How to break in atc 250r??

[jakep53]

Ok how would I go about this today I pulled out my blown motor and put my freshly rebuilt engine I got with the bike in... I have yet to start it because I have no idea how to break in a 2 stroke I read a bit about it and got out of it: start motor and let it idle for 10 mins with a few blips of the throttle ( problem I see is being air cooled won't it over heat??) then let the engine completely cool then after its cooled go through all the gears but don't go above half throttle then let completely cool then lastly go through all the gears wot then let it cool and you done.. would this be the right way to go about things?? and what fuel mixture should I run 20:1 32:1 or 40:1?? any other tips greatly appreciated as I don't wanna stuff this up!!

[DohcBikes]

This will be a good thread.

Engine break in is a debatable topic. First of all, it is best to know the engine builder's tolerances because some will build them to take longer or shorter break-in depending on how the builder setup the cylinder and rings. I'll leave it to the smoker guys to recommend oils and mix ratios, but I will recommend that you start with jetting that you know is too rich, because playing with lean jetting on break in is a big no-no.

When I break in a four stroke, even a V8, I am easy on it for about ten minutes, then I give it hell just like if I were racing it. I learned from a very good dirt track engine builder to break them in the same way you will use them. I have never experienced any engine damage as a result of using this method. For reference, I build engines to very tight tolerances.

Looking forward to hearing from the two stroke guru's on this, as i'll be needing the same advice very soon...

[christph]

When I got a new cylinder from Duncan Racing a few years ago, I got a print out with break in instructions. I don't have the details at the moment, but I know it was a gradual procedure. It advised running the engine through a couple heat cycles before riding it, e.g., run it for 5 mininutes, let it cool, repeat. After that you ride it for 20 minutes or so at no more than half throttle, being sure not to lug the engine or rev it out. Do that twice (letting it cool between runs) and then you are ready to fine tune the carburetor for the entire rpm range, do plug chops, etc. After that you're good to go. As stated above, I know there are different philosophies about how to break in an engine. I know for every new machine I've bought the manufacturer recommended a gradualist approach. I think the idea is to give the parts time to mesh and break in together. Frankly I can't imagine running it to the hilt from the beginning. With a new engine you might also have metal flakes in the oil and I don't think you want that circulating through the engine at maximum load.

[jakep53]

This will be a good thread.

Engine break in is a debatable topic. First of all, it is best to know the engine builder's tolerances because some will build them to take longer or shorter break-in depending on how the builder setup the cylinder and rings. I'll leave it to the smoker guys to recommend oils and mix ratios, but I will recommend that you start with jetting that you know is too rich, because playing with lean jetting on break in is a big no-no.

When I break in a four stroke, even a V8, I am easy on it for about ten minutes, then I give it hell just like if I were racing it. I learned from a very good dirt track engine builder to break them in the same way you will use them. I have never experienced any engine damage as a result of using this method. For reference, I build engines to very tight tolerances.

Looking forward to hearing from the two stroke guru's on this, as i'll be needing the same advice very soon...

I have no idea what the engine tolerances are as the guy I got it off got it off some other guys mate and no longer had contact with him and when I pulled out my other engine I found the piston and cylinder to be brand new other that all the scrapes it has now so I think this engine was just rebuilt and the guy I got it off had never ridden it so I don't think it was broken in and I rode it hard straight away!! also wouldn't you want it running slightly rich because it is running slightly rich so I was just going to leave it!!

[jakep53]

When I got a new cylinder from Duncan Racing a few years ago, I got a print out with break in instructions. I don't have the details at the moment, but I know it was a gradual procedure. It advised running the engine through a couple heat cycles before riding it, e.g., run it for 5 mininutes, let it cool, repeat. After that you ride it for 20 minutes or so at no more than half throttle, being sure not to lug the engine or rev it out. Do that twice (letting it cool between runs) and then you are ready to fine tune the carburetor for the entire rpm range, do plug chops, etc. After that you're good to go. As stated above, I know there are different philosophies about how to break in an engine. I know for every new machine I've bought the manufacturer recommended a gradualist approach. I think the idea is to give the parts time to mesh and break in together. Frankly I can't imagine running it to the hilt from the beginning. With a new engine you might also have metal flakes in the oil and I don't think you want that circulating through the engine at maximum load.

thanks for the advise I think thats what went wrong with my last engine that it had just been rebuilt and I didn't know about it!!

[danbur55]

Jake. Out of curiosity can you look to see if the cylinder ports were chamfered. Just struck me that if top end was done and not chamfered could be the cause for yoy

[Bren_downe]

Jake, get on air foolers. Com there's is tons of info and even break in procedures specific to your bike.

[jakep53]

Jake, get on air foolers. Com there's is tons of info and even break in procedures specific to your bike.

yeh I joined up the other day but haven't really had a good chance to check it out!!

[jakep53]

Jake. Out of curiosity can you look to see if the cylinder ports were chamfered. Just struck me that if top end was done and not chamfered could be the cause for yoy

I will check that out tomorrow...so the edges should sorta be rounded??

[RIDE-RED 250r]

I have never encountered instructions from an engine builder/manufacturer that recommends running a fresh engine hard during break-in. It's always a gradual process to ensure proper seating of rings to the freshly honed cylinder. During this process the piston rings and cylinder generate more friction and therefore heat.

