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Help! Running on one cylinder and out of ideas

Old 08-31-2013, 11:47 PM
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Help! Running on one cylinder and out of ideas

I bought my '98 with 17,000 miles, a non-runner that I thought would be a quick fix. Wouldn't start from sitting for a couple of years. Previous owner said it was running great when he parked it due to a leaky clutch slave gasket. I fixed the gasket, replaced the battery, removed and went through the carbs, changed the plugs, but I can't get this thing to run right!! Seems to be running on one cylinder. Bike has no power and can barely pull its weight down the road. Intermittent loud backfiring while riding.

The front cylinder gets hot but it is not firing properly- I can pull the plug wire off and the bike runs exactly the same. Here is what I have eliminated so far:

PVLIR thing: I have removed the tank completely and run the bike with an external tank, runs exactly the same.
Carbs: I have revived many old carbs and I think I know what I'm doing- soaked the carb bodies in cleaner overnight, blew every opening with compressed air, carb cleaner for all the jets and everything is good. I kept track of emulsion tubes and needles for each carb. Vacuum seems to be working properly on the slides.
Spark: getting a nice blue spark.
Plugs: brand new.

Starting fluid in the front carb seems to want to fire when shot into the intake, but not as much as I would like. Sounds like it could still be a carb issue? I guess my next move is to do a compression test, I can't think of what else could be going on other than bigger problems! Any ideas from the brain trust? Love this site, thanks in advance for any suggestions!
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Old 09-01-2013, 12:20 AM
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So, you are positive that it is a fuel issue on the front cylinder? Maybe you made a mistake assembling the carbs?

Are you using the stock coils/spark plug wires? Otherwise, if you have fuel AND spark, then check your timing. Go off of the FSM (Factory Service Manual) and make sure your timing is correct.

Edit: Also, refernce the FSM and make sure all your vacuum lines are connected correctly.

Last edited by CruxGNZ; 09-01-2013 at 12:23 AM.
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Old 09-01-2013, 12:50 AM
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Might be helpful if you put your location in your profile, so if a fellow VTR owner was near you you'd a have a bike to compare to esp in regards to various hoses etc. and if necessary swap known working parts over

Have you tried swapping the coils round to see if the problem moves with it?

As mentioned by CruxGNZ above > Honda VTR1000F Service Manual PDF > https://www.superhawkforum.com/forum...79/#post318452

Last edited by Wicky; 09-01-2013 at 12:53 AM.
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Old 09-02-2013, 09:35 AM
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Thanks for the replies. Carbs getting put back together wrong (by me) seems like the most likely problem, I will pull them apart again. I do have the FSM and I've been using it, as well as the helpful info on the forum. Not sure what I could have done wrong.. both carbs have fuel in the bowl.
The reason I suspect the front cylinder is the fact that the bike will continue to idle and make the same power when I remove the front plug wire. If I remove the rear plug wire, the motor dies instantly.
The front header does get hot, but not nearly as hot as the rear.

I ruled out a tank vacuum issue because the bike runs the same with the tank removed and the bike hooked up to one of those Motion Pro auxiliary fuel tanks. I also ruled out coil or plug wire because I got such a nice blue spark when a screwdriver is inserted into the plug cap and grounded to the header nut. Are those correct assumptions? I know that to assume just makes an *** out of u and me...
Thanks again for the help!
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Old 09-02-2013, 10:37 AM
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Originally Posted by 81forest View Post
I also ruled out coil or plug wire because I got such a nice blue spark when a screwdriver is inserted into the plug cap and grounded to the header nut. Are those correct assumptions?
Not always. Sometimes a spark behaves differently under load than it does during testing. But it is a good indicator that it's not the problem.

Did you seat the needle slide diaphragm correctly? Push both of the needle slides back and let go. They should return at the same rate. If your front one returns much faster, then it's not seated properly (there is an air leak)
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Old 09-02-2013, 12:30 PM
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I will get back in there and check again, but when I buttoned up the airbox both slides seemed to be returning properly at the same time. Thanks, I'll post up what I find.
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Old 09-02-2013, 12:34 PM
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You may want to run a quick compression test on that front cylinder...
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Old 10-19-2013, 11:17 AM
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Originally Posted by 7moore7 View Post
You may want to run a quick compression test on that front cylinder...
Ok, didn't look at the bike for awhile but I got a chance to finally do a compression test yesterday, it came back with a beautiful 155psi! So, the compression is good. I've had mine apart a few times now and I'm exasperated so I kind of wimped out and just bought a used set of carbs on ebay. I don't know what else to try. If the new carbs make any difference at all, then at least I know it's a fuel issue right? Will post results! Wonder what it would be like to actually ride the SuperHawk!
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Old 11-16-2014, 04:15 PM
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Still here..

wow, one year ago that I wrote that last post.. Still in the same situation, same bike, same problem!

I went through the carbs again. Bike runs fine on the front cylinder, but does not run on the rear cylinder. Not even on starter fluid sprayed down into the intake!

So it must be ignition related...? Question: someone mentioned that a coil can be bad, but still spark. I have not had time to swap coils yet, will do so soon. Bike definitely has spark, because that rear dead cylinder still flames up from the starter fluid occasionally.

What are the other culprits for "ignition cutting out on one cylinder but still sparks when tested"?

Thanks a ton in advance, I hope to ride this thing someday!!
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Old 11-16-2014, 07:20 PM
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Originally Posted by 81forest View Post
wow, one year ago that I wrote that last post.. Still in the same situation, same bike, same problem!

I went through the carbs again. Bike runs fine on the front cylinder, but does not run on the rear cylinder. Not even on starter fluid sprayed down into the intake!

So it must be ignition related...? Question: someone mentioned that a coil can be bad, but still spark. I have not had time to swap coils yet, will do so soon. Bike definitely has spark, because that rear dead cylinder still flames up from the starter fluid occasionally.

What are the other culprits for "ignition cutting out on one cylinder but still sparks when tested"?

Thanks a ton in advance, I hope to ride this thing someday!!
So the problem moved from the front cylinder to the rear cylinder?
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Old 11-17-2014, 10:26 AM
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Originally Posted by CrankenFine View Post
So the problem moved from the front cylinder to the rear cylinder?
Thanks for the reply and good point- looking back through this thread I see that the rear cylinder seemed like the good one before. Now it does not fire at all. Back to the carbs maybe?! Ugh. Still can't figure out why it won't run on starter fluid.
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Old 11-17-2014, 12:11 PM
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Well it's very curious if the front was bad but now it's the rear. Forgive me for not re reading every post again but did you try swapping coils and or spark plugs front to rear just to absolutely isolate it is not a spark problem?
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