03 RM 125 Break In

gharmon
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gharmon
Edited Date/Time 10/10/2013 4:24pm
I just finished putting the sons 03 RM 125 back together today. I put in a new bottom end. I also sent the cylinder to Milennium Tech. (Eric Gorr) to have cylinder replated and some repair work where there was some detonation damage.

Since I spent a fair amount of money on this I just figured I would ask y'all how most of you break in a new rebuild? Anyone want to tell me their break-in sequence?



After reading on here that the RM 's (I also have an 07 rm 250) need a little something besides pump gas I have been running 100LL aviation fuel in my 250. Does the 125 need it also? One last question, it has a 460 main jet, is this about right for a 125 rm? I sure don't want it running lean at WOT.


Thanks for the help,

Gerald
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xnationalwrench 10/9/2013 6:59pm
10/9/2013 6:59pm
gharmon wrote:
I just finished putting the sons 03 RM 125 back together today. I put in a new bottom end. I also sent the cylinder to Milennium...
I just finished putting the sons 03 RM 125 back together today. I put in a new bottom end. I also sent the cylinder to Milennium Tech. (Eric Gorr) to have cylinder replated and some repair work where there was some detonation damage.

Since I spent a fair amount of money on this I just figured I would ask y'all how most of you break in a new rebuild? Anyone want to tell me their break-in sequence?



After reading on here that the RM 's (I also have an 07 rm 250) need a little something besides pump gas I have been running 100LL aviation fuel in my 250. Does the 125 need it also? One last question, it has a 460 main jet, is this about right for a 125 rm? I sure don't want it running lean at WOT.


Thanks for the help,

Gerald
It sort of depends on the clearance you set everything up with. The tighter the clearance the easier break in I would do, something like ride with out high RPM's for 10 minutes then let it cool down completely then go 20 minutes running it a little harder. I would check the torque of the cylinder head nuts along with the base nuts and everything thing else for that matter at that time. And would use the same fuel mixture s the 250. as far as jetting considering the temp/humidity you will need to do some jetting runs when it is broke in.
JM485
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JM485 10/9/2013 7:19pm
10/9/2013 7:19pm
I always break my bikes in using carbon based oil (chevron) so the rings seat properly. As stated above, give it at least a few full heat cycles before you really pound on it. I also try to keep load on the motor as much as possible when riding.
Jakes Dad
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Jakes Dad 10/10/2013 3:59am
10/10/2013 3:59am
Having to repair from detonation is a sign the squish may have been off. Hopefully this has been accounted for, if not you better get some solder and do a proper squish check.

I believe the 03' still had the round slide carb so I'm not to sure on that jetting. Running 30 to 1 using Maxima K2 and 100LL fuel, squish is at .030in. The main is a 360 with the needle set 2nd from top, this is the flat slide carb.
gharmon
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gharmon 10/10/2013 6:47am
10/10/2013 6:47am
Jakes Dad wrote:
Having to repair from detonation is a sign the squish may have been off. Hopefully this has been accounted for, if not you better get some...
Having to repair from detonation is a sign the squish may have been off. Hopefully this has been accounted for, if not you better get some solder and do a proper squish check.

I believe the 03' still had the round slide carb so I'm not to sure on that jetting. Running 30 to 1 using Maxima K2 and 100LL fuel, squish is at .030in. The main is a 360 with the needle set 2nd from top, this is the flat slide carb.
I will be straight honest with you, I don't know what squish is or how to check it. I have been seeing you guys talk about it here a lot. I sent the cylinder and head and all associated parts to Milenium and told them to get everything right and send me the correct piston I would need. We talked at length on the phone, so I hope it's what it's supposed to be.

It has the flat carb on it. So you are saying that you are running a main jet of a 360 vs the 460 I'm running? Hell I guess that should be rich enough huh?

JM485: You are saying to break it in with pump gas instead of the aviation stuff? Am reading that correctly?

Thanks guys!!

The Shop

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Matt Fisher 10/10/2013 8:59am
10/10/2013 8:59am
Av gas would be great for the 125, particularly if you had the head modified for race fuel. If the motor was set up for pump gas, then the 100LL would be less necessary, but still a good insurance policy against detonation, as well as providing better power, lasting longer in a can, and being easier on the carb's o-rings (no alcohol in the AvGas).

I would use stock or Pro Circuit suggested jetting, as you're not running a big-bore, crazy porting, or some super high compression setup. It's still the same basic bike that rolled off a Suzuki showroom a decade ago.

Warm it up then cool it off a couple of times and then go ride.
JM485
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JM485 10/10/2013 3:21pm
10/10/2013 3:21pm
Jakes Dad wrote:
Having to repair from detonation is a sign the squish may have been off. Hopefully this has been accounted for, if not you better get some...
Having to repair from detonation is a sign the squish may have been off. Hopefully this has been accounted for, if not you better get some solder and do a proper squish check.

I believe the 03' still had the round slide carb so I'm not to sure on that jetting. Running 30 to 1 using Maxima K2 and 100LL fuel, squish is at .030in. The main is a 360 with the needle set 2nd from top, this is the flat slide carb.
gharmon wrote:
I will be straight honest with you, I don't know what squish is or how to check it. I have been seeing you guys talk about...
I will be straight honest with you, I don't know what squish is or how to check it. I have been seeing you guys talk about it here a lot. I sent the cylinder and head and all associated parts to Milenium and told them to get everything right and send me the correct piston I would need. We talked at length on the phone, so I hope it's what it's supposed to be.

It has the flat carb on it. So you are saying that you are running a main jet of a 360 vs the 460 I'm running? Hell I guess that should be rich enough huh?

JM485: You are saying to break it in with pump gas instead of the aviation stuff? Am reading that correctly?

Thanks guys!!
No, definitely not, what I was referring to was the brand of oil. I break my bikes in with Chevron two cycle oil since it is carbon based. Hopefully that clears up any confusion, sorry if I wasn't clear on that.Grinning
Jakes Dad
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Jakes Dad 10/10/2013 4:24pm
10/10/2013 4:24pm
Proper squish will free up 10 to 15% horsepower and more importantly provide the "cooling ring" affect from the turbulence from the msv maximum squish velocity. This turbulence is directed back towards the chamber for a more violent or complete burn of the intake charge. With a wider more open squish the heat from the burn works it's way back around that circular edge of the cylinder head creating additional heat and detonation will occur. I always throw a little spam out there for my porting guy Brent at TDC 2 Stroke Performance. But any of this little bit of knowledge I have Brent was kind enough to teach me. It has saved me a ton of money in our racing as far as engine failures.

This video gives you a pretty good account of how to check squish using solder and calipers to measure. Watching the entire video will give you some more knowledge about what happens when short cutting squish by using different base gaskets and how it affects port timing. But if you skip to the 3:00 mark it shows you how to use the solder and turn the motor over to get the piston to squish the solder. http://www.youtube.com/watch?v=ZUe0p0DqFCk

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