Gas Gas EC200 Rebuild

[Osnabrock]

I've done a couple of rebuilds of bikes in the last few years.  I've found that a winter rebuild keeps me in better spirits   This year I thought that I'd try something new and maintain a thread about it.  We'll see how it goes.
I recently sold a bike that I had minimally rebuilt, with intention of turning that project into a more "custom" bike project for this winter.  With that void created I needed to fill it with something.
I've found myself riding a lot more off-road than I have in past years and I needed a true "woods" bike.  I've also found myself wanting to check out the 2 stroke side of riding.  Some folks think that the 2 stroke engine is the only way to go when it comes to woods riding.  From what I understand, they are generally lighter, generally have better throttle response, and are generally cheaper to maintain in the long run.
I was initially looking at purchasing a new KTM 300 with all the bells and whistles (electric start and all) but I couldn't rationalize the cost.  I then started looking for an older YZ or CR two stroke.  Everything I was finding was pretty beat up.  They'd either be around $2,500 and ready to ride but pretty spartan or around $1,000 and needing a new top or bottom end.  I then came across a GAS GAS EC200 through a friend of a friend in the price range I had set for myself.
I knew about GAS GAS bikes from a few of the Euro magazines that I pick up from time to time, as well as some of the large "hard" enduro events around the world.  It's a Spanish brand that came out of the demise of BULTACO.  They are primarily known Stateside from the trials motorcycle world but also make competent enduro machines.
I looked at the bike and found that it had a whole lot of aftermarket parts on it and ran well, thought I couldn't take it for a ride since it was in suburban Minneapolis.  I thought about it for a day and committed to purchase it the next.
I got it down the stairs and into my basement for the winter.  We'll see how this goes..........
Here's the photo as it appeared on Craigslist and how it appears now after last night's work of tearing it down.  

[Lonesome Dave]

It looks like its in good shape, very cool.  The frame looks huge.  This ought to be fun to watch. 

[Bogus Jim]

When you are done with the rebuild, take some video when you ride it up the stairs and out of the basement. You are going to ride it out of the basement, right?   

[Osnabrock]

The bike is in good shape.  The weekend after I purchased it, I took it out to a trail ride with my moto club.  I was a little concerned about switching over from my four stroke DRZ to a two stroke. 
The last, and first time, I rode a two stroke was when my friend offered me to take his daughters KTM 200 for a spin around the yard.  In my first 20 seconds on the bike I killed it once and nearly sent it bars over rear fender.  It didn't bode well.  I wasn't used to the power.  Of a 200!!!!!!??
I must say, I enjoyed the 2 stroke woods bike that a EC200 is.  The GAS GAS took a little more speed to get over the bits that a bigger bike would take in it's stride, but it was just as comfortable.
Where the 2 stroke excelled was in the muddy sections, where I usually call it a day and wait it out.  The weight difference became obvious.
Tonight I encountered one of the first differences between a four stroke and two stoke mechanically, the reed cage.  While a four stroke carb feeds right into the cylinder, a two stroke uses a reed to perform the duties of the valves of a four stroke, only allowing air in during the intake stroke.
So far everything looks good.
I'll attach photos of the reed cage.
And no Bogus Jim, I won't be riding it out of the basement.  You might be able to see, it's pretty tight down there.  There's a tough chicane at the bottom of the stair where the chimney exists.  Plus, I had to use a tie down to bring my fork height down to 46 1/2" just to make the stair ceiling height.

[Osnabrock]

Today I pulled the cylinder and piston.  I wanted to check the specs on the connecting rod and piston rings.  The person I purchased it from only had it for a short time and couldn't tell me how long it had been since the top end was last rebuilt.  Usually, people get about 75 hours on a top end before it's rebuilt.  It doesn't seem like alot can happen in that time, but that's the way two strokes are I guess.  I just passed 40K miles on my KLR without doing anything other than oil changes, checking valves, and other usual stuff.
Upon pulling the cylinder and piston, I found that it almost looks brand new.  The connecting rod tolerances were from 0.8mm-1.0mm and my reading was 0.7, a little tight but there's not much I can do about that.  The ring gap tolerance was 0.4mm-0.6mm and mine read 0.5 an 0.45mm so those were good too.  It should at least get me through one more season.  My mind will be at ease knowing that. 
So the only thing that I need to do is clean up the power valve cavities, reassemble the cylinder/piston, and perhaps replace the gaskets at the same time.  I'm thinking I might just reuse the current gaskets since they came off so well.  I have a feeling they're pretty new too.

[greatbuffalo]

I was just watching the GNCC Hare Scramble last week and noticed all the Gas Gas machines out there. They are gaining ground on the KTMs.

Cool project. Will be fun to follow.

