Fun fact: it was James Watt who developed the horse power measurement. The measurement is "work done over time". He had a horse, put a rope on it, put a weight at the other end of the long rope, and dropped it down a water well. With the rope over a pulley, he made the hose pull the weight out of the well, and measured time and distance to get "1 Horse Power". But if he had chosen a different Horse, stronger or weaker, we would have a different amount of power today that represents 1 hp. Good thing we were not riding pigs back then. :)
The simple mods I did to my 1988 CR250 back in 1990 to make it a bullet. It was still soft in the lower rpm's, but a rocket from mid range to a pretty high revving top end. I never got a bad start with that bike. 1) Make sure the cylinder plating is good. Use scotch brite to clean up the plating. 2) Make sure the exhaust power valve is working correctly. I put as big of a radius as I could on the "slider" fingers as I could with out making an opening when the valve was closed. This retains the lower rpm power that is there, but helps flow and maybe a bit more exhaust open duration for higher rpm's. 3) I think I lowered the cylinder by not using a cylinder base gasket for more compression, but I am not sure today. 4) I epoxied (JB weld regular is good), the rear transfer hooks, making them straight, to aid in lower rpm power. 5) Jetted the carb to the edge of too lean. Probably dropped the needle one groove, and went down on the main jet a size or two. Out of the 250's MX bikes I had, I have had a 1982 YZ250 (ported locally), 86 YZ250 (ported professionally), 88 CR250 (Ported by me), 96 RMX250 (stock OK not an MX bike), 97 KX250 jetted and a prototype head of mine, and a stock 2019 YZ250 all,--- 2-strokes. That CR would smoke all of them from mid range to top RPM and on the start straight. The KX had the best lower rpm power by far.
I also had a habit, (bad or good), of lowering the gearing up front by one tooth, a pretty big jump. I had to shift more, but it would get rid of the low end dead spots on my bikes and pull harder.
I've got a 1990 CR250. Brought a boyzen rad valve ($340) and a brand new genuine keihen carburettor ($600) and I will get the motor rebuild from the ground up. There's a dude 2hrs from me that has a good reputation of making bikes go hard. I will give the carb to the mechanic at the time of rebuild. I think the 4hr return trip will be worth it.
@@MXRiderFiftyTwo I don't think the carb will make much if any difference from the stock carb. They are great carbs that just need to be jetted from the factory, because they ship them rich, (to be on the safe side for air quality around the world.). Matching the pipe to the porting is the main thing. For example, I wanted more lower rpm power for my 2019 YZ250 2-stroke. So I bought a lower rpm pipe (FMF Gnarley), some V-force reeds, and lowered the cylinder (no cylinder base gasket, but a good sealer, still with .048" squish clearance (acceptable), for more compression (need to run 100 octane fuel, but is worth it to me), but more importantly, the lower exhaust port will match the lower rpm pipe better for more low end power. I gained great boost down there, and still smooth. I did not out a tach on it (dumb me), but i don't think I lost much top rpm over-rev.
@@HPRaceDevelopment I have a dyno. A little "land and sea" water brake engine dyno that I made the drive system and water system for. I use it for small engines like around 30cc. One thing I have found is there is no real calibration for dyno's, and computer factors can be changed to make them read what ever you want also. I was actually able to calibrate mine is kind of a half azzed way, (by trusting the manufacture claim for one of their engines, which is probably accurate but I have no way to be sure). The manufacture claimed 2.8hp at 12,500rpm with no air filter and no exhaust at all. So I set up a new engine, broke in the ring, set the jetting (per plug color at wide open), as well as I could, and calibrated my dyno until it read 2.8hp with that engine. I keep that engine for calibration only. I had this bike, and with very little port mods, good jetting, the stock pipe, it was probably the fastest 2-stroke 250 I ever had, (including my stock 2019 YZ250 2-stroke), with awesome mid to top power. My bike had to be 45hp or a bit higher, (I think that is at the crank. It is typical to subtract 10% if a chassis driven rolling dyno.). But my main point is, because of a lack of calibration alone (not even counting the cheaters), way more often than not, when we see dyno numbers, they are not accurate to a small degree of error. There are huge swings with the same power plant from dyno to dyno.
