opinions on break-in procedure

Got questions? We got answers....
Post Reply
commanderjjones
Member
Posts: 41
Joined: 09:08 pm May 15 2017
Country: United States

opinions on break-in procedure

Post by commanderjjones »

Tonight I'll finish my complete engine rebuild and will be firing it up before dark.

I've seen/heard a lot of varying opinions on break-in. Most seem to agree with running various rpm's and under a load for a half hour or so, then letting it cool down and check bolt torque, so that's probably the route I'll take.

But what about running 24:1 pre-mix in the first tank full ??? I'm old school and back in the day that was standard procedure, but I've not seen anyone mention that in years, nor did I see it mentioned in the manual. Still a good idea or not necessary ?

Can't wait to see how much difference the RB mod's have made.
User avatar
Tedh98
Supporting Member II
Supporting Member II
Posts: 1576
Joined: 01:08 pm Mar 20 2009
Country:
Location: Atlanta, Georgia
Contact:

Re: opinions on break-in procedure

Post by Tedh98 »

Warm it up and ride it hard. That method has always worked for me.

Whichever way you go, make sure you always warm up the engine. Especially if you are running a forged piston.

I cringe ever time I see a guy unload his bike, start it and then rev the snot out of it.
John_S
Gold Member
Gold Member
Posts: 875
Joined: 06:59 am Jan 27 2017
Country: US
Location: Florida

Re: opinions on break-in procedure

Post by John_S »

I would use the oil and ratio you're going to always run. I start it and let it idle for a minute or two, checking for coolant leaks while its warming up and then jump on and start riding around casually like I always would until its up to temp. After that I don't baby it but I also am not going to be screaming the engine to redline just yet. I run it like that (about 3/4 of my normal effort) for about 10-15 minutes. Bring it in to cool off a bit, and check it over again for leaks. After that I ride it as I normally would.

I wouldn't do any of that though until I did a leak down test and it passed at 6 psi for 6 minutes with zero loss. An air leak could potentially cause more damage than any break in procedure method. After the first days ride I do a compression test to have a number to go by in the future.
User avatar
Tyl3r
Platinum Member
Platinum Member
Posts: 1335
Joined: 06:51 pm Nov 26 2012
Country: USA
Location: SW Pennsylvania

Re: opinions on break-in procedure

Post by Tyl3r »

It's interesting to hear what everyone does. Now, I've only done one top end, in process on the second one. When I broke mine in, I followed this heat cycle procedure from the KDX KIPS and Top End Info thread over on the TT forum (https://www.thumpertalk.com/forums/topi ... to-kdx200/). I have not had any issues, seems to have worked well:


how to break in a 2 stroke, brought to you by Chokey

from moto814

1) Assemble the engine properly and torque all fasteners to specs.

2) Start the engine with the bike on a stand and allow the engine to come up to operating temperature (top of the raidator hot to the touch). Do not allow the engine to run at one RPM at all. Constantly vary the RPM and do not allow the engine to idle. When then engine reaches operating temperature (about 3 to 5 minutes of running time), shut it off.

3) Let the engine cool completely (at LEAST one hour). You want the engine to be dead-stone cold. Longer is better.

4) Start the engine with the bike on a stand and allow the engine to come up to operating temperature (top of the raidator hot to the touch). Do not allow the engine to run at one RPM at all. Constantly vary the RPM and do not allow the engine to idle. When then engine reaches operating temperature (about 3 to 5 minutes of running time), shut it off.

5) Let the engine cool completely (at LEAST one hour). You want the engine to be dead-stone cold. Longer is better.

6) Start the engine with the bike on a stand and allow the engine to come up to operating temperature (top of the raidator hot to the touch). Do not allow the engine to run at one RPM at all. Constantly vary the RPM and do not allow the engine to idle. When then engine reaches operating temperature (about 3 to 5 minutes of running time), take the bike off the stand and put it in gear. Take it for a ride. During this ride you want to keep the engine under a load at all times. Do not coast. Do not let the bike idle. Do not allow the engine to stay at one RPM. Riding on a mild slope is fine for this, as is slightly dragging the rear brake the entire time. Do this for about 15-20 minutes. Then shut the bike off.

7) Let the engine cool completely (at LEAST one hour). You want the engine to be dead-stone cold. Longer is better.

8 ) Re-torque the head and base nuts.

9) Go ride.

The cool-down steps are crucial to this operation. You must let the engine cool completely for the break in process to work properly.

