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2001 CR 250 Rebuild

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you are correct. no bridge in the exhaust port so no need to drill. If your going to use a forged piston instead of a cast make sure your piston to cylinder wall clearance is right. forged and cast aluminum expand at different rates. If you one of people that starts your bike and immediately rev's the shit out of it to because it's not jetted right, stick with a cast piston.

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Thanks BBars.

With the Boyesen Power Reeds, am I not supposed to use the stock large, angled rev plates at all? And instead use the included Boyesen small rectangular rev plate? The install directions make it sounds this way but seems strange to me...

Bikes coming along well. Just got the left and right crank cases back on with the new crank seals. The new ones were relatively simple to press in. I found a mountain bike tool that fit perfect for landing on the OD of the seal and just hammered slowly and evenly. Still trying to locate a clutch hub holder to get that center bolt back on.

Edited by Cleetis
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Thanks Hard Hit.

Instead of using a clutch hub holder I put the bike in a high gear and threw a stiff broom handle in spokes of the rear wheel. I was able to get the clutch center nut to the ~700in-lbs spec with this moethod. Saved me from a $20 tool.

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cheap clutch tool, take a metal and fiber plate and install them in the clutch. Drill 2 holes in them for pop rivets while they are installed at 180 off like 12 and 6. Remove them, pop rivet them. Drill more holes and more rivets to hold things good. You could do all the drilling in the basket but this way will keep the junk in the motor to a minimum.

Install new tool and torque to spec. Don't forget to bend a couple tabs up on your NEW washer. You can reuse em is they haven't been reused before.

A wire wheel mounted to a grinder works better than anything for removing carbon. The spooge is easy to get rid of, gas is cheap just use gloves. I don't bother with the moly for assembly, 2 stroke oil does the trick, not that moly is bad, I just don't keep it around.

Be dam careful when lowering the jug on the cases to make sure the nipply sticking up is going into the female groove on the bottom of the jug. If you are off it will bend an expensive part and bind the PV up. The manual explains how to adjust it. A 10 or 15mm PV spacer give more low end as well as a 4mm pipe spacer.

Sanding that intake is a waste of time.

Do a compression test after you get the motor put together. Record it and check it every 20 hours. If it drops you know you are overdue for a rebuild. I run an hour meter for records too.

Lots of guy ditch that carb and put on a pwk........

Honda sets the stock carb up a bit rich generally. Poor Mileage can come from rich jetting as well as too high a float setting.

Grease the inner and outter parts of the seals before installing them. I like to clean my lower end out with diesel while I have my top end off If any dirt gets down in there, then put the 2 stroke oil to the lower end rod bearing and crank bearings.

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Right, you can buy a cover from boyesen that has it integrated in to the cover or just get a spacer and run 2 gaskets. I had to dent my SST pipe with w 15mm spacer.

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With the 10mm spacer you don't have to dent the pipe. with a 15 on a SST I had to, other brands you may not have to dent it. regardless the dent is so small that it doesn't affect power and you can't see it either. Dents in the small part of the pipe affect power much more than in the large part. It takes a good size dent in the large part to change things, something the size of a pea = no difference.

Those spacers work and are helpful.

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So I just started the bike up for the first time since the new top end, new reeds and new crankshaft seals. Fired up third kick- stoked. I just let it warm up then reved a few 1/4 throttle revs and turned her off. Then, put it in neutral and tried to wheel it in the garage. It rolled a few feet and I heard a light clicking noise so I stopped and rolled it backwards a little (light clicking again) then rolled it forward again and it locked up. Now, when in neutral it always locks up rolling forward and when I roll it backwards it makes a light clicking noise... When it gear it acts like it should and it starts back up just fine. I'm going to tilt the bike on its left side tomorrow and pull the right crank case again and look around.... but, does anyone have any theories or leads on where to look first? My only theory so far is that the kick start spring came unseated in the case when I installed that right cover again.

Edited by Cleetis

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So I just started the bike up for the first time since the new top end, new reeds and new crankshaft seals. Fired up third kick- stoked. I just let it warm up then reved a few 1/4 throttle revs and turned her off. Then, put it in neutral and tried to wheel it in the garage. It rolled a few feet and I heard a light clicking noise so I stopped and rolled it backwards a little (light clicking again) then rolled it forward again and it locked up. Now, when in neutral it always locks up rolling forward and when I roll it backwards it makes a light clicking noise... When it gear it acts like it should and it starts back up just fine. I'm going to tilt the bike on its left side tomorrow and pull the right crank case again and look around.... but, does anyone have any theories or leads on where to look first? My only theory so far is that the kick start spring came unseated in the case when I installed that right cover again.

your on the right track, have you ever split the cases ?

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Nope, havn't split the cases before. Hoping that I dont need too. When pulling the right case cover and then reinstalling can I reuse my one day old gasket or is that a bad idea?

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Reuse it if it doesn rip apart when you pull the cover. I'd have to back and reread the thread, prolly info in that part that I've forgot, did you allready get into that clutch cover? Doing a top end shouldn't affect the bottom end.

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I also replaced the crank seals so I had to pull the left and right case covers, kick start mechanism, idler gear, entire clutch assembly and governor gear.

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you need to check that entire right side then, take the clutch apart, make sure you have the washers in the right places, and facing the right way, make sure nothing came loose and also make sure that the kick start gears are on the right marks and the spring collar is in place correctly keep us posted

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Hrm, got her on her side with the right crank case cover off. Took out the clutch plates too. Everything looks normal and it even shifts through all the gears while I spin the rear wheel. Neutral exists and works too... its like nothing is wrong. Can something go wrong between the state the bikes in now and buttoning her back up? I don't understand...

Edited by Cleetis

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yes if the kicker gear is not assembled right it will hit the clutch basket gear and make said noise

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Aha! I figured it out, but am not sure I want to disclose the problem... take some guesses from this picture... not the kicker assembly...

2i099vb.jpg

Some buttoned up victory pictures of her...

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29dgzko.jpg

Edited by Cleetis

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clutch actuation arm?

Its hard to tell from that picture but an 'only-snug-tight' nut from the upper triangle shapped engine bracket vibrated off during the first start and fell into the front sprocket and jammed up in there. Depending on if I rolled forwards or backwards the nut would move and lock up the rear wheel one direction or the other. Neutral didn't jam either direction when the bike was on its side because that damned nut would fall free of the sprocket but would still be held in that area by the sprocket cover. Oops!

Now I just need to properly jet this silly carb. What jetting kits do most people get for the TMX? The JD kit looks like it only comes with Needle and main jets, and no pilots??

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