250-500cc Next Project - 6 speed WR 250

[msmith345]

I'll have to hash out the ideas a little better first. Might do some physics and bust out the pencil and paper and do some calculations as well. Keeping roughly the same lever feel, with just a lighter pull will be a bit complicated.

Clutch pull seemed lighter initially before the thrash test. I used an extra clutch actuator from a 360, that seemed to be about a 1/4 inch longer on the arm, which should have given some of the mechanical advantage others have used by extending the arm. The cable I was surprised with. It still flexes. I was under the impression that the $40 (3 month wait) longitudinally wound cables would not compress like that. They still do.

Hydro clutches, I'm trying to avoid. I've had some bad experiences with them in the past. When they work, they're great. When the seal lets loose and you have a loose lever flopping around, they don't work so hot.

Suspension works real well as is, but it always seems to work better after it gets all changed around by someone else. Maybe it's the weight loss from the $500 in my back pocket. Right now, I've only got new springs in it, 48/5.8 I believe, clickers adjusted around for the best feel on that day's terrain. Works good, but it's more a question of how good could it be.

 

[Kyle Tarry]

I'm completely with you on the clutch. I bought the Terminator cable and I am not impressed with it. Based on what I read here, I was expecting magical unicorns to leap out of my bike's vent tubes, but in reality I think it only slightly changed the lever feel. It definitely still has plenty of "stretchy cable" feel to it.

I am going to make a bolt-on arm extension for the release pull lever to experiment with that in a reversible fashion. I figure that changes on this side of the cable have a double benefit because it reduces the lever pull force, but it also reduces the cable tension, and so should assist with the cable stretch and housing compression as well (which, for example, a reduced pull clutch lever won't help with). If you want to collaborate on some things, feel free to get in touch with me via email or PM. I have access to a full machine shop and use CAD on a daily basis so I can prototype parts pretty easily.

On suspension, you seem like you'd easily be a competent enough mechanic to do some tweaking on stuff yourself. I figure that we can DIY revalve and get to at least 75% of the performance level of a professional revalve, for about 10% the cost, so it's a valuable tradeoff. A bunch of guys have been into the WR forks and shock quite a few times, and have posted a good array of info in the revalve thread here. I've changed my thinking on forks somewhat, and for my next iteration I am going to try more float on the midvalve and more damping on the base for a more linear feel, which I think will be nice; I've already been able to make big improvements over the stock stuff, at least for my skill/speed/terrain. In my opinion the stock stuff was more of a scramble/GNCC setup for a decently fast rider, whereas I am slower and wanted more compliance for slower technical riding.

 

[Eaglefreek]

If you guys haven't already, lube the heck out of the Terminator cable, I didn't notice much of a difference until I did and I have to relube it every other ride. With the Righteous Stunt clutch perch, MP cable and adding 5mm to the arm, my clutch pull is quite a bit easier. Still not as easy as a hydro or a KDX200, though.

 

[Kyle Tarry]

I lube my cable too, and it definitely make a big difference. I don't do it every 2 rides, but maybe I should!

Do you have a sense for how much the RSM clutch perch/lever changes the leverage ratio, relative to stock? In my opinion, it would be better to do that leverage change down at the other end (at the release lever on the trans), because down there it reduces the tension in the entire length of the cable, which probably helps reduce cable drag and cable/housing stretch. However, the downside of doing it there is that you now require more cable travel for the same disengagement (the RSM perch also requires more lever travel, but not more cable travel).

I am going to try extending the arm on the order of 3/8 of an inch or so (need to take some measurements to see what the length is now and what I can fit) and see how that works.

I have also going to slightly softer clutch springs, about 10-20% softer than stock. This means that there is a higher risk of having the clutch slip or be unable to hold the power, but I have not seen any issues yet. I figured that if the 125 guys can go to 165+ with stock clutches and not slip, the 250/300s probably have a similarly large amount of margin built into them too.

Does your RSM clutch have the bushing or the bearing? I have a spare clutch lever, I might try milling the hole out and installing a sealed ball bearing in there. I will take some measurements tonight and see what off-the-shelf bearing options there might be. A decent bushing usually has a pretty low amount of sliding friction anyway, so it probably won't make a difference...

 

[Eaglefreek]

Do you have a sense for how much the RSM clutch perch/lever changes the leverage ratio, relative to stock?

