Top Speed Help!!!!

[Black Rabbit]

So i bought my 08 250 about a month ago and I love it, I ride it everywhere! But theres one issue my top speed seems very low. I get to 80 and it will not budge any faster. I have read in different forums that must people can easily get to 90 and can make their way to 105. i weigh 145 lbs soaking wet so I know its not me weight. I recently cleaned the air filter, did 2 oil changes (overfilled the first time), got a new front tire, and used one treatment of Seafoam.After all that it runs a whole lot better but she still wont budge one mph over 80

I really dont want to take the bike to the shop, but im running out of ideas that it could be. Would spark plugs effect the top end? should I get my carbs cleaned? Thanks in advanced!

[capriccio]

Check the sprockets and find out how many teeth are there.

[choneofakind]

Tuck in further. Pull the snorkel; the main jet is rich. Go down a slight hill.

Don't worry so much about top speed, its a 250. Even jetted and with a full exhaust, I only got to 103 actual speed at mid Ohio, and I'm 135 and tucked in completely.

Edit: that straight is also a slight downhill, but who's keeping track?
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[Black Rabbit]

thanks guys, Im not worried about top speed, but i was pushing it one day and it only went to 80 just trying to make sure nothing is wrong. Im alot more happy doing 50 on back roads. How many teeth should the rear sprocket have?

[Alex]

Originally Posted by Black Rabbit

I have read in different forums that must people can easily get to 90 and can make their way to 105.!

Don't believe everything you read. All of the published tests of the new-gen 250 have the top speed listed between 92 and 95 mph. 105 mph is close to redline in 6th gear as a theoretical maximum, but most stock bikes don't have the hp to pull to redline in top. The speedometer variance can be large with this bike (and many motorcycles), so unless it is a GPS-verified speed, don't put too much stock in it being completely accurate.

That said, if your bike is stopped at a true 80 mph and won't go any faster on level ground with no wind, it does sound like it might be down a bit on power. Air filter, jetting, aligned rear wheel, lubed chain, wheel bearings, and riding position would all be things I'd look into to see how they might affect your performance.

[mrcrunch]

What rpm and what gear (6th i presume) when you hit this "80" top speed? That should let us know if your motor is under-performing.

[Black Rabbit]

thanks Alex

[Black Rabbit]

i usually shift up to 6th at around 70 mph

[csmith12]

Originally Posted by Black Rabbit

How many teeth should the rear sprocket have?

Stock gearing is 14front and 45rear.

[Black Rabbit]

45 rear, im guessing the front is stock as well but I cant see it

[Zola]

There can be enormous difference in the jetting when these roll off the assembly line. Our '08 has pulled red line in every gear since new. Never any hesitation off the line. No flat spots. A great runner from day one and a joy to ride. One of our two '11 250s would not rev above 10K in 6th and was hard pressed to pull a verifiable 80. The other was modestly better but the '08 ate both of their lunches until carburetor issues were sorted out.

When both '11s were properly jetted and mixture screws set, life became much better. Many riders here have done the work themselves at little expense with great results.

If you're not comfortable doing the work you may be able to find a ninjette.org member near you who is willing and able to help (many good folks on this site), or, if you have a reliable dealer near you - we've got a superb one; Hollinks Motorsports, Spencerport, NY - check them out for a written estimate.

[choneofakind]

Also, if you're going for top speed, try winding up 5th to about 12500. That should get you over the 80mph hump. Then shift to 6th (which should be in the power band at that point) and see how far it'll go.

I only say this because at 80, 5th will be higher in the power band than 6th. Even if going at it in a lower gear doesn't get you any speed over 80, it will at least get you to where it stops accelerating quicker so you aren't waiting so long.
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[Black Rabbit]

nice, ill start calling around tomorrow, to compare prices on a carb clean and maybe rejet. Thats the last easy thing I can think of

[xSean13]

Got mine to about 110 indicated (idk actual) coming down a mountain from north carolina today.

[pomartin]

with my 187lbs i got it to exacty 160km/h (100 mph) by speedometer.

and another thing... has EU different stock sprockets? cus i have 43 rear??

[choneofakind]

Originally Posted by Black Rabbit

nice, ill start calling around tomorrow, to compare prices on a carb clean and maybe rejet. Thats the last easy thing I can think of

I wouldn't worry about the carb cleaning as long as it's not exhibiting signs of needing cleaning. If you're going to rejet (which might do the trick) do some reading and give it a try for yourself. Its really not hard and having someone else do it is going to be expensive, especially considering that you're really only doing this because you can't get over 80 in 6th.

