Breaking-in a new engine

[deacon]

My two cents, worth less than a penny is, If in doubt be patient and break it in. I don't have the experience of either of you, but I do know this. I would rather run it thick for a couple of tanks and take it easy for a while, than to put another kit together. It took me longer to adjust the rear sprocket than to break the engine in.

 

[Prasinos]

if you sharpen the teeth of the sprocket on a grinder on the faces (think blades not points), it makes it WAAAAAAY easier to adjust. I sharpened mine and my chain tensioner can move back and forth a full inch and the chain wont come off.

 

[Bikeguy Joe]

I think you posted that in the wrong place...

 

[Salty Gator]

Salty- I won't dis-qualify your "qualifications" with my "qualifications", but I have been tuning and running two strokes and four strokes for about 40 years now.. I had a couple of small engines (one 2T one 4T) that I got just to run and tinker with when I was 10-11. Had mini bikes and engines of all kinds ever since. I have re-built and repaired motorcycle/car/aircraft/mowers/weed eaters/outboards engines, transmissions, ect.ect. ect.ect. ad nauseum.

I just tuned/worked on a 1976 Mitsubishi weed eater with a remote float bowl type carb no mower shop would touch. I have worked on everything from .010 cubic inch model engines to 1000 cubic inch diesels and all in between. I have lost count (not that I was actually counting)

I think this makes my point, no?

I KNOW these engines are different (very similar to most DKW derived piston ported two strokes of the 30's- the 60's.)

Maybe the "modern" two strokes don't need break in because people throw them away the first spring when the old gas won't light them off, and they never see enough service to know if they would last or not.

I was just wondering out loud.

Hey Joe,
You and I should start up a business then !.... LOL ....between the two of us I bet we could fix anything !....




Grins,
Salty

 

[Prasinos]

I think you posted that in the wrong place...

so i did....

 

[Randog707]

I broke in my engine with 2cy synth and it runs fine.heres some oil to gas mixing ratios,
16:1 = 8oz oil to 1 gallon of gas
25:1 = 5oz oil to 1 gallon of gas
32:1 = 4oz oil to 1 gallon of gas
40:1 = 3.2oz oil to 1 gallon of gas
50:1 = 2.5oz oil to 1 gallon of gas

 

[Randog707]

Heres a great link for finding out you oil to gas ratio..Gas Oil Mixture Ratio Calculator

 

[rkorson4209]

Putting a teaspoon of oil down the sparkplug hole could not hurt.

I recommend getting the better quality engine hardware kit from SBP and install it before you install the engine in the frame. Way too many folks have bolt failure soon after getting the bike together.

Really This is a good idea. I am getting another kit, just waiting for it. Should , or can i do it to the motor I already have, it only has 160 mi. on it. Never even heard of this, but now makes sense

 

[GearNut]

The hardware upgrade can be done to any motor, however if done to a used motor it is nearly a requirement to replace the cylinder base and head gaskets. On a brand spankin' new motor (never run) you can usually get away with reusing the gaskets, but that still is taking a slim risk of leakage.
Please note that is has been found that the threaded holes on a typical chinese HT engine are drilled much deeper than they are threaded. Nobody knows exactly why the threads only go partially into the holes. If you are doing a hardware upgrade you can further improve the upgrade by tapping the holes in the engine to increase the thread engagement on the studs. The more threads that the studs can engage, the stronger the install. The soft alloy that these engines are made out of needs all the improvement it can get! You need a metric 6-1.0 tap for the mounting studs, intake studs, and exhaust studs. The cylinder studs used vary from manufacturer to manufacturer. You need to determine the tap size specific to your engine.
http://sickbikeparts.com/catalog/product_info.php?cPath=22&products_id=43

 

[xlite]

Personally I do not think replacing hardware for no reason is a good idea. Several guys I built motors for made matters worse doing that. IMO the original chinese studs, nuts, and bolts are fine if installed properly.

 

[Creative Engineering]

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

 

[linnix13]

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,

 

[xlite]

wow some people suggesting 50:1??

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,

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.

 

[I Love My Bicycle]

Heres a great link for finding out you oil to gas ratio..Gas Oil Mixture Ratio Calculator

Thanks!!!

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

 

[wes]

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

 

[linnix13]

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

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!

 

[Salty Gator]

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

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


Snicker,
Salty

 

[linnix13]

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!

 

[Salty Gator]

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!

Glomph.....splormph....pleckuh....boompaph.....poooomp.....pooooomp.......plup....plup....plup......



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



Laughs,
Salty

 

[xlite]

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!

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.