Top Speed Help!!!!

[ilovejesus]

I just went on a high speed run and I topped out at only 93 mph!!!! Why so low?

[choneofakind]

...because it's a 250 pushing about 26 hp stock. Wind resistance is hard to fight when you're on a bike with a small engine.

[ilovejesus]

I'm only 5'7 130lbs. I've seen others stock going 100 and they are like 6ft+ 200lbs+

[choneofakind]

I'm 5'10" and 135. I topped out at 102 at Mid-Ohio. I had a full exhaust and modified intake at the time.

Check your jetting if you want to, the stock mains tend to be a little rich.

But I wouldn't worry about it as long as the bike responds well and is reliable.

[Alex]

/merged with similar "low top speed?" thread

[Jiggles]

You will never be able to legally ride on those 95mph highways until you invest in a sexy Area P full system

[ilovejesus]

What's the max you guys gave gotten?

[Jiggles]

I was reading a thread earlier where the guy claimed he got to 115mph. Not to be outdone I tried to beat him and was able to attain 117mph

[gallardo73]

dear friends

I have a 2012 ninja 250 and i just change the oem muffler for the two bros m2 carbon fiber slip on.I did not fuel remapped or dyno.
Well my problem is that my bike does not go over 92 mph at all no matter how hard i push the rpm on 5th gear and then shift to 6th i would not go over 92mph at all,my clutch is fine so I do not know what to do...
thanks for your help

[dirty nasty]

You need to re-jet. You've changed the amount of air flowing into/out of the engine. Your carburetor's factory jetting is not set for having more air flow out of the engine. These bikes come lean (not enough fuel, too much air) from the factory to keep the EPA happy. Adding a aftermarket slip-on that flows more air leaned it out even more. You can't go as fast as you used to because your bike isn't getting the amount of fuel needed to feed it. Running too lean can result in detonation (the popping noise you hear on decel) and if it's really severe can damage your engine.

You need to richen your air/fuel mixture up (add fuel, take away air) when doing any intake or exhaust modifications. This is done by swapping main jets, shimming your needles, sync'ing your carbs and setting your mixture screws. This should restore your power, possibly with a bit more due to the slip-on (but not much on these bikes, you probably won't notice), and slightly increased fuel consumption (again, not like it matters on these bikes). Effectively, all you're doing by using a slip-on is making more noise.

[gallardo73]

hey karl thanks!! now let me bother you a little more lol
what kind of jet kit will you recommend for my bike and the two bros slip on exhaust that i have??? I heard about dynojet and factory pro but again i do not know..thanks again!!

[Motofool]

Originally Posted by gallardo73

.......but again i do not know..

It is not too late: replace the original mufflers

[dirty nasty]

Originally Posted by Motofool

It is not too late: replace the original mufflers

This is the point I was trying to make.

Sorry to burst your bubble, but setting fire to your cash is a better idea than a slip-on. At least spring for the full system. Even then the gains will be minimal on a street ridden 250, even with a full system. About the only time I'd say an aftermarket pipe makes sense is on the track where every bit counts for our 250s. Re-jetting can be a huge PITA, especially for someone with little or no understanding of how to do it. I'm not claiming to know how, because I really don't. I've always kept my motorcycle engines as they were from the factory. I had one MX bike with a modified engine and it when the planets aligned it ran like a bat out of hell. Problem is the planets very rarely aligned. Your bike's engine will perform at its best the way Kawasaki designed it to. Those little Japanese engineers tinkering away in their offices know a lot more about how to make reliable, economical, efficient power than some parts builder who didn't design the bike. I'd look into tire, brake or suspension upgrades instead.

If you want to follow through with this idea I'd go DynoJet for absolutely no reason other than they're what my mom's boyfriend used on his FZR when he added a pipe and K&N filter.

[Alex]

What top speeds were you seeing before you put the noisemaker on?

[gallardo73]

i dont remember exactly. I purchased the bike on february and i put the slip on few months after.I believe it was 110mph or something like that.
If the solution for getting that speed back is putting back the oem muffler i guess i will do it...

[Jiggles]

Originally Posted by gallardo73

i dont remember exactly. I purchased the bike on february and i put the slip on few months after.I believe it was 110mph or something like that.
If the solution for getting that speed back is putting back the oem muffler i guess i will do it...

110 lol

And lets be honest here, the very minimal change in air flow that a slip on causes is not going to affect the bike THAT much

[choneofakind]

Originally Posted by Motofool

It is not too late: replace the original mufflers

[gallardo73]

I am not an expert rider just looking for some help and wisdom from you guys
any help is much appreciated....

