need help with a 47cc engine rebuild!!!

:thumbsup: i have a picture of my bike so far the only thing i have realy changed is i put in a hp clutch nd springs. along with a nice looking chain gaurd. one thing i also cant figure out is i have used yamabond on my exghaust port and it leaks air still. does that mean the cyclinder is cracked and it does it only when running. thank for the help im new to this lol.

bobmarley316 said:

i am currently trying to rebuild a 47cc engine cag of course lol. i wanan put a big bore kit on it and a performance pipe, i had a idea of using the stock pipe and geting a new one made with fatter tubbing.if anyone has idea or help i would aooreciate it.

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If you have shop tools and a dremel you can double,,almost triple the hp and power of your cag with about 6-10 hours of intensive labor and under $150 bucks to make it truley reliable........

The stock mufflers come in a large array of headpipe sizes...if you have the cag with a 1" - 1 1/8" OD pipe you can mod the center section of the expansion chamber with 4-6" of exhaust pipe...........

I myself and a few other members have done it with satisfactory results.....I even went a step further and made a dual chambered pipe out of 3 stock exhausts and it works phenomenal on my stock modded 5 port 1pc cylinder with 6 port windowed piston.........







My Trophy Cag Sleeper

bobmarley316 said:

ok thanks cam. I'll fix that up and i was looking at getting a big bore kit. is there anything overly hard to changing a piston and cycl to a 49cc kit?.

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Theres nothing too overly hard but just know that in order to get any performance theyll need to be refined/blueprinted.......Any kit you buy will need to be except Sams kits because he refines them..............

The engines were designed for long term use lawn equipment tool engines...None of the internals flow together smoothly to gain velocity to make true actual performance,, power and revs until theyre modded to deliver the goods.........In 2 stroke;-high velocity and high compression makes power...In 4 strokes its high compression,,tight camlobe overlap and high flow volume........

Just know if you just buy a BBK from someone except Sam that when you assemble that engine its not gonna give the true performance it should and wont last very long...........Either buy one of same kits and raceport the lowerend for high velocity flow or do some research here and bust out the dremel and have fun...............Good Luck

The flow has to be smooth to get velocity.....It takes time but the power is incredible in all 3 powerbands............LOL



The corners of the cylinder are the biggest restriction of true velocity...Not on my cylinders....Between the lowerend and the lower enginecase the flow is smooth sailing all the way to the top........LOL



Heres what a stock lowercase looks like with just a FCC installed and the way most keep their engine lowerends..mp in the middle hinders flow



Heres what a raceported lowerend with FCC looks like...The speedbump in the middle is turned into a ramp to aid uninterrupted velocity and the case in the center is dremeled out so the 3rd port on thid build-up isnt being hindered to flow fuel into it..The difference in performance is like night and day......

I buy my BBK's from BigMotorSport in Canada and he ships to the USA fast..hes gotta sweet deal on stage 2 BBK's with full circle cranks for $70 bucks shipped free>>they need a lil refining and if your buddy can build pipes then im sure he may be of assistance blueprinting it for true power/performance and especially longevity and can be done by either following my thread or one from mexicano,,2 strokeblowingsmoke and a handful of others....................Good Luck

http://www.pocketbikeplanet.com/showthread.php?t=60828

http://www.bigmotorsport.com/products/Stage-2-Big-Bore-44mm-Upgrade-Kit.html

bobmarley316 said:

and if it ok with you i was going to show him those pics of your two pipes that you made. he was thinking of cutting out the bottom and the back 6 inchs and adding a beefier pipe in its place. then that should solve my air leak problem lol

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Its perfectly fine with me............Ive made alot of pipes for my builds....

If you have never done this before I would get a Boosted306 49cc B/B 3 stage head kit, for $65, and save yourself alot of grief.

Hands down id say get a hp pumper carb like a wt603 wt667 or wt813......The physical size of the carb body is irrelevant..The internal passage on the pumper carb is way larger and definately way larger than you can mod the stock carb to maximum..........The largest bit you can use to mod the venturi on a stock 12mm venturi cag carb is 14mm..The smallest of the 3 carbs listed the wt603 walbro has a 15.8mm venturi and can be modded to almost 17mm's..............That small 3.8mm incriment between the pumper carb and the stock carb makes a big difference to making power or not.............

walbros are so easy to mod for serious performance.....Ones a wt991 and the others are wt813's..all are highly modified for different applications they were bought for..







This carb is a wt603