Malossi BBK for People 50 2T

[Triesandluth]

Tries is gonna scoot down to Charlotte and help me out when its time to do my Malossi BBK.........he doesn't know that yet though......

LMAO,  it better be when it's not cold as a well digger's ass. I'm already fed up with this ridiculously cold weather. And I may want to take care of several little things unless I plan on doing a nice big project on the side of a road.

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[paceneedsstides]

I can wait a couple months if needed.

[Triesandluth]

You seem mechanically inclined and smart enough,  man! Just take your time, prep the cylinder, and piston if necessary (mine was fine), jeta little rich, and try to break it in easy.  You might consider going back to the stock pipe and heavier rollers for a hundred plus miles to keep your rpms down while breaking it in. 
That doesn't mean I wouldn't want to make the trip,  it would just be a lot more fun to be able to rip up the streets when I get there instead of pussyfooting around!

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[chaz35]

I'll take some pics, but no guarantees.  I have a lot of trouble posting pics to this site, took all day to post the pics of the piston.

The crank is oem Kymco.  Looks just like the other one, except the rod is tighter.  Side play wasn't as tight as I expected, but a lot better than the old one.  Probably won't replace the bearings at this point, I am just trying to get this thing to run.  I had it completely apart, engine out of the scooter 2x's now and doesn't seem like that big of deal to do it again.  Helps I have another scooter to ride.

The crank bearings are huge, and service manual shows can have a lot of radial and side to side play before need to be replaced.  Another sign worn out, you notice they are noisey.  If I was building a screamer I would install new, better bearings.

I am not doing any mods other than what comes in the Malossi bbk for Kymco AC.  No port matching, same oem reeds, manifold, carb, etc.

I did convert my CVT back to 100% oem just to see how it would run with BBK.  I ran the oem muffler and carb and plan to do that again for break-in.  Also, this next time I plan to plug the wire back and restrict my CDI to limit revs.

pace, just follow my bbk build, and don't do any of the dumb stuff I did, should be OK lol's.

Cheers

[chaz35]

There is one thing about the BBK I don't understand.  How does the wrist pin needle bearing stay centered on the small end of the rod?  The oem piston is smaller, so the needle bearing is pretty much captured.  The bbk piston is wide enough for the needle bearing to move side to side and move almost out of the small end of the rod.  Is there something that keeps the needle bearing centered in the rod?  Doesn't look right to me?

[Triesandluth]

Good question.  I'm not entirely sure, unless we should be getting a wider bearing.  If i remember correctly mine only had maybe 2.5mm on each side that it could move,  but I do believe that the one I ordered when I thought my original was bad is just a little, maybe 1mm wider.  It would seem more logical for it to have less play to avoid pressure being uneven and beating it up. 

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[chaz35]

Thanks for reply.  I will have to measure, but think is over 1/4" on either side of rod, a lot of play IMO.  I may post this question on 49ccscoot see if anyone knows, has comments.  Cheers

[paceneedsstides]

I will most likely wait till i have a beater to run as backup so if something goes wrong or takes longer than it should I don't have to rush or possibly mess something up. and I haven't looked that close at my BBK yet but will take a look this week now that I"m jobless with plenty of time. Also Chaz all my pics come from my phone and I use a photo reducing app to post them here.

[Triesandluth]

Thanks for reply.  I will have to measure, but think is over 1/4" on either side of rod, a lot of play IMO.  I may post this question on 49ccscoot see if anyone knows, has comments.  Cheers

Great idea. 

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[chaz35]

On the pics, I have phone to take pics, that's how I take them, but don't know how to go from phone to this website.  I can get them to my computer, but then have to post to a hosting service, then link them to this site.  I tried to use flicker, but had problems with that, then tried shutterfly, but couldn't get that to work.  Finally used photobucket, worked OK, but site seems a little flaky.  Not easy for me to post pics.

[Triesandluth]

I will most likely wait till i have a beater to run as backup so if something goes wrong or takes longer than it should I don't have to rush or possibly mess something up. and I haven't looked that close at my BBK yet but will take a look this week now that I"m jobless with plenty of time. Also Chaz all my pics come from my phone and I use a photo reducing app to post them here.

Not a bad plan, waiting for backup ride.  The cylinder should be pretty well taken care of, malossi did well there.  Just use a small file to smooth the port edges.  Don't change the shape or size, just make sure they're not sharp.  And there's some other things you can d do to ensure a solid break in and not me anything up.
I also use my phone and a size reducer.  Easiest way I've found.

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[paceneedsstides]

This is app I use on phone when I post a pic here I click on this app first then choose image from gallery then can choose different sizes to get it under 192K. As for BBK yeah I was thinking of using a file instead of Dremel and just clean up sharpness on cylinder and piston skirt heard that helps oiling.

[chaz35]

Thanks for info on screenshot, I will try it.  Cheers

[chaz35]

I looked at small end rod bearing play again.  Stupid me, I was moving piston outside the cylinder side to side.  Yes, the small rod bearing does move out from under the rod like that, but the piston can't move that much when sitting in the cylinder.  Anyway, I am OK with it now.  I compared the old destroyed piston to the new one too, and they look identical, except one has hole in the top of the piston lol's.  Another imaginary problem solved.

Decided to get Malossi 19mm carb kit for this build.  Will probably wait awhile, make sure runs, gets broken in OK.  Then put new chrome Tecnigas Next-R pipe and 19mm carb on it.  Cheers

[paceneedsstides]

Nice we gonna be twins. . .