500 cc 2-stroke Honda CR500AF

[shimaze]

You all like chainsaws ...2-stroke power? This is a 2005 CR500AF. It is 500cc of pure 2-stroke power rated at 60HP. It is an absolute beast, crazy fast! It is like riding a really big chainsaw

 

[Little Al]

Must be de rated for dirt use my Aprilla Disc valve GP bike was rated on the Dyno at 56.6 BHP at the rear wheel at 14,900 Revs & that was only a 125 CC

 

[shimaze]

I am sure at 15k RPMs your Aprilla did in fact make nearly as much HP as an engine 4 times its size. The CR500 was not de-rated for dirt use, it just simply could not rev to almost 15k RPMs. The 60 HP is a average / estimate of the Honda CR500 and I am not sure what RPM that 60 HP is measured at, but I am certain it is no where near 14,900. But I am certain that at any given RPM, the 4x engine will make close to 4x the power, provided it can rev that high. The difference is the very high RPM you ran the motor at on the dyno. HP is a calculation based on torque x RPM divided by 5252. The 2-stroke 500cc Honda will never reach anywhere close to RPM level of your Aprila. So at the same RPM, say 5252 where the horsepower and torque are always equal and this applies to all engines. I am certain the 4x engine would make a lot more power. If I could get the CR500 to rev to 14,900 (which I can not), I bet it would easily make 200 HP. But if your rotary valve engine where the same size as the reed valve engine, it may make a bit more power at the same RPM. The problem is that a rotary valve engine is such an odd ball engine as is Aprilla in general. In the US, Aprilla didn't fair to well because it could take 6 months for a single part to arrive. But they were a lovely bike and certainly well made and more advanced than other popular brands.

If the two bikes were to race side by side, my CR500 would have already shifted at a much lower RPM into 3rd gear and been long gone by the time you got to 14,900 RPMs

 

[bikemike]

You all like chainsaws ...2-stroke power? This is a 2005 CR500AF. It is 500cc of pure 2-stroke power rated at 60HP. It is an absolute beast, crazy fast! It is like riding a really big chainsaw

Use to be the most desirable hillclimb bike power to weight ratio with a head swap and tuning they could come close to 90 hp but rings didn't last long. Wish I had one of those old girls

 

[bikemike]

I am sure at 15k RPMs your Aprilla did in fact make nearly as much HP as an engine 4 times its size. The CR500 was not de-rated for dirt use, it just simply could not rev to almost 15k RPMs. The 60 HP is a average / estimate of the Honda CR500 and I am not sure what RPM that 60 HP is measured at, but I am certain it is no where near 14,900. But I am certain that at any given RPM, the 4x engine will make close to 4x the power, provided it can rev that high. The difference is the very high RPM you ran the motor at on the dyno. HP is a calculation based on torque x RPM divided by 5252. The 2-stroke 500cc Honda will never reach anywhere close to RPM level of your Aprila. So at the same RPM, say 5252 where the horsepower and torque are always equal and this applies to all engines. I am certain the 4x engine would make a lot more power. If I could get the CR500 to rev to 14,900 (which I can not), I bet it would easily make 200 HP. But if your rotary valve engine where the same size as the reed valve engine, it may make a bit more power at the same RPM. The problem is that a rotary valve engine is such an odd ball engine as is Aprilla in general. In the US, Aprilla didn't fair to well because it could take 6 months for a single part to arrive. But they were a lovely bike and certainly well made and more advanced than other popular brands.

If the two bikes were to race side by side, my CR500 would have already shifted at a much lower RPM into 3rd gear and been long gone by the time you got to 14,900 RPMs

The ape rilla did make power at rpm but they do not have the torque like the big 1 lunger 500. The cr 500 and other big single high compression bikes were know to rip shoulder sockets out un acceleration or slip of the clutch. They did not turn crazy rpm like the 125 mx.
I like my piss revin rpm engines but sometimes the piss revin has its downfall it's all apples n oranges

 

[bikemike]

Wish I owned ur bike the cr500. Hell even the older louder aircooled cr500 would be a blast

 

[bikemike]

Almost as hard to find a good old air cooled 500 as it is to find the kawi 750 tripple

 

[shimaze]

I can't imagine what the CR500 would be like with a 50% increase in power. It is already a bit of a struggle to hold on when you twist the throttle!

