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DirtBikeManiac24

Highest horsepower yz250

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I have a friend that has an 06 yz250, he wants to know whats the highest amount of horsepower you can get out of the bike if you port and polish, big bore, powervalve mods, or anything else you can do to it?

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yes, anyone there? what would be the highest hp gain by a 250cc 2-stroke assuming all necessary mods? will it be at par or above a 450cc 4-stroke? how bout for a 125cc 2-stroke?

what are the necessary mods?

thanks.

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The 03 KTM was 50hp off the showroom. CR500 is about 62hp I think. I think a stocker 06 YZ250 is 47HP, but not sure.

Shooting from the hip, I'm gonna say 53-55hp. That would be a little over a 10% gain. The YZ125, maybe 38-40hp.

Diclaimer-The above info is seat of the pants and not deemed reliable. Actual horse power may vary. Please consult your Yamaha dealer for actual performance specifications. Always wear protective riding gear. Not intended for highway use.

KH

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The 03 KTM was 50hp off the showroom. CR500 is about 62hp I think. I think a stocker 06 YZ250 is 47HP, but not sure.

Shooting from the hip, I'm gonna say 53-55hp. That would be a little over a 10% gain. The YZ125, maybe 38-40hp.

Diclaimer-The above info is seat of the pants and not deemed reliable. Actual horse power may vary. Please consult your Yamaha dealer for actual performance specifications. Always wear protective riding gear. Not intended for highway use.

KH

that 50 hp coming from a stock SX250 should be more than that...same as with the YZ250 stock engine at 51 hp.

a stock CR500 is 68 hp at 8000 rpm.

that 38-40 hp from a YZ125 is peak horsepower from the stock engine.

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Diclaimer-The above info is seat of the pants and not deemed reliable. Actual horse power may vary. Please consult your Yamaha dealer for actual performance specifications. Always wear protective riding gear. Not intended for highway use.

KH

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The 03 KTM was 50hp off the showroom. CR500 is about 62hp I think. I think a stocker 06 YZ250 is 47HP, but not sure.

Shooting from the hip, I'm gonna say 53-55hp. That would be a little over a 10% gain. The YZ125, maybe 38-40hp.

Diclaimer-The above info is seat of the pants and not deemed reliable. Actual horse power may vary. Please consult your Yamaha dealer for actual performance specifications. Always wear protective riding gear. Not intended for highway use.

KH

KH's info is right on the money. The CR500's and KX 500's were anywhere from 54-56 in stock form. The current yz 250 is in the neighborhood of 46-47.

55 is probably somewhere near the max for a fully modded 250.

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yep...the stock YZ250 is just a hair shy of 47 hp. But 47 usable ponies beats the heck out of 55 unusable...... :mad:

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I still think my favorite "55" hp was in the Honda CR 500. You did not especially feel the hp. It was always there. The torque was a different story. You could click the bike into 3rd and idle around most any mx track. You only needed 4th for high speed.

I wish Yamaha would have made a decent open class bike unstead of making all of us hate them for the yz 490.

How bad was the yz 490? Mine was an 1982....a "J" model.

I walked out on the salesman selling me my 97 yz 250 because it was a "J1" model. I felt like it was a bad omen. The salesman had to knock off another 200.00 at that point before I would buy the bike. Here is what that steaming turd of a bike looked like. http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=180041250440&ssPageName=ADME:B:WNA:MT:12

Also notice the rear suspension. The shock and linkage weighed more than a pw 80.

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I owned an 88 and raced Open B MX class back when everyone had to have a Five. I bought it new. It was my trail bike too. What a beast!

True to the word 5th gear wheelies without pulling up on the bars.

KH

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I'm not really sure but I know that 125 shifter karts make around 44-45 hp. That would be totally unrideable for a dirtbike though. I would imagine a 250 could make 60-65hp at very high rpm.

