Got the big bore kit for the Dinli yesterday and put her all back together. What do you al recommend for seating the rings etc.... Anything special? Run it like I stole it?

 

2 strokes run alot better if you run them hard durring break in. Just dont go wide open for long periods. Ride it hard for a few min then let it cool. Short bursts of WOT then just cruise around varying throttle. Dont be afraid to get on it just dont run it hard for long periods. The best way to seat the rings is riding it hard in the beginning. If you dont the rings will not seat right and will seat loose.

 

I will usually let the engine idle for about 10 minutes the first time it fires and blip the throttle lightly every so often. Then I let it cool completely down and do that a couple of more times. I then like to baby the engine for the first hour, not lugging it but not over revving either. When it is a engine I care about(or one I will be racing) I will then take the top end apart and lightly sand down any high spots on the piston. I also radius all the sharp edges on the piston before installing it.

 

1000000 differrent correct ways. [img]i/expressions/face-icon-small-happy.gif[/img] [img]i/expressions/face-icon-small-happy.gif[/img]
Good reply's so far IMO
My opinion is:: it depends on the piston used. I forget which piston is forged and cast, so I'll explain calling them stock or weisco.
A stock piston I recommend 2 manytoys method.
A weisco I recommend MWQ's way. And yes, right down to taking it apart and sanding the bageezus out of the piston in places. I also drill 3 holes under each ring gap and champfer. This helps drag oil up onto the sleeve.

Personnaly, I think seating the rings is a mis-conception and over-rated. [img]i/expressions/face-icon-small-happy.gif[/img]

 

Yes theres loads of different opinions on breakin of a 2 stroke. So heres another one concerning the rings only. One thing to remember is with the hone marks in the cylinder on a new topend will be worn down by the rings and that process will create lots of heat in the rings. Heat and rings is a bad thing and the rings will lose a little of their springyness/ ability to press outward on the cylinder wall if they get too hot. So a idle speed warmup a few times of a minute or less and then a complete cool down between them is important. Also if you have a tight ring gap then if the rings get hot they will expand and close that gap and start pressing outward very hard on the cylinder wall which is bad of course and could expand itself into the exh port and hang a ring thus ruining your new topend. This is of the most concern with a larger exh port from high HP porting. I have tried other methods but when i have used the heatup and cool down method I have not hung a ring in a race ported motor since. After that, riding at varying rpm and loads will ensure even wear in the cyl,piston. 95% of the time any method will be fine. But thats my method that works for me.

 

Here is a very old and pretty long article on top end break in
URL http://edj.net/2stroke/jennings/topend_rebuild.pdf

 

I like the "break it in hard" method as well.[img]i/expressions/face-icon-small-smile.gif[/img]

 

Go to this site. It will explain the break in period. This is an awsome article.

http://www.mototuneusa.com/break_in_secrets.htm

 

I prefer the slower/step up break in myself. One thing for sure is check the plug/jetting before you run it hard or you could get real good at rebuilds!

 

thanks for the replys. About every week I do a breakin on 2 strokes, but these are diesel powered engines and we take about 48 hours to do them. I did put a bigger jet in it last night but it seems to have less power then the stock 89cc. Maybe needs more tweeking. We'll see.