[Osnabrock]

Last night I got most everything put back together.  It all went smoothly but I'm questioning my decision to reuse the cylinder gasket.  I'm thinking buying a new base gasket might be the prudent thing to do.  No sense on skimping on an item that only costs $10 or $15, right?
The current tank capacity on the bike is pretty good, being about 2.5 gallons.  I did find a used oversized tank that would give me 3.5 gallons.  I figure that's a pretty good upgrade, so I'll see if it's in the budget.  I could probably ride for 4 or 5 hours with that large of a tank, though I'm still unclear as to how far a tank will take me in the woods on this bike.
To make up for my lack of real progress today, I thought I'd go back and find a video that talks about the difference between 2 stroke and 4 stroke engines.  http://www.youtube.com/watch?v=GwFB3RcVcHI
I also came across another odd bit about the two stroke engine, the power valve.  It was something that I had to disconnect during the cylinder removal but I really didn't understand it until I looked it up.  Take a look.......
http://www.youtube.com/watch?v=GD8QnsY925Y

[greatbuffalo]

I think while you got it broke down it would be wise to eliminate a potential issue by replacing that gasket. Think how pissed you'd be on the trail if it failed. Worse yet, how pissed your buddies wound be having a short day and dragging your ass back to camp. When in doubt, throw it out.

Having been away from 2 strokes for many, many years, I take it this has a pretty sophisticated oil injection system. I was always so scared that that system would fail on my old Honda and detonate my motor. Worried about my outboards doing the same when I was into boating.

[Osnabrock]

After having a day to think about it, I'm definitely going to change the base gasket.  There's no sense not to, other than the fact that I've got the top end put back together again.  Still, it came apart in an evening and, it will go back together in an evening.
Tonight I took a bit of the dirt off the plastics.  I got an extra, used, set off of Ebay about a week ago.  I never spend much time thinking of the appearance of my bike,  this is no different, so the plastics will only serve as a back up set.  I've twice torn the radiator shrouds off my DRZ and once twisted the hell out of a front fender.  I need replacements on hand.
The bad news is that I didn't get the oversized tank that I'd been eyeing.  When it came down to it, I figured that even the standard tank of 2.5 gallons will likely provide more fuel than most of the other folks that I ride trails with, so why spend the money?  There's always some hidden costs in a rebuild.
Concerning the oil system on the bike.........this bike has nothing sophisticated about it.  It's premix gas only.  50:1 ratio.  No fancy oil injection but no extra weight either.  I think the dry weight on the bike is around 222 LBS. 
My work for tomorrow will be making up a parts list and placing an order with my local GAS GAS dealer which happens to be about 50 miles from Watertown, SD and about 170 miles from me in Minneapolis.  Parts next day!!!!!!!!!!!!  Not bad for a Spanish bike.

[Osnabrock]

I was away for a long weekend.  When I returned my box of parts came.
I ordered a few things for the engine:
-base gasket
-head pipe gaskets
-fuel filter
-radiator hose gasket
I also ordered a few things that I'll need in an attempt to make the bike street legal:
-rear fender extension with plate holder
-tail light
I was surprised that everything, including the bodywork and tail light, was in stock as the bike isn't commonly considered road worth in the States.  I know that the state can be picky that all the added components, to make a bike street legal, come from the manufacturer as available "original" equipment.  This makes a lot of bikes ineligable. 
My plan for the next couple of days is to take the cylinder back apart and install the new base gasket and get the engine back together.

[Osnabrock]

I got everything back together again without a hitch.  I really dislike putting things together only to take them back apart again.  My frame of mind is that once you take things apart, they never go back together quite the same again.  I suppose engines are different, especially if you're installing new components.  Anyway, now the new base gasket is in.  I installed it with gasket sealer on the cylinder side for good measure. 
Today I figured that I'd pull the shock.  When I was messing with the sag and the all the settings, when I first got the bike I noticed that there might be some maintainance required.  I'm mulling over doing the service myself or if I should send it off to be serviced/rebuilt.  I've found the shop service manual for the shock so that's the way I'm leaning right now.  In case I don't.............
Does anyone know anyone around who offers rebuild service?

[Bogus Jim]

This guy gets a lot of thumbs up on advrider, but maybe you want somebody local.

http://www.stmsuspension.com

If you are just changing oil & seals and you can find someone to do a nitrogen fill, it's tempting to do the work yourself and save the labor/shipping costs.

[greatbuffalo]

Theres also a guy I've delt with in Idaho that goes by Sasquatch on ADV. He did work on my Tiger shocks.

[Osnabrock]

Well, I've done a little bit of digging through the box of bits that I got with the bike.  I discovered that I've got an extra spring, of the same spring rate, for my Ohlins as well as a receipt in the paperwork that suggests that the shock was reworked sometime before I purchased it.  I think that I'll pass on servicing it now, unless I feel differently later this winter. 
I did find that the going rate for giving a shock a once over is around $100 to $150, plus the cost of any replacement parts.  Not bad if you ask me.  I think for that price I'd definitely hire the work to be done by someone who has the expertise as well as the tools and replacement parts at their fingertips.
I also just scored a rear subframe off of Ebay.  When I disassembled the bike, I noticed that a tab was broken off of the left hand side of the subframe.  It didn't hold much more than the airbox and bodywork but I feel better knowing that everything's as it should be.
I'm also finding that one of the previous owners kindly used anti-seize on a number of the bolts.  I'm happy to know that the PO was thoughtful of what they were doing.  It bodes well for the true condition of the bike.
Next step will likely be greasing the swingarm and linkages.

[loingrader]

+1 on sasquatch in idaho.  he does good work, and a very nice guy to boot.