I just noticed it was easier to pull, I don't know how to translate that into a lever ratio. I thought about getting a fish scale and seeing what the difference in pull would have been, but I didn't.

I have also going to slightly softer clutch springs, about 10-20% softer than stock. This means that there is a higher risk of having the clutch slip or be unable to hold the power, but I have not seen any issues yet. I figured that if the 125 guys can go to 165+ with stock clutches and not slip, the 250/300s probably have a similarly large amount of margin built into them too.

I read somewhere, that someone suggested to take out two of the clutch springs. I tried it and it slipped horribly.

Does your RSM clutch have the bushing or the bearing?

Bushing

 

[msmith345]

Well, chrimany. Seems like I'm losing my mind.

I found the answer to the complaints with my clutch feel. I pulled it apart last night, and in 2 enduros since the 250 conversion, the clutch basket has developed serious grooves. I pulled out the 360 actuator arm and put the stock 300 one back in place. The clutch rod had some grooves worn on it from the 360 arm hitting it at full clutch pull. If the grooves weren't there, I don't think it'd have happened. But as a precaution, I'd warn against using that setup. It's a longer arm, and an easier pull at first, but maybe not a drop in fix. It's almost identical to the arm on an '02 CR250 though, with the exception that the older 360 had a longer pull. The actuator part is the same design, which is different from the 300's.

So, clutch problem figured out, time to pull the basket from the CR250 bottom end and get myself good for this weekend. Well, the CR has some grooving too. Not as bad as the one I've got in there, but still not good. So, I go looking for my file, not in my tool box, not on my work bench. Yeah, no where to be found. Someone must have borrowed it without mentioning it to me. So aluminum bar and 220 grit wet sand paper was used to smooth it out. It's not great, but it's better. Planned on ordering a fast by Feracci clutch basket today, but their site's down and I can't find one. Probably end up picking up another file and cleaning up the CR basket to put in tonight.

On to the next complaint, the lack of power. This part I'm a bit pissed about, it was a huge oversight on my part. I had a pile of front sprockets for the 360 in a box. 14-17 tooth. Well, somehow, I managed to mistake a 15 tooth for a 14 tooth, and then managed to fit it on the bike. That's why the chain wasn't fitting. That's why there was no snap. That's why it was so fast once up on the pipe, and that's why I had to use so much clutch. I found this out because I trashed my chain and Supersprox rear sprocket last weekend. I ordered up a new 13/48 combo and installed last night with a new chain.

So, I should have a lot more snap this weekend, and a slightly better clutch pull. But damn, I'm irritated that I missed that sprocket -- and that someone "borrowed" my file from my tool box.

I'm surprised I was able to run the bike on some of the stuff I've been running with that tall of gearing. This bike may yet be the rock star enduro weapon I had planned on it being.

 

[msmith345]

CATASTROPHIC FAILURE!

Well, 2 enduros on the rebuild. The clutch "fix" above. Show up at the harescramble Sunday and go for a practice lap. Clutch is slipping whenever I get on the pipe. I make the 7 mile lap and am debating throwing it back on the trailer, or salvaging some points and avoiding a DNS.

So, I suck it up and line up, with the intention of putting in 1 lap, then loading up. Super fun course though. On the first lap of the race the slipping clutch seems a little odd. I have my clutch cable completely slacked. Then on a long uphill, the clutch slipping turns into a clunking. I make it to the top with a lot of racket. I'm about 4 miles into the lap. I've got to finish it out to get points, the damage is already done anyway. I get into a higher speed section and I realize that above third gear, there is no noise, and there is no slipping. Hmm...so I start thinking about the transmission and keeping it above 3rd gear, readjusting my clutch which is now ridiculously light, it feels like there is no resistance on the pull, but it's working awesome. I come around scoring and drop it into 2nd and give the pits area a taste of the racket. Lots of looks of horror on their faces. Damage is already done. I decide to go for another lap, it's just too good of a course. So, I take off keeping it in 3rd and going way to fast through some sections, so I can keep my momentum. Manage to pull some long hill climbs in 3rd, with lots of clutch abuse and a LOT of momentum at the bottom of the hill. Not sure I would ever have hit that hill in 4th gear pinned had I had a 2nd gear to down shift to, but it was something. Scream it in 4th, drop to 3rd, scream some more, drops down to a chug, and some clutch fanning and makes it to the top, bouncing off rocks left and right, not even remotely in control.