@jaialcorn8945 only 125 I rode that could wheelie in the sand in 6th gear. I'm a Yamaha guy but want one of each '89 CR. 80, 125, 250 and 500 in my collection, just love the look of that year. Hopefully in a cpl years I complete the collection
I had an '87 CR, it was quite mellow for a MX bike, but I used it for desert riding and it was great in that environment. The conventional forks on those old bikes were had a bit of flex and were quite plush, which was not great for MX but pretty great for off road riding. A riding buddy currently still has an '01 CR 250 with a high compression head on it, that year bike has huge ports and seriously gets with it when it's on the pipe 😆 Currently riding an '18 300 XC which has a carb but also the balance shaft. I may never part with that machine, it is awesome.
I don't get all the 2-stroke guys who always claim and wish and want big hp numbers. These old bikes never had it. I have owned and raced them all. They are what they are, love them for what they were. When I started reading MXA in the late nineties, the 250's would dyno at around 42 hp. So I am not surprised. My initial guess was below 38, and it turned out to be true. I remember our local shop dynoed a KX 125 around the year 2000, and brand new it only made 23hp at the wheel. And all the CR500 lovers who claim 80 hp, they only made around 52 hp depending on the year. I owned a CR500 once, hard to ride well, short powerband and poor suspension. I am fond of the memories I have of these bikes, but I have not put my rose colored glasses yet 😊😅
There are some factors out of control in your knowledge of your history, like that KX125 was not running well (jetted very rich from the factory), and there is no calibration for dyno's, because I know 125's (properly running and properly measured), were making 30 plus HP at the rear wheel in reality by the mid 80's. Owned and raced them all? Really? I had a few 250's and some smaller bikes first in the 890's and 90's, my next to last being a 97 KX250. I think they were all faster than my stock 2019 YZ250 2-stroke. I think they YZ is the slowest 250 MX bike I ever had. But,---ahem,I did gain some weight over the last 20 years off a bike. :)
@@HPRaceDevelopment If this 50 hp is from the rear wheel then it’s not so much lower hp than CR 500 has. But that CR 500 has a lot more torque as it doesn’t rev nearly as high where it makes it’s hp peak. 250 revs much higher and even higher when modified. Actually piston speed in 250 is higher than in 125 as the stroke is so much longer (72 mm vs. 54.5 mm). If a 250 is at 10000 rpm when going above it´s peak hp then similar piston average speed 24 m/s for a 125 is at 13250 rpm. This was one of the reasons why I changed my TC 250 piston to a 1-ring Wiseco. It´s modified so it revs higher than stock.
@@jannep6772 Ahhh, you know something about engine building. :) Me too, and I know how dyno's are, (not calibrated). I doubt a 250 2-stroke MX bike running on gas is making 50hp at the rear wheel. That would be about 55 at the crank, (assuming 10% drive train loss). But, it is not that the engine can't make that much power. It is that much power out of a 2-stroke 250 gets too hard to ride on a MX track, of yesterday. But on the other hand. Today, the tracks are much faster because of the faster 4-stroke engine, so maybe they can use the peakier 55hp.
You can keep it wide open until it has topped out for a few seconds before you let off the gas. Make sure it is done revving. You might be missing some power at the very end of the curve, and some top rpm. In some weird cases, there may be a little surge of power up that that you did not quite reach.
@@HPRaceDevelopment No, if it will rev more, like you admitted, then you did not measure the entire curve. No, the over-rev will not make more power than peak, but it is something a racer would look at if they want to hold it on longer instead of shifting again for a up coming corner, for an example. You can hold it topped out for several seconds. If it is in good shape and jetted well--it will not blow up. With just a little bit of porting, and the stock pipe,--that bike would smoke my 2019 YZ250. Stock for stock, I think it was better there too. Not much lower rpm power, but from the mid range on top,--that Honda was really fast.
