how to get 75hp

[100hp honda]

this is getting more complicated . couple issues have surfaced. '85-'86 250r and '84-'01 cr250 used 125.3 rod, might be deck height issues with any year cr250. '87-'89 250r used 130.3 rod so its deck is +5. cr250 may need a spacer plate but i dont know how big. i can make some phone calls but at this time i cant find any difinitive answers on the saber rod as far as length but its longer than 130, im thinking around 140 probly from snomobile. i found out a few more things, '88+ cr250 used biger swingarm bushing and '90+ used 8/7 clutch but 2 of the metals are thinner for some stupid reason.

[CR480R]

deck wont be a problem.. the difference are made up in the piston height.. not cylinder or cases.. spacers are only needed on a 250r when the early piston is used with the long rod, or if the crank is stroked

[100hp honda]

deck wont be a problem.. the difference are made up in the piston height.. not cylinder or cases.. spacers are only needed on a 250r when the early piston is used with the long rod, or if the crank is stroked

im unfamilar with any 250 engine. ill do more research to figure this out

[LOVEMYCR500]

I have 3 TRX 250r's and my beloved CR500. ATC 250r and TRX 250r motor is the same thing. Before the Pro-x cylinder came out for the TRX, the big ticket was to take a mid 80's CR250 cylinder (up to 1989 CR250 cylinder bolts to the TRX/ATC bottom end) minus the power valve because it won't work and run it. Better yet was to big bore sleeve it to a 300 cc and stroke the crank. So I know up to 89 to bolt pattern is the same on the jugs as the ATC/TRX bottom ends. I just don't know on the CR 250 cases how the power valve deal works. TRX bottom end is longer, to provide room for the counter balancer and probably the provision for the forward kick start which would be interesting to do on a motorcycle. On one of my TRX's I have the Puma cylinder, the smaller brother to the Saber, it's a 85 mm bore where as the Saber is a 95 mm bore. On the Puma, you have to epoxy the voids in the cases around the cylinder sleeve and then machine this area so the cases can except the larger sleeve. On the Saber, the void area is eliminated completely and the cylinder has provisions at the bottom of the sleeve to fill this area for strength. Cool idea on Calvin's part. I believe there was one person in the thread that said something about not having enough crankcase volume, actually there is too much after performing this case mod and then seeing what is done to the crank. Most of the cranks I have seen for the Saber have the crank tins removed, the rod is out of a artic cat snowmobile measuring 144 mm. I't a huge peice of metal. They also have to machine the crank leaving some voids more like how a Banshee crank looks, then it is balanced. The crank is about $800.00 to $1,000.00 to build after it's done. There is a hardened steel counter shaft gear set that you can buy and all the motors I know of have done this. Most drag racers over ride their tranny's and it seems to make it last longer by doing this. You also have to remember these guys are only going 300 ft and then pulling the clutch in. A lockup clutch is a must, there is a cool one out (I have this on the Puma) that only uses 5 fiber's and steels vs the 7 of each that the stock clutch basket runs. It uses tungsten ball bearings that run in a groove (about 25-50) and as the clutch begins to spin faster it forces these balls outward and applies pressure to the disks. This is cool because you can use the stock clutch cover instead of having to make it wider and modifying your kick starter shaft longer to compensate. The Puma I build is a duner, 431 cc's (85 mm bore, port layout looks just like the picture Bob put up, 76 mm stroke 4 mm more than stock) Uses a lightened YZ 490 137.5 mm rod) I bought the hardended gear set for the countershaft, and cryo treated it along with the stock gears that I still need to run. This is not a overridden tranny and will use the clutch to shift so I wanted to make sure this was a bulit proof bottom end. This motor on gas is in the mid 70's hp with a small 40.5 mm carb. The guy who built this motor for me has built 3-4 TRX Sabers stickly for drag racing. Not that this could be over come, but all these cylinders come cast with pretty radical port timings. 196 degrees on the exhaust with 32 degrees of blow down. The Sabers are very expensive to build before pipe, ignition, and carb it's a $5,000.00 motor with almost $1,000.00 in the crank.

