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Old 06-16-2011, 11:18 AM
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Ha! Told you they would chime in soon . . .
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Old 06-16-2011, 11:20 AM
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Originally Posted by evines View Post
That doesn't sound at all like a clutch or gear issue.

I'm sure smarter people than me will chime in shortly, but that sounds like a carb issue to me. The main jets take over around 4K RPM, any RPM below that is pilot jets. I think you have clogged/dirty main jets.
More likely the emulsion tubes (or needle jet holders, same part. 2 different names ) are dirty as they have a line of small holes on them.

They are also different front to rear so don't mix up any of the parts if you decide to take them apart and clean them yourself.
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Old 06-16-2011, 12:01 PM
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Another possibility is spark plugs, especially if they are the originals. The "stuttering" you describe could be ignition misfire under load. It would run fine with no load (in N). And that's easy to check, just pull the plugs.

Edit: I should have said "sputtering".

Last edited by VTRsurfer; 06-16-2011 at 12:03 PM.
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Old 06-16-2011, 12:04 PM
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Thanks all.

So even though the bike revs smooth and freely while not under load, fueling? Would engine load differ the fueling?
I can rev it up to red and hold solid any RPM range along the way smooth and clean. In N of course.

Seriously, thank you all! I am eager to get this bike out and crack it around.
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Old 06-16-2011, 12:06 PM
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stuttering or sputtering? Not sure which one to pick to describe.
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Old 06-16-2011, 12:11 PM
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Regardless, like the advice here, the fix is cheap. Adequate elbow grease, time and solvent. Just avoid looking for zebras when you hear a clopping sound. Its usually a horse. The simple fix is usually the one that works best.

The S'hawks love being fettled with and reward an interested owner quite nicely.
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Old 06-16-2011, 12:19 PM
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Is there a procedure for the carb removal and cleaning here on the site? Sorry I'm a noob.
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Old 06-16-2011, 12:28 PM
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Im the original owner of a 99 with only 11k (due to deployments and having 5 other bikes to ride)

I have the same problem and have torn it down, cleaned the **** outta it, looked at the petcock diaphrams, etc. ran fine last year, now it has an irritating hesitation, stumble at 4500 rpm. Im not a noob at wrenching on bike but I'll be damned if I can figure it out.

I'm now leading toward electrica now.. Maybe a goofy ground or something wrong with the ECU. Hopefully yours is just a clogged jet or a bad petcock diaphram.
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Old 06-16-2011, 12:34 PM
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" an irritating hesitation, stumble at 4500 rpm"

Does yours rev fine with no load?
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Old 06-16-2011, 12:39 PM
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Originally Posted by kennywiz View Post
" an irritating hesitation, stumble at 4500 rpm"

Does yours rev fine with no load?
Yup. wack the throttle and it barks. Even runs great under hard load / WOT going through the gears. But then when highway cruizing at 65-75mph somethings just not right. Its faint but noticable and annoying. I guess I'll test or bypass the side stand switch and ignition switch to rule them out..
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Old 06-16-2011, 01:03 PM
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Originally Posted by 2armor View Post
Yup. wack the throttle and it barks. Even runs great under hard load / WOT going through the gears. But then when highway cruizing at 65-75mph somethings just not right. Its faint but noticable and annoying. I guess I'll test or bypass the side stand switch and ignition switch to rule them out..
Not same issue as mine.
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Old 06-16-2011, 01:05 PM
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Originally Posted by 2armor View Post
Yup. wack the throttle and it barks. Even runs great under hard load / WOT going through the gears. But then when highway cruizing at 65-75mph somethings just not right. Its faint but noticable and annoying. I guess I'll test or bypass the side stand switch and ignition switch to rule them out..
if your bike is clean and ready to rock, it's the K&N air filter. Get that out of there. Replace it with stock or BMC. Believe me. It'll run like a champ after that. Mine used to stumble and I replaced it. First ride out there's zero hesitation.
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Old 06-16-2011, 01:09 PM
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Originally Posted by AK Ronin View Post
if your bike is clean and ready to rock, it's the K&N air filter. Get that out of there. Replace it with stock or BMC. Believe me. It'll run like a champ after that. Mine used to stumble and I replaced it. First ride out there's zero hesitation.
That was actually the first thing I did after the issue started. I figured it was from sitting 4 months during winter. I went back to a newstock airfilter 2 months ago and replaced the two little secondary breather filters that were dry rotting. Then after no change in pefromance, I moved on to cleaning carbs, petcock inspection, etc.. Thatnks for the tip tho!!
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Old 06-16-2011, 01:12 PM
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I can say that after I did the OEM filter and carb clean, it was noticeable better. I figured I'd 2-3 tanks of gas through it with Sea foam to ensure clean carbs. Still not perfect.. Or at least the way it was before..
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Old 06-16-2011, 01:20 PM
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Thanks all!

