ok my buddies connecting rod bearing siezed up in his rm and we are about to do a complete low end and top end overhaul. he is looking at putting money into it and fixing it right. i have broken in many snowmobile and atv motors and used the same philosophy drive it wide open and burp it about every 3 seconds, or even when you are driving slower never hold the throttle at the same rpm's. my question is does this apply to dirtbikes to? i have never broke in a dirtbike motor before and am looking at getting rid of mine and getting a new yz125 this spring so i will need to know this as well. the reason is cause dirtbike motors are so windey and very high rpms.
breaking in a RM125
- Thread starter weez440
- Start date
Yea go ahead and start it wide open on a new motor when it's dead cold and sieze it! :coocoo: If you was my friend you wouldn't touch my bikes if ya ever did that. You should do that heat cycle method and you don't chop the throttle you roll it on and off to keep lubrication constant. Do your friend a favor and not touch it :laugh:
- Thread starter
- #3
the REASON i ask is cause dirtbikes seem to rev up higher rpm's and if you break them in at a slower speed the rings create a ring that bows down on the cylinder creating less compression on top end. i didn't come on here asking for a smartass comment i came on here asking the people who knew what they were talking about. i bought a brand new atv in 2003 and broke it in my way the way i always did and i told the dealer what i got on top end and their mouths dropped wide open and said you must have got a fast one. well it wasn't that i just knew how to break it in. so does anyone have an educated experience on motorcycles? and MXP you need not respond cause any experience you have apparently isn't educated.
There are many that subscribe to the "hard" break in theory you mention using for ATV's and sleds, I'm not one of them. We usually heat cycle ours through 3 cycles (ride for 15 minutes easy, let cool down. Ride for 20 minutes easy-moderate, let cool down and then Ride 30 minutes moderate-hard but no extended wide open, let cool down. Then go race.) Sometimes a failure at an inopportune time leads to not enough time to follow this procedure before needing to race, then the abbreviated version is a 15-20 minute run at easy to moderate throttle and then head to the line and hope for the best.
- Thread starter
- #5
thank you chili for your educated experience i appreciate it i have yet to decide how the breakin period is gonna take place cause there are many ways of doing it. i just wish this spring when i buy my new dirtbike that someone else would buy one with me and we could try it two different ways to see what motor creats more power. i will deffinately keep your method in mind but we got about 4 months of winter until we can do this so we got time on this subject. once again thank you
2-Strokes 4-ever
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For many years the "3 cycles of easy with a cool down in between" has worked for us.....NEVER have had a siezure, good seating-in of piston and rings produces the longest top end life possible. We mix our 125s at 32:1 and keep air filter clean.
I break my bikes in a little aggressively but I break the riding sessions in 10 to 15 minute intervals to avoid excessive heat...The idea is to seat the rings without putting too much heat on a new motor and the short riding sessions help avoid too much heat...And always let the bike warm up a few minutes at idle speed when the engine is cold before doing any riding...Avoid the urge to "clean it out" as well.....During each 10-15 minute session I stay in the lower gears while varying the rpms and always do a few brief spurts at full throttle during each run while avoiding over reving it..Which means just enough time to allow the bike to blast through most of the rev range then immediately letting off the throttle...
I also like to break my bikes in on flat hardpacked dirt or a grassy area...The reason why is when you do a full throttle run the grass gives you very little wheelspin...say like if you ride on sand and go to give it full throttle and the wheel breaks loose the motor will spin up much faster and the bike will over rev (you want to avoid this)...Same is true if you're going wide open and the rear wheel comes off the ground..So I do break in on a flat hardpacked/grassy surface.
A couple of things to note...
1. Always let the bike fully warm up when the motor is cold.
2. Avoid lugging the bike (too high of a gear at low rpms).
3. Do a few brief spurts of full throttle...But avoid over rev and no constant rpms....Always be in a transitioning mode of accelerating and decelerating rpms.
I've broken in alot of new and rebuilt motors this way and never had any problems
I also like to break my bikes in on flat hardpacked dirt or a grassy area...The reason why is when you do a full throttle run the grass gives you very little wheelspin...say like if you ride on sand and go to give it full throttle and the wheel breaks loose the motor will spin up much faster and the bike will over rev (you want to avoid this)...Same is true if you're going wide open and the rear wheel comes off the ground..So I do break in on a flat hardpacked/grassy surface.
A couple of things to note...
1. Always let the bike fully warm up when the motor is cold.
2. Avoid lugging the bike (too high of a gear at low rpms).
3. Do a few brief spurts of full throttle...But avoid over rev and no constant rpms....Always be in a transitioning mode of accelerating and decelerating rpms.
I've broken in alot of new and rebuilt motors this way and never had any problems
- Aug 3, 2004
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I'm about to the point where I believe that the time it takes you to warm the bike up for the first time is all the time needed to break it in. I mean, what are we breaking in here??? Not a flat tappet camshaft that we must be very carefull with. Not a low quality piston that may not be in spec. Not a set of bearings with tolerances that may be too large. We are mating aproperly clearanced high performance, exacting tolerance racing ring to a cylinder that has a nicom, etc. bore finish. This isin't your car here?!?! A serious 125 race bike is going to need ring replacement about every 5 hours, with pistons at every 10 hrs. With most of your break in methods, the ring would be half way to needing replacing before break in is done.
Breaking in a dirtbike is pretty easy & basic.
Just start it up, ride it around in first gear at WOT for awhile until it can rev up cleanly without skipping or anything.
Now, head to the main ride (pavement), and pull up the front tire in a wheelie, then shift up into second when you are at the balance point, then 3rd, and so on. Don't stop riding a wheelie until the bike is in it's highest gear and has rev'd to the point where it comes down on its own.
After doing this about 5 times the bike will be broken in and ready for normal use. Just remember to pin it WOT and ride around in first gear as soon as you start it up untill it is warmed up, and you are golden.
Just kidding :) Sorry couldn't resist.
P.S. Don't foget to put a main jet in thats about 3 size's smaller, and only ride the bike when its extremely cold out, as that will allow the bike to run cooler. The colder it is outside, the better. And don't forget to use a main jet thats way to lean.
Sorry again LOL!!!
Just start it up, ride it around in first gear at WOT for awhile until it can rev up cleanly without skipping or anything.
Now, head to the main ride (pavement), and pull up the front tire in a wheelie, then shift up into second when you are at the balance point, then 3rd, and so on. Don't stop riding a wheelie until the bike is in it's highest gear and has rev'd to the point where it comes down on its own.
After doing this about 5 times the bike will be broken in and ready for normal use. Just remember to pin it WOT and ride around in first gear as soon as you start it up untill it is warmed up, and you are golden.
Just kidding :) Sorry couldn't resist.
P.S. Don't foget to put a main jet in thats about 3 size's smaller, and only ride the bike when its extremely cold out, as that will allow the bike to run cooler. The colder it is outside, the better. And don't forget to use a main jet thats way to lean.
Sorry again LOL!!!
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