Dirt bike engines in GP bikes?

Believe it...I said so

 

Fascinating thread!
I did a somehow similar project with Derbi GPR chassis with a CR80 engine, some fabrication was necessary, it turned an otherwise weak 50cc into a nice little funny toy, it's the best fit for a karting track which is the only track we have available for now in my corner of the woods. It's quite a fit to race 1000cc in a karting track

 

Neat thread.Isn't this where we all start?I'm looking for an engine for an rs250 frame.Banshee is the only thing.Didn't come on to say that though.+3 to the bullshit about the Hawk/Kawi KX500 bike.I know it isn't making 79hp and I REALLY know it ain't 218 lbs.If he poured a ton of money into making the Hawk chassis lighter?MAYBE 260.How do I know?Because my Hawk weighs 318/w 89 hp.And every part has been lightened,replaced or re-engineered.Hawk engine weighs about 130-soo if a KX engine weighs 60 lbs-he'd be around 260.Just sayin.

 

You know or speculating?

 

Pardon the poor choice of words.In my experience i've never seen a single 500 cc 2 stroke make that much power.Here's the best dyno run my engine ever did.Running on jetfuel And the money shot on the scale.If you make claims ,be prepared if someone cries foul.

 

That's one bad ass Hawk.

 

Just because you have not seen it, doesn't make it so. As far as the dyno graph, I do not see anything that says it belongs to a Hawk, but I don't doubt you.

 

What the heck did you do to that Hawk???

 

You have a bike that runs on jet fuel? Do tell how you have accomplished this. I would love to build myself a true diesel buring bike but have yet to see one. Perhaps I could use a similar setup to the one you have using jet fuel.

 

The letters on the can were MD12 or something like that.Hord referred to it as Jetfuel.On 87 octane unleaded it only pulled 84.5. Racegas makes a difference. Falicon Billet crank/Ti cariilos/big valves/Stage 3 heads/Titaninum valve train........the works.Making it light took alot of time and aluminum,a CNCmill and a good lathe.I grew up racing MX in the 60'&70- two stroke singles a specialty.You may get a 500 cc single to hit 80 hp,for a couple of minutes ,before it grenades.For comparison-a Maico/ATk 690 makes 78 hp stock.There's no way to get that 190cc of power out of a 500.And then roadrace it?????KABOOM.

 

stock 1994 kx500 from the showroom floor on to schenck eddy current made 60 hp (crank). Independent research dyno, engine was being considered for a drone aircraft.

With high enough compression to warrant 110+ octane and a pipe and porting for top end hp, I dont think its an unrealistic power number at the crank.

Astonished at the weight number though. My stripped rd was 281 when I was running points and a small 5.5ah constant loss battery. Granted the buffalo quad leader does not help here.

 

If I thought I could get 70 reliable HP out of a 500 i'd use one.Even though they shake like hell.No trick to rubbermount it.A 485cc banshee can go 110hp or so?That would make an interesting power/weight ratio.250 lbs/110hp?Almost 250 gp spec.I've seen 4 Hawk hybrids with 500 engines. 3 cr500/1 kx500-I know of one guy who races one now.His is the only succesful one I've seen.The problem with them is vibration and proper gearing.I considered a KTM 300-360 into a 125 weight frame-that would be fun.I have several Hawks and engines,total loss on this bike(remove gen/starter/etc)will bring it down to about 290.Close,but no cigar.Gotta build that banshee.......No expense was spared in lightening-New brakes,rotors/wheels/custom everything-I make our own parts and took plenty of time.

 

Like I said....
And I suppose 60hp from a 250 single isn't possible either!

 

Yeah,no sense argueing opinions!Peace ,out.

 

Next thing you know you'll be trying to say you can get 40HP out of a 125...

 

You can get a KTM 300 up to about 55!That much I DO know(RWHP that is..).Measured at the crank......

 

KTM

I built a '89 KTM 500 with '08 SMR suspension for road racing. Not quite all done yet but I have done some test rides. Mine weighs in at about 210# and stock they have about 65HP see here: http://www.ktm495.mxbikes.com/identify.htm

My guess with a FMF pipe, Mikuni carb (reblacing the Bing) and modern reeds 70HP is doable, maybe a tad more. When I finish up I'll put out the #'s. It certainly "feels" like it's at least that much not that counts for anything. It truly is a handfull. Build pics here: http://s719.photobucket.com/albums/ww197/DBR0051/KTM 500 Supermoto/

Thanks, Dave
WERA #462

 

KTM

Just a thought. I have a RZ350 and they have that kind of power. This KTM, again "feels" a good bit faster than that, actually a ton faster. JMHO.





Dave

 

Not yet, but as soon as I install the "new reed" and get 15% more power!!!

 

Keep talking guys, I'm putting together our killer 2012 motor and looking for all the tech tips I can get. New Reed, you say???