What's the best way to break in a 4 stroke?

[OldSchoolin86]

Your first 10-20 hours on the motor will be its break in.

10-20 hours just might be overkill.................

[McDerry]

10-20 hours just might be overkill.................

Thats the break in on most any engine.

Which is 500-1000 miles on a street bike or a car.

mowing the lawn twice casually...

50-100 miles on a atv.

Break in is all about getting a good seal with the rings. You don't want to baby it or you'll never get enough pressure behind the rings to grind them smooth before the crosshatching from the hone job is rubbed off. And if you beat on it to heavily, it will wear unevenly.

Medium load, mid gears, mid range rpm band with constant variation. The main sign that the rings are sealing up well is the fuel consumption drops like a rock.

[The Goat]

that 200cc enduro engine in my 200x had a suggested break in period of 1000 miles. Riding casually, every other day or so...that's about a year and a half.

[cr480r]

round ring + round bore = sealed...

[McDerry]

that 200cc enduro engine in my 200x had a suggested break in period of 1000 miles. Riding casually, every other day or so...that's about a year and a half.

thats in street mileage, at 50 mph its 20 hours.

Its just truing up the rings to the bore. Even in a fresh bore there still a slight variance in the ring to wall clearance. Even at 0.0005 it creates a airpocket where the expanding gas in the combustion chamber can get between the ring and the cylinder wall and push the opening larger.

[Gag_Halfront]

round ring + round bore = sealed...

It's just that easy, eh?

[cr480r]

It's just that easy, eh?

yep... the final bore finish plays a big part too...

[sandpuppi101]

LOL,I see everyone has there own way to break in a Thumper motor and of course nobody agree's as usual.What " I "do for initial break-in ( 4-stroke),is make sure the oil is in the entire system,turn the motor over manually or whatever you have too but get the motor turning over to where the top is well lubed .Being a new motor,which I am assuming,there is probably already motor grease lubing the cam,just make sure the oil is up there also.After you've turned it over ,start it up and let it pur like a kitten for a few,and listen for anything out of the ordinary.While at an idle ,and while listining,give it a small burst of throttle,just a bit.I let them warm up and then shut em down,for a few cycle's before I even ride thumper's.Get her up and running again after a few warm up's and take her for a leisurely ride,with the little burst.The burst of throttle is a good thing when seating the ring's,seals,spring's,valve's,guide's,etc.and help's with the lobe's also.One thing no one mentioned ,was that with the horizontial motor's,the combination that kill's a motor like that is the lack of oil and overheating,and you get a oval cylinder after year's of use.Do a plug chop also help's .I know it's probably how you's don't do it ,but I've had pretty good sucess building 4 stroke's and this is how I go about it.I do this for @ 2 tank's of gas.

[Danold]

I just rebuild my 200x with a new .50 piston. I let it idle for 5 min, rode it easy for about an hour, and changed the oil. The hone is wore off in a few spots but only like 20%. The problem im having is it runs like its way too rich. I didnt not rejet or do any thing to the carb. Should it run extremly rich after a fresh rebuild? It ran great(despite the oil burning) before.

As of now the motor is split to fix the kickstart spring. The piston and head are covered with black soot. It was assembled with new gaskets and valve seals so it shouldnt be burning oil.

[Nick_R_23]

I have rebuilt EVERY engine of all the stuff in our yard at least once, and I have tried every break in method, babying it, heat cycles, giving it hell, and when its torn back down again either years later or to replace a part, theres never any difference in compression, piston, cylinder, or ring wear, blow by, or what have you, it just doesnt make a difference.

Id say give it hell, thats the only time the engines never gonna be BRAND NEW again, so might as well get the most out of it from the start!!

-Nick

[rugabugadouglas]

if ya got a warranty beat it it can be replaced for free

[300rman]

rev it to the moon.
blow it up.
remove motor.
place in dumpster.
replace with equal sized two stroke.
hold on to your nuts!

[edog]

rev it to the moon.
blow it up.
remove motor.
place in dumpster.
replace with equal sized two stroke.
hold on to your nuts!

That's a great idea.Why didn't I think of that.

[lndy650]

heat cylcles are good and dont beat on it till 2-3 tanks of gas are through it imo...
i hate people that say to beat em right away its the dumbest thing you can do.

[The Goat]

rev it to the moon.
blow it up.
remove motor.
place in dumpster.
replace with equal sized two stroke.
hold on to your nuts!

and the bias I see so frequently rears its ugly head again.

that engine is producing what edog? about 17 hp if I remember right....add on your mods, and you'll get even more.

a 175cc air cooled 2 stroke will produce about....15-25hp stock. certainly not that big of a difference. and before you flame that, think about what a stock 250r produces...

now that wasn't directed at 300rman...more so the many threads I see that are basically "my dad can beat up your dead"

I think it was 3leggeddog who pointed out that if 4strokes were slow...why was most everyone but the big boys having trouble keeping up with derrick's 450 at tf?

Edog...here's your break in procedure...don't beat on the damned thing for a tank or two of gas...and then don't beat on it too hard for the first 10 tanks or so. run 20w50 in it, change your oil every other ride for 3 times...and congratulations, you'll have a working running engine. If you do beat on the thing the first tank of gas...guess what...it probably won't hurt anything at all.

my breakin procedure for my 250 beartracker was 4-5 hours of hard hard riding...and then wot fifth gear pinned for over 3 miles. guess what...it's the best engine I've ever had....and stronger than most 250s in a quad utility.