Also, do the warm up procedure I outline here before EVERY ride. Your top ends will last much longer if you do.
04/05 KX220 Hybrid all decked out
18 KTM 500 EXC-F Dual Sport/Sumo toy
24 KTM 300XC-W Cheater bike
thirdgenlxi
Supporting Member I
Supporting Member I
Posts: 489
Joined: 12:09 am Mar 06 2015
Country: USA
Location: Lenoir, NC USA
Contact:

Re: opinions on break-in procedure

Post by thirdgenlxi »

Tedh98 wrote:Warm it up and ride it hard. That method has always worked for me.

Whichever way you go, make sure you always warm up the engine. Especially if you are running a forged piston.

I cringe ever time I see a guy unload his bike, start it and then rev the snot out of it.
Ohhh man I'm glad I'm not the only one, lol..... I too cringe when I hear somebody start up a bike stone cold, and immediately sit there and hold it wide open. And they do it alllllllll the time. I always make a mental note... "don't EVER buy a bike from that guy!", lol. Even the ones that start it up cold and immediately take off riding..... noooope. And then they wonder why they burn through top ends :blink: :naughty: :roll: Nobody seems to have a clue about thermal expansion of dissimilar metals

I always warm my bike up..... even if I'm just riding it across the parking lot to the bathroom, I will NOT ride it cold, or rev it. I start it up and let it idle for a good 5-10 mins, until coolant temp is up to at least 130 deg or so, then I'll blip it a few times to clear it out and then take off. I'm a firm believer that this may be why my top end has lasted so long, and still looks great. I warm everything up..... cars, bikes, lawnmower, weed eater, chainsaw, etc..... I never run anything on a cold motor. I know some people consider it a waste of gas, but between my 2 bikes and 2 cars, I have a total of 949,000 miles combined (314k of that is on a high revving 600cc sportbike), and I have not had a single engine problem or failure out of any of them... so I stick with what seems to work, lol
User avatar
SS109
KDXRider.net
KDXRider.net
Posts: 5770
Joined: 05:11 am Aug 23 2009
Country: USA
Location: Tucson, AZ, USA
Contact:

opinions on break-in procedure

Post by SS109 »

1. Check all fluids

2. Start bike and let get to full temp.

3. Shut off, let cool, recheck all fluids, and check for leaks

4. If all good, restart, let warm to full temp

5. Ride the hell out of it.

I admit, before I take off riding on a fresh top end I do several (10 or so) 3rd gear accelerations/decelerations to make sure the rings seat quickly but, honestly, it is overkill.
Youtube Channel: WildAzzRacing
AZ State Parks & Trails OHV Ambassador - Trail Riders of Southern AZ
Current KDX: '98 KDX220
Old KDX: '90 KDX200 -White/Blue
'11 GasGas EC250R
ohgood
Supporting Member II
Supporting Member II
Posts: 925
Joined: 10:00 am Jan 04 2014
Country:

opinions on break-in procedure

Post by ohgood »

commanderjjones wrote:Tonight I'll finish my complete engine rebuild and will be firing it up before dark.

I've seen/heard a lot of varying opinions on break-in. Most seem to agree with running various rpm's and under a load for a half hour or so, then letting it cool down and check bolt torque, so that's probably the route I'll take.

But what about running 24:1 pre-mix in the first tank full ??? I'm old school and back in the day that was standard procedure, but I've not seen anyone mention that in years, nor did I see it mentioned in the manual. Still a good idea or not necessary ?

Can't wait to see how much difference the RB mod's have made.

running a heavy ratio like that is leaning out your mixture. it's better to install larger than normal jets, warm it fully and ride normally, then rejet after that first ride (or during it) so that you don't end up lean on the fresh top end. start with whatever fuel: oil ratio you normally use, and stick to it.

I've slowly stepped down from 65/160 jets since my last rebuild, so that I would be certain it was never lean from the previous jetting, which was 40/142. it's just running better and better each time I jet and test.

remember, more oil means more lean.
ohgood
Supporting Member II
Supporting Member II
Posts: 925
Joined: 10:00 am Jan 04 2014
Country:

Re: opinions on break-in procedure

Post by ohgood »

as far as breaking it in, that's a myth!
you warm up the bike like always , check for leaks, then ride.
commanderjjones
Member
Posts: 41
Joined: 09:08 pm May 15 2017
Country: United States

opinions on break-in procedure

Post by commanderjjones »

ohgood wrote:[.......running a heavy ratio like that is leaning out your mixture..........remember, more oil means more lean.
How do you come up with that statement? Not saying it isn't so, but it defies logic. Care to educate me on this???

