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2531
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8/7/2009
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NM
US
Edited Date/Time
11/14/2020 12:18pm
I just picked up a mint 02cr250 and want to do a decent build.
What the best engine combo? Can I use the better 03 cylinder on the 02 bottom end? What about reed cage set up? Will the newer 03 reed setup bolt on?
I wanted a 03-07 but this bike came up and it was to clean to pass up.
What the best engine combo? Can I use the better 03 cylinder on the 02 bottom end? What about reed cage set up? Will the newer 03 reed setup bolt on?
I wanted a 03-07 but this bike came up and it was to clean to pass up.
In all seriousness, I had TMR do mine and was impressed with the bike and in my dealings with Tom. True stand-up guy and an encyclopedia of two stroke knowledge.
I have heard good things about what PC can do with these as well.
I wouldn’t worry about 02-03. Slight difference but nothing earth shattering. Have a good tuner do the head and porting and they rip.
I would advise picking up a spare cylinder and power valve if you run across one, since they’re getting hard to find. There are slight differences between 02, 03, and 04 power valves, so make sure to have that years set. 05-07 was a completely different cylinder and power valve.
The Shop
I know H4L on here knows the ins and outs of these early case reed bikes. Pro circuit Or Tom Morgan may be an option. I usually do my own porting as I’ve seen some questionable work from bigger shops.
Eric Gorr has a Tech Tips article for free on his site for the '02-04 CR250. From what I recall, it basically cut the base by 0.030" and raised the exhaust port by 0.060". So you'd get more low end from the base cut and have it pull farther on the top end from raising the exhaust port. Based on my experience with shifting the gaskets around, I think this would work pretty well for cheap. I also had an '05 CR250 with the base cut and head opened up to match. It was super crisp from the bottom through the midrange, but fell off a bit on top.
The TMX can be finicky without proper squish. Hence why many went to the PWK. The PWK is really set it and forget it though. I ended up liking the TMX on my '05 better after the head was modded.
I had a V-Force 3 reed valve on my '03. Minor improvement.
Brakes: braided steel lines improve feel front and rear. Oversized rotors are hard to find for the '01-'03 due to the different caliper bracket bolt spacing. An oversized rotor on my '05 made the brake performance close to KTM levels.
Forks: '02 still used the 20mm base valve pistons, but still aren't bad. Springs and maybe revalve should have them working good.
Side note: I have a Gnarly pipe and Turbine Core silencer from my '03 still. Will sell super cheap if you're interested.
Edited to add: some epoxy in the transfer ports also helped in the low to mid transition without impacting top end much. I did this on the ‘03 cylinder I had.
Lots of other useful info on the Honda 2-stroke forum on TT.
I’ll pass on the gnarly setup. One reason I’m building one of these older Honda’s is to have the top end performance. That’s something the newer ktm/husky just doesn’t do very well.
Remeber doing a lot of stuff with the PV. Very picky about the set if I remember right. Made a little stop limiter that I thought worked really well, but I don't remember the details. I do remember I got to were I would never clean them if the moved smoothly because I thought they sealed better with carbon filling up all the cracks. I know it ran better with dirty PV's.
Tried a sorts of pipes and ended up with the stock pipe and silencer. And YES, you have to have a sealing ring for the air box, but you've got that.
Nothing in here should dissuade you from PC. H4L had a very good experience with them and the bike reportedly ripped. I just got a vibe I didn’t like and went elsewhere.
Sadly, Varner was magic with these from what I hear, but based on the other thread here, his customer service has been such a train wreck that I wouldn’t risk my cylinder there.
Tom does deck the cylinder, so if you’re after a mid-up motor make sure to discuss that with him. I told him I was an out of shape Vet C/B rider and didn’t want to have to ride it like a 125, so I believe he tailored it more towards the fat old guy end of the power curve, lol.
They've commented that the 03 cyl. has the best oem porting specs & platform to work off of. After tuning these bikes & owning them since 03 these have been my findings as well. Have owned many 02,03,05,06 & 07 models & the 03 cyl. is my favorite.
I've been running an 03 PC cyl./ head & reed cage combo on an 02 bottom end since 05 with very good results.
It's at the 4:40 mark.
https://youtu.be/nPw8thCyXHw?t=280
Thanks for the info!
They have a cookie cutter engine setup where the only options offered to choose from are a pump gas head, or race fuel head. No other options are available.
PC does not mill the cylinder base, and does not use epoxy in any of the ports or transfer tunnels. These engines run well and are a good value for your money. Big improvement over stock.
However, overall customer service, and their unwillingness to answer detailed questions or offer any setup help are definitely NOT PC's strong points.
Conversely, Morgan offers some of the best customer service in the business. Quick to respond to inquiries, and willing to offer customized options based upon the needs of each client, he's top shelf on service.
Pit Row
We e-mailed JD ignition in Italy a few months ago and they were offering a double map 05-07 iginition. Didn't inquire about 02-04 but they're worth contacting.
But in all seriousness I will just have to see what jd says. I can’t ride the bike to its potential with the stock ignition anyways so I’m sure it would be fine. I just like shiny things that go braaapppp!
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