2 Stroke Break In

["Dangerous" Dan K]

2-Smoke Break In

I’ve heard and read about 50 different opinions on the proper way to break in a 2 stroke after a new top end. The one that seems to be repeated most is basically:
1) Run on stand until warm, blipping throttle, 3-5 minutes.
2) Let cool (at least 1 hour)
3) Run on stand until warm, blipping throttle, 3-5 minutes.
4) (at least 1 hour)
5) Run on stand until warm, blipping throttle, 3-5 minutes.
6) Take bike off stand, ride easy, staying under half throttle and varying throttle, don’t hold any one RPM and don’t coast.
7) Let cool (at least 1 hour)
8) Ride again, don’t go over ¾ throttle.
9) Let cool again.

Another friend of mine has always done it by just heat cycling it a few times, not revving the motor much at all but blipping the throttle just enough to keep it running. Then ride as usual.

Yet another way I’ve heard is to ride it right from the start, keeping it under load. First ride no more than ¼ throttle, 2nd ride no more than half, 3rd ride no more than ¾ and 4th ride full range to WOT but don’t hold it there. Then ride 5 on you’re set to ride it like you stole it.

I’m leaning toward method #1, and my buddy is going to continue to do it the way he always has, with is the second method listed. Basically warm up with minor throttle blipping and let cool a few times, then ride as normal. I’m curious as to how the rest of you do it.

[Paul_E_D]

All those methods are fine. I've gone as far as to race on a fresh piston. No cycles. I've also done the heat cycles, but not blipping throttle, rather holding 4k rpms eeeeeeeeeee til the motor reaches 50 degrees, then cooling. 6K (higher note) eeeeeeeeeee til 50 degrees, then cool. Then go ride.

Honestly, I've never seen any difference. I can feel the compression go up in the second cycle though. I'm more likely to the cycles when I've done a bottom end as well. I'll also run one session at or below 10krpm, then uncork it.

[Sheppo]

I ride for 30 minutes or so mixing up RPM never holding it at any speed or full WOT pulls. cool an hour, recheck torque on head bolts. Ride again 30 minutes or so. Same mixing up RPM including a full WOT pulls.. cool and retorque. Then I am all set to RIP.

[catch2otwo]

All those methods are fine. I've gone as far as to race on a fresh piston. No cycles. I've also done the heat cycles, but not blipping throttle, rather holding 4k rpms eeeeeeeeeee til the motor reaches 50 degrees, then cooling. 6K (higher note) eeeeeeeeeee til 50 degrees, then cool. Then go ride.

Honestly, I've never seen any difference. I can feel the compression go up in the second cycle though. I'm more likely to the cycles when I've done a bottom end as well. I'll also run one session at or below 10krpm, then uncork it.

so its eeeeeeeeeeeeeee and not UT GUHHHHHHHHH?

["Dangerous" Dan K]

Cool, thanks for the replies. Sounds like I should be OK then. Heck, if the ride doesn't make a difference I might just do the heat cycles like my buddy on the stand, so the first time i pull it out I can ride it normally rather than worrying about throttle and whatnot. It's a 125, sometimes high RPMs and clutch slipping is needed just to get through/over stuff, I'd have to find some pretty tame trails to stay under half throttle for a ride.

[Paul_E_D]

so its eeeeeeeeeeeeeee and not UT GUHHHHHHHHH?

Yes, and that's eeeeeeee in celsius...

[SSearchVT]

On a fresh build - Start it and keep it running and cleaned out (blip the throttle). Put you hand on the side of the cylinder - when you feel it warm up - go for a 15 or 20 minute buzz around the yard. No high revving, hard, long pulls - just a simple ride (first and second gear). Shut it down and let it cool - check the torque for the head and base bolts, make sure the bolts or springs for the expansion chamber are good, and the carb clamps are good.

It never hurts to 'nut and bolt' the entire bike...

After that - ride it and have fun.

[richw]

Depends what on motocrossers piston is wild tapered and almost loose.

Older or maybe Quads if piton is long and straight then care needed