On my 96 about at 3/8 of the throttle its starts to bog down and loose power. The shop i had the hesitation checked out by told me i needed, dyno stage one jet kit, carb sync, and have the valves adjusted. He said its running way to rich and that's the need for the jet kit but would this really make my bike hesitate im not okay with spending 800 on getting all of it done unless i know that will fix it please any advice would be greatly appreciated.

 

Normally -- if you start with a stock bike and add an exhaust pipe, the bike gets leaner. This is because you're allowing more air to pass through, lowering the ratio of gas to air -- aka leaner.

So - on your bike - do you have the stock exhaust? Do you have any intake modifications (ie K&Ns) ?

Did the previous owner have an exhaust on the bike, and put the stocker back on when you brought it? This scenario I could see that the bike would be rich -- as they would have tuned it for the freer flowing pipe, and now it's back to stock it's running rich.


If EVERYTHING is stock - then - a jet kit isn't the answer. Normally you replace the stock jets to get more fuel when you improve airflow on either exhaust/intake

Have you looked at the spark plugs yourself -- what color where they? White/very light tan color means lean -- black means oil/rich.

I'd be more apt to beleive it was lean than rich...

As for valves - in my experience you notice tight valves first when the bike is hesitent to idle when warm. It is never a bad thing to do.

Finally -- carb sync is entirely possible. For the benefit of listeners --- the basic way the carbs work is that the engine pulls air (vacuum) through the carb. As the air rushes past the carb openings it pulls gas into the mix (venturi effect) When the bike is new the cylinders each have the same compression, and the carbs are equally clean. As the bike ages these properties change -- imagine drinking through a new straw, and then trying to drink through a straw with a kink in it. The carb sync process balances the vacuum between the carbs -- so that each carb is once again delivering the same fuel/air mix (basically -- short form)

If your carbs are out of sync then the fuel mixture in each cylander could be different (richer/leaner) and you will not get optimum power. This tends to effect the bike across the board and not at a specific rpm (in my experience)

My last comment - given that you experience a flat spot (butt dyno?) I would agree with it being a carb issue... especially if you noticed this around ~5000 rpm. Before you get into carb tuning you will want to do the carb sync - and to do it properly you'd want to sync after as well. The tool costs ~$100... and you might have a friend that has one. The expertise is a different matter. A bike shop will charge a full morning to do this I suspect.

ramble ramble --- really more history on the bike would help

 

Okay so bought the bike after it had been sitting for three years. Took it to a buddys shop he cleaned the carbs for me and did new gaskets, i replaced the plugs because i thought that was my throttle issue, they were black very black. I did a oil change and replace the anti-freeze. Carb sync will only run me 85 so its not bad but he said its better to do the jets and then sync it because its jetted for sea level and i live in reno nevada and if i sync before and then do the jets ill have to sync it again. And that is exactly where i have my dead spot is aroun 5000 rpms

 

Ok -- reno would explain why it would be rich. Hadn't thought of that as around here, it's all sea level.

The dead spot is wear the end of the transition from idle to mains -- it's a common problem, indicating jetting. Black plugs - high altitude - etc... you're right - it all says too rich.

The carbs are fairly simple -- just a matter of getting to them. If it is anything like the F4 you need to pull the gas tank and air box. They should be accessible then...

good luck!

 

So a simple carb sync probably will not fix the dead spot?

 

If you had of sad one plug was bad --- I might have said the sync was enough. If all are bad, it's almost certainly time for jetting. Sorry - just from the info I see, jetting seems the most reasonable explanation.

 

$85 for a carb sync? That is pretty steep!

 

Its 130 at honda maybe you have the hook up but ill take 85 over 130 anyday im not being a dick but that's kinda rude im asking.for.mechanial advice not financial

 

To do a carb sync you need to remove the gas tank, air box, connect to the carbs... test, and put it back together. That's at least 1 hours work.

 

sorry, i came in here because i read the title too quickly and thought you were in need of some bad advice. if for some reason that does indeed turn out to be the case; please feel free to PM me.