Bottom end rebuild? (pic heavy)

[reepicheep]

The non reusable tools won't be bad. I probably dropped less then $50 on them, and have actually found other uses for them since then.

From memory, the only "odd" things I had to buy were:

1) A steering wheel puller (to get the cases apart). Basically a threaded post on a big Y looking thing... you bolt the ends of the "Y" to the cases. Then the threaded post in the middle of the Y gets tightened in against the crank, and the case half pulls out. That keeps you from putting big old pry marks on the cases ;).

2) A bearing splitter... basically its a heavy steel guillotine looking thing. It clamps down between the crank bearing and the crank wheel so it catches on the back of the bearing. Then use your wheel puller thing again to pull that whole assembly forward, and it pulls off the bearing.

3) A stator bell puller... which also worked on my son's KX-60. It's basically a big metric bolt with the right threads, maybe $9 from EBay or Dennis Kirk or somebody... I forget where I got it from.

The other "special" tools were things like a torque wrench or socket set... stuff you need regardless. One thing that was a pain to work around (but I did) was the big clamp thingy you can put on the stator bell to immobolize the crank for torqing other parts. People have recommended "rope down the spark plug hole" to do the same thing, and it would probably work, but that requires the top end be assembled, and I'd rather not put that much pressure on the crank if I can avoid it.

 

[julien_d]

I'm going to give my 2 cents on the oil spewing out your vent hose. It's obvious from looking at the front of your engine cases that it was previously split by someone with little knowledge, patience, or both. I would venture a guess that upon reassembly, things did not get properly sealed. You need to use yamabond or similar between the case halves to prevent leaks. Again, you won't know for sure until you get the cases split, but it should become rather apparent at that point where the pressure leak was.

 

[dirt bike dave]

One thing that I really don't understand is what's going on inside the bottom end. Is the oil in the transmission under pressure while the bike is running? So if there was a hole between the two cases, would both cases become pressurized and that's why gas/oil would have been spewing out the breather?

The oil in the transmission is not normally under pressure, because it is normally isolated from the crankcase. If there is any slight pressure normally, it is from the spinning of the gears.

Your motor obviously ran for a bit with chunks floating around and either had bad crankshaft bearings or a bad 'big end' (lower rod) bearing. The wobbly crank or loose rod probably wore down the dividing wall between the crankcase and transmission.

If you are lucky, the hole is only on one half of the crankcase. You will have to split the cases and remove the crank to see how bad it is. A minor hole can often be repaired.

My guess is the hole is probably down low near the bottom rear of the crankcase, near the center seam.

Basically, with the motor running, the combustion pressures pushed through the hole in the crank case and forced your tranny oil out the breather tube.

The tranny probably got the gas in it after the motor stopped running. When you were kicking it trying to get it restarted, or if you left the fuel on after the bike died, some of the gas ended up draining through the hole between the crank case and transmission.

 

[dirt bike dave]

BTW, not sure where the OP is located, but there is a sweet off-road converted 2003 RM265 for sale in the classified. This would be a lot of fun to ride, and all you have to do is put gas in it.

http://www.dirtrider.net/forums3/showthread.php?t=177765

 

[julien_d]

Yeah, that is a really really really nice bike. If I had the money it would be mine by now.

 

[whenfoxforks-ruled]

That RM set back up for MX, with the big bore, eats 450's for lunch. That motor has some real snap off bottom, white knuckled! I now where 1 of them is at, besides Wolfs' bike. It is not selling either, an 05 and 1000 more! If they would have divided that stimulus money from aig to us taxpayers, I would have both of them, and turn them white! Yellow means chicken in my book! Vintage Bob

 

[_JOE_]

That RM set back up for MX, with the big bore, eats 450's for lunch. That motor has some real snap off bottom, white knuckled! I now where 1 of them is at, besides Wolfs' bike. It is not selling either, an 05 and 1000 more! If they would have divided that stimulus money from aig to us taxpayers, I would have both of them, and turn them white! Yellow means chicken in my book! Vintage Bob

My old bike is now a 265 and it is pretty peppy. ;) Yes, you can change the color to white(to match your boots?) but you can't change the name stamped in the cases. That RM was my last.......

 

[julien_d]

Yeah my only gripe with the last RM I rode was the light switch they call a clutch. Made woods riding very difficult. I imagine an autoclutch takes care of that problem nicely though.....