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Im thinking of investing into the Big bore kit for 49cc pocket bikes and was wondering is there anyone out there that has done this conversion? does it give much of a speed boost? what kinda boost am i looking at here? and what would be good add-ons with teh big bore kit?
 

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i wouldn't trust that 52cc conversion from scooterparts4less or whatever site that is. if they stand behind their product, they would list the details of the diameter of the pistons, the compression ratio, some close up pics comapred to the stock pieces, etc. all they say is it's 52cc and that's it. go custom. i had a 65cc kit made from my local machine shop for only 450 including porting/polishing, decking the head, balancing and blueprinting and will waste any 52cc bike.
 

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IcePick said:
Its actually 55cc. I have it.
We've had 2 of them. If you got the one from scooterparts4less it's actually 52cc, with a 44mm bore opposed to the stock 40mm bore, the stroke stays the same. Notice on the scooterparts4less auction they have updated it to 52cc's, they were misrepresenting them at first but now have corrected that issue.
Honestly a stock bore engine with a Walbro 668 is stronger & more responsive. I personally hate the carb supplied on these "big bore" engines.

If you were to blow up your stock engine the big bore would be a good idea. Otherwise don't waste your $$$. Just my $0.02 ...

Boogie, What piston did you use on the 65cc? I have a 65cc cylinder setting in my shop.

 

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the piston was custom made by the machine shop, it was designed after JE's lightweight race piston. it was risky to have a machine shop make the piston, but it works. definitely a huge improvement. i'll try to ask my shop if they're willing to make another one. it's lightweight magnesium and the molds for the piston are stamped or something like that.

mybluemidi, id recommend spending an extra 200 for wayy more power than what the 52cc kit will get you for $150.
 

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most of them are under 'machine' in the phone book. you can also try contacting any local chopper or hot rod shops and ask if they know anyone in the area specializing in cnc or machining. also try looking under 'metal' too.
 

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magnesium??? is that common for use on a piston? i know magnesium is light weight and strong. its used on some high end freshwater fishing reels, light weight car rims, and for the landing gear on navy jets (dunno about others im in the navy). but being on an aircraft carrier taught me that magnesium is FLAMABLE. and it is very hard to extinguish. try to put water on burning landing gear and youre gonna get burned. with the heat generated by the motor, is it wise to make the piston outa magnesium? just wondering.

obtw, just make sure u keep it outa the saltwater. highly corrosive stuff too. hehehe so dont go riding at the beach hehe.
 

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the magnesium is super light and strong, plus it transfers heat really well. yes it's flammable, but the top has a t-307 stamped steel plate dome and is coated with a little somethin somethin. when i take apart my motor to work on the crank, i'll take a few pics of the setup for you guys.
 

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nice. id like to see that. hey youre in san diego right? we should go riding some time. know of any good parking lots around that i can practice my turns on? im getting kinda sick of straight aways. just hit up a park over at the in-laws in escondido where the whole parking lot can be a track. islands in cool places and no other cars were there. but i want more hehehe.
 

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yea you and yogub live in paradise valley right? i'm in eastlake, so otay lakes road connects our areas together. not too far away.

there's a park here at eastlake near the olympic training center with a nice downhill turn owned by the eastlake community... i guess if i can find out where to get consent from it can be nice to ride there. the road goign to the park is nice and windy too.
 

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ive ridden around there too. the trail starts just down the street from the parking lot of otay lake and ends right at the opening of the OTC. but i dont know the parking lot u speak of. but im down if u are.
 

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the parking lot is at the park. when you go straight, there's a right turn that goes uphill a bit. going down that turn should be nice. there's constant security in the area tho because one of the chula vista community hqs is right next to the park, so it wouldn't be safe until we can get the consent first (they've radioed some cops to me before when doing a photoshoot for some cars).
 
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