looking for special piston or crank

[dericsdad]

Anyone have any ideas??

I am looking for a 55 or 56mm 2-stroke piston with a 12mm diameter pin...

or a minerelli style crank with a 14mm little end rod hole.


Or... a different connecting rod with a 14mm small end to fit a minerelli crank.

I am thinking of building a bigger bore stroker motor for our outlaw mx series up here:devil: .

Thanks,

Dan

[dericsdad]

dOES ANYONE KNOW IF THE BIG END OF THE MINERELLI CON ROD IS THE SAME AS AS CR80, OR SOMETHING SIMILIAR...

I AM ATTEMPTING TO BUILD THIS BIG BORE STROKER WITH
PARTS THAT ARE READILY AVAILIBLE.

I THOUGHT ABOUT BORING OUT THE LITTLE END OF THE MINERELLI ROD, BUT I AM AFRAID IT WILL BE TOO THIN AND
WILL BREAK.

DOES ANYONE HAVE ANY OF THESE PARTS LAYING AROUND??

[chris grissom]

I might can help. On the rod are you wanting a 14mm pin or rod ID? A CR,RM,YZ 85 rods have 18mm ID's and use a 14mm pin. The mineralli styes use 12mm pins. Also the lower rod pins are different sizes, as are rod big end widths. You can not grind the ID as that will remove the hard surface. On the piston you can use +2mm over 125 MX bike pistons but what are you planning for sleeve work? The stock bores / sleeves won't handle that much over, even the 54mm stuff out there. You will also have to bore the cases, but that is reasonable. Consider how much mass that size piston would put on the engine before proceding. There are better rod lengths (not strokes) and stroke changes to achieve the engine size you desire. I can help PM me for details.
Chris

[dericsdad]

Thanks Chris for replying.

I work at an automotive engine remanufacturing company here in WI and so I can get any/all machining/resleaving done that would be necessary...

But if you know of an easier way to achieve 115cc plus displacement, I'd greatly achieve any help you can give!

Our series is unlimited except we need to use stock cases and stock frames.

I know in europe they have had larger displacement verticle style scooter engines, and thought about those cranks/cylinders as an option...

Let me know your ideas!

Thanks,

Dan

[chris grissom]

Dan with the resources you have available you will be able to pull it together. The easiest route is a 49mm stroke and the 54mm bore which are both readily available to make 112cc and change. I use a rod length that is twice my stroke, 45 stroke = 90mm rod length. It is hard to get the 90 size stuff like you mentioned the 90Jog in europe, so we have to improvise. They are some nice billet 44mm 50/70 cranks available but you want the 90 cases and they would need a stuffer fitted to make up for the small dia. crank webs and you would need 50 sized clutch components. KTM 65 (I apreciate you keeping this confidential) rod length and adapation to the minnerali cranks works good but limited to 12mm pins. Even stroking this crank up to 45 or maybe even 46 is possible but fitting a shorter pin to crown piston is challenging. You could use a 54mm bike piston but the later models are 15mm pins, but that would be better because you could make a sleeve down bushing for the upper pin hole and 15mm down to 12mm would give you a thicher reducer. Are you willing to fabricate a sleeve? Watch ring locating pins and port alignments. One off builds like this are my speciality. But they take lots of planning and time to source and compare parts and build.
Chris

[wrhracing]

I have a 50mm stroke crank with a long rod, 93mm long,uses the larger 14mm top bearing. Use that with a malossi 56mm piston, cylinder kit, or use one of Cris G's examples. Its all up to you.
Good see n ya Cris.

[TTracer#22]

I have one of Billy's Motors for sell right now that is something in the range your talking about 117cc and it's ready to leave my shop at a fare price lets talk.

briant_sizemore@bak.rr.com

[TTracer#22]

I have one of Billy's Motors for sell right now that is something in the range your talking about 117cc and it's ready to leave my shop at a fare price lets talk.

briant_sizemore@bak.rr.com

[wrhracing]

And that motor will surpass your needs.....

[dericsdad]

Billy,

your pm inbox is full.

Tried to send you a pm, thanks for your help!

i'll keep you updated on the results.