250-500cc Next Project - 6 speed WR 250

[msmith345]

Well, the last project was the 1992 360 engine in my 2012 WR300 frame. It's good, but it was really only ever intended as a temporary solution while I rebuilt the WR300 and figured out what to do on the rebuild. Racing season is over, so it's time to start work on the WR300. The 360 will probably go bike in it's own frame until I decide to do a wide open race and swap it back in for the weekend.

I've acquired a very low hour WR250 top end from this site. It's a good bunch of guys (and gals) out there. It's not a 300, but I figure my buddy always beats me on his '09 WR250, so I might as well give it a shot. I can always (finally) send out the 300 for a replate before the next top end and swap it back to a big bore. Then maybe build out the CR250 bottom end I've got sitting around with the 250 top end...who knows?

With my 360, came an extra 6 speed. Once I found that in the box of parts, it was a given that it would be going into the rebuild. That option of gears is incredible on the 360, so I can't see it being any less spectacular on the 250/300.

So, the end result will be a 2012 WR250 with a 6 speed and 38mm Lectron with a DEP CR250 pipe. This should be an excellent set up for the enduros I've been running, and that I intend to run next year. (2014 tentative schedule) Should be MUCH less tiring than the 360, but not near as much fun on the hills and transfer sections. I think it should be adequate if I run a bit more aggressively like I did on my old KTM 200.

I'll probably split the cases and start fitting things up next week. The piston fragments on the 300 seem to have all stayed in the top end, so I'm thinking I'll be able to get away with just flushing the bottom end real well. I check it over when I split the cases to do the transmission. If things don't look confidence inspiring, I'll go ahead and replace the bearings.

I will need to locate a flywheel puller (I haven't looked to see if I have one that fits yet). So, if anyone knows that size off the top of their head, let me know, otherwise I'll get my search on.

Any other recommendations as I figure out this build? I'm thinking I'll need to play with gearing once I have it together, 13/48 will probably not be low enough, maybe 13/50?

I'm definitely not buying a new Husky until the next owner. So, I plan on keeping this thing going for quite some time. I'm completely in love the feel of this bike, so that's why the stock pile of engines and parts.

 

[MOTORHEAD]

As cheap as bearings are, I wouldn't even consider splitting the cases without changing them after a blown top end.

I think I'm going to do a 6 speed swap on my 250 also. I had an '08 with a 6 speed and it was really nice. The 80+ mph top end is cool.

 

[Xcuvator]

I have done alot of stuff to my old 04 WR 250, but the 6 speed was the best after the suspension was sorted. The only problem is that I finished my 165 project a few months after the 250 6 speed conversion and make over. The 165 seems to get all the riding.

 

[msmith345]

As cheap as bearings are, I wouldn't even consider splitting the cases without changing them after a blown top end.

Yeah, good point. I'm sure that's the conclusion I would've come to once I actually got to pulling things apart.


What gearing did you guys end up running on your 6 speed 250s? Does it pull strong on the 13/48 gearing, or did you need to drop it a bit to get the spread a bit closer?

 

[Eaglefreek]

15/48 or 15/50 according to this thread http://www.thumpertalk.com/topic/532293-wr-250-5-speed-to-6-speed-swap/

 

[juicypips]

22mm x 1.5mm rnd thread as far as i recall.

loved the 360 in the 250 mission look forward too reading more about splitting cases.
imo i dont replace bearings unless theyre shot. ive had crank bearings go through a top end and the breaings were fine.

use your judgment its your engine and your peace of mind.

 

[msmith345]

22mm x 1.5mm rnd thread as far as i recall.

loved the 360 in the 250 mission look forward too reading more about splitting cases.
imo i dont replace bearings unless theyre shot. ive had crank bearings go through a top end and the breaings were fine.

use your judgment its your engine and your peace of mind.

Thanks, I did a bit of looking and that seems to be the right size. Now I just need to figure out if I've got one, if I do where it's at, if not get it ordered.

I haven't split the cases yet on this, but I've done it on other engines. It's really not too complicated. Sometimes it's a bit annoying getting all the pieces lined up perfect, but just like working on anything don't rush, don't force anything, and don't let yourself take risks...and use the right tools for the job.

 

[juicypips]

you got it in one, take your time and be methodical in your approach.
if you cant find a flywheel puller im 80% sure you can split the cases with it intact just hope the crank shaft bearing slides off the correct side.
you would have to get lucky with it tho.

 

[msmith345]

you got it in one, take your time and be methodical in your approach.
if you cant find a flywheel puller im 80% sure you can split the cases with it intact just hope the crank shaft bearing slides off the correct side.
you would have to get lucky with it tho.

Looks like it's the same size puller as a Honda XR and the Kawasaki KLR 650 (and a bunch of Honda street bikes) $9 from motion pro. Should be pretty easy to locate one.

Thinking it over, I've got time to fully split the cases and go ahead and replace the bearings now. If something got in there and I had a failure mid season, I wouldn't have this kind of free time (not racing until March, still have the 360 in for winter riding). So, for peace of mind I might as well do it now. That gives me a new base for next couple hundred hours.

 

[MOTORHEAD]

Yeah, good point. I'm sure that's the conclusion I would've come to once I actually got to pulling things apart.