I have an ESR big bore top end on one of my R's and the gradual process that you listed is exactly what ESR stated on the sheet I got with the kit. A few idling with occasional blips on the throttle heat cycles.. then the roll up to 1/4 under load heat cycle, then to 1/2 throttle..and so on... The Honda manual calls for the same type of break-in, as do many other reputable builders.

This is indeed a hotly debated topic, but I have yet to see any builder or manufacturer list to run it hard for break-in. People do what they like with their machines, I trust those who manufacture the machine that they know what method yields the best overall results for performance and longevity.

As to premix ratio: There is tons of info readily available on this topic. After doing my own research I decided on Maxima 927 (castor based oil) at 32:1 for both of my R's. One of the articles I found was written by Harry Klemm if I recall. It was very in-depth and informative. One thing I personally would not recommend is going any higher than 40:1, especially during break-in. Many folks blame to much oil in their premix for poor performance.. Well, I can tell you that with proper jetting you can tune to run good at almost any ratio within reason.

Pick what type of oil you wish to run and at what ratio then stick with it. Once that is decided get the jetting tuned in for optimum safe performance. Remember, absolute peak performance is on the edge of too lean. A little burble is OK and will leave you a little wiggle room for changes in temperature/humidity as well as offer a little extra protection on a long full throttle pull..

[nd4speed]

Why not just say how you have broke in your own engine in the past? After my 2 stroke rebuilds I run 32:1 oil ratio as a always run. I start the motor with the choke on. I leave the choke on and i rev the motor lightly to warm up the motor for like five to ten minutes- usually I touch the cylinder until it is too hot to touch anymore. Check for leaks and then re torque all the nuts and studs. Then I ride it around at no more than like 1/2 to 3/4 throttle with the choke left on if possible for like 10-15 minutes. Stop, check for leaks, let it cool, and check the nuts/studs again. Then I ride for like 20 minutes going through all the gears, but never holding it wide open. I swear during this portion of the ride I have noticed the power change and pull of the motor. Stop and check stuff again but usually at this point it s pretty much done. Then I ride it around, not abusing it, for a couple hours and that's that.

[jakep53]

I have never encountered instructions from an engine builder/manufacturer that recommends running a fresh engine hard during break-in. It's always a gradual process to ensure proper seating of rings to the freshly honed cylinder. During this process the piston rings and cylinder generate more friction and therefore heat.

I have an ESR big bore top end on one of my R's and the gradual process that you listed is exactly what ESR stated on the sheet I got with the kit. A few idling with occasional blips on the throttle heat cycles.. then the roll up to 1/4 under load heat cycle, then to 1/2 throttle..and so on... The Honda manual calls for the same type of break-in, as do many other reputable builders.

This is indeed a hotly debated topic, but I have yet to see any builder or manufacturer list to run it hard for break-in. People do what they like with their machines, I trust those who manufacture the machine that they know what method yields the best overall results for performance and longevity.

As to premix ratio: There is tons of info readily available on this topic. After doing my own research I decided on Maxima 927 (castor based oil) at 32:1 for both of my R's. One of the articles I found was written by Harry Klemm if I recall. It was very in-depth and informative. One thing I personally would not recommend is going any higher than 40:1, especially during break-in. Many folks blame to much oil in their premix for poor performance.. Well, I can tell you that with proper jetting you can tune to run good at almost any ratio within reason.

Pick what type of oil you wish to run and at what ratio then stick with it. Once that is decided get the jetting tuned in for optimum safe performance. Remember, absolute peak performance is on the edge of too lean. A little burble is OK and will leave you a little wiggle room for changes in temperature/humidity as well as offer a little extra protection on a long full throttle pull..

Thanks for the advice I went on air foolers and they had this break in procedure just a little more detail so I will do that!!
I run my 4-strokes not really hard but I give em a little but I will do it as above....
My dad is going to go to the Honda dealer and check out what they have got there and then I will go from there!!

when I pulled my plug it was running rich so would it be safe to leave it at that until it's broken in and then fine tune the carb??

[nd4speed]

The motor hopefully has good seating rings which will create more suction and more fuel pulled in so after a rebuild I would experience a rich carb mix with out jet changes anyway so no need to mess with those at first.

[jakep53]

Why not just say how you have broke in your own engine in the past? After my 2 stroke rebuilds I run 32:1 oil ratio as a always run. I start the motor with the choke on. I leave the choke on and i rev the motor lightly to warm up the motor for like five to ten minutes- usually I touch the cylinder until it is too hot to touch anymore. Check for leaks and then re torque all the nuts and studs. Then I ride it around at no more than like 1/2 to 3/4 throttle with the choke left on if possible for like 10-15 minutes. Stop, check for leaks, let it cool, and check the nuts/studs again. Then I ride for like 20 minutes going through all the gears, but never holding it wide open. I swear during this portion of the ride I have noticed the power change and pull of the motor. Stop and check stuff again but usually at this point it s pretty much done. Then I ride it around, not abusing it, for a couple hours and that's that.

Thats the thing I have never rebuilt a 2-stroke and this is my first 2-stroke i've owned!!!! Thanks for the break in procedure I will follow these instructions and the one on s and it should be good!!

[RIDE-RED 250r]

There isn't a whole lot of difference on the hows and whys of break-in between 2-stroke and 4-stroke. In fact, a 4-stroke has a few more components that should be allowed to break in if a full top to bottom proper rebuild is done.. (cam and rockers)...

Yes though, as long as it is safely rich you should be A-OK for break-in.