So, I come around from that lap and call it quits, load up. Happen to realize one of the guys I always see at those races happens to be Troy Deck from this site, so that was cool to make that connection. He witnessed the terrible sound.

So, next steps are:
1. Assess the '02 CR250 bottom end I have sitting on a shelf. Upon last inspection, everything rotated freely, but I had not split the cases.
2a. If the CR bottom end feels good, I'll swap the top end and electrics over to it. Drop it into my frame, make sure it's all ready for the enduro on Sunday (the 13th), then ready for my 9 hr Ironman attempt at The Off Road Cup on the 19th.
2b. If the CR bottom end doesn't feel good. Then the '92 will receive it's final prep and will be raced for this weekend. And I'll try to have the 250 ready for the 9 hour.
3. Split the cases of the '12 and see what the damage is to the transmission, and try to figure out how and why it failed. A 250 doesn't put out near the power the 360 does, so SOMETHING must have happened.
4. Rebuild '12 bottom end with the original 5 speed.

So, project 6-speed 250 has come to an extremely abrupt end. It's done.

 

[juicypips]

Man that flat out sucks, so put 250 back to five speed?
Am so surprised clutch noise an everything stopped on 3rd gear +
You may find a clutch plates cracked and is rotating against friction causing funky noise?!? Maybe ive no clue really but curious as to what it is thats happend.

 

[msmith345]

Man that flat out sucks, so put 250 back to five speed?
Am so surprised clutch noise an everything stopped on 3rd gear +
You may find a clutch plates cracked and is rotating against friction causing funky noise?!? Maybe ive no clue really but curious as to what it is thats happend.

Yep, I'm curious too. There wasn't so much a clutch noise, as it had the same feel that it does if the clutch is slipping. It power was there, then get into the power and the engine kept building RPMs, but the bike started slowing down. So, it was pretty weird at that point there was no odd noise. Eventually that worked into a horrible grinding spinning. Here's a crop from a parts diagram with my notes on what I think was the problem, and why I think I was able to ride in 3rd/4th gear without issue.

Note I did not mark it, but #14 is 4th gear, #15 is 3rd gear. I believe where first gear interlocks with 5th and where 2nd interlocks with 6th is where the problem is. I think those engagement fingers either rounded or broke off. I don't know why this would have allowed the freewheeling aspect prior to the noise, unless that was in fact the clutch slipping.

I'll have my case tools back sometime this week, and we'll see how screwed up everything is. One things for sure, I expect to see a lot of metal in my oil.

 

[juicypips]

Please let us know, seems odd if the interlocks on the gear teeth have failed as its a dog box designed to be jammed into gear without clutch.
Perhaps the 250 motors too powerful for the frail old 360 gears...
Yeh i would expect very silvery oil and a few bearings needing a good clean or replace.
Just aswell the 250's a cheap rebuild.

Incidentally i dont know about you but the crank bearings 6503?? The are expensive if you get c4, like £18 each here
I slammed a set of c3's in my 360 a few weeks back and so far no problem they came in under 18 the pair..
All helps i think

 

[msmith345]

First problem found. This might have been the cause. Somehow the pin came out of the power valve actuator. And the bearing, which is the same as the clutch throw out bearing, but doesn't have a keeper for the needles, came apart. All but one of them are accounted for. Found them throughout my oil. The magnetic drain plug had not caught them all.

Should have my tools back tomorrow to split the cases, but I don't have a good feeling about this. My oil was silver.

More than likely, I'll be repping old school with the 92 for a while. It's gonna look funny with my watchdog on it.

 

[msmith345]

Well, still waiting on the return of my tools.

Sidenote: I used the CR250 bottom end (with the PVL ignition) for the enduro over the weekend. Crap if you were moving slow in the technical as there isn't any flywheel weight, but there was some awesome loamy berms through the woods for a few miles they all seemed to have a rock garden right near the exit of the turn, but DAMN that thing was cutting those berms and accelerating so hard I didn't even notice the rock gardens, it was just turn, roost, jump, brake, turn, roost, jump. It's a viable keeper for a second bike, but it's definitely not a grunter. I made a poor line choice 0.8 miles into the enduro and drowned my bike (and I took a swim as well). So, that set me up for 56 minutes late to the first check, and it was a matter of screwing the time and hauling as fast as I could without making any stops. Worked out to about a 3 hr moto with a 1 minute gas stop before I threw in the towel at the end of the C course after tweaking my knee and shoulder in a near highside.

