48mm BBK "Thinking outside the box"

hammer · Post by **hammer** » Thu Mar 17, 2011 4:29 pm

I am finally laying out all the parts for my 48mm spree. This project will all the goodies. Pipe, intake changes, modified reeds, gears, lightened clutch pals and Areache carb to name a few.

I have a question for the most Performance Technical minded members on the board.

I wondering about doing some work on the bottom end of the cylinder skirt and adding window ports to the piston on the boost port side.

Your thoughts would be very welcome.

devenex · Post by **devenex** » Thu Mar 17, 2011 5:37 pm

Your suggestions/questions are all new ideas to me, but I'd love to see some pics of your setup.

The only times I've heard of piston skirt mods are for some stroker setups where they need to raise the skirt some to avoid hitting the crankshaft (I think anyway, haven't done this myself).

I'm sure many more knowledgeable members will chime in shortly though.

Wheelman-111 · Post by **Wheelman-111** » Thu Mar 17, 2011 5:51 pm

Greetings:

The BBK itself isn't a year old. Not many have experimented beyond bolt-up installation. You be exploring Strange New Worlds if you muck with it. Whatever you do with the ports, have a goal in mind - Max output at X,000 RPM? Then match up everything: Carburetion, Porting, Exhaust to make it sing where you want it. This is Advanced, PhD-level 2-stroke tuning. If you have a hundred cylinders to mess with, and a Team of Engineers, you are more likely to succeed.

hammer · Post by **hammer** » Thu Mar 17, 2011 6:25 pm

After looking at this a little closer I wonder if a simple notch at the bottom of the piston skirt on the boost port side similar to the the notches that already exist in the piston that accommodate the schnuerle ports would work.

I think that one thing to consider is that the piston 7mm larger and the larger diameter piston could be shrouding the flow to the boost port.

It looks to me that the added notch would be a pretty conservative modification. There is already a notch in the bottom of cylinder at that location. I could just match the added piston notch with the existing cylinder notch at the bottom of the cranks stroke.

tazland001 · Post by **tazland001** » Sat Mar 19, 2011 11:57 pm

Let us know how your mods perform. Very anxious to hear your results.

Taz

hammer · Post by **hammer** » Sun Mar 20, 2011 12:14 am

I was hoping you would chime in Taz. Any insight or anything to share? What have folks been running into with the 48mm kit?

fastplastic · Post by **fastplastic** » Sun Mar 20, 2011 2:51 pm

its a nq50 you can only go so fast you should be asking for help tuning in the 48mm bbk to make it run and run right dont worry about your piston, your gears are the limiting factor

tazland001 · Post by **tazland001** » Sun Mar 20, 2011 4:25 pm

First off I am not going to stop until I can get the spree engine up to at least 45 to 50mph. Even if I have to make a stroker kit to accomplish this goal. I have no problems tuning these kits. I just start off with an 85 main jet and go from there. Its not that hard to dial these kits in. To be honest the response from my eBay customers is really good. Everyone is very pleased with the added acceleration and top end gains to a scooter that drives like a snail stock. The intake should help out a lot on increasing the top end.

Taz

hammer · Post by **hammer** » Sun Mar 20, 2011 4:37 pm

To fastplastic

I am installing the taller gear set and tires with a much larger roll out. Maybe some piston modifications or cylinder porting is would benifet to the 48 bbk run right and perform up to its potential. There is more to this game than just buying bolt on parts or swapping out motors. My path is one of which I ask some questions, do some research and maybe even experiment. Along the way there will be both success and failures. I consider this project a challenge. Sorry it does not meet your approval.

fastplastic · Post by **fastplastic** » Sun Mar 20, 2011 8:38 pm

i have a 44mm kit that does 43mph with gears....... to say i just "bolt" things together is not the case..... do what you want you will be disappointed in the end i am sure of that.......

hammer · Post by **hammer** » Sun Mar 20, 2011 9:22 pm

I am not sure why all the negativity.

My last Spree project I got an honest 37mph with a stock bore with 1984 Spree gears. I wasn't disappointed in that.

Now back in 1986 I crewed a car for an ARCA team and our Olds Cutlass went 199.8 mph. I must admit I was a little disappointed in that.

It always has to do with expectations doesn't it?

hammer · Post by **hammer** » Sun Mar 20, 2011 9:28 pm

Prior to my scooter days

Honda Spree and Elite 50 Forums

48mm BBK "Thinking outside the box"

48mm BBK "Thinking outside the box"

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