On gas, I really think if you radically ported a CR 500 motor, had the correct pipe, and carb you could make 70-75 hp. I know of a unported Saber in our area on gas with the correct pipe and carb that made 78 HP on the dyno. This Cylinder sounds good but it would make your 500 run like a radically ported stock 500 cylinder, not much down low and you better hang on on top.

sorry for the long response,

[dannygraves]

loads of info there

[dannygraves]

I'd bet an '89 cr250 bottomend with the larger swingarm bolt would bolt right into a gen-1 or gen-2 chassis, and only need sprocket alignment in the gen-3... do the saber jug...helz yeah, now where did I leave that extra $7000

[pstoffers]

I have 3 TRX 250r's and my beloved CR500. ATC 250r and TRX 250r motor is the same thing. Before the Pro-x cylinder came out for the TRX, the big ticket was to take a mid 80's CR250 cylinder (up to 1989 CR250 cylinder bolts to the TRX/ATC bottom end) minus the power valve because it won't work and run it. Better yet was to big bore sleeve it to a 300 cc and stroke the crank. So I know up to 89 to bolt pattern is the same on the jugs as the ATC/TRX bottom ends. I just don't know on the CR 250 cases how the power valve deal works. TRX bottom end is longer, to provide room for the counter balancer and probably the provision for the forward kick start which would be interesting to do on a motorcycle. On one of my TRX's I have the Puma cylinder, the smaller brother to the Saber, it's a 85 mm bore where as the Saber is a 95 mm bore. On the Puma, you have to epoxy the voids in the cases around the cylinder sleeve and then machine this area so the cases can except the larger sleeve. On the Saber, the void area is eliminated completely and the cylinder has provisions at the bottom of the sleeve to fill this area for strength. Cool idea on Calvin's part. I believe there was one person in the thread that said something about not having enough crankcase volume, actually there is too much after performing this case mod and then seeing what is done to the crank. Most of the cranks I have seen for the Saber have the crank tins removed, the rod is out of a artic cat snowmobile measuring 144 mm. I't a huge peice of metal. They also have to machine the crank leaving some voids more like how a Banshee crank looks, then it is balanced. The crank is about $800.00 to $1,000.00 to build after it's done. There is a hardened steel counter shaft gear set that you can buy and all the motors I know of have done this. Most drag racers over ride their tranny's and it seems to make it last longer by doing this. You also have to remember these guys are only going 300 ft and then pulling the clutch in. A lockup clutch is a must, there is a cool one out (I have this on the Puma) that only uses 5 fiber's and steels vs the 7 of each that the stock clutch basket runs. It uses tungsten ball bearings that run in a groove (about 25-50) and as the clutch begins to spin faster it forces these balls outward and applies pressure to the disks. This is cool because you can use the stock clutch cover instead of having to make it wider and modifying your kick starter shaft longer to compensate. The Puma I build is a duner, 431 cc's (85 mm bore, port layout looks just like the picture Bob put up, 76 mm stroke 4 mm more than stock) Uses a lightened YZ 490 137.5 mm rod) I bought the hardended gear set for the countershaft, and cryo treated it along with the stock gears that I still need to run. This is not a overridden tranny and will use the clutch to shift so I wanted to make sure this was a bulit proof bottom end. This motor on gas is in the mid 70's hp with a small 40.5 mm carb. The guy who built this motor for me has built 3-4 TRX Sabers stickly for drag racing. Not that this could be over come, but all these cylinders come cast with pretty radical port timings. 196 degrees on the exhaust with 32 degrees of blow down. The Sabers are very expensive to build before pipe, ignition, and carb it's a $5,000.00 motor with almost $1,000.00 in the crank.

On gas, I really think if you radically ported a CR 500 motor, had the correct pipe, and carb you could make 70-75 hp. I know of a unported Saber in our area on gas with the correct pipe and carb that made 78 HP on the dyno. This Cylinder sounds good but it would make your 500 run like a radically ported stock 500 cylinder, not much down low and you better hang on on top.

sorry for the long response,

[LOVEMYCR500]

hey one other thing that I forgot to mention that makes the Saber motor I guess over our CR 500's, with the correct pipe, the Saber will rev to 9500 rpms no problem even with this heavy rotating assembly and live. With the long 144 mm rod and stock 72 mm stroke, the rod/stroke ratio is 2. This is getting along the lines of a banshee rod/stroke ratio. That's the unfortunate thing about the CR 500 in the fact that it's not a bad ratio at 1.8 (TRX is the same at 1. but the CR 500 would probably do better with the same bore size but with less stroke, say making it like a 450 cc to build more top end HP and have better liveability on parts. I think if you could just get another 1000 rpms out of the 500 the way it is (8500 rpms) it could live pretty well and have a huge broad powerband.

