1998 VTR runs rough at high rpm under a load
 

Sounds like it might be the petcock diaphragm.

I also thought that but i put a fuel bladder around my neck and went down the road and it still did it. I have a feeling its electrical???

Then check the pick up sensor in the clutch cover.

would that effect the ignition? I was thinking side stand switch posably. I rode it in to work today so ill do some checks and see what i can find.

It's the pick up for the ignition rotor, so yes it can effect the ignition.

The side stand can cause similar issues but the fact it only happens at high RPM & load would point to more of an ignition issue as you have ruled out a fuel issue.

The clutch switch is working fine, put a new battery in it and the charging system is working 100%. One of my techs thinks it could be the ''unit converter'' that controls the coils. Im not about to throw down on new one not knowing 100% that its the real problem. I guess my next move will be to take one off a bike that works and try it. Not going to lie im really starting to hate this bike!!!:mad:

Does it completely cut out, of just bog down?

Some people have had the side stand bounce enough at certain rpms/speeds that the switch cuts out (effectively turns the motor of for a split second). If this is the case the test is to bypass the side stand switch... basically connecting the three terminals at the switch and riding it.

It's a small chance, but it could be a possibility. Don't hate on our bikes! We're quite fond of them!

I've heard of coils reading the right resistance but still acting up under load...

Well yours would be the first converter that I have heard of going bad..... and I've been around these bikes since '97.

So if you can locate one to try, give it a shot but I really doubt its an issue.
I do have a stock ECU you could try if you want to eliminate that also but I still think it sounds like the pick up. Attachment 15491

how did you connect the fuel bladder?

Directly to the fuel line with a T connector.

Thank you I greatly appreciate the offer!! One of my co workers (works at our other store or i would have done it sooner) is going to let me barrow his and ill give it a try. I'm with you on never seeing one go bad and i have owned over 15 honda sport bikes.

It bogs down but it does it like a light switch consistently not like a carb issue that you can normally play with the throttle and keep climbing rpms. I checked the side stand switch and its good. I like riding the bike and I think the handling is amazing but I’ve never had a bike that I couldn’t fix and that sucks
lol

barrowed parts from my friends bike but its a 02 or 03 so the electrical is diff. back to the drawing board

My chain and front sprocket are worn out and it acts like you describe, in my case it's the front sprocket slipping on the chain. Only under load, like 2/3+ throttle at higher rpms. If it hadn't happened to me before I would suspect carb or electrical problems too....

and yes I'm changing them tomorrow :-)

If it makes you feel any better, i'm having exactly the same issue!
Has improved slightly with new plugs, but am yet to solve it..
I'm going to try new coils next. Might do the stick coil mod on here, and see if that improves things.
Good luck, please post up if you manage to sort it! :confused:;)

I will and you do the same! i put a set of known good coils of another bike and i didnt help... such a weird problem

I wish it was that easy my friend but its def not a chain and sprocket thing

Have you checked the timing is all correct. It seems you have checked just about everything. It almost sounds like the timing is out by 180 degrees. If you described the symptoms as if it's got a limiter on at 7000rpm and the bike wont go past that then that would be it.

Pulling the cam covers off will show the timing marks lining up properly. It's how much the crank turns between firing pulses. If 180 out, the rear cylinder fires, then the front one fires 90 degrees later. You need it to be 270 degrees later. The fix would be to set the rear cylinder to TDC on compression, remove the cams and turn the crank 1 full turn anticlockwise until it comes back around onto RT. Then refit the cams.

As you have pretty much checked everything else I think the timing and valve clearances is the next thing to check.

I would like to know the end result to this issue. it's got my brain ticking over.

(:-})

Since you don't know which cylinder is affected put it back on the stand, put it in 1st engage clutch and apply brake to simulate road going load. Pull the front plug wire first cuz it's easier to get at and if it bogs at 6k then that's the troubled one. If that one doesn't bog then pull the rear plug wire and test again. Maybe this would shed some light on the source.

ill keep ya posted and thank you for the help.

Can I get a status on youre problem?
 

Hi. I just saw youre (old) post, and I have the exact same problem with my vtr. Did you solve the problem? Many thanks in advance.

I had a mechanic improperly install a cam after a valve adjustment and had a problem exactly as you describe until he fixed it for me.

Good luck

Oh, thanks for the heads up.
 

I can write a little more, just in case it changes anything.

It runs rough from about 7000rpm more or less. And that happens EVERY time under load. I can climb all the way up to the top rpm on maybe 1/4 throttle. It always cleans up a little between 9500 and 10500. I am not sure if that is 100 percent or not. I bought this bike like this, so i have never experienced it working properly. I will list what I can come up with of things i did to it lately even though not everything has anything to do with the problem:-). I have changed the air, and oil filter, engine oil, cooling fluid, sparkplugs, checkt the coil and caps, cleaned the carbs, adjusted the mix screw to 2,5 turn open to se any changes (I'we heard this has only to do with low rpm issue, but testet anyways). I have also checked the vacuum hoses. The plugs looks ok too after a couple of months of use. The top speed is about 200km/h(125mph) @ maybe 7000rpm where it cant climb further. Thats about it:D

Do you have more info about the cam problem?
 

Hi. And thanks for the info. Do you have more details about the gam problem? Did you have to adjust the valves also or just the cam?

Thanks in advance;)

This thread sucks. We read the whole thing only so find the OP never reported back.
banish it!!:)

When I bough this latest VTR, I had similar heavy throttle missing, popping on deceleration, rough idle, carb farts and stalling at lights. I took the simple route and had success. This included a stock filter element, removing oversized orifices and setting up per "hawk".

V Twin have you checked the pet cock diaphragm on the vac side? When I ask have you checked it it'd am asking if you did a light check on it?

Not light checked:-(
 

Hi. If you mean the diaphragm under the tank, I did, but not with light, no. Only visually:oops: should i check it again with light? I checked it extensively:roll:

Yes the diaphram that is in cased under the tank. The petcock assembly has three hoses hooked up to it 2 fuel lines and a vac line.

There will be 2 diaphragms a spring and a rubber cap in the assembly. If either diaphram is damaged it will cause a lot of head aches. I know this from experience. I did a visual check on mine and it seemed fine and my problems got progressively worse. Next time I pulled it apart I had a huge hole in it. It formed in less then a few weeks.

Also make sure you hook the vac line into the correct port when reconnecting. It goes to the rear of the assembly not on the nipple facing downwards.