[gallardo73]

well you know what jiggles? I just found an oem muffler for my bike on ebay
and i am getting it hopefully i can get the bike to go at least 110 mph what do you think?

[xSean13]

Originally Posted by Jiggles

110 lol

And lets be honest here, the very minimal change in air flow that a slip on causes is not going to affect the bike THAT much

Don't hate. Got mine to 110 indicated. Last time I checked it vs. the speed app on my phone, the bike speedo was 5mph fast.

Granted, I was coming down a mountain.

[Jiggles]

Originally Posted by gallardo73

well you know what jiggles? I just found an oem muffler for my bike on ebay
and i am getting it hopefully i can get the bike to go at least 110 mph what do you think?

If you get it to 110 that means you have at minimum a 10% speedo error. How much are you paying for the oem muffler? Hopefully not more than $40

I hope you are not buying it from this guy

[Jiggles]

Originally Posted by xSean13

Don't hate. Got mine to 110 indicated. Last time I checked it vs. the speed app on my phone, the bike speedo was 5mph fast.

Granted, I was coming down a mountain.

All these damn cheaters boosting their numbers with gravity! Damn cheaters

[gallardo73]

Hahahahahaha good link jiggles!!!!

[mikecronis]

Got to a shy over 110 indicated, but I suspect that's optimistic. Probably more like just at "the ton" of 100 mph with a slight downhill gradient. I was 1k from redline but she had no more guts. Bike is modded typically with an '08 except for the exhaust (stock). GPS shows 9% optimistic after I changed the front sprocket to a 15-tooth for more relaxed 80mph cruising. This tends to be typical with the 3 Ninja 250r bikes I've owned since 2002. I put a Muzzy on my 2002 and in North Dakota was able to get to 113 indicated with a rejetting, but again, it might really have been 102 mph.

If you're only getting 80mph indicated by GPS, you might be running too thick an oil (I lost 8 mph top-speed switching to 20W-50 and I encourage anyone to switch-out oils and do a top-speed-run like I did immediately afterwards). Use as thin an oil as you dare like 5W-40. Use a point or two over the suggested manual's octane rating. Make sure your carbs are cleaned and synched at a shop (unless you're a carb-master-expert like eHal). Make sure your tires are properly inflated. Getting a lighter chain also helps.

[Somchai]

@Jiggles - +1

The day before yesterday i found a road with very less traffic and so i could go as quick as possible, until i had to slow down again because of many traffic coming up again.
My speed read at my Koso RX2 was 157 km/h, what is 97.5 miles, at 11900 rpm in the sixth gear with the oem sprockets 14/43 (my Koso-meter I'd set up with gps). I think 12500 rpm should be possible but then to get more i think i need to run downhill.
The power of my bike i think could be around 40 hp with all the changes what is Leovince full-system exhaust with Leovince Fast-Fuelsystem (this two changes makes 5-6 hp more, see the dyno from Leovince) and ignition advanced by 5 degree. I'm using Motul 300V and running my injection-setup really rich.
So i think to go faster there's the need to change the sprockets.

[Jiggles]

Originally Posted by Somchai

@Jiggles - +1

The day before yesterday i found a road with very less traffic and so i could go as quick as possible, until i had to slow down again because of many traffic coming up again.
My speed read at my Koso RX2 was 157 km/h, what is 97.5 miles, at 11900 rpm in the sixth gear with the oem sprockets 14/43 and confirmed by gps. I think 12500 rpm should be possible but then to get more i think i need to run downhill.
The power of my bike i think could be around 40 hp with all the changes what is Leovince full-system exhaust with Leovince Fast-Fuelsystem (this two changes makes 5-6 hp more, see the dyno from Leovince) and ignition advanced by 5 degree. I'm using Motul 300V and running my injection-setup really rich.
So i think to go faster there's the need to change the sprockets.

Your a bit off with the hp figures, the most hp you will ever crank out of a stock 250 is around 32hp. That is with a top of the line exhaust and modified intake. Have you rejetted your carbs? If not your probably around 26hp, if you have jetted your likely near 29-30hp

[Somchai]

@Jiggles - -2

[Jiggles]

Ok mr my 250 makes 40 hp

[choneofakind]

Dude, those are obviously weak non-american horses. Your bike makes like 33 max, even with a Leo full system and a proper fuel map.