Mine too, and small engine mods with good jetting made it even faster. Coming down from speed on a bumpy straight, (which they don't have anymore), I have had that front end swap from stop to stop about as violently as possible. Stiffer fork springs and some body adjustment pretty much cured it. I am sure you bent a shock linkage bolt or two also. That was a problem with that bike. I used a better grade bolt and ended the problem for me.
That's roughly the era when I got my first Dynojet and we had most of the bikes @40 hp stock, a race bike pc pipe muffler, porting, piston to head clearance @1.0mm was @43 44on c12 race or av gas....your bike or maybe the dyno reads lower than the dynojets back in the 90s and again not so long ago we would pull out the old porting specs and build and dyno the bikes we built for VMX racers and most of the CR250R YZ250 were @44-45 with the mods... with the 88 cr the bore and stroke is the same as the current ktm and 250sx and the yz250s. 38mm carb the same bore and stroke etc... your naturally going to be similar territory. If you invest time to map out ports and measure crankcase volumes, comp etc you might notice that cr is in the ball park. In the end yz rm and kx 250s from the early 2000s were with the exception of power valve mechanisms all based off the late 80s cr. I feel if you put front end with 2000 or later kyb forks and 270mm disc the lap times of the later 80s and current bikes would be similar..
Our dyno is a bit lower than some. While I agree the 90s era crs will go what a yz will - this is all this bike had. Its in perfect mechanical condition - speaking with a friend who did a lot of these, he said its m in line with what he would expect on my dyno. On the same day we dyno this clients cr500 - later mellower year and it still put down 55 for reference.
@@inevespace Not on my dyno…people seem to really struggle on that. We feel our dyno is a very accurate to true wheel numbers. Most dynos are fudged a bit higher to more represent crank numbers.
@@HPRaceDevelopment People need to understand that you really cant compare results between different dynos. Only way to really make the comparison is to have both bikes ran on the same dyno...
The weak point about this bike was its suspension. Get that motor running like it can, (and it can), put on some new YZ suspension/linkage, and it would be up there with the best 2-strokes today IMO.
Not in any faster amateur class, against 4-strokes on these faster tracks today. But I had this bike, and I know I can make it run with the modern 2-strokes with YZ suspension (suspension was terrible on that year bike) and a few motor mods and pipe. I got that bike screaming easily, with the stock pipe. Had to be 45hp plus at the crank, and I think it was the fastest 250MX bike I ever had,--including my 2019 YZ250 2-stroke, (which may be the slowest I ever had, stock).
@@OGLD No worse than my 2019 YZ250, probably less. The aluminum frame does transfer vibration more efficiently than chrome moly. The brakes in 88 were great. They worked awesome for the rougher tracks that were not road racing speeds like today. The 4-stroke tracks are at least 30% faster today and most of the bikes are still over 215lbs. Nothing on a dirt bike course but modern, MX needs brakes as big as my 2019 YZ250. The brakes are so strong today, you never need more than one finger on the front brake lever, and with many boots, you can't feel the rear brake pedal when touching it, (same with the shifter). I think I wold crash less with the late 80's brakes, and go just as fast doing it. :)
A good 125 back in those days could make 36hp at the wheel. This bike runs between 45-50hp at the crank. I had one. Did a tinge of porting myself, stock pipe, good jetting,---and it would smoke my stock 2019 YZ250. If his dyno has any kind of calibration, (They don't), I could build that engine for him (if we can still get parts) to test again. That bike was fast in the higher rpm's. Real fast.
It definately doesnt make 52 at the flywheel. and good dynos - like ours - dont lie. Its why we own it. There is no hiding when you have to move mass. The mass never changes - and time keeping is pretty darn accurate and reliabke these days.
