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Discussion in 'Thumpers' started by CSMonte, Dec 8, 2008.
No on the oil. Have you seen a set of pitted gears in person? he wants a new bike.
Hey All, a couple of questions about gear wear and countershaft spline wear: I've got my '97 XR600 engine completely broken down and looking at my gear sets, mostly everything looks good but the 5th gear pair have what looks like might be wear. I'm posting up a few pics of what I'm seeing. If I should replace the set, is the NX 5th a better bet? Also, I have a small chunk out of a tooth on first and wonder if it should be replaced or maybe dressed with a file or something? Finally, are my countershaft splines jacked up enough to replace or not? Any input will be greatly appreciated!
I would run the splines as-is with a Honda XR650 or Fritzco sprocket and no lube. Clean the sprocket and splines and clean them on a regular basis. I would ask the same question about the trans gears and see what is said.
Thanks! Yes, it'll be interesting to hear the group's wisdom on the gears...
The countershaft supersedes to an NX/650L spline one which is an MN9 middle number, you may find others that supersede as well, did this a few years ago with my XL600RMG Oz europe model with electric start, basically XR600 engine not the other XL600 with the 100mm bore. It had 81,000Ks on it and has had no work done to it except a cam chain.
Good luck with your build, I have another XL electric start and I am fitting the engine in an XR600 chassis.
Once the hardening goes the gears will get noisy almost like a diff whine, plus little bits of metal will start travelling around the engine, look for a complete set from a 650L with a good spline, check my build out and look at my worn gears.
Red, Thanks for link to your build. Interesting on the gears, because I have no experience or visuals. Now thanks to your pics, I have an idea. I also heard something about the dogs can get a bit rounded & pop out if gear. It would be nice to see someones bad set compared to a good set of dogs. Also I'm going through the valves on mine now & I saw in factory service manual that the valves cannot be resurfaced. So I just bought new ones. I asked around why & a guy that machines engines and valves stated Honda has an inexpensive way of using very hard shell on not so hard metal in valves. Once the skin is ground off, the valves will wear and deform quickly. I see you had your valves resurfaced? Still running ok?
The machinist I have been going to for almost FORTY years machines the XR valves. The valve is all steel and is not coated like the CRF series valves.
Here is a sample of a worn XR650l second gear and fifth gear dogs.
This is the counter shaft second gear. The fifth gear meshes into it. You can see the worn edges of the windows as I call them.
Here are the fifth gears. The top one has the worn dogs and the lower has nice crisp edges. The bottom is a used gear.
With the worn gears as the bike is shifted into second gear under load the transmission will pop out of gear and when doing so will damage the shift fork.
I think it hardens the travel up.
A shorter spring is normally stiffer
AWESOME!! Great to know what I should look for if I ever go inside. I suppose I'll save my old valves! I wonder why manual states, not to grind?
It does say that in a weird way, but I have been getting it done for 40 years with no ill effects, you can reface steel valves on all models except the CRF titanium ones.
Just an aside to the gears, I have been to the factory in japan and have seen how they are made, sintered metal powder pressed to a shape and then machined and hardened, you can snap them like a biscuit before the hardening process I was given some out of a big box full of gears to try.
It was disappointing to hear from the factory around 92 that they had changed the hardening process so the gears would last about 20,000Ks as we were getting lots of complaints about wear even as low as 5,000ks that I had experienced on one of my race bikes using mobil 1, we had pulled it down to rebuild it to sell. We in Oz do lots of road Ks as we have full rego on all models since 1981 otherwise we would not have had such a big market for XRs because all land is owned by the goverment except for private of course and you need rego to ride in forests and such although now some states have a less restrictive and cheaper rec rego purely for that purpose with limitations where you can ride like no highways or town limits. Yamaha certify WRs locally and we had to do the same with CRFXs, factory would not help, some enduros use public roads
The gear hardening story goes like this, the Honda factory said "Amercian riders do not cover big distances on road so we do not need to" true or not that is what they told us!
We used to have the biggest XR market in the world per population.
Great gear pics mcma111
Finally buttoned up the XR and got a plate for it to. Shake down on the highway and it cruises 65 no problem. Can't wait to get it dirty!
So a couple years ago I had Steve build my 600R motor with a 2mm over 10.5:1 JE piston. Coupled with an FCR and a ported exhaust manifold and an FMF, it does fine. I used to think it was reasonably powerful.
Then I rode my buddy's uncorked and ECU swapped KTM 500.
It feels insanely slow now. I'd like to change that, and I figure a cam might be a decent idea. If y'all had to recommend a cam for my current setup, what would it be? I've heard bad things about Hotcams and good things about Web Cams.
I used a Terry Miller custom grind on my son's CRF 23O. I sent to the specs to Web and they ground it for me. It really woke up the little 230 with an XR250 carb. Web lists three cams for the XR600 and Terry recommended the second one depending on riding style. The third one requires shortened guides so if you want a drop in the first two would work. I really wanted an HRC 628 but those are unobtanium. If you could get the specs you could have Web grind one for you. Good luck!
IIRC Web 450/451
Yup that's it.
How dead is this Hotcams cam? It came as a spare with my 2nd XR650L, I'm guessing it's not worth anything now? Or can it be reground?
Looks like toast to me. Have a look at the rockers and the head as well.
Just asking, Steve I wasn't planning to use it, but I also wasn't sure if it could be reground or something. I'm asking because I lack the information.
And Jab, yeah, that's what I figured. It was in a box with a loose head that is likely burnt up as well, so my guess is that they died together.