Air fooler break in

[loganm]

Now, what is the "proper" way to break these motors in? Basically I took it back to the shop that did the work and he took one look at it and told me that I didn't let it warm up enough and I didn't break it in well enough. He also said it is difficult to do it to these motors. Also told me to go down 10 sizes on the main jet and start from there.

Now, when I heat cycle the motor, should i just let it idle with an infrared temp gun pointed at the cylinder until it reaches ~200? degrees, let it cool back to ambient temp, then repeat that once before I let it warm up to operating temp and ride it gently, then let it cool back down to ambient temp, etc.

I'm pulling the bottom end apart yet again, since it sat in the shop with just a shop towel over the crankcase, and when I go to wash it out with diesel it was making a grinding noise turning the crank, so I'm replacing the main bearings for piece of mind, and to check and make sure I didn't assemble it wrong and create a timebomb in the transmission.

I will get a leak down test done before it goes back in the bike.

[oldskool83]

Run 15 mins, light throttle. let sit....15 mins more let sit. 15 mins more even more let sit. go ride.

This varies between people like as*holes. Everyone thinks they are correct.

Have shop build your bike they are gonna start it and write up the bill and tell you its good to go and your gonna go rip like ya never had any cares....so who is right, who is wrong. Battle of the century.

[barnett468]

Now, what is the "proper" way to break these motors in? Basically I took it back to the shop that did the work and he took one look at it and told me that I didn't let it warm up enough and I didn't break it in well enough. He also said it is difficult to do it to these motors. Also told me to go down 10 sizes on the main jet and start from there.

imo, yes it is difficult to break a 2 stroke engine in properly especially in cold weather and he gave you xlnt advice because reducing the amount of fuel [leaning it out] will reduce the chance of the rings getting "washed out" and will also reduce the amount of carbon build up which often occurs during break in.

Reducing the amount of oil in the gas will also help because it will allow the rings to lightly rub against the cylinder which is actually what allows them to break in . If you read the labels on some 2 stroke oil bottles, you will see that they can be mixed anywhere from 20:1 to as little as 100:1 . Amsoil is one of these, but in fact, most oils can be mixed at 100:1 as long as the rpms don't exceed around 4000 for a prolonged period of time . High ratios can be run under these conditions because the oil "migrates" out of the engine more slowly at lower rpms . In your case, I would probably mix it at around 60:1 or 70:1 irregardless of what brand of oil it is, but no leaner.

Also, since it didn't get it warm enough, or didn't warm up to operating temp fast enough, I would also run a hotter spark plug like an NGK B6ES . This will help it get warmer faster, especially if you live in an area where it is cold . The new plug will also make it easier to read when you look at it to determine the jetting.

Another thing that will help it get warm quickly is putting a blow dryer inside the air box and setting it on low . This will simply simulate warm weather as if you were breaking it in on a warm summer day instead of sending freezing air into it in the middle of winter, however, I have found that if you place the end of the hair dryer within less than 1" from the object you are trying to heat, it may shut off because it has a thermal safety switch in it.



Now, when I heat cycle the motor, should i just let it idle with an infrared temp gun pointed at the cylinder until it reaches ~200? degrees, let it cool back to ambient temp, then repeat that once before I let it warm up to operating temp and ride it gently, then let it cool back down to ambient temp, etc.

In your particular case, I would turn the idle up and let it run for 15 minutes as oldskool suggested then ride it without letting it cool down because the air moving over the cylinder fins or radiator will keep it at the proper operating temp . Just don't rev it to the max for a prolonged period during this time, however, short bursts of hard acceleration are ok, and will "load" the engine forcing the rings against the cylinders helping to insure that they will break in properly and quickly . After 30 minutes or so, I would let it cool down and check the plug color for jetting and increase the oil ratio to the level I normally run.


NOTE - Some of these suggestions apply to this particular case only and are not applicable to all situations . People should check with a professional engine builder in their particular area for their suggestions like loganm did.
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[loganm]

Boss bearing on eBay makes a full seal kit for this motor, plus crank bearings, and the hard to find main shaft bearing. However, I would not recommend any of the bearings. The crank bearings don't spin as smooth as I would like. Not really noticeable when running it but iffy on the quality. And the main shaft bearing requires some case modification to seat all the way. RJATV on eBay sells high quality replacement main bearings, nachi brand. $35 for both bearings

The seals however seem to be good-quality, and they're new rubber vs 30 year old NOS.

[atc300r]

I don't heat cycle my motors. On a topend rebuild I run 1 gallon of 32:1 non-synthetic oil 91 octain non-ethol . On a topend rebuild with new crank bearings and seals I run a full tank at 32:1 non-synthetic 91 octain non-ethol. I ride it easy and don't go over 1/2-3/4 throttle stopping every 15-20 mins for a cool down. I recheck all nuts and bolts. After I hit reserve I drain the tank and switch to synthetic oil at 32:1 91 octain gas non-ethol.Works for me and I have 4 air cooled 250Rs and 1 liquid.

[oscarmayer]

i typically let it idle to temps then shut it down. let it sit for an hr, then run it up to temps again and let them idle for about 10 min or so, then shut down for couple of hours. finally start up, run tot temp, ride 15 min at no more than 1/4 throttle. putting around 1-2 gear only. after about 15 min turn it off and let it sit, do the same thing with no more than 1/3 throttle max for 20-30 min. let it cool. finally have fun.
this is how we brake in the race motors.

[atc007]

Always warm an engine up correctly. Ride it. Don't bog it,don't over rev it. Cleanliness in the build, fresh oils,and a good clean oiled air filter are the main keys.

[loganm]

Where do I find jets at? eBay is a mess. I'm looking for a few different sized main jets, all I'm finding is 4 packs of the same size jet.

[El Camexican]

JetsRus is my soure