@@HPRaceDevelopment But even if it is a crank dyno, Like mine with a rpm reducing belt system, there are bearings and other friction losses that really are not measured. I don't know if there is a calibration method for your dyno, but I had to develop my own using a stock engine, and assuming the manufacture numbers are correct. I don't think there is any real calibration for dynos, and I bet you if you took the same engine set up to 4 different dyno's across the nation, the variance of the results would be statistically considered "out of control".
Fun fact: it was James Watt who developed the horse power measurement. The measurement is "work done over time". He had a horse, put a rope on it, put a weight at the other end of the long rope, and dropped it down a water well. With the rope over a pulley, he made the hose pull the weight out of the well, and measured time and distance to get "1 Horse Power". But if he had chosen a different Horse, stronger or weaker, we would have a different amount of power today that represents 1 hp. Good thing we were not riding pigs back then. :)
Loved these back ,then I had these each year along with 500 after this year I only bought 500s ,great times. Good that you showed ,Thank you
89 cr is one of my dream bikes.
Best looking years imo, want an 80, 125, 250 and 500 to restore/ride and I'm a Yamaha guy.
That was the first production bike with the "Low Boy Pipe" and lowered gas tank because the pipe was lower.
It felt 10lbs lighter than my 1986 YZ250.
Great bike, happy to have one myself. Same pipe as well. Never selling it.
Loved the test! Thanks for doing this
The simple mods I did to my 1988 CR250 back in 1990 to make it a bullet. It was still soft in the lower rpm's, but a rocket from mid range to a pretty high revving top end. I never got a bad start with that bike.
1) Make sure the cylinder plating is good. Use scotch brite to clean up the plating.
2) Make sure the exhaust power valve is working correctly. I put as big of a radius as I could on the "slider" fingers as I could with out making an opening when the valve was closed. This retains the lower rpm power that is there, but helps flow and maybe a bit more exhaust open duration for higher rpm's.
3) I think I lowered the cylinder by not using a cylinder base gasket for more compression, but I am not sure today.
4) I epoxied (JB weld regular is good), the rear transfer hooks, making them straight, to aid in lower rpm power.
5) Jetted the carb to the edge of too lean. Probably dropped the needle one groove, and went down on the main jet a size or two.
Out of the 250's MX bikes I had, I have had a 1982 YZ250 (ported locally), 86 YZ250 (ported professionally), 88 CR250 (Ported by me), 96 RMX250 (stock OK not an MX bike), 97 KX250 jetted and a prototype head of mine, and a stock 2019 YZ250 all,--- 2-strokes.
That CR would smoke all of them from mid range to top RPM and on the start straight. The KX had the best lower rpm power by far.
I also had a habit, (bad or good), of lowering the gearing up front by one tooth, a pretty big jump. I had to shift more, but it would get rid of the low end dead spots on my bikes and pull harder.
I've got a 1990 CR250. Brought a boyzen rad valve ($340) and a brand new genuine keihen carburettor ($600) and I will get the motor rebuild from the ground up. There's a dude 2hrs from me that has a good reputation of making bikes go hard. I will give the carb to the mechanic at the time of rebuild. I think the 4hr return trip will be worth it.
@@MXRiderFiftyTwo I don't think the carb will make much if any difference from the stock carb. They are great carbs that just need to be jetted from the factory, because they ship them rich, (to be on the safe side for air quality around the world.). Matching the pipe to the porting is the main thing. For example, I wanted more lower rpm power for my 2019 YZ250 2-stroke. So I bought a lower rpm pipe (FMF Gnarley), some V-force reeds, and lowered the cylinder (no cylinder base gasket, but a good sealer, still with .048" squish clearance (acceptable), for more compression (need to run 100 octane fuel, but is worth it to me), but more importantly, the lower exhaust port will match the lower rpm pipe better for more low end power. I gained great boost down there, and still smooth. I did not out a tach on it (dumb me), but i don't think I lost much top rpm over-rev.
