Hi All,

I am fitting mahle pistons to my cdb, I know you need to modify the underside of the piston to clear the oil squirters.

I have done a search on SN but have not been able to find any info on this, is there a thread on here demostrating how this should be done ?
If not, do any of you who have had this done have any photos to show what was done pls.

Thanks,

Greg

 

You need to do a dry build of the short motor first Greg to see if the pistons touch the bore squirters at BDC.
If they do you have a couple of options:
1) Have the bore squirter mounting boss on the crankcases spot machined to lower them for clearance.
2) Relieve the bottom of the pistons to clear the bore sqirters.

Mick

 

Thanks Mick,

That was quick, really appreciate the help. I think SN is tops, I have been a mechanic for 25 years and have learned more about high performance engines on here in 5 months than I did in all of those 25 years and its a big thanks to people like yourself.

I have got another crank and will get a set of bearings for the dry build.
I have done a fair bit of porting 2 strokes so I think I will have a go at doing the piston mod, what could I use to make the marks at bdc as the space is quite tight ?

Cheers,

Greg

sorry but this was an instant reply, my typing s...cks

 

No probs
The bore squirters will make the bottom of the pistons if your gentle in rotating the engine or you can use some Engineers Blue on the bottom of the piston webs to highlight the contact area.
You can also see the bore squirters/contact points through the sump area when you bring the pistons down slowly towards BDC.

Mick

 

Thanks Mick, I will give it a try.
I will do the dry build and see how much I will need to remove, would I need to do the same on the opposite side of the piston to balance the piston ?
we used to cut holes in 2-stroke piston skirts on the inlet side only, had them at 13000 rpm all day long if you made the hole in the right place that is.

Thanks again for the help.

If there are no photos of this being done, then I wonder if it would be worth posting some pics ?

Regards,

Greg