Derbi engine nubs........Variant SLE, piston port engine

hiya

putting a Parmakit on my piston port SLE

the piston is 44mm and hits the inside lip of

the cases on the downstroke.

my question.......how deep do i need to dremel

the lip back?

thinking of boring the cases all the way down

to open it up.

is there a chance of going too deeply into the case?

Re: Derbi engine nubs........Variant SLE, piston port engine

Yeah you don't want to bore further than needed as you could fuck up the bearing mounts and add unnecessary case volume. Figure out how far out the piston goes beyond the skirt by inserting the piston to align with the exhaust, then you can measure the distance you need from the base to the back skirt of the piston.

Re: Derbi engine nubs........Variant SLE, piston port engine

yep

i*ll do that.

after i split the case.

i was really worried about dremeling into something.

case volumn is not that high on my list

thanks

Re: Derbi engine nubs........Variant SLE, piston port engine

Its only like 1mm from what i heard

Re: Derbi engine nubs........Variant SLE, piston port engine

trim the skirts, more intake duration

Re: Derbi engine nubs........Variant SLE, piston port engine

ya know.

this is a really tempting option.

if Ryan N is correct and only 1mm needs to be trimmed

off the case nubs, then trimming the piston skirt 1mm

sounds like a good idea.

plus the gains on intake duration

thanks sabat.............

Re: Derbi engine nubs........Variant SLE, piston port engine

I just took my nubs all the way down.

I hated them so much.

Only danger I ran into was in the case matching.

If you are going to open the case transfers you can't go deep at all or you will punch through to the inside of the stator well.

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