Transmission problem
 

Decided to go for an afternoon ride today. Well, I didn't even make it out of the staging area before things went wrong. Warmed it up properly and started to head out and my bike just died. It felt like it locked up. At first the shifter didn't feel like it wanted to move down. However, it moved upward and then it shifted fine. Did a slow kick to feel for any problems with the engine but it was smooth. So, I kicked it and it fired right up but could hear something like a knock. Cruised it up through the gears and 4th is making a noise like some teeth are missing.

Questions. I'm pretty sure something went South in the trans (duh) so I will be splitting the cases. Supposedly the engine is a '05 EC250. Can someone help me with making sure? The numbers on the engine is EC25 0104037183. Second, where do I find replacement parts? Since I'm in there I plan to rebuild the whole bottom end. Anything in particular to watch for or should be upgraded? Any other input on splitting the cases? I have rebuilt Japanese bikes before but never a GG.

The rebuild procedure is pretty standard fare, and since the trannys are largely common throughout the years the exact date likely isn't critical.

First step is to pull the drain plug and see what's stuck to it. We can help with the parts.

OK, started tearing it down tonight. Drained the oil and found a tooth from a gear stuck to it along with a lot of metal shavings. So, case splitting happens tomorrow.

Guy I bought the bike from has another EC250 bottom end he is willing to give me, however, it is a 2000 model. Can I drop the whole gear set from it in to my '05?

There was a change in engine mount locations around 2005. There may also be a change in the swingarm shaft size around the 2000 time as well so the cases may be different. If the cases are different you should be able to swap over the transmission gear sets. If you do swap the internals, you may want to consider changing the bearings while you are in there. You can get these at a bearing supply house or dealer. These bearing and seal sizes work for the older 200, 250 and 300 bikes up to 2004. They probably cover newer bikes too, but double check the numbers or sizes to be safe.

GasGas Transmission bearings
Bearing # Grainger #
Counter shaft bearing 6305C3 4ZXJ1
Countershaft Seal 30x40x7
Clutch bearing 6205Zc3E
Trans shafts 6203c3 4zxe8

LHS CRANK SEAL KOK 20x35x6 (VITON) ktm 47030076100 04-14 105 85 65
RHS CRANK SEAL KOK 38x52x7 (VITON) ktm 0760385273 94-14 250 300
COUNTERSHAFT SEAL 30x40x7 Suzuki 09283-30061
Shift Shaft Seal 12x22x7
KICKSTART shaft SEAL 20X30X7

The big nut on the crank clutch side is a reverse thread think , my one went funny after stripping it down and kept coming loose.
I replaced and used red lock tight it's never loosened since lol

I found this on the engine vs frame fitting between the old bikes and the really old bikes. ;-)

http://www.gasgasrider.org/forum/sho...nt+engine+weld

The internals should most if not all swap over. Since your inside put in all new bearings. I ordered my bearing from USA bearing and belt. They will have a crossover chart for the sizes you need. And most of your bearings should be stamped with the size on them somewhere. Pick the best parts between the two motors, check the crank play, throw in some new bearing and hammer it with a piece of mind knowing you did it right. If you need some help let me or another local know. I live in Maricopa and have torn these motors down a few time, really not much to them. I will be off the entire month of November.

Thank you very much for all that!

Funny you mention that as I found it lose on mine as well. It was eating in to the side cover right below the sight glass.

Yeah, whenever I split the cases on any bike everything inside gets replaced. Bearings, bushings, seals, etc. will all be new.

Since I'm in there, it would probably be a good idea to rebuild the crank. I thought I read something about it being a CR250 crank and rod. Is that correct? If not, where can I find a good rod for it? Plus, I have read a few things on doing something with the base gasket(s) and head. Could someone point me to a definitive thread covering all that needs to be done?

I wish there was some way to identify the exact year engine as I suspect it isn't actually an '05 but instead is an earlier model. I just can't afford to buy parts that don't fit or I won't be riding for a long time.

The Rod is the same as a cr250 but the crank is different.