Gas Gas EC200 Rebuild

[greatbuffalo]

often wondered how this stuff worked.

[Osnabrock]

I installed my rear Michelin Bib Mousse today and took some photo's to share.
I've done my fair share of tire changing in the past but always went the traditional route of using innertubes.  I've suffered through install and removal of radial/tubeless tires and patched a couple tubes in the field but I had never installed mousses.  I had heard that they were a pain to install because it's essentially the same as installing a tire on a rim and tube that's inflated.  I had done the front a few days ago and it went pretty smooth but this time I found a few other tricks that made a "not so difficult" task a little easier.
First of all, the materials........
-A rim from my Gas Gas
-A Michelin Cross Competition M12
-A Michelin Bib Mousse
-A tube of Bib Mousse lubricant
-Assorted tire levers
-A rim lock
-Rubber glove
-Not shown: a C-clamp

[Osnabrock]

The first step is slathering the Michelin Mousse lube onto the inside of the tire.  The directions on the lube tube say to use a half tube for a front tire and one full tube for the rear.  I wanted it to be lubricated well since it was a used mousse and a used tire.  I had cleaned the inside of the front tire of all the old crusty tube bits and did the same of the rim itself.  I used the remaining on the mousse itself.  There were a few spots where the previous owner had nicked the mousse so I put a little extra lube in those areas.
Next I tucked the mousse inside the tire.  I did my best to keep the lube on the mousse from getting on the bead of the tire thinking that it would keep the tire from holding the rim well. 
I put the tire on my tire changing stand (5 gallon bucket) and installed the rim lock loosely.

[Osnabrock]

The next step was to install the tire on the rim. 
I started near the rim lock, making sure the rim lock was where it needed to be.  I then worked on the first bead over the rim.
The second bead I started opposite the rim lock.  The trickiest part is the rim lock because you have to compress the mousse inside the rim with the rim lock to get the final bit of the bead situated.  This is where the C-clamp comes into play, using it to compress the rim lock into the tire and mousse.  The carcass of the tire is more resistant that the mousse so it pushes it in nicely to get the bead where it needs to be.

[Osnabrock]

The final bit is the part that was a new discovery for me.  I had a hard time seating the bead on the front tire. Since there's no tube, there's no valve stem, and since there's no valve stem there's really no way to use air pressure to seat the tire's bead.  In fact, I had plugged up the old valve stem hole with a rubber plug and wrapped the rim with a few layers of duct tape to keep dust out of the tire's interior.
I made it work by using the tire levers opposite of how you usually do and sort of pried the tire's bead onto the rim.  It was less than perfect and I'll have to go back and use the method that I discovered when doing the rear.
What I found when I did the rear is that I could force air in through the rim lock hole by making a gasket out of a piece of rubber from an old tube and putting my compressor's air nozzle over the rim lock bolt and force air in temporarily to seat the bead.  It worked perfect. 
The wheel goes back on the bike........

[plumber mike]

Thanks for posting up that guys like us can install those using our fancy wheel change stands.

Please keep us informed as to the performance of it when you get out on the trail. I'm torn as to whether the pro's outweigh the con's or vice-versa. Low speed trail riding in MN should not cause heat related failures, so the only other negative is no adjustable pressure. This could be good, and wind up with a consistent feeling bike, or you might find yourself looking for a little more stability that 5 more psi could offer. I just don't know really, but you will soon enough

[Osnabrock]

Both my brake rotors need replacing.  They are both at minimum spec thickness.  They cost about $120 a piece so I was hoping to get a little more life out of them. 
The one ride that I took before the riding season was over told me that the rear brake system needed some attention, which I seemed to fix by rebuilding everything from the master cylinder rearward. 
I recently acquired a cheap (used) rear brake rotor that had a lot more life in it that the one that I was presently running.  When I took off the old rear rotor I discovered that it was bent VERY badly.  It seemed to be evenly bent.  Definitely not normal, just weird.  The bike even has a "sharkfin" protecting the rear rotor.
I'm guessing that with the new, straight, rotor installed it will perform much better.
Take a look.  Any ideas as to how this rotor was bent so badly? 

[Bogus Jim]

It could've happened during a tire change, if someone was careless. But odd that it's so uniformly bent.

[Osnabrock]

Good thought.  After looking at it with that in mind, it's actually bent away from the tire and towards the swingarm.  Perhaps they turned it around but the writing on the disk would suggest differently. 
I can't figure it out.

[sam i am]

The fact that it is so evenly bent maybe means that it warped due to heat?  Previous owner could have been a rear-brake-dragger and that combined with maybe a sticky guide pin for the caliper to slide on could have caused one side of the rotor to heat up for a long period of time resulting in warping to one side?

[Osnabrock]

That sounds about right. 
The brake caliper piston had some pitting on it that I sanded off.  That could have caused the pads from releasing fully and causing heat to build up.
The whole brake set up sit much better on the bike now.  Before caliper would sort of shift when the brake was applied.  No longer.  I'm hoping all is solved now.
This weekend I'm riding the trails so I'll find out real quick.

[Hank]

If it got that hot, wouldn't it be really discolored?   I can't imagine heat doing that.   Looks like physical damage to me, but its hard to say!

[Osnabrock]

I'd think that if the perimeter of the rotor got hot it would expand, whereas the center wouldn't, and cause the cupping.  I'd think that the uniformity of the cupping would mostly rule out mechanical means. 
To make matters worse, the wear pattern from the pads on the rotor show that they were wearing more on the inside radius of the rotor.
I don't know what to think.  I'll give up figuring it out unless it surfaces as a problem again.

[Dr Psyko]

I remember from working in the exotics car biz that when cars would warp brake discs it was usually from severe overheating and rapid cooling. A dragging brake, through a creek and stuck?

[Osnabrock]

I got out on the bike today to test things out.  New mousses, fresh top end, and fresh forks.
A half hour into the ride we were shooting through a fast section.  I was higher in the gears than I had been before, I think it was 5th, when I heard a bit of a shriek and a weird noise followed.  I down shifted thinking that their might be a problem with that specific gear but the weird noise continued and then the bike just died.  I coasted to a stop.
I paused for a little while to think if it was wise to attempt to start the bike and decided that it should be ok.  I was betting that it wouldn't start but it did but it still had the same odd noise so I tried to hone in on where it was coming from.  The exhaust? A loose motor mount?  The clutch?
I pushed the bike off of the trail and found a nice place to spend some time with the bike and told my riding companions to check back with me in about an hour.
I checked all the bolts, the power valve, pulled the plug to see if there was anything rattling around in there. I then pulled skid plate and pulled the magneto cover off and found that there's some play in the crankshaft.  I think one of the crank bearings went bad.
This rebuild thread is about to get a bit longer.  I think I'm going to have to pull out the engine and split the cases.