At The Back Of The Pack
Arm chair racerFirst time rider
I have been reading some posts about ATC 500r here, and first off, I'd like to say i realize there weren't any pre-production 500r bikes(sheww, that was a long thread).
I picked up a 1985 CR500 over the weekend, and was toying with the idea of building a 500r out of my '85 250r roller.
Is there any advice you guys can give me on this build? Are these bikes even ride-able with such a massive power-plant?
Power User
Got the holeshot
Several members 500 conversions. I've ridden a couple. They are obviously a real handfull. They certainly excel in drag racing and hill climbs. People love them in the dunes too. Louis does very well on the MX track with his.
Got The Holeshot
Arm chair racerJust too addicted
Yes they are rideable, depending on your skill.. The frame will need gusseted and the lower motor mounts will need moved for starters. I've rode a few and they are cool, but I'd take a puma or sphinx 363 or bigger all day long over a 500 motor. The coolest thing about the 500 motor is how it builds so much torque at such a low rpm. They are tractors to say the least.
1985 250r-LED Performance 4mm Stroker motor
1978 ATC70 w/ Piranha 140cc
1972 - K1 - CT70 w/lifan 125cc
2017 YZ 250x- Braap
Youtube channel = http://www.youtube.com/user/ter5678/videos
At The Back Of The Pack
Arm chair racerAt the back of the pack
Man I wish we had choices like the 250r guys. I'd buy a puma for T3 in a heartbeat.
3 86 Tecate 3
1 87 tecate 3 (with kx 540 motor)
1 87 tecate 4 (with 330 motor, 250r geometry)
1 83 atc 70
1 Kfx 50
1 kfx 400 ( with 470 parting out bike)
1 78 KZ 1000 ( with 1340 turbo)
1 Aprilia SXV 550 Supermoto
1 01 ZRX 1200 prostreet (sold)
Problems when we put a 85 CR500 motor into a 85 250R frame was mostly vibration that would turn your hands into a blur on long straights, having to remove the fuel tank to get to the spark plug and the exhaust pipe did not fit very well since its a good bit longer than the 250 pipe is and there is not much extra room to work with.
The 250R fuel tank barely clears the 250 motor and the 500 engine is a lot taller so plan to have work there as well.
Sadly i do not have any good photos of that bike and we only raced it once at the 85 Score Off Road world Championship but it got mangled in practice crash after i hit a downed rider's bike and we parked it and i raced another bike. To be honest i did not like the combo and had no interest in the machine after having ridden it, mostly due to the vibration at high RPMs.
Power User
The day begins with 3WW
I'd just redo the dirtbike and ride it as it is. I can go more places with less power normally then more power...except for hillclimbs that's about it.
At The Back Of The Pack
Arm chair racerFirst time rider
Did you balance the crank? I've read a lot about them not being counter balanced, and tearing motor mounts to shreds. Just curious if it's still a rattle trap when balanced...Originally Posted by John_Neary
This is great info! I'm on the fence about the build, so I appreciate all the pros and cons I can get from people in the know.
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No we did not balance the crank and i suspect that was the core issue as other open class engines like our KTM495 did not bother me at all with vibration.
FACT ! I have no edit button
Arm chair racerThe day begins with 3WW
in general, balancing a single cylinder crank doesn't change how much it vibrates, it only changes where in the rpm range it vibrates.
you can not add a counter balancer to an engine.
stick two wires in a light socket and then grab both ends and that will be about how it feels...at least after you are doing riding it.
FACT ! I have no edit button
Arm chair racerThe day begins with 3WW
Hey John . . you're lucky it wasn't a KX500 engine . . NOBODY, knows how to make an engine vibrate better than Kawasaki . . They were so good at it that even their engines that had a counter balancer vibrated.
The first time I rode an ATC250R I thought it was broken because after riding the Tecates, it didn't feel like it was hardly running.
.
I had a 85,88 and 90 CR500 and they detuned the engine with each year, the 85 was by far the most brutal 500 i ever rode. I also had a 90 and 91 KX500 and honestly they felt much smoother and easier to ride and the power valve gave the engine a dimension the CR500 never had. Likely why the KX500 was considered the greatest desert bike ever made while no one in their right mind would ride a CR500 in a race like the Baja 1000.
FACT ! I have no edit button
Arm chair racerThe day begins with 3WW
sorry, i didn't specify . . i was referring to the lovely 84 and 85 X500's
Wires, Hoses, & Digital Wizardry.
Got the holeshot
Somebody here did this very thing to a CR500 mill for their TRX. I want to say his screen name was Mart?
Yep, I found the thread, and it was Mart: http://www.3wheelerworld.com/showthr...balanced+cr500
Red Rider's Sand Machine Updated 07/23/14
Power User
Roostin Away
Actually, he is converting the 450 into a 2stroke. He's definitely a mad scientist.
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There's nothing like the sound of screaming 2strokes and the smell of race gas in the air
At The Back Of The Pack
Arm chair racerAt the back of the pack
Wow pretty cool counter balance on that 500!!!!!! BIG DIFFERENCE
Last edited by tecaterob; 10-01-2015 at 08:52 AM.
3 86 Tecate 3
1 87 tecate 3 (with kx 540 motor)
1 87 tecate 4 (with 330 motor, 250r geometry)
1 83 atc 70
1 Kfx 50
1 kfx 400 ( with 470 parting out bike)
1 78 KZ 1000 ( with 1340 turbo)
1 Aprilia SXV 550 Supermoto
1 01 ZRX 1200 prostreet (sold)
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