I will try the carb cleaning, new air filter, change plugs, and inspect the petcock.

If there are any other suggestions PLEASE advise.
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Old 06-16-2011, 01:20 PM
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Originally Posted by kennywiz View Post
Is there a procedure for the carb removal and cleaning here on the site? Sorry I'm a noob.
Sorry, didnt mean to jack ur thread with my similar issue. Did you ever get the carb info? I would start by doing a full inspection of everything obvious and clean the carbs real good, check all fuel lines, do spark plug replace, check the petcock diaphrams & spring, and double check petcock vaccum hose mount location too. It should be mounted to the port on the back of the petcock. Many screw it up when they re install the tank and put it on the wrong nipple (vent nipple instead of the actuation nipple). Good Luck!
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Old 06-16-2011, 01:42 PM
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This could help for some info/pictures if you dont have a manual:

https://www.superhawkforum.com/forum...-set-up-24769/
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Old 06-16-2011, 02:09 PM
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That carb dis-assembly may be beyond my known abilities. Which picture are the mains and the emulsion tubes I was advised to clean?

Thanks
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Old 06-16-2011, 02:16 PM
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Originally Posted by kennywiz View Post
That carb dis-assembly may be beyond my known abilities. Which picture are the mains and the emulsion tubes I was advised to clean?

Thanks
The picture in post #13 of that thread are the emulsion tubes (one for front carb, one for rear- note hole locations on the main tube). Double click to enlarge it..

Pull off the carb bowls and you'll be looking at them along with the pilot jet and main jet. The MAIN jet is a small brass flat head screw looking part that is actually screwed in the bottom of the emulsion tube. You can remove the main and emulsion tube seperately or as one unit. Take them apart to clean tho..

Last edited by 2armor; 06-16-2011 at 02:18 PM.
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Old 06-16-2011, 02:20 PM
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So I would have to remove the carb assembly and flip it to access the bowls?
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Old 06-16-2011, 07:50 PM
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Originally Posted by kennywiz View Post
So I would have to remove the carb assembly and flip it to access the bowls?
Correct.

Disassembling the carbs is a snap, if you have intermediate mechanical skills. However, removing them requires some finesse, especially with the "choke" cables. The stock airbox plumbing is a PIA, if the PAIR hasn't been removed. And you don't want to separate the carbs. Leave them linked together. Having said that, after you've pulled them once or twice, it's a snap.

But what I would do is replace the plugs first...that's easy.
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Old 06-16-2011, 08:15 PM
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I haven't looked yet. Do I have to remove much to get to them? ( The plugs)

Thanks
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Old 06-16-2011, 08:22 PM
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Originally Posted by kennywiz View Post
I haven't looked yet. Do I have to remove much to get to them? ( The plugs)

Thanks
With the correct tools: thin wall 18mm spark plug socket (Craftsman works) and extensions, the front plug is easy. You have to prop up the rear of the tank to get to the rear plug. Having the tank near empty helps a lot.

I should add that if you have the factory tool kit, there's a U-shaped allen wrench that doubles as a rear tank prop.

Last edited by VTRsurfer; 06-16-2011 at 08:28 PM.
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Old 06-17-2011, 08:48 AM
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"WELL THERE'S YOUR PROBLEM!!!!"

As I was unscrewing the airbox cover, I found that a bird decided that was a great place to nest!
Evidently birds canread. It saw "SuperHawk" and decidied this was a good place.



I vacuumed everything out and wiped the airbox clean. Put in a new filter and zoom zoom zoom!

Still, I would like to change the plugs. I see the front to the right, correct? I lifter the tank but could not find the rear.

Last edited by kennywiz; 06-27-2011 at 10:36 AM. Reason: na
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Old 06-17-2011, 08:57 AM
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Um, yeah. Removing the nest from the airbox was the next thing I was going to suggest . . .

That is pretty crazy, but it's not the first time this has happened. I think there are pictures on this forum of someone else who had the same problem.
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Old 06-17-2011, 09:38 AM
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Thats funny. Damn Ren I bet. They like places like that. Wish my problem was that easy to find!

Actually it looks like a mouse nest.. check the wire harness now too. They like chewing on wires..
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Old 06-17-2011, 02:29 PM
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Apparently it WAS a zebra and not a horse when you heard the clopping sound. What an exotic cause for the symptom.
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