Sputtering and loss of power between 90-100 mph

[N.H.B]

Guys I just had a tune up less than a month ago and while I was riding today and seeing how fast I could get the bike to go, between 90-100 mph the bike sputtered and lost power. As I slowed it regained power and drove fine. I also did not have a problems in the 4 lower gears either after this just in fifth gear between 90-100 mph. I have a 2001 Suzuki Intruder VS 800 GL with about 6800 miles on it. I know the first thing I gonna hear is to slow down but I need some help figuring out why this happened, shouldnt the bike at high speeds just be stable and reach a point where it would not go any faster and not to sputter or bog down and lose power?

Thx Larry

[Loweboy]

Your fuel might have been pushed back in the tank beyond the discharge hose and it was starving for fuel. Was your tank full?

[N.H.B]

Hi Loweboy. I just went outside and looked in my tank and I could hear the gas schloshing around but could not see it. I dont understand how this could effect the bike at these speeds, please explain??? Thx

Larry

[DrBob]

You may simply have hit the rev limiter in high gear, as the rear-drive gearing on a VS800 is designed for low-end power and not high-speed blasts. The Intruder VS800 is only rated for a top speed of 99 MPH, and there is a margin of error in the speedometer, so you may simply have reached the upper limit of the bike's speed. If you are not quite getting the full 99 MPH, your carbs may be a little lean, starving it for gas at high speed. Or your air filters may be a little dirty, starving it for air.
And you're right, I'm going to say it: SLOW DOWN!!! Or at least sign the organ donor card.

[N.H.B]

Thx DrBob for your insight. Where do I check the air filter at, in the meantime I'll do some research on where it is. What does carbs being lean mean? Good to hear from you Doc .

Larry

[N.H.B]

Oh Drbob are you a member of www.intruderalert.com?

[Loweboy]

NHB, the engine torgue squats the back end of the bike and extends the front fork tubes, placing the centerline of the tank on more of an angle then it already is. To reach spped of 100 mph plus, the engine is working hard and the bike is in it's torqued posture. Take notice when you let off the throttle because the front end dives. This is the opposite of what you experience when you roll the throttle on. Now, picture this gallon of gas left in your tank when you accelerate to 100 mph. Would the gas be nice and level and just sitting there waiting to go into your carburator? Or would it be crammed into the back of the tank from the force of going 100 mph? A buddy of mine got a ticket under the same circumstances. His bike(Kawasaki KZ1000) could have easily left any patrol car in the dust but when he cracked it, it bogged down and wouldn't get him over 70 mph. He had fuel but not enough to feed 4 cylinders trying to launch him into freedom. I won't say to go out there and try it again but if you have a switchable fuel valve, use reserve and there might be a difference. The reserve outlet pipe is usually much shorter than the regular one and will give you more fuel when the demand calls for it.

[DrBob]

Yup, I’m the same Dr Bob from the intruder alert site. Are you coming to the fall gathering in KY? It's not too far from you. I am going- the summer one in Asheville was a great time.

The air filters are inside the air boxes, the black plastic containers that you can see on on the side of the bike. The one for the back carb is under the seat, below the painted side cover, and the one for the front carb is just below the frame covers where the front end bolts to the front of the frame. The filters should be replaced every 7500 miles, and I pull mine out every six months or so and blow them clean with an air compressor, as the spring pollen in Atlanta will really clog them up.

If the carbs are not adjusted correctly, they may not flow enough gas to mix with the high volume of air flowing through them at high RPM, so the fuel/ air mixture is “lean”. If they are out of adjustment the other way, and flow more gas then they should, the mixture is “rich”. Or if they are not synchronized correctly (in adjustment with each other) then the bike may run poorly, vibrate, cough and sputter, or do other odd things either at high RPM or when decelerating. If the bike runs good at normal highway speeds, then don’t mess with them.

[N.H.B]

Loweboy and Drbob I appreciate both of your input, you have made me feel welcome now. I hope to see you guys on the road!!! Ride on!

[N.H.B]

Drbob I have decided to check my air filters, how do I remove the seat and side covers? Also what do I have to do at the front of the bike as you mentioned? Thanks

Larry