She's running GREAT! RB's jetting was spot on right out of the gate. It's not a screamer on top end (and I didn't expect it to be), but MUCH better than it was previously. Now I can pull up the front wheel EASILY in 3rd, and do the same in 4th with a little effort (but no still clutching). I'm a happy camper. Can't wait to hit the woods this weekend.
User avatar
Tyl3r
Platinum Member
Platinum Member
Posts: 1335
Joined: 06:51 pm Nov 26 2012
Country: USA
Location: SW Pennsylvania

opinions on break-in procedure

Post by Tyl3r »

commanderjjones wrote:
ohgood wrote:[.......running a heavy ratio like that is leaning out your mixture..........remember, more oil means more lean.
How do you come up with that statement? Not saying it isn't so, but it defies logic. Care to educate me on this???

She's running GREAT! RB's jetting was spot on right out of the gate. It's not a screamer on top end (and I didn't expect it to be), but MUCH better than it was previously. Now I can pull up the front wheel EASILY in 3rd, and do the same in 4th with a little effort (but no still clutching). I'm a happy camper. Can't wait to hit the woods this weekend.
Yea, I was scratching my head on that one too :hmm: lol how does premix affect your air to fuel ratio?
04/05 KX220 Hybrid all decked out
18 KTM 500 EXC-F Dual Sport/Sumo toy
24 KTM 300XC-W Cheater bike
User avatar
KDXGarage
KDXRider.net
KDXRider.net
Posts: 14047
Joined: 06:45 am Nov 01 2004
Country: United States of America
Location: AL, USA
Contact:

Re: opinions on break-in procedure

Post by KDXGarage »

More oil means less gas. He is not talking about how the engine runs. He is talking about the fuel mixture itself. For a given mixture of fuel, leaner or richer means less gasoline (leaner) or more gasoline (richer).
Thank you for participating on kdxrider.net. :bravo:
To post pictures from a device: viewtopic.php?f=88&t=24128
commanderjjones
Member
Posts: 41
Joined: 09:08 pm May 15 2017
Country: United States

Re: opinions on break-in procedure

Post by commanderjjones »

Jason wrote:More oil means less gas. He is not talking about how the engine runs. He is talking about the fuel mixture itself. For a given mixture of fuel, leaner or richer means less gasoline (leaner) or more gasoline (richer).
That makes more sense. Thanks for the clarification.
User avatar
KDXGarage
KDXRider.net
KDXRider.net
Posts: 14047
Joined: 06:45 am Nov 01 2004
Country: United States of America
Location: AL, USA
Contact:

Re: opinions on break-in procedure

Post by KDXGarage »

No problem. It took me a little while to understand it when I heard it.
Thank you for participating on kdxrider.net. :bravo:
To post pictures from a device: viewtopic.php?f=88&t=24128
thirdgenlxi
Supporting Member I
Supporting Member I
Posts: 489
Joined: 12:09 am Mar 06 2015
Country: USA
Location: Lenoir, NC USA
Contact:

opinions on break-in procedure

Post by thirdgenlxi »

Most people get this backwards, and always think more oil = richer mixture, when it's actually the opposite. People get OIL mixture and FUEL mixture mixed up... more oil does indeed make for a richer OIL mixture, but that's not what the engine runs off of, it runs off the FUEL mixture. Since the oil and fuel get sucked in together as one "charge" before getting mixed with the air, how much of that mixture is oil and how much is fuel is what determines the air/fuel ratio. One way to think of it, even though it's not technically correct on what's actually happening, but just for a visual reference to help understand..... think of it in viscosity. You're moving the mixture through a fixed orifice in the carb (the jets), and more oil would make the mixture thicker, resulting in less of the mixture flowing through the jet, thus less making to the engine = lean condition. Less oil in the mixture would make for a thinner viscosity, meaning more of it can flow through the orifice, meaning more going to the engine = rich condition. Again this is not theoretically correct, but just for a visual representation on what's going on. Think of trying to suck a thick milkshake through a straw vs a thin watery one....

A little visual..... hand drawn by yours truly :boogie: :lol: Hopefully that helps clarify a little bit though. Of course these ratios are waaayyyy out of actual proportions of what we would actually run..... definitely blown waaayyyy out of scale, lol. But makes for an easier visual representation. Actual is more like 3-4% oil and 96-97% fuel

Image
John_S
Gold Member
Gold Member
Posts: 875
Joined: 06:59 am Jan 27 2017
Country: US
Location: Florida

Re: opinions on break-in procedure

Post by John_S »

Jason wrote:More oil means less gas. He is not talking about how the engine runs. He is talking about the fuel mixture itself. For a given mixture of fuel, leaner or richer means less gasoline (leaner) or more gasoline (richer).
Theres a good chance I'm wrong. I thought if you're jetting was great at 40:1 and you switched to 20:1 you're bike would run lean and you would need bigger jets. If you ran 80:1 your engine would be running rich and you'd need smaller jets.