Is the top end fresh ? I thought it might get closer to 40. I used to have one of these, very rideable power and friendly bike on the track.
its fresh. Just what she makes on my dyno. Our dyno is stingy vs most…
@@HPRaceDevelopment I have a dyno. A little "land and sea" water brake engine dyno that I made the drive system and water system for. I use it for small engines like around 30cc. One thing I have found is there is no real calibration for dyno's, and computer factors can be changed to make them read what ever you want also. I was actually able to calibrate mine is kind of a half azzed way, (by trusting the manufacture claim for one of their engines, which is probably accurate but I have no way to be sure). The manufacture claimed 2.8hp at 12,500rpm with no air filter and no exhaust at all. So I set up a new engine, broke in the ring, set the jetting (per plug color at wide open), as well as I could, and calibrated my dyno until it read 2.8hp with that engine. I keep that engine for calibration only.
I had this bike, and with very little port mods, good jetting, the stock pipe, it was probably the fastest 2-stroke 250 I ever had, (including my stock 2019 YZ250 2-stroke), with awesome mid to top power. My bike had to be 45hp or a bit higher, (I think that is at the crank. It is typical to subtract 10% if a chassis driven rolling dyno.). But my main point is, because of a lack of calibration alone (not even counting the cheaters), way more often than not, when we see dyno numbers, they are not accurate to a small degree of error. There are huge swings with the same power plant from dyno to dyno.
Good torque numbers. 👍
I swear my 89 CR125 had quite a few more ponies than 3 of my buddies 98 RM125's. Loved that bike.
89 125 was an absolute Top End Rocket!
@jaialcorn8945 only 125 I rode that could wheelie in the sand in 6th gear. I'm a Yamaha guy but want one of each '89 CR. 80, 125, 250 and 500 in my collection, just love the look of that year. Hopefully in a cpl years I complete the collection
I had an '87 CR, it was quite mellow for a MX bike, but I used it for desert riding and it was great in that environment. The conventional forks on those old bikes were had a bit of flex and were quite plush, which was not great for MX but pretty great for off road riding. A riding buddy currently still has an '01 CR 250 with a high compression head on it, that year bike has huge ports and seriously gets with it when it's on the pipe 😆
Currently riding an '18 300 XC which has a carb but also the balance shaft. I may never part with that machine, it is awesome.
i would love to see a KIPS kx250 on the dyno
I don't get all the 2-stroke guys who always claim and wish and want big hp numbers. These old bikes never had it. I have owned and raced them all. They are what they are, love them for what they were.
When I started reading MXA in the late nineties, the 250's would dyno at around 42 hp. So I am not surprised. My initial guess was below 38, and it turned out to be true.
I remember our local shop dynoed a KX 125 around the year 2000, and brand new it only made 23hp at the wheel.
And all the CR500 lovers who claim 80 hp, they only made around 52 hp depending on the year.
I owned a CR500 once, hard to ride well, short powerband and poor suspension.
I am fond of the memories I have of these bikes, but I have not put my rose colored glasses yet 😊😅
There are some factors out of control in your knowledge of your history, like that KX125 was not running well (jetted very rich from the factory), and there is no calibration for dyno's, because I know 125's (properly running and properly measured), were making 30 plus HP at the rear wheel in reality by the mid 80's.
Owned and raced them all? Really? I had a few 250's and some smaller bikes first in the 890's and 90's, my next to last being a 97 KX250. I think they were all faster than my stock 2019 YZ250 2-stroke. I think they YZ is the slowest 250 MX bike I ever had. But,---ahem,I did gain some weight over the last 20 years off a bike. :)
Very interesting. How much HP does a TC 250 2-stroke 2018 have without mods?
