advice on rebuilding a engine please

[burrell_]

just looked for u spudulike it has stihl 1121 on one side and as u gessed mahle 427n12 w4on the other thats the Cyl

and as for the piston mahle 42l33+

[burrell_]

and this is the CYL witch i made such a good job of (to me this CYL looks like it has what i can messure a 3mm sleve in the bore ) but if the Cyl has bin plated in the bore then its no good now

[Nick B]

Hi Burrell how easy is to get the top end of a saw

I think I have just heat seized my 023

not had a look yet but the starter cord is jammed solid

[burrell_]

that dont sound good mate take a look at this let me find it first

25 mins and u will be stripped it down

[burrell_]

try looking at this very handy if u need parts hope it helps u out

http://www.keepandshare.com/doc/2056760/021-023-025-pl-pdf-july-9-2010-3-18-pm-482k?da=y

[blazer]

From working on a few 'hot' 2-stoke bike engines yrs ago, some hi-reving bikes had only x1 ring, with 1-ring it doesen't seal so well but has less drag. Some had an L-shaped top ring, so the pressure forced the ring against the cylinder wall. I had one bultaco 250cc that wore the rings where they pass the exhast ports, so if compression dropped, I changed the rings. Some bikes you had to be careful not to have the ring joint running over a port - as the ring could break up, so look at the piston by the cylinder and position the rings away from ports. If you had a piston ring compression strap it may prevent broken rings on assembly.

 

Good luck

[Nick B]

Thanks for that Burrell:thumbup:

That dose not look to hard will strip it down and see what I can learn

I must try to remember to use the bigger saw next time

[spudulike]

and this is the CYL witch i made such a good job of (to me this CYL looks like it has what i can messure a 3mm sleve in the bore ) but if the Cyl has bin plated in the bore then its no good now

 

Almost all 1980 onwards cylinders will be plated with Chrome and laterly Nikasil. The one exception is Poulan that had a straight aluminium bore and plated their pistons - weird.

 

Some old 60s saws had cast liners as used in some four strokes but your stihl will be plated - not sure where the 3mm liner idea comes from but I have never seen or heard of liners being used - re-plating a cylinder is possible but the cost is prohibitive.

 

The bore and piston should be 42mm and you should not be able to see aluminium showing through the bore - if it has been honed with a fourstroke hone then it is probably scrap as the chrome will have been ground off. You can test this with acid - you should not see fizzing, or use a sharp edge and seee if you can scratch the bore, the chrome will not scratch, aluminium will.

 

Mahle means that the piston is original OEM as is the cylinder. Not sure how you cleaned it up, there is a tried and tested way and a hone doesn't come in to it!

 

I have salvaged more cylinders than most people have had hot dinners:thumbup:

 

Spud

[burrell_]

i used a expanding reamer to get the score out of the bore

how do u get scores out of ur bores mate

[burrell_]

we might be in busness as iv just tryd to run a sharp knife down a bit of the bore and it dont mark it and iv just run the knife on the out side of the bore and it score miles easier

Edited January 17, 2011 by burrell_