I have never ridden a factory steel frame CR500, but I have heard the aluminum frame is night and day different because of the lighter weight of the aluminum CR250 frame. You'll notice this is a 2005 Service Honda CR500AF. Honda ceased production of the CR500 in 2001. AF stands for aluminum frame

 

[bikemike]

Oh you would like the increase of your bike was over 8 foot long on a hill or grass drag

 

[shimaze]

...8 foot long

The hill climb bikes look funny because the swing arm is longer than the bike. But I understand the purpose

 

[bigbadbob]

Had a CR500 about 25-30 yrs ago, had it for 6 months, too much animal for me. Thought I would be killed on it. I remeber going up a dirt road with a slight incline. Got it up on one wheel and it stayed there forever,,,,till I ran outta balls,,,

 

[shimaze]

Yeah, I did something similar on a small bike once going up a steep hill. I let off the throttle a little too early before getting to the top and then had to get back into the throttle. The front came up and almost over on me. By shear luck, the bike rotated 180° with the front wheel in the air and I went back down the hill without wrecking. It looked like I knew what I was doing, but I really just got lucky. I was only 12 or 13 years old.

On the CR500, I got a little brave and thought I would show off a little. So I cracked the throttle pretty good and the bike stood straight up on me almost instantly. I had no choice but to tap the rear brake and that brought the front wheel down. I didn't try that foolish mistake again!

 

[Little Al]

I am sure at 15k RPMs your Aprilla did in fact make nearly as much HP as an engine 4 times its size. The CR500 was not de-rated for dirt use, it just simply could not rev to almost 15k RPMs. The 60 HP is a average / estimate of the Honda CR500 and I am not sure what RPM that 60 HP is measured at, but I am certain it is no where near 14,900. But I am certain that at any given RPM, the 4x engine will make close to 4x the power, provided it can rev that high. The difference is the very high RPM you ran the motor at on the dyno. HP is a calculation based on torque x RPM divided by 5252. The 2-stroke 500cc Honda will never reach anywhere close to RPM level of your Aprila. So at the same RPM, say 5252 where the horsepower and torque are always equal and this applies to all engines. I am certain the 4x engine would make a lot more power. If I could get the CR500 to rev to 14,900 (which I can not), I bet it would easily make 200 HP. But if your rotary valve engine where the same size as the reed valve engine, it may make a bit more power at the same RPM. The problem is that a rotary valve engine is such an odd ball engine as is Aprilla in general. In the US, Aprilla didn't fair to well because it could take 6 months for a single part to arrive. But they were a lovely bike and certainly well made and more advanced than other popular brands.

If the two bikes were to race side by side, my CR500 would have already shifted at a much lower RPM into 3rd gear and been long gone by the time you got to 14,900 RPMs

Did you think I was referring to an MX bike ? the Aprilla I had was a Road Racing machine To wards the end of my racing days the 2smoke was a dying beast so at some non championship meetings would get lumped in with different capacity bikes both 2&4 stroke there was a class called street fighter which was limited to 500cc & a good number were super motard bikes some with 500 2 smoke motors of which some were Honda's I have no idea on the BHP out put of these but I was very rarely beaten by that class of bike the only bikes that finished in front of me were the 250 cc Twin 2 smoke Honda RS 250 or the Yamaha YZ 250 road race GP bikes that produced some 80 BHP at the rear wheel I could hold them & in some cases pass on the bends as the Aprilla was more nimble & obviously lighter but it was a good bye on the straights more so if they were longer on the Sulby straight in the Isle of Man ultra lightweight TT on the second lap I was clocked at 158 MPH Shame the racing is now limited to stroke motors mind towards the end of 500CC moto gp bikes they became almost un riderable the tiniest touch of throttle & it spit you down the road Wayne Rainy & Mick Doohan being prime examples

 

[shimaze]

Did you think I was referring to an MX bike ?

I wasn't sure. But I do know that Apprilla made a really neat two cylinder MX bikes in both 450cc & 550cc. My point is that there is a huge difference in 60 HP at 6k RPMs and 60 HP at 15k RPMs. I guess the 125cc you had would be faster on the track than a much larger engine at a slower RPM. Question: Did your race bike have a piston/rod/crank or was it a rotary engine?

