'98 GG EC250 motor rebuild Q:s
 

Maybe someone can help me out.
Last ride my GG suffered some kind of internal engine failure.
Pushing down the kick starter, it started making a clank,clank sound.
Much like the ratchet sound the kick starter makes when returning
back up. At first I thought the problem was inside the start
mechanism. The motor started and I rode home. I did not hear
the clanking sound on the ride. Exhaust sound must have hidden it.
Removed the left side engine cover, water pump, etc... Spinning the
engine over by turning the clutch basket, and the sound is clearly coming
from the bottom end.

My assumption it is a big end rod bearing or the crank main bearings.
I'll pull the top end off soon and see if I can see any play in the crank.

So I am going to need to do a full bottom end rebuild. Might as well
replace anything that might be worn so as not to have to split the cases
again the the near future. Might as well replace the piston and small
end bearings, water pump seal, etc....

Does anyone know a mechanic familiar with the GG engine in Southern
California? I do not have the tools or skills to split the cases.
Only mechanic I know of is Steve Marolda from MotoWest. But, he has
not been in business with GG for over 10 years.
He mentioned that he has no idea where to get GG parts anymore.

So can someone suggest a parts dealer that I can get the parts to do
a full bottom end rebuild?

Thanks for your suggestions.
Jeff

The noise could be from a bad crank bearing or a crank stuffer screw that backed out. The parts are easy to get, as they cross over to honda, yamaha and industrial parts. All Balls has kits too. There were some crossover years so you may want to pull apart the bottom end to see what bearings and seals you need.

I would rebuild the crank, replace the crank bearings, crank seals, waterpump seals, counter shaft seal, shifter seal and kickstarter seal. I would install a new piston and reeds. Whoever pulls apart the engine will tell you if you need any other transmission or powervalve bearings need to be replaced.

The GG 2 stroke engine is very similar to a Honda CR250 from the early 1990s. Any reliable engine builder should be able to do your rebuild for you.

Honestly, if you were able to pull the engine out yourself without a problem, you maybe able to do the rebuild job yourself. Check out this video to get a feel for what is involved. https://www.youtube.com/watch?v=RS6dtHwED1Y

Halls Cycles in Springfield, IL has a very good supply of parts in stock. www.Halls-cycles.com

Good Luck

Thanks Zman. I will call Halls, Matto? and some other Google located
parts suppliers and see if they can supply the parts I'll need.

Mr. Marolda said he could do the work, just not supply parts.

Since this is a counter balanced engine, getting the gears for the
balancer properly aligned is crucial. Been there, done that before.
Notice the dots on the two gears not aligned in the attached picture.

Might as well replace the clutch fiber plates while it is apart.

Mr. Cook from Smackover has worked on this engine before. Just don't
want to ship this boat anchor across the country again.

Cheers everyone. Jeff

Measure the clutch plates. My 07 is on originals and I'm not easy on them.

I agree the stock GG clutches last a very long time. 8 out of the 9 older GG bikes in our riding group still have the original clutch. The one we replaced was in a GG MC125.

Looks like I found the problem.
The 1997-1999 GasGas uses a Ducati stator / generator
system that is different than the newer models.

The flywheel came loose somehow. Taking it apart it
is missing a thrust washer under the nut. Not allowing
it to press tight to the ignition portion of the stator flywheel.

Have no idea why it failed all of a sudden, since it has been
fine for years.

On the under side of the stator flywheel has holes that align
to the protrusions on the inner flywheel.
It has ovaled the alignment holes and since was loose it rattled
back and forth when the motor turned over. I guess the magnet
passing by the coils caused the stator to slip causing the noise.

Hope the pictures explain it better than I can.

I doubt these parts are available anymore.
I hope replacing the washer will allow the flywheel to fit tight
enough not to slip.

Cheers, Jeff

Too bad you didn't find it before pulling the motor. However the good news is you don't need the rebuild. I'm not familiar with the counterbalaned engines but I doubt you really need the Ducati generator unless you have some high current lighting installed.

Your kokusan stator should be similar to later bikes. I expect you have a 2K2. If you replace it with a 2K3 you'll get about 70W of lighting power. The Ducati generator also acts like a big flywheel weight so you will notice some difference there. It should be no problem to keep the bike operating.

Alternately a machine shop could sleeve those generator holes to restore a tight fit on the flywheel rivets.

Good observation NeilE
This is the same suggestion I got from an old time
Gas Gas mechanic. Remove the Ducati portion and just
run the "inner" stator, or replace the whole stator plate
with a 2K3 style assembly.

Yes, I'm bummed I didn't figure out the problem before
pulling the motor. Feel like a NUUBE mechanic.

I buttered up the stator part, with the holes, using some JB
weld. covered it with cling wrap, (as a mold release), between
the parts. Seems to have worked fine.
I should get the thrust washer next week. As well as the gaskets
that got ruined taking the side covers off.

I hope to be riding in a couple weeks.

Cheers guys and thanks for the suggestions.
Jeff

If I recall correctly the Ducati lighting coil is more than 100W.

Use the correct washer, proper torque on the nut and that should fix the problem. IMO if it still works don't change it.

Good news. Finished fix'n the stator and putting the motor back in the frame.

The Spanish Princess is back on the dance floor and ready to boogie.

Now we need the rain to stop and dry out the canyon roads in So. Cal.
Cheers Jeff