Top Speed?

[YZ-Rider]

I have a 2001 YZ-280 (250 bored by 30), it has a Pro Circuit exhuast, aftermarket rev box(can't think of brand), and the sprocket has around 56 teeth. Sorry no photo, I haven't had a chance to take one. I was wondering what my top speed was because I have a V-Force3 high performance reed valve system I have yet to install and I wanted to know the before and after top speeds to see the improvement.

[Xolotl]

Nobody could ever give you an accurate enough top speed between the two for you to be able to tell the difference. I'll say that with or without the reeds, the top speed is plenty fine. My trailtech read my YZ250 at 81 mph...

[YZBrad]

Its not going to be very fast at all with a 56 tooth rear sprocket. Thats the biggest ive ever heard of.

[LostTrail]

If you're into top speed, gear it at 14/48. It seems that you're intentions were to make the bike a rocket that can rip your arms off, because you bored it over that much and changed the gearing to better suit insanity.

[YZ-Rider]

It's around 56, in the 50's anyway, 52, 54, somewhere in that area, I don't remember what exactly it is. I didn't think it would make a difference in top speed much, but I still wanted to see what you guys thought. Any chance someone could give me a top speed guess?

[kx_rider53]

Im not sure about the speed but gearing plays a big role in top speed.

[The Spanky]

A 56 tooth rear sprocket would never clear the chain guide. I highly doubt that's what you have on it.

[YZ-Rider]

I highly doubt thats what I have on it as well, which is why I stated twice that it was around 56 and not exactly 56. I attempted to count them and I lost count around 50 so I estimated it was around 56, as in 51, 52, 53, 54, or maybe 55, but not 56. It does not have a 56 teeth sprocket. It is near 56, such as 52 or 54.

[kx_rider53]

Shouldnt it say it on the sprocket?

[KillerHiller]

Shouldnt it say it on the sprocket?

Let's just say you'll be lucky to hit 70 if you have a 52 and it's probably more like 60mph... or less if you have a 54 or 56.

What is your front sprocket? The rear tells you how many teeth it is right on it. Go get a marker and color in one tooth. Start counting and we will be here.

The YZ280 sounds like a cool bike, and it sounds like you have it geared to low, unless your doing observed trials with it.

KH

[sniperd]

You realize that it being bored .030 over does not make it 30cc's over right?

The reeds arent going to give you a better top speed, You would need more gearing, OR MORE RPM's to go at a higher top speed. I dont think the reeds will give you any significant rpm's to result in a more then 1-2mph difference at most.

[MMTroop]

Well, this is mostly an estimate, but i watched a show on ryan capes setting the world record distance jump on a cr250, with gearing changes and a different pipe. and that bike hits 90...they had a speedometer like u see on the highway in construction areas. so i say a stock 250 2 stroke goes about 85 or so. i dont know if that helps or not.

[YZ-Rider]

Thanks for all the tips and help guys; I just got this about 2 weeks ago with all this already installed. I am 15 years old and my dad and some other people do all the work on it so I really could not be more of a tard right now. I went from a TTR-125 to a YZ-250 and I really to not have the space to top out so I just wanted to know what you might think it was so I could tell my friends that when they ask. Sorry if my post was a little hard to understand but it was like 3 in the morning when I posted this topic. I was not for sure what the reed valve thing did but everyone said it would make it go faster so I thought that’s what it did. Sorry to waste your time and I know a lot of you tried to give me advice and I thank you for that. As for the 280 thing, My dad said it was bored over by 30, and since every time I've heard of someone boring something over, they add what the bored it by to the size, such as my friend has my old 125 and he wants to bore it by 25, so it would be a 150, I thought it was the same for idea for me, so no I did not realize it being bored .030 over does not make it 30cc's over. I did not think to look on the sprocket for the teeth amount and as for the front I have not checked so I do not know, sorry to give very hazy information but it’s all I know. ?

[mxrider14]

I highly doubt thats what I have on it as well, which is why I stated twice that it was around 56 and not exactly 56. I attempted to count them and I lost count around 50 so I estimated it was around 56, as in 51, 52, 53, 54, or maybe 55, but not 56. It does not have a 56 teeth sprocket. It is near 56, such as 52 or 54.

Not to sound rude or anything... but 51-56 is a huge difference... if you want a "guess" you need to be more specific. Thats like saying how fast will this streetbike go? Its around 600cc.... you know, 250, 400, 600, 750, 1000cc, somewhere in there ?

[YZ-Rider]

Not to sound rude or anything... but 51-56 is a huge difference... if you want a "guess" you need to be more specific. Thats like saying how fast will this streetbike go? Its around 600cc.... you know, 250, 400, 600, 750, 1000cc, somewhere in there

I know, like I said, sorry for the horrible information.

?

[KillerHiller]

Don't worry! Being 15 and owning a YZ250 is pretty cool.

You have to learn about things like gearing somewhere, and that's why Thumper Talk is here.

We all ask the occasional question that's a little off. No big deal.

KH