 

[Ted Jenkins]

I am sure at 15k RPMs your Aprilla did in fact make nearly as much HP as an engine 4 times its size. The CR500 was not de-rated for dirt use, it just simply could not rev to almost 15k RPMs. The 60 HP is a average / estimate of the Honda CR500 and I am not sure what RPM that 60 HP is measured at, but I am certain it is no where near 14,900. But I am certain that at any given RPM, the 4x engine will make close to 4x the power, provided it can rev that high. The difference is the very high RPM you ran the motor at on the dyno. HP is a calculation based on torque x RPM divided by 5252. The 2-stroke 500cc Honda will never reach anywhere close to RPM level of your Aprila. So at the same RPM, say 5252 where the horsepower and torque are always equal and this applies to all engines. I am certain the 4x engine would make a lot more power. If I could get the CR500 to rev to 14,900 (which I can not), I bet it would easily make 200 HP. But if your rotary valve engine where the same size as the reed valve engine, it may make a bit more power at the same RPM. The problem is that a rotary valve engine is such an odd ball engine as is Aprilla in general. In the US, Aprilla didn't fair to well because it could take 6 months for a single part to arrive. But they were a lovely bike and certainly well made and more advanced than other popular brands.

If the two bikes were to race side by side, my CR500 would have already shifted at a much lower RPM into 3rd gear and been long gone by the time you got to 14,900 RPMs

Depending on the year most Cr 500's made peak at 8,600 RPM. For years the CR 500 was the king. KTM came along with it's 550 and others. My many 250's put out an easy more torque and HP than a stock CR. That said my 250's have at least $5000 worth of machining and mods to the motors. The CR's were still plenty fun in the sand dunes if not so fast on the tracks. Actually many 2 stroke 250's bikes would walk away in hill climbs and drag races compared to a STOCK CR 500, So what when I tuned up my son's CR with a little work he never could let it all the way out, but he had a grin trying. Thanks

 

[CR888]

My big red pig Honda XR650R puts out 60ish bhp at the rear wheel. But a CR500 would have a bunch of torque the second you touch the throttle unlike a high rpm 125 that you need to change gears constantly like peddling around a push bike.

 

[Little Al]

I wasn't sure. But I do know that Apprilla made a really neat two cylinder MX bikes in both 450cc & 550cc. My point is that there is a huge difference in 60 HP at 6k RPMs and 60 HP at 15k RPMs. I guess the 125cc you had would be faster on the track than a much larger engine at a slower RPM. Question: Did your race bike have a piston/rod/crank or was it a rotary engine?

It more or less conformed to a single cyl unit construction to include gear box with quick change ratios it had a bore /stroke of 54x 54.5 mm with rotary disc induction & a 38 or 40mm choke size carb Liquid cooled with being able to change Squish band in the head bottom end rebuilt every 500 KM's piston ring replaced after most race meetings unless it was a short race piston every 1000Kms fuel /oil mix between18/20 to 1 dependent on the time each lap the throttle was held wide open. power valve & ignition computer controlled, specialist made exhaust Quick shift gear change no dipping the clutch or closing throttle when you pressed the gear pedal it operated a sophisticated kill switcth which killed the engine momentarily to enable the gear to change. Quaife 6 speed cluster in the GB ability to add extra gear for High speed circuits shame it's not usable yet to new for historic racing & not eligible for current GP racing

 

[1Alpha1]

Any idea what the dry weight on that CR500AF is ?

I used to have one of these. 1986 Honda XR-600R.

46 hp @ 6000 rpm

39 ft. lbs. torque @ 5500 rpm.

282 lbs. dry. (Never felt that heavy to me).

 

[shimaze]

It weighs 230 pounds. I am not sure what a steel frame original CR500 weighs or exactly how much difference there is between the two, but riders on the CR500 forums claim there is night & day difference. I know that it is extremely light weight and is in a whole another universe compared to my Harley Davidson Road Glide Ultra!

 

[1Alpha1]

It weighs 230 pounds. I am not sure what a steel frame original CR500 weighs or exactly how much difference there is between the two, but riders on the CR500 forums claim there is night & day difference. I know that it is extremely light weight and is in a whole another universe compared to my Harley Davidson Road Glide Ultra!

Yeah, I was guessing right about that weight. I've heard that the older, steel-framed CR500's weighed in at about 215-220 or so, dry.

I have a 2003 BMW R1150RT. I bought it new back in Nov. of 2002. I like it and it has it's strong points. Light weight isn't one of them though.