How to break in top end?

[Gingerbread Man]

I have just installed my 44mm bbk on my 87 Spree. 85 main jet, air/fuel mixture screw 2 turns out, 3oz Yamalube to .66 gallon of 91 octane. Taz says go half speed for a few weeks. Ok that's fine but..

How did you break in your fresh top end?

[skeeter2]

I can tell ya that 85 is lean for break in. I would go with a 90 at least......

[Trafficjamz]

Taz says go half speed for a few weeks.

As far as heat cycles go .....
first time you start it let it run about 1min then let it cool down completly
next for five min then let it cool all the way
then ten
then 15 min

Always remember to let it cool down all the way, it is just as important as heating it up.

When you go through the first tank, then you are ready for the first ride.
Keep the rides short
vary the throttle alot when riding from 1/4 to 1/2
don't do WOT at all
don't go up hills.
DO go through about 3-4 tanks of gas before ever attempting WOT.
Check you plug alot to make sure you dont run lean.

[Trafficjamz]

I can tell ya that 85 is lean for break in. I would go with a 90 at least......

85 is fine

Premix @ about 30:1

[Gingerbread Man]

Thank you trafficjamz that's just what I was looking for!

[PimpinSpree]

Do a few short heat cycles the first couple times you start it, take it easy for the first 100 miles and upping your jet a size or two for break in wouldn't hurt either

[skeeter2]

I was just giving my opinion. did 85 really work for you guys? I couldnt get s*** for power until a 91-92

[mustangwagz]

ive done 3 tanks on jet 90, and im still babying it. lol

whats your compression, and what plug you using?

[Gingerbread Man]

My compression is 160 PSI. I am using the NGK BPR6HS.

[Trafficjamz]

My compression is 160 PSI. I am using the NGK BPR6HS.

That is too high. put another headgasket on and recheck.

[premix56]

Do you guys baby all fresh top ends like this or just big bores? I did a 2nd over stock bore on my 01 sa50 and had it WOT with in 30 second. Of starting the engine.

[Trafficjamz]

Do you guys baby all fresh top ends like this or just big bores? I did a 2nd over stock bore on my 01 sa50 and had it WOT with in 30 second. Of starting the engine.

How did that work out?

There are too schools of thought for breakin, hard and soft.

hard break in sounds like what you are talkin' about.

slow or soft break in for any brake in for any brand NEW bore here at trafficjamz

[PimpinSpree]

Do you guys baby all fresh top ends like this or just big bores? I did a 2nd over stock bore on my 01 sa50 and had it WOT with in 30 second. Of starting the engine.

i always do it gently on everything. Regardless of bore, your trying to get the rings broken in properly

[808BMW]

You can get away with less break in on a used cylinder, heatcycling the cylinder stabilizes the metal. Yes, you are still seating new rings to the fresh hone, but the bore is flexing less around everything. Brand new bores move around more, and run hotter.

I baby it on anything, especially a brand new bore. I've seen more than a few seized bores that have less than 50 miles on them, patience is a virtue.

[Bear45-70]

I thought this guy had been to motorcycle school. I wonder why he is asking basic questions like this, that any school should have a already taught? This break in stuff is generic as *.