 

[juicypips]

Im glad to see a flaw in the cr ingnition seeing as i ride woods mainly grunty motors what im after.
Shame about tools i fricking hate people borrowing mine as i always end up with an extra hammer and missing sockets! As if a hammer makes up for you nicking my sockets!
Anyway you only need 8mm an circlip plires, 27mm socket thats about it.
Hope injurys are minor and heal fast!

 

[msmith345]

Im glad to see a flaw in the cr ingnition seeing as i ride woods mainly grunty motors what im after.
Shame about tools i fricking hate people borrowing mine as i always end up with an extra hammer and missing sockets! As if a hammer makes up for you nicking my sockets!
Anyway you only need 8mm an circlip plires, 27mm socket thats about it.
Hope injurys are minor and heal fast!

It's the case splitter, crank puller, and flywheel puller I'm waiting for. Need to get that apart to actually see the transmission...it's bugging me. Been sitting there stripped down and ready to split for a week. At least I had getting the other bottom end ready to keep me distracted from wanting to see the damage. If I wasn't ADD enough, I'm also in the process of buying my first house (was actually doing the whole offer/counter offer stuff over the phone while driving to and from the race), so yeah too many shiny things, too little focused thoughts.

 

[juicypips]

Dammit i forgot about those lol
Yup shiny things keep me busy but i don't have enough funds to buy all the bling, lower the cost of billet products please
Got new lid on the way too couldn't decide between Airoh or fox so ordered them both :s last years models so only cost the same as one full price.
Ive never used case splitters thats what three tyre spoons are for, crank puller? Blowtorch n gentle persuasion.
But flywheel puller is the stumper must admit ive never got a flywheel off without one, unless you count the time i left the nut undone.... Lol

 

[juicypips]

So did you work out what went bang?
Looking into pvl ignitions again msmith you think theyre still junk?
Any other aftermarket setups worth investing in?

 

[msmith345]

Well, still haven't gotten my tools back. Almost finished moving (only Internet is on my phone, so unless I'm at work, I'm not really checking in here), then it's onto setting up my shop and getting that puppy split.

I may have been too harsh on the PVL system. It works well, just not enough weight for enduros. They do make wright's for it, but at near $500 up front cost, I'd be hard pressed to spend another however much for the weight to make it run right.

On my 390 I'll likely go with an MZB/Powerdynamo (they don't make one for the 250/300/360 that I've seen). Electrex seems to make a lot as well - at a much cheaper price point (and are UK based I think) they may have something for the 250-360.

 

[juicypips]

i can get pvl for£160 as theyre only in germany, so the cost isnt too much of an issue, i was planning to make the 360 into a more revvy motor as the large bore will give the torque and the internal magneto may help the beast come on power quicker (im hoping)
i sold the parts of my 250 to a friend for cheap its lacking ignition so if i can get pvl set up on 360 he can have my old wr ignition as i can run lights from a battery, for the most part i already have bar and head torches for night so its no loss in that department.
i will look into mzb many thanks for the knowledge and good luck with re-aquiring your tools.

 

[2premo]

if you want your 360 to be a "more revvy motor" abandon your current cylinder
I did an expose on what I learned from 3 different 360 model years the 92 was the highest revving followed closely by the 93 and the 99 was waaaaaay back
get a 92 to 97 cylinder, warning on the 92 you will need a pipe or at least the head piece
by the way the bonus is up to 97 they kick start like a 250, the decompressor is for 98 -2002
I bought a NOS early cylinder for my 99, need a piston to try it, as I understand the cylinder change is the only one all the years

 

[uranys]

if you want your 360 to be a "more revvy motor" abandon your current cylinder

I was going to get my '00 cylinder ported and replated but I ended up getting a '93 cylinder instead. 2premo speaks the truth, it's much more lively on top that the '00 cylinder without sacrificing much if anything on the bottom. I'm pleased as punch with it so far, the only problem being is the faster motor is highlighting the suspension shortcomings.