Those can easily cross 50
@@HPRaceDevelopment If this 50 hp is from the rear wheel then it’s not so much lower hp than CR 500 has. But that CR 500 has a lot more torque as it doesn’t rev nearly as high where it makes it’s hp peak. 250 revs much higher and even higher when modified. Actually piston speed in 250 is higher than in 125 as the stroke is so much longer (72 mm vs. 54.5 mm). If a 250 is at 10000 rpm when going above it´s peak hp then similar piston average speed 24 m/s for a 125 is at 13250 rpm. This was one of the reasons why I changed my TC 250 piston to a 1-ring Wiseco. It´s modified so it revs higher than stock.
@@jannep6772 Ahhh, you know something about engine building. :) Me too, and I know how dyno's are, (not calibrated).
I doubt a 250 2-stroke MX bike running on gas is making 50hp at the rear wheel. That would be about 55 at the crank, (assuming 10% drive train loss). But, it is not that the engine can't make that much power. It is that much power out of a 2-stroke 250 gets too hard to ride on a MX track, of yesterday. But on the other hand. Today, the tracks are much faster because of the faster 4-stroke engine, so maybe they can use the peakier 55hp.
I reckon there was a slight issue somewhere, maybe jetted a little "fat" I think there's a couple more HP hiding in there...
Nope.
Did you say you were going to dyno a cr500?
We did
Are you going to post it?
Yep!@@JohnJ77777
Awesome thank you!@@HPRaceDevelopment
You can keep it wide open until it has topped out for a few seconds before you let off the gas. Make sure it is done revving. You might be missing some power at the very end of the curve, and some top rpm. In some weird cases, there may be a little surge of power up that that you did not quite reach.
she was done… it will rev more but not make more power
well past the tuned length of the pipe
@@HPRaceDevelopment Measure it anyway. The entire curve.
@@EarthSurferUSA we did
what you see is all she has
@@HPRaceDevelopment No, if it will rev more, like you admitted, then you did not measure the entire curve. No, the over-rev will not make more power than peak, but it is something a racer would look at if they want to hold it on longer instead of shifting again for a up coming corner, for an example.
You can hold it topped out for several seconds. If it is in good shape and jetted well--it will not blow up.
With just a little bit of porting, and the stock pipe,--that bike would smoke my 2019 YZ250. Stock for stock, I think it was better there too. Not much lower rpm power, but from the mid range on top,--that Honda was really fast.
@@EarthSurferUSA Yes we did. So ill bet you 10 grand it doesnt pick up a second wind. if your game - ill retest it for you.
had one of these good bike.head shake bad but good powerfull bike with great brakes \turning fit & feel
Mine too, and small engine mods with good jetting made it even faster. Coming down from speed on a bumpy straight, (which they don't have anymore), I have had that front end swap from stop to stop about as violently as possible. Stiffer fork springs and some body adjustment pretty much cured it.
I am sure you bent a shock linkage bolt or two also. That was a problem with that bike. I used a better grade bolt and ended the problem for me.
That's roughly the era when I got my first Dynojet and we had most of the bikes @40 hp stock, a race bike pc pipe muffler, porting, piston to head clearance @1.0mm was @43 44on c12 race or av gas....your bike or maybe the dyno reads lower than the dynojets back in the 90s and again not so long ago we would pull out the old porting specs and build and dyno the bikes we built for VMX racers and most of the CR250R YZ250 were @44-45 with the mods... with the 88 cr the bore and stroke is the same as the current ktm and 250sx and the yz250s. 38mm carb the same bore and stroke etc... your naturally going to be similar territory. If you invest time to map out ports and measure crankcase volumes, comp etc you might notice that cr is in the ball park. In the end yz rm and kx 250s from the early 2000s were with the exception of power valve mechanisms all based off the late 80s cr. I feel if you put front end with 2000 or later kyb forks and 270mm disc the lap times of the later 80s and current bikes would be similar..