Pull your snorkel (this will get the main jet a little bit closer to right) Shim the needles to richen the midrange. Then go rip it through every gear and see how it pulls. You've seen my 0-60 thread; open it up all the way to 12500 or 13000 in every gear. Don't shift to 6th before you get to 80! Lol.

what elevation are you at?
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[Black Rabbit]

i have no clue on elevation lol, im in Lancaster Pa though. Ill check your 0-60, I have no clue how to pull the snorel or rejet but Ill do a little digging I rather do things myself if Im able thanks choneofakind

[Black Rabbit]

ahhh i see what you mean, after dong a little research I see that might do the trick. I'll probably give it a try next week

[choneofakind]

Let us know how that goes. I think you should be able to break 80 in 5th easy.

As for pulling the snorkel and shimming, there's a great DIY for each. Use the search bar and it should be pretty quick to find.

[LCR]

I've been to 100.5 GPS on the Nascar straight at Texas World Speedway

[dirty nasty]

Not sure what it was, but tonight I got my pre-gen to indicate 110 MPH. I'm 6'1" and 175lbs.

Check tire pressures, chain, wheel bearings, brakes for dragging, things rubbing the tire. If all that is okay take a look at the spark plugs. They'll tell you what you need to do with the jetting.

[Jiggles]

Originally Posted by dirty nasty

Not sure what it was, but tonight I got my pre-gen to indicate 110 MPH. I'm 6'1" and 175lbs.

Check tire pressures, chain, wheel bearings, brakes for dragging, things rubbing the tire. If all that is okay take a look at the spark plugs. They'll tell you what you need to do with the jetting.

My pregen has about a 15% error, it gets to 100 quite easily

[dirty nasty]

Mine's as accurate as a Cadillac's digital speedometer is. I have no idea how accurate that is either, but that's all I have to compare it to. That's all I've got and indicating 110 MPH. Take it with a grain of salt. It sure felt north of 100.

I will admit it was an ever so slight down-hill. It was also over 100 degrees that day, so maybe my tires gained some pressure which decreased rolling resistance. On a no wind, sunny summer day on completely flat ground I can get it to indicate 100 fairly easily. 105 if I decide to wait a minute or so and tuck in REALLY well.

[alex.s]

ignore the speedometer. the real test is- does it hit the revlimiter in 6th

[alex.s]

Originally Posted by choneofakind

Tuck in further. Pull the snorkel; the main jet is rich. Go down a slight hill.

Don't worry so much about top speed, its a 250. Even jetted and with a full exhaust, I only got to 103 actual speed at mid Ohio, and I'm 135 and tucked in completely.

Edit: that straight is also a slight downhill, but who's keeping track?
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i would be more apt to suggest its lean up top... rich bogs and jumps but lean just kinda sits there and doesnt go any further. it might be something simple like a dirty main

[dirty nasty]

I agree with alex. My pre-gen is 100% bone stock (no modifications WHATSOEVER to the bike) and it runs lean from the factory. I'm not sure how the new-gen is, but I can only imagine it could need richening up. Even with the stock intake and exhaust on my bike I'm considering going up a size on the main. My plugs look a bit too white for my liking after a high speed ride with lots of WFO action.

[choneofakind]

Originally Posted by alex.s

ignore the speedometer. the real test is- does it hit the revlimiter in 6th

dude, mine came so close at Mid-Ohio. Just a little past 13,500 in 6th and then I ran out of space.

Originally Posted by dirty nasty

I agree with alex. My pre-gen is 100% bone stock (no modifications WHATSOEVER to the bike) and it runs lean from the factory. I'm not sure how the new-gen is, but I can only imagine it could need richening up. Even with the stock intake and exhaust on my bike I'm considering going up a size on the main. My plugs look a bit too white for my liking after a high speed ride with lots of WFO action.

The only time a plug check is valid is if you keep it at the rpm that you want, and then hit the kill switch and check it right then and there. No joke, if you want to plug check to test the main jet, you want to literally go WFO, hit the kill switch, and pull off and check the plugs.

The main jets are the only part of the jetting that Kawasaki got right on the pregen. The needles need a washer and the mix screws need to be tuned.

[dirty nasty]

Originally Posted by choneofakind

The only time a plug check is valid is if you keep it at the rpm that you want, and then hit the kill switch and check it right then and there. No joke, if you want to plug check to test the main jet, you want to literally go WFO, hit the kill switch, and pull off and check the plugs.

