Rotax break-in

[Jon Romenesko]

I stuck our Rotax at Bandi at the last race, and it’s fresh back from Accelleration Karting and ready to be broken in for The Track race! Does anyone have any specific tips on breaking-in the Rotax? Or should I just follow the manual’s instructions of the 2-15 minute sesstions?

[Doug Welch]

Follow the manual to the letter.

[Anonymous]

I go even farther than what the manual says:

I use castor 927 oil only at 32:1

20 mins at 2,500 rpm on the track
cool to ambient temp

20 mins at 5,000 rpm on the track
cool to ambient

20 mins at 8,000 rpm on track
cool to ambient.

20 mins at 10,500 rpm on track
cool to ambient

all of the above you push the gas until you reach your rpm limit for that test then let completly off the gas so the repm drop ~1,000 rpm below your setting and then back on it again–yes I do this

15 mins at race conditions on track

This is a good 4-6 hr break-in proceedure; use ~2-3 gals gas; and run rich jet.

I have never stuck a motor and never had any problems doing it this way. Over kill maybe, but I don’t want the cost of a stuck motor!!!!!!!

[Anonymous]

Hey Jansen,

You want to take this one?

[Anonymous]

Okay now what did I say that was wrong!

[Rodney Ebersole]

http://www.mototuneusa.com/break_in_secrets.htm
This link is a good read about break in and ring seal.
Why is it that a rotax has to be broken in so carefully?
Are the sealors/builders using too tight of piston clearance, or small ring gap? I’m sorry but if a motor is built well for racing there shouldn’t be nothing to break in, other than getting some good cylinder pressure to make the rings seat. The rings wont seat untill you get good heat and pressure.
I am here to learn too. In the past I have even made and used electric break in stands. The only advantage I could find is that you could tighten up the cylinder clearance and ring gap. Even then good ring seal didn’t happen untill combustion pressure/heat is experianced by the top ring.
O well that was mostly 4 cycle stuff, I have stuck a couple of 2 strokes on my first outing with them from running them too lean and building it too tight.

[Mike Jansen]

Since I destroyed a lower rod needle bearing after break in (and you’re right it’s not fun $$$) I would suggest following a few tips stated.

1) use an old plug and run the mixture rich. The plug’s junk afterwards but you’ll not stick it
2) Don’t use a 98 needle

3 heat cycles is enough as long as you let it cool for a while and ambient isn’t necessary just 10 minutes between.

I will say that Welch and Vito haven’t blown an engine and neither did I so do it right and it’ll treat you right too. I can’t emphasize being rich enough. It’ll only foul the plug. Once it’s broke in you can let the engine clean itself!

[Jon Romenesko]

@Mike Jansen wrote:

2) Don’t use a 98 needle

So, in other words, use the K27 needle?

[Mike Jansen]

That’s the stock one and put the clip position down to three, max. Again, bogs are not harmful but lean k-blammos are.

And please, check the fetzer valve and make sure it’s inserted correctly. It’s all about ball bearings nowadays…. 8)

[Jon Romenesko]

The Fetzer valve is fantastic. Those Accelleration karting guys know their Fetzer valves & ball bearings like none other. 8)

[Mike Jansen]

I keep telling Rich to watch his Fetzer valve but he’s not listening. Perhaps one day he’ll clean it and all will be well with him! 8)

Break it in right and you’ll have a happy rotax. Good luck!

[Anonymous]

My Fetzer valve is always clean! It is the jerk behind the valve that is the problem learning this sport.

[Author]

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