What gearing did you guys end up running on your 6 speed 250s? Does it pull strong on the 13/48 gearing, or did you need to drop it a bit to get the spread a bit closer?

I was running 14/47 and 48. Never even considered trying 13/48.

 

[justintendo]

call halls and you can get one cheap...and know it will fit

 

[msmith345]

Hall's a great if you need a part quickly, they have it in stock, and your local dealer wouldn't be able to have one ordered in quick enough. It's not a matter of cost, because it will cost you extra. Around $15 shipping for a tiny part. So, that shout out for them really isn't called for on a $9 flywheel puller that is not an uncommon tool and is used across multiple machines. Not knocking them, it's just that there are multiple options.

 

[msmith345]

Just wanted to update, now that I actually looked at things. The flywheel puller is not as I have mentioned above, it won't be the same type as a KLR or XR. I crossed that out from my above post to hopefully prevent some confusion.

 

[MOTORHEAD]

I think it's a 22mm x 1.5 pitch. I've got a whole drawer full of pullers, but I think that's the right one for the WR.

 

[msmith345]

Well, an update. I didn't even need a puller. It pulled straight off by hand.

The cases split nicely. Cleaned up all the gasket and took a tooth brush and mineral spirits to everything, then wiped it all down and sprayed with fogging oil to keep things nice. Really not much out of the ordinary.

Bearings pulled out fine. I used a 2x4 with a hole drilled in it. 5/16 inch all thread, two nuts, an assortment of washers and a 27mm 1/2 socket. Fashioned all those up into a puller. Hit the cases around the main bearings with some heat them pulled them out.

Really the only challenge was all of the needle bearings had fallen out of the 6 speed tranny, so some cold grease on the shaft to get those to stick in place and all was set. The other challenge is that the 6 speed requires different bearings for both ends of the shift drum, and for one of the tranny shafts. I've got some 360 cases laying around, so I'm going to pull those and swap across to fit everything up. I'll probably go ahead and order up the new bearings and drop them in when I know everything is going to work. I'm assembling everything into the clutch side of the case first, so testing the shifting should be pretty easy.

It's looking pretty good some far and I'm getting pretty high hopes for a killer enduro weapon it's going to be.

 

[2premo]

on needle bearings use Vaseline not grease
on the gearing, what are your plans for the bike, racing as I understood, what type and what terrain, I run 15/48 stock gears on a 360 and could see a well tuned 250 handle these everywhere but tight woods riding or in your case racing

 

[juicypips]

pulled off by hand?!? make sure you tourqe the thing up when you rebuild wobbly flywheel not too sure how that would affect the running.
glad it went smoothly im thinking of tearing down my bottom end now .... but its still spinning so i may give it a miss.

gearing i find im up tthe gears and in 6th befor 200m from start on most hard packed surfaces, have 14/48 gearing.
waiting for my chain to wear so i can fit the 15 front as the chains against the adjusters tight to the swing arm.

 

[msmith345]

And I finally got everything together after a few days of working on it until the wee hours of the morning. My plan was to go ride tomorrow since it is going to be ridiculously nice. But it wouldn't fire, so I started going through everything and it's gotta be the ignition. I was hoping it wasn't, but no spark. Excellent compression, and fuel, but no spark.

So, now the 360 is sitting on my bench, and not enough time to swap it back into either frame to ride tomorrow. Pretty bummed. I guess this gives me a chance to find a CR ignition, but dang...just ugh.

Going to spend the day on the Strada tomorrow and try to figure out what to do next.

 

[juicypips]

bummer, is the 250 ignition not the same as the 360? my 1999 and 2002 are identical ignitions but your year gap may be a bit big.
so whip the ignition off the 250 and go through all the connections, you may find its the ht lead from the coil to the spark plug not screwed in there i opt for copper wire instead of carbon, i dont trust it to be conductive.

 

[msmith345]

As an update on this, since the 1992 360 used the Motoplat ignition, it isn't compatible. So, UPS will be delivering the PVL #70049 to my door this afternoon. I'm not sure that there's really anything to document on the install, but I'll definitely be posting up my thoughts on it when I get it fired up.

I do have high hopes for this setup, despite some of the hard starting reports I've found since purchasing. The small internal flywheel should be very noticeable, and I may need to add the FWW after I see how it runs. We'll see, but I'm pretty excited to find out. A 250 with less flywheel, possibly a more aggressive ignition, the 38mm Lectron and a 6 speed. It should flat out rip. The Concho National Enduro should be a great first race of the year test on it, being a fast wide open run. Then I'll hit a very gnarly 100 miles of enduro the following Sunday at White Rock, AR that will really put it to the test in technical single track.

Along with the ignition, I ordered a dial indicator with an aluminum adapter for the spark plug hole machined with a set screw. It's a simple setup, but I tested it last night and with that tool and I'm very confident of the point of TDC and that I will be able to set the timing incredibly accurate with it.

I've got an awards banquet for the 2013 season to go to tomorrow night, but I'll be hoping to get this installed either tonight or tomorrow morning and get it fired up. Too bad that they are allowing riding tomorrow and Sunday, as I won't be hauling my bike with. I'd love to get a test ride in there, but it's not int he cards. To top it off, it's snowing again today, so my test ride will have to be limited to blasting through the streets of suburbia on snow dusted roads...might not get a very good test ride in if I can't get above half throttle.