RM125 RM125 motors interchangeable?
- Thread starter cb750mike
- Start date
If it's an RM mix with C4. and run!
So I ended up keeping the RM. The 250 was just in to bad of shape to trade. Compression was good but I think the valves needed to be shimmed. A lot of tapping noise along with a lot of misc. stuff missing or broken. So now I’m ordering a new top end rebuild kit and getting my cylinder bored out. What’s the best way to break in a 2 stroke? What mix ratio do I use for break in?
You do not alter the premix for break-in. EX: Richening the oil/fuel mixture would LEAN the fuel/air mixture. Opposite of 'protecting' the engine.
Break-in of any engine is to bring all the components to temperature TOGETHER. Same with cool down.
I like to perform a few complete heat cycles on the stand before actually riding it. -BIG DAN
Break-in of any engine is to bring all the components to temperature TOGETHER. Same with cool down.
I like to perform a few complete heat cycles on the stand before actually riding it. -BIG DAN
Bored out?? That’s a plated cylinder unless someone resleeved it with steel. I send my stuff out to be replated. I use light atf to assemble and then run heat cycles like srad said.
Big Dan has his own way to break in engines. I do run a thicker oil as per the YZ manual states to do for break in, but not as thick. It is only a small ratio off from standard mix. Manual staes to use a 15:1 ratio, and I do a 25:1 so it's not so lean. On a 2 stroke, the oil lubes, and the gas cools.
3 heat cycles total before letting her rip.
1st is on the stand and to warm up the engine, adjusting the carb to idle high, and tiny littl blips on the throttle 1/32-1/16 twist is all. Let the engine get to a warm temp for about 5-8 minutes.
2nd is the same only now you are giving it up to 1/4 twists, adjusting idle at temp, and litening to the idle for any strange noises.
3rd is riding it through all the gears using 0-1/2 throttle in the first 1/2 of minutes, and 0-3/4 in the last 1/2 minutes of riding. 10-15 minutes total if everything is shifting and sounding good.
Let the engine fully cool between cycles.
Remember to always warm a 2 stroke up before taking off and having a good hammer time. This will ensure you don't have a cold seize.
Also, unluss the bike is pre 1988, and/or has been sleeved with a steel cylinder, you need to get it replated if the cylinder has damage. Send or buy a piston from whomever you have do the work.
Good luck, good choice!
Ok so update. Talked to our machinist and ordered a 1mm bigger piston and getting my cylinder smoothed out. Yes it is nickel plated so it would’ve been almost $1000 just to bore it out and replate it for a 56mm piston. Tried getting the old piston out and I guess with the motor sitting open for the length of time it sat, the needle bearing seized onto the wrist pin so there was no beating it out. Cut up the piston to get it off the connecting rod. So as I prepare to start putting the motor back together. What do you guys prefer on these 125 2T for crankcase oil, coolant, and premix oil? Coolant I was thinking engine ice since I’ve had no issues with it in any of my race (on road) bikes and I use to use castor 927 premix oil in my kx250. What do you guys think or prefer? Thanks for the help guys and safe riding!!!
Ps. My picture won’t upload of my cut up piston for your guys enjoyment because the file is too large. Damn iPhones!
Ps. My picture won’t upload of my cut up piston for your guys enjoyment because the file is too large. Damn iPhones!
Chemicals are so over rated.
I started using the orange stuff from RMATV, it's actually better than ice.
I use Honda HP 80/85 in the transmissions. But you can use Rosella, or ATF typ F, and MANY others.
Mix, well.... I am the YZDOC so I use 2R.
Email the photo to yourself, than save it, than upload that photo. This is why we don't have nice things.
You use the liquid performance high performance racing coolant from RMATV? Now if I remember right the crankcase oil doesn’t reach the crankshaft right? The gas/oil mix cools and lubricates that right?