[aloha450x]

hey one other thing that I forgot to mention that makes the Saber motor I guess over our CR 500's, with the correct pipe, the Saber will rev to 9500 rpms no problem even with this heavy rotating assembly and live. With the long 144 mm rod and stock 72 mm stroke, the rod/stroke ratio is 2. This is getting along the lines of a banshee rod/stroke ratio. That's the unfortunate thing about the CR 500 in the fact that it's not a bad ratio at 1.8 (TRX is the same at 1. but the CR 500 would probably do better with the same bore size but with less stroke, say making it like a 450 cc to build more top end HP and have better liveability on parts. I think if you could just get another 1000 rpms out of the 500 the way it is (8500 rpms) it could live pretty well and have a huge broad powerband.

wholy shit yu know what's up. so ifyou talk a few mm's off the rod and shave the bottom of the cylinder you will accheive this? will you need to shave the sleeve too a c-hair. correct? how many mm's and how makes the rod? or better yet what bike does the rod belong to?

[100hp honda]

deck wont be a problem.. the difference are made up in the piston height.. not cylinder or cases.. spacers are only needed on a 250r when the early piston is used with the long rod, or if the crank is stroked

im still learning the 250 so let me understand this. when they went to 5mm longer rod, they made up the difference in pin height and not in the cases ?

[LOVEMYCR500]

in the 1985 and 1986 ATC/TRX 250r motors they ran a 125.3 mm rod length and a pistin pin height of 1.142" (approx). Honda ran into some piston wear issues with this length of rod. In 1987 and through it's final year of production the TRX 250r ran a 130.3 mm long rod and the piston pin height was closed to .94". The length of the rod was taken up with the piston pin height. The engine cases weren't touched at all. The big ticket with the MX racers motors was to run the 86 piston in the 87-89 motors and run a spacer plate under the cylinder. Some motor builders felt this extra area got more crankcase area to fill softening the bottom end hit a bit down low, but since you get more cylinder area to fill increased mid/top end performance. After looking at the mid to late 80's CR 250 cases picture on here I think you might have a shot at this saber deal on top of those cases. The only drawback but I guess it's small, the Saber head doesn't have a headstay mount on it so if this isn't a big deal, great even with a balanced crank I think this is going to be one viberating SOP with no counter balancer and you would want to get the motor tied in the chassis real well.

[100hp honda]

from everything i heard the puma is a better way to go and it uses a head stay so that wont be a issue. the vibration is undetermined right now because to the best of my knowledge nobody has ever built one on anything other than a counterbalanced motor. it might shake like a hooker in church, then again it may be smooth as a cadillac

[LOVEMYCR500]

My Puma doesn't have a headstay mount on the head but I know there was work being done to make one but looking at how the head is designed (7 head studs) it will be a challange. This cylinder is really the way to go and if you got the correct year CR 250 motor to put the cylinder on then installed it in a newer CR 250 chassis, that would be a easy one to do. I know right now there are 431 cc Puma's on alky in the mid 90's for HP and my guess before it's over they will be pushing 100 hp. I haven't started my bike yet to tell how the vibes are going to be but since it's balanced it shouldn't be too big of a deal. Did the mid to late 80's CR 250's run the 8 plate bigger clutch basket like the 500 or is it a smaller 7 plate basket?

[100hp honda]

My Puma doesn't have a headstay mount on the head but I know there was work being done to make one but looking at how the head is designed (7 head studs) it will be a challange. This cylinder is really the way to go and if you got the correct year CR 250 motor to put the cylinder on then installed it in a newer CR 250 chassis, that would be a easy one to do. I know right now there are 431 cc Puma's on alky in the mid 90's for HP and my guess before it's over they will be pushing 100 hp. I haven't started my bike yet to tell how the vibes are going to be but since it's balanced it shouldn't be too big of a deal. Did the mid to late 80's CR 250's run the 8 plate bigger clutch basket like the 500 or is it a smaller 7 plate basket?

the headstay version is available . do you have any photos or your motor and pipe configuration ? i want to get a idea of how i could make the pipe work on a 2wheeler

[CR480R]

I would modify an ESR pipe for an atc250r

[CR480R]

I would modify an ESR pipe for an atc250r

[100hp honda]

i talked to a couple motor builders last week, they have the pipe and ignition figured out already. it uses a HUGE pipe and i just wanted a rough idea how it could be routed on a 2wheeler and still have full suspension travel of the front tire without a collision

[LOVEMYCR500]

I don't have anything I could take a picture with to post or I would. My motor is in a quad and I'm not using the one all the draggers are using because this is a dune bike. The quad pipe won't work anyway. The best thing to do is build the bike and take it to Matt Shearer (Shearer Custom pipes) in Ca and have him build you a pipe that will fit your chassis