best CR500 engine?

I am building an AF 500 and going to buy a 99' cr 500. I am going to buy the kit that guy sells on banned's website. I was wondering, what is the best cr500 engine out there? opinions??? Power, Weight, etc. aluminum or steel, parts availability, power, durability. I know that pre 88' and post 93' had longer 4/5 gears, better for enduro/trails. give me your opinions?????

the 85's was the most agressive/powerful, from then on the porting was changed for more low end and less hit progressivly through the years, also i think it's the 85 and 86 have a smaller rear mount (the one the swingarm mounts to as well), so to get these to fit into a newer frame you'll have to drill out the axell mount, a steel convertion is much easier then an ally.

The one you have is the best one!!! Only kidding, but (IMO) any 1995 or newer motor that has good bearings throughout, shifts well and has a good top end will last you a looooong time. Just focus on getting a nice running, good shifting motor and go from there.

As new as you can find.

I have a 95 now and feel its a much smoother motor than the 87 I had before.

A flywheel weight is a must have too

I'd suggest anything '91 and newer for parts availability. If you want a stronger hit, you can always have the cylinder ported, etc.

What year bike are you converting?

sorry guys, im buying a 99' cr 250. Not a 99' cr 500. i've read a lot and found that the gen 1s are the easiest to modify. just mounts, no hacking of the frame! I currently have a 2000 cr 250, but have seen the hacking you have to do to the frame, so im just going to pick up a nice 99' cr 250 and go from there.

I had a '86cr500 and currently have a '99cr500 and can say hands down the '99 has the better engine. The '86 was a powerhouse and I'm sure had more HP, but the characteristics of the '99 make it much more rider friendly.

For dunes, 85 or 86. Anything other than dunes, the newer the better. Better power delivery, starting, etc.

I'd go with a newer 250 frame(better handling with gen 3).. just my .02 cents

what kind of riding are you doing and what is your stature? DO A NEWER BIKE if you are going to do one. The 99 250 to make it work good is just as much work if not more and the bike will never handle as well as a newer style AF.The suspension is dated and the seat is a board. And even when you fix that the bike is rigid as hell as has some front end issues.

so, what other years to do recommend? i currently have a 2000 cr 250, but have heard that there is frame modification, and the gen 1s are just 2 new front frame mounts and a new coil mount. what about the gen 3 cr 250's????


I am also thinking of this winter project (brother-inlaw owns a welding shop) there a thread somewhere that explains what all the "Gens" are?

I am trying to find a CRF250R on the cheap to turn into a 500AF

so, what other years to do recommend? i currently have a 2000 cr 250, but have heard that there is frame modification, and the gen 1s are just 2 new front frame mounts and a new coil mount. what about the gen 3 cr 250's????

The Gen 3 250 has less room front to back so there is a clearance issue with the front of the engine, especially on the right side. There is also the "Y" issue where it has to be raised or highly modified.

IMO, your Gen 2 250 would be easier to convert than a Gen 3. Check the 500 forums for more info. Lots there. :thumbsup:

I am trying to find a CRF250R on the cheap to turn into a 500AF

Those are Gen 4 frames and, yes, there are listings of the different Gen's either here or &

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