It has to do with how thin your mix would be at 80:1 compared to how thick it would be at 20:1 and how easily they pass through a jet. At 20:1 there would be 4 times less actual gas to combust than 80:1 because the oil in your mix doesn't combust but falls down after combustion for lubrication. Both of those things causing the need for larger jets at 20:1. I'm still confused but the main point I took from the reading I've done is if you're rich at 32:1 people will suggest trying 40-50:1 to lean it out...but instead you would be making it run richer.

As Bufftester always says....pick an oil brand and a ratio of your choice, jet it for that, and don't change anything or you'll have to rejet it.
John_S
Gold Member
Gold Member
Posts: 875
Joined: 06:59 am Jan 27 2017
Country: US
Location: Florida

Re: opinions on break-in procedure

Post by John_S »

Thirdgen, I was typing my post and didn't see yours.
thirdgenlxi
Supporting Member I
Supporting Member I
Posts: 489
Joined: 12:09 am Mar 06 2015
Country: USA
Location: Lenoir, NC USA
Contact:

Re: opinions on break-in procedure

Post by thirdgenlxi »

John_S wrote:
Jason wrote:More oil means less gas. He is not talking about how the engine runs. He is talking about the fuel mixture itself. For a given mixture of fuel, leaner or richer means less gasoline (leaner) or more gasoline (richer).
Theres a good chance I'm wrong. I thought if you're jetting was great at 40:1 and you switched to 20:1 you're bike would run lean and you would need bigger jets. If you ran 80:1 your engine would be running rich and you'd need smaller jets.

It has to do with how thin your mix would be at 80:1 compared to how thick it would be at 20:1 and how easily they pass through a jet. At 20:1 there would be 4 times less actual gas to combust than 80:1 because the oil in your mix doesn't combust but falls down after combustion for lubrication. Both of those things causing the need for larger jets at 20:1. I'm still confused but the main point I took from the reading I've done is if you're rich at 32:1 people will suggest trying 40-50:1 to lean it out...but instead you would be making it run richer.

As Bufftester always says....pick an oil brand and a ratio of your choice, jet it for that, and don't change anything or you'll have to rejet it.
You are correct in your logic...... it would indeed be running leaner at 20:1 vs 40:1. But like I mentioned above, while the viscosity thing is a good way to visually understand it, that's not the actual reason. Remember, the jet is a fixed orifice. Each time the engine makes a vacuum and pulls in an air/fuel mixture, it's drawing in the same metered amount of fuel mixture each time (in relation to the throttle position, of course), regardless of the oil mix ratio. In that metered amount of fuel that it's drawing in, you have a percentage of oil and a percentage of fuel. The fuel is the only part of that mixture that the engine cares about from a running and A/F standpoint, the oil is just tagging along for the ride and to lube everything up. But it takes up "space" in that mixture. So if more of that mixture that it's sucking in is oil instead of fuel, it's going to lean out, and you need more fuel to bring the air/fuel ratio back up to a stoichiometric ratio. You have to go to the bigger jet size not because of the viscosity, but to increase the physical amount of fuel being drawn into the engine, since the percentage of fuel within the mixture is lower with the added oil, so you have to increase jet size to compensate to get the same amount of fuel into the engine and keep the air/fuel ratio correct. Hopefully that makes sense, lol
Last edited by thirdgenlxi on 10:56 am Jul 19 2017, edited 2 times in total.
thirdgenlxi
Supporting Member I
Supporting Member I
Posts: 489
Joined: 12:09 am Mar 06 2015
Country: USA
Location: Lenoir, NC USA
Contact:

Re: opinions on break-in procedure

Post by thirdgenlxi »

John_S wrote:Thirdgen, I was typing my post and didn't see yours.
Ahhh I just did the same, hahah :lol: Oh well..... hopefully that helps clarify
Dave B
Supporting Member I
Supporting Member I
Posts: 46
Joined: 08:46 pm May 30 2016
Country: Canada
Location: Ontario, Canada

opinions on break-in procedure

Post by Dave B »

Break in procedure is a highly debated issue with everyone having a different opinion. I have broke in slow and broke in on the starting line with the drop of the gate. Only thing I always do is use a NON synthetic premix oil for the first tank of gas to help seat the rings.
User avatar
Tyl3r
Platinum Member
Platinum Member
Posts: 1335
Joined: 06:51 pm Nov 26 2012
Country: USA
Location: SW Pennsylvania

Re: opinions on break-in procedure

Post by Tyl3r »

Ahhhh I get what you guys mean now, must not have been thinking along those lines when I read it the first time.
04/05 KX220 Hybrid all decked out
18 KTM 500 EXC-F Dual Sport/Sumo toy
24 KTM 300XC-W Cheater bike
Post Reply