Breaking-in a new engine

There is a simple reason why the holes are deeper than the threads.

The holes are power tapped...if the tap hits the bottom of the hole, under power, the tap will break. This halts production, and scraps a part. Drilling the hole a little deeper ensures that the tap will not bottom out.

2-1/2 times the diameter is generally accepted as being a good engagement depth for studs in Aluminum.

The 6mm studs are .230" in diameter, so .575" thread depth is good.

I always bottom tap the engine mounting holes and the exhaust stud holes as they are never threaded deep enough. I've never had a problem with the jug assembly studs...I suppose eventually I will...

Whether or not you should replace the studs from new depends on several things.

1) Are they actually studs? Or are they lengths of all-thread that have been cut from stock?

Studs have threaded ends with a length that is not threaded in between. Studs are made on a screw machine using specialized cutters, or roll forming tools. The ends will be clean and chamfered, (beveled). The studs will be a uniform length. All thread is, just as the name implies, threaded the entire length. All thread is manufactured using an entirely different process, and the grade of material used is generally softer to accomodate the manufacture. The all-thread pieces will typically be different lengths, and the ends will appear saw cut with a non uniform bevel...probably sanded by hand, after cutting.

NOTE: Different grades of all-thread are available here in the U.S. My comments on all-thread apply to what comes in the factory kit.

2) Did they get bent during shipping?

Whether your kit came with studs, or all-thread...if they got bent during shipping, throw them out. Do not attempt to straighten them. They are likely already fractured, and for the small amount that hardware costs it's not worth the risk of having to drill out a broken piece.

So...If your kit came with "real" studs, and they are straight...use them.

If your kit came with all-thread, or any of them are bent...replace them.

As far as engine break-in goes...I haven't had any problems running them heavy on the oil initially, (20:1). I run two tanks, or one gallon at 20:1. After that it depends on the oil you are using. I've been using pennzoil for both break-in and there after. After break-in I use 4 ounces per gallon, which is a ratio of 32:1. I haven't had any problems with carbon fouling.

I, too, agree with Joe. I've never had any other 2-cycle engine where a heavier oil mix was recommended during break-in. So, why do I do it...

1) It hasn't hurt anything to run a little heavy on the oil initially.

2) I have yet to throw away an engine.

Jim

wow some people suggesting 50:1??

i broke mine in on 13:1 for 200kms, then 16:1 for 300kms and then 20:1 for the entire life of the engine, it always smoked a bit but ive never seen a 2 stroke that didnt smoke,

__________________
i'd rather have a bottle in front of me than a frontal lobotomy,


-linnix13(at)gmail,com

Apparently haven't seen one that uses 50:1 yet. I use 50:1 with cheapo Walmart Supertech brand and many tens of thousands of miles with excellent results.

Smoke ain't the only problem with the "oil barons". There's that black trail left behind on the ground. Well... at least it helps you find your way home.

Let's not bring up pistons, walls, pipes, plugs, or Al Gore.

Thanks!!!

This should be a prime info and should be posted on the front page.

WOOH!!! 13:1, would you like some gas in that oil...Sorry i had to, i love oil threads!!!

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funny thing actualy, i did an experiment back a while, and i wanted to see how rich(or lean?) i could go, you will never guess what mixture i got it to run on! now it ran on this but had no power and only went at full revs, but wouldnt take me up any hills, and stalled super easy, not to mention there was a 40ft trail of smoke behind me that made cars slow down and some stop, just guess what my mixture was! guess!

__________________
i'd rather have a bottle in front of me than a frontal lobotomy,


-linnix13(at)gmail,com

How about some blood in my alcohol level.........


Snicker,
Salty

i was at 20:1 and knew it would run on 13:1 so i went down to 10:1 it ran fine, a bit more smoke but it still had full power, so i halfed that!! 5:1, and it still ran, it was sluggish and alot of smoke, but i could still see riding it like that in the long run, i finaly said all or nothing and dropped it down to 3:1, and thats when it was hard to ride, stalling bogging, so much smoke it looked like fog! but it ran, man did it run, on 3:1!!! insane little engines!

__________________
i'd rather have a bottle in front of me than a frontal lobotomy,


-linnix13(at)gmail,com

Glomph.....splormph....pleckuh....boompaph.....poo oomp.....pooooomp.......plup....plup....plup......



Is that what it sounds like ?....an oil leak trailing behind you like the Exxon Valdez ?



Laughs,
Salty

That was one of the most interesting threads I read on this forum. I tried the opposite. Once I ran for two weeks with no oil at all to see how long a 2-stroke will go. When it finally seized going up a big hill I let it cool down, put some regular premix in, broke it loose, and weezed home. Needless to say the compression was never the same on that puppy. But TWO WEEKS! Another time I did it on a bet and collected too. Shorter interval and no apparent damage.