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Hey guys this seems like the perfect thread to ask....How much HP does a 79' yz400f have? Not just dreaming, I have one and was just wondering how it compares to the new stuff.

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I remember them being listed in the 38 hp area. Air cooled and mildly tuned. A great bike. They were not able to really step on 2 strokes for max power until water cooling. The 78 yz 400 would be quite trail bike like in its power output vs today....

However, 98% of us woudl be better off with the engine. Very torquey and fun to ride.........but no, the bastards had to "upgrade" that great bike into the pos yz 490.

The YZ 400 was far mor effective in all ways .

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would a fmf fatty pipe increase hp on a yz250? or is it just more tourque?

I have a factory fatty, not the regular plated fatty. I do hear they are almost identical in performance. The answer to your question is not terribly easy.

Go back to 99 when Yamaha brought this new engine to market. It was pulling only 42-43 hp. Todays 06 yz 250 is around 46-47. Where did the extra power come from? More radical porting, higher compression, and a more advanced carb.....just like we do to our bikes. Nothing magic.

I thin you could add a fatty to an older bike and possibly get some gains. I found none on my 06 using it. It did gain massive pinging, however. It pinged enough that it would have to be adressed. Full on race gas helped.

If we were tuning our bikes for high power on a dyno only, I would pick the pro circuit pipe. It would show higher numbers on a dyno, for sure. At peak. Low end would suffer.

The fatty felt like a stock replacement pipe after the engineers had started drinking and using drugs. They woudl have designed the stock yz ppe after they cleaned up and left rehab.

Obviously, this is my opinion. I believe the engineers got clean and sober early in the yz design department. They only designed the oil check hole on the bike while under the influence.

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The 2001 was a great engine...a great engine. Compared to our 06's, your 2001 has less low end, but much more top. This was one of my all time favorite yz engines. The flywheel on this model is also quite light.

I would try to find a DEP pipe for it. You would probably like it.

Better yet, just ride it for 90 days. At the end of that time you will have a good idea what you would lke to change......notice I said CHANGE.

You will play hell trying to improve it.

If you want more low end, buy the intake spacer from a 2003 and up yz 250. It costs about 10 bucks. It will cost you top end, however.

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u wouldnt happen to know the hp on my bike would u? with a fmf fatty

i'd be interested...how much more hp gain? is the gain spread entirely within the rpm range, mate?

is the fatty applicable also to smaller YZ bikes like the 125cc? how about the SST?

thanks for any info...

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Hell no its got stacks of bottom end power for me =D if anything i want more topend :mad:

Seeing ive just sold my 01 yz125 and just bought a 01 yz250

IM LOVING IT!!!!!

every gear im on rear wheel hehe

i just need a new muffler been lookin at fmf powercore2

It would be a guess. We would have to asume the top end is in good condition and its jetted properly.

In theory you would be around 45-47 hp. Obviously worn parts could change this dramatically.

I was not trying to say your bike was weak in the low end. Its just not putting out the low end of an 06. You can tune it to do so, but you'll give up top end...just as the stock 06 did.

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yeh my bike was running sick in powerband but i fixed that because the guy that had it last repacked it with fly wire door material and old burnt packing with no inner metal tube thing! So it was hard for the engine to get rid of the smoke at high rpm! I took all the packing out and put mnuffler back on with no packing :mad:

AND BOY i shat myself :mad: sooooo louad!

Please, if there is a god, please study the meanings of certain terms.

"Running sick in the powerband makes little sence"

Getting rid of the smoke makes slightly more, but dammed little.

Any of us will happily help you with ANYTHING you so desire and have a good time doing so, but please, try to give us somehtign to work with.

Its also quite offensive to ask about low end power, then become pissed when someone gives you a real answer.

Your always welcome here, but please give us something to work with.

Thanks and welcome to TT.

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That is a great start! Thank You!

Unless the silencer is plugged, thats not going to make a huge difference.

What jets do you have in your carb. Mu gut feeling is that you have a jetting issue.

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