RM-Z 250 Horsepower

How much horsepower does the RMZ 250 have???

About the 32-34 hp range

do you mean out of the motor or at the rear wheel?

your title should say. mine says 34.5 hp

99.9% of the time when someone asks the hp output of a motorcycle its real wheel hp they are referring to.

99.9% of the time when you see actual dyno results of a motorcycle its rear wheel hp.

99.9% of the time when you see advertised hp of a new motorcycle its exaggerated by 10% or more.

When you read 34.5 on your title or in a magazine its a lie.

We have dynoed a RMZ250 so many times I lost count. I lost count in late 2003.

2004 RMZ250 29.5- 31 rwhp depending if u got a good one or not

2005 RMZ250 29.5- 31.5 rwhp depending if you got a good one or not

I have never ever seen a stock RMZ250 have over 31.5rwhp

RMZ250 with pipe and tweaked to the max. = 33-34.5rwhp

RMZ250 big bore and pipe( no other mods) = 36- 37 rwhp

RMZ250 big bore/pipe/cams = 37.5- 39 rwhp (depending on whether they were smoking out when they pressed the cam gear on or not)

RMZ250 port work by knowledgeable builder w/pipe = 35.5 - 37rwhp

RMZ250 port work/pipe/cams = 38-39 rwhp

RMZ250 big bore/port work/pipe/ waving the magic wand = 38.5-39.5 rwhp

RMZ250 big bore/port work/pipe/cams waving the magic wand= 39- 40 rwhp

RMZ250 big bore/stroker/port work/pipe/ no cams/waving the magic wand= 40-41.5rwhp

RMZ250 big bore/stroker/port work/cams/waving the magic wand= 40.5-41.5rwhp maybe 42 if you ran it on a Tuesday

RMZ250 big bore/stroker/port work/welded and reworked exhaust port/ pipe/ carb mods/ignition/ cams/welded and polished crank/ polished rod/ rem polsihed tranny (everything)/ceramic tranny and crank bearings/ ceramic wheel bearings/ceramic coated head,valves,exhaust port,piston, head pipe/ taking a screwdriver and prying the brake pads away from the rotor/ oxygenated fuel/leaned to the point of destruction/ adjusted ignition timing you got sick/ waved the magic wand/ said a prayer = 42.5-43.5 rwhp

No matter what hp your RMZ250 makes cold it looses between 1 and 2 rwhp when the oil temps gets above 250f.

No matter what hp your RMZ250 makes cold it looses between 2 and 3 rwhp when oil temps get above 300f.

The major variable in all the above dyno runs is whether we were drinking vodka or not.

I am a much bigger fan of getting head work done and your bike massaged by a knowledgeable builder than just making it big bore or even adding cams..

I would save the cylinder for boring after you crash it. Its very likely that at some point you will either drop a valve or something that and ruin the cylinder. Then you can bore it.

Cams most of the time make good power. Some cams make the bike crank easier. I would do the port work before adding the cams or at least at the same time. Cams always work much better with a good head work.

so speaking of power, how does an RM-Z 250 compare to the other 250 four strokes?

The yzf and rmz are about the same in stock form. The CRF is a little down on power in the stock form. The 06 KXF makes a little more power.

The KTM definatly makes more power in stock form.

Modded out it all depends on who you have do the mods. The right engine builder can make any of the 250 4 strokes rip.

I am a much bigger fan of having a knowledgeable "hands on" engine builder do the work rather than some of the big name mass production engine houses.

The KXF comment was a joke guys.

I thought someone would catch it.

Great post RC.... I'm not to knowledgable about these RMZ's and was just wondering what is the safest route to go with engine tune ups with the RMZ's ? how much stress do these little motors handle ? what would be the best balance in terms of power and reliability ?

i.e hotcam worthwhile ? and porting ?.... high comp piston ? do the RM's live as close to the reliability edge as the CRF250's ?

my application would be enduro/cross country... so i'd like so low end snap... whilst maintaining some reliability... or am I a fool for going this route on one of these bikes ?

a great deal on a near new one has come up and I really don't know didely about them... I'd like to get the yz250f as i'm alot more familiar.. but i'd like to try something smaller and more nimble handling wise.... and something that doesn't have WP suspension :thumbsup:

thanks for any help

If I was going to mod out a RMZ250 and keep it the most reliable as possible I would have the head ported by a knowledgeable engine builder. Also add a pipe and get it tuned by the same builder.

Proper head work a will match hp with a big bore cylinder. HP delivery characteristics will be slightly different. I would also heep the compression close to stock.

Many times even on our practice bikes we will zero deck the cylinder also. Mainly to get the squish out of the bore. This also adds a small amout of compression. Depending on how much you have to cut the cylinder base.

With this set up you can run pump fuel and still makes lots of power.

thanks for that RC... had a feeling you might have said concentrate on the porting. Why do you say pipe though ? is it to get something a bit more free flowing ? with the application of the bike I'd be very conscious of noise wanting to keep it to 94-95Db or lower... so i don't think i could have anything more free flowing.

The RMZ head pipe is a good peice. Its hard to find one that makes more all around power. Thats unless you are looking for a head pipe that has specific power characteristics.

If you are trying to make power you will need to have atleast a canister. I havent seen one aftermarket canister that doesnt make power. With porting alone you cant expect gobs of power.

The stock canister isnt desireable in any type of riding.

With porting and an exhaust this model makes good useable power. if the noise bothers you purchase ear plugs.

i think he was referring to the noise others around him will experience. Many people are under the assumption that louder= more power this is NOT true. Just because you buy a more free flowing exhaust doesn't mean your bike has to get louder.

yeah I'm affraid TNT is right... i don't mind having a nice loud exhaust.. it's more the people that are rallying against our government down here to have all our thousands of sqaure miles of forest closed down to us due mainly to noise. I'd like to buy them all earplugs.. but i'm not sure if they'd wear them :thumbsup:

surely you can create great power without creating a loud exhaust note ? i'd have to say that even the FIM 96Db standard it too loud for use in public area's (judging by the public's feedback).

did you guys see the dirt rider article on exhaust noise?? some of those fag's want to get it down to 60 decibels or so, that's like a human convo!!! they make more noise than that snoring

Actually I spent most pf the previous moth performing sound level testing on a stainless steel muffler I designed for the airboat industry.

During testsing I noticed witht he sound level meter only 5 feet away a loud conversation in our shop can be in the 80db range.

you just need to make one for the RMZ then :thumbsup:

I'm sure we won't have this problem when we're riding electric bikes :thumbsup:

the day we ride electric bikes is the day i quit motocross period.....

that's like a human convo!!! they make more noise than that snoring

They should baffle greenies snoring to 20 db. That way the suffocate and die :thumbsup:

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