The main jets are the only part of the jetting that Kawasaki got right on the pregen. The needles need a washer and the mix screws need to be tuned.

I learn something new every day! Thanks!

[alex.s]

if the main jet is just a little bit dirty it will seem like its just the wrong size and act lean. topping out at 80 just isnt right, either the sprockets are setup for cruising or his main line is running lean... or maybe the brakes are dragging. you might put it up on stands and verify the wheels spin freely

[Motofool]

Originally Posted by Black Rabbit

So i bought my 08 250 about a month ago and I love it, I ride it everywhere! But theres one issue my top speed seems very low. ..........

Why messing with the jets and other sophisticated performance enhancements before performing a valve adjustment and all the other services that each new owner should do, improving the current marginal performance up to factory specs?

80 mph as top speed means engine is unable to develop standard HP's.

[alex.s]

yeah thats a good point. how many miles does the engine even have on it?

[dirty nasty]

This reminds me my 6000 mile service is coming up soon. I've been wringing the piss out of my engine. I've got 5200 on it now and these last two days it has seemed a bit crankier at start up. Valve adjustment time!

[choneofakind]

Good point on the valves.

Even if the sprockets are really tall, downshifting would work. A cleaning might be in order though. I guess I ruled that out just based on the fact that it doesn't seem to have been sitting.
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[Black Rabbit]

Originally Posted by Motofool

Why messing with the jets and other sophisticated performance enhancements before performing a valve adjustment and all the other services that each new owner should do, improving the current marginal performance up to factory specs?

80 mph as top speed means engine is unable to develop standard HP's.

Funny that you mention that, I just went to a mechanic and he suggested the same! I have about 10,000 miles on her. Soon as I get the dough, Im getting the valves adjusted back to factory spec. Hopefully that will get her running like she should. Thanks Motofool!

[Motofool]

You are welcome!
I hope that adjustment will make your baby fly at 100 mph!!

[choneofakind]

Careful, warp speed comes soon after 100!

Black Rabbit, have you looked into adjusting the valves yourself? There's plenty of writeups and info here about that. Idk how mechanically inclined/comfortable you are with the idea of cracking open the valve cover and doing some work yourself, but it will save you about $300ish
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[Black Rabbit]

Originally Posted by choneofakind

Careful, warp speed comes soon after 100!

Black Rabbit, have you looked into adjusting the valves yourself? There's plenty of writeups and info here about that. Idk how mechanically inclined/comfortable you are with the idea of cracking open the valve cover and doing some work yourself, but it will save you about $300ish
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ill look into it, it just sounded complicated lol. I usually do all my own maintenance though

[bdavison]

Something's not right if its only getting to 80mph indicated. On mine, at 90mph indicated, it is still trying to accelerate albeit at a slower pace. Mine has 20,000 miles on it. I'm 6'3" and 185lbs.

Did you break it in using Kawasaki's flawed "don't go over 40mph" thing or did you vary the speeds when you broke it in. I'm still of the opinion that following that 40mph limit that Kawasaki recommends ruins the bikes true potential by never really breaking in the engine.

The other question is how big are you? If you are big in stature, and wearing loose clothing that acts like a parachute, this might be a reason you are unable to get it to go faster. I'd check simple things like working on your aerodynamics before diving head first into the mechanicals.

[Black Rabbit]

Originally Posted by bdavison

Something's not right if its only getting to 80mph indicated. On mine, at 90mph indicated, it is still trying to accelerate albeit at a slower pace. Mine has 20,000 miles on it. I'm 6'3" and 185lbs.

Did you break it in using Kawasaki's flawed "don't go over 40mph" thing or did you vary the speeds when you broke it in. I'm still of the opinion that following that 40mph limit that Kawasaki recommends ruins the bikes true potential by never really breaking in the engine.

The other question is how big are you? If you are big in stature, and wearing loose clothing that acts like a parachute, this might be a reason you are unable to get it to go faster. I'd check simple things like working on your aerodynamics before diving head first into the mechanicals.

I bought it used so I have no idea if the proper break in procedure was followed. I weigh 145 and I dont wear loose clothing

[choneofakind]

I've never done a newgen valve adjustment, but I've had my cams off for head work and as long as you know how to get the cams timed right (they're marked, its nearly fool-proof) it isn't bad. Is there someone with a 250 near you who needs to do their valves? go help them to learn how it goes.
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