I also feel confused. 35hp is level of air cooled CZ 250 from 70s
Our dyno is a bit lower than some. While I agree the 90s era crs will go what a yz will - this is all this bike had. Its in perfect mechanical condition - speaking with a friend who did a lot of these, he said its m in line with what he would expect on my dyno. On the same day we dyno this clients cr500 - later mellower year and it still put down 55 for reference.
@@inevespace Not on my dyno…people seem to really struggle on that. We feel our dyno is a very accurate to true wheel numbers. Most dynos are fudged a bit higher to more represent crank numbers.
@@HPRaceDevelopment People need to understand that you really cant compare results between different dynos. Only way to really make the comparison is to have both bikes ran on the same dyno...
@@HPRaceDevelopment so you give numbers on wheel, without recalculation to crank? I thought your setup gives "crank hp".
Can it be tweaked to closer numbers without huge money?
Eventually we will have a project on one but shop is too busy at the moment
Have you ever dynoed 1989-1990 yz 125?
no but from what ive seen and heard it would likely make 22-24
Sweet
The weak point about this bike was its suspension. Get that motor running like it can, (and it can), put on some new YZ suspension/linkage, and it would be up there with the best 2-strokes today IMO.
I bet you could make it compete mate!
Not in any faster amateur class, against 4-strokes on these faster tracks today. But I had this bike, and I know I can make it run with the modern 2-strokes with YZ suspension (suspension was terrible on that year bike) and a few motor mods and pipe. I got that bike screaming easily, with the stock pipe. Had to be 45hp plus at the crank, and I think it was the fastest 250MX bike I ever had,--including my 2019 YZ250 2-stroke, (which may be the slowest I ever had, stock).
I'd rather have this one than a new KTM. Beautiful machine.
Until you start riding it for more than 20 minutes. Those old bikes vibrate like paint shakers and the brakes are terrible by todays standards
@@OGLD No worse than my 2019 YZ250, probably less. The aluminum frame does transfer vibration more efficiently than chrome moly.
The brakes in 88 were great. They worked awesome for the rougher tracks that were not road racing speeds like today. The 4-stroke tracks are at least 30% faster today and most of the bikes are still over 215lbs. Nothing on a dirt bike course but modern, MX needs brakes as big as my 2019 YZ250. The brakes are so strong today, you never need more than one finger on the front brake lever, and with many boots, you can't feel the rear brake pedal when touching it, (same with the shifter). I think I wold crash less with the late 80's brakes, and go just as fast doing it. :)
36 wheel horsepower right?
Thats what we show
@@HPRaceDevelopment Ok that ain’t too bad. What did the 500 have?
@@TopRevs 55
@@HPRaceDevelopment Awesome
A good 125 back in those days could make 36hp at the wheel. This bike runs between 45-50hp at the crank. I had one. Did a tinge of porting myself, stock pipe, good jetting,---and it would smoke my stock 2019 YZ250. If his dyno has any kind of calibration, (They don't), I could build that engine for him (if we can still get parts) to test again. That bike was fast in the higher rpm's. Real fast.
Cool
At the flywheel it makes 52...dynos can lie..👈🤔
It definately doesnt make 52 at the flywheel.
and good dynos - like ours - dont lie. Its why we own it. There is no hiding when you have to move mass. The mass never changes - and time keeping is pretty darn accurate and reliabke these days.
@@HPRaceDevelopment You should take a reading at the flywheel, that will be the true bhp...do that on your video and I'll subscribe. 👈
@@Workerbee-zy5nx Your subscription isnt worth that effort, sorry.
@@HPRaceDevelopment But even if it is a crank dyno, Like mine with a rpm reducing belt system, there are bearings and other friction losses that really are not measured. I don't know if there is a calibration method for your dyno, but I had to develop my own using a stock engine, and assuming the manufacture numbers are correct. I don't think there is any real calibration for dynos, and I bet you if you took the same engine set up to 4 different dyno's across the nation, the variance of the results would be statistically considered "out of control".