I just purchased a 98 VTR recently, and have done some maint. as well as thoroughly gone over much of it, as it was sitting for a few years from the orig. owner, one issue eludes me.

There is an off-throttle lag, sounds almost like a "coughing".

Also, when I accelerate hard on the highway, I sense almost a "Vtec" kicking in. Perhaps I'm so used to FI bikes that I forgot what carbs were like, as I've not had my last VTR since 2000? Is this delayed accel normal?

Ideas? I'm thinking to pull off the tank, check the air cleaner and shoot the carbs full of carb cleaner to start. Next, would be bringing the bike to my local Honda dealer for a carb sinc/tune.

 

Beware filling the carbs with cleaner as potent as berryman B-12.
The rubber o-rings swell up around that stuff, and can make a minor problem much more than minor.

 

FWIW it's tough to beat a set of well-tuned carbs for response. Having had the chance to ride many late-model bikes in the past two years (I was editor of a bike mag), I would gladly put my Dynojet-kitted VTR against any of them for response. The problem is with your calibration.

 

A good carb cleaning may go a long way. Can be done at home. Suggest a good diagram of the carbs, total break down removing all gaskets and O-rings, over night soak, Sync of carbs, and a 12 pack for the tear down.

good luck
Fish

 

A carby strip down and clean will be a good start, and then a dyno tune might be the go to make sure the settings are right.

 

Check Hawkrider's suggestions. I've followed his suggestions and throttle response is strong and immediate. Things like set the TPS at 450-500ohms, air mixture screw 2 1/4 out, shim needles .40, partial bafflectomy, filter upgrade, PAIR removal, etc. What an amazing difference. Didn;t even change jetting and the plugs/pipes are burning perfect coloration.

 

Not trying to stir the pot here but you may want to do the TPS adjustment separately. I tried it (rode it that way for two weeks) and went back to the stock (@800 ohm) setting. The lower setting gave me no discernible benefit, in fact, it dulled/softened engine response noticeably at low and mid rpms.

 

I remember you mentioned that before. What i noticed is that when you turn the TPS you can actually feel when it loads the spring and after messing with it for a little bit, I could do it by feel and come up with 400-500ohms. I did this at the same time I did the needle shim and air mixture.

Maybe I have a stupid way of doing things, but I don't like to remove the tank any more than necessary, so I do everything I can and if there is a problem, I'll go back in. I also adjusted the throttle cables, re-routed the vacuum/fuel overflow and coolant lines and cut the flap out of the airbox; and cut the paper filter out and inserted a piece of foam oiled up with filter oil and sealed the outer edges with filter grease(K&N). The differences were that it never ran so good thankfully.