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Discussion Starter #1 (Edited)
BACKROUND: Allright hey guys so I bought a cag pocket bike from a guy on craigslsit and I traded my mp3 player for it....haha. It wouldn't start, had no brakes, or a chain. When I took off the peice of crap black box aircleaner there was literally dirt clogging the whole carb.....like a pile in the intake part....not kidding. So I cleaned that out and got it started up, had a couple tuning problems, adjusted needles float, etc. Also I ran the clutch with 2 stock springs and a spring I found on my garage floor....lol. It was always engaged even at the lowest idle I could put it at so off the line It sucked but when it hit its powerband that thing ran! I also did the petcock mod, which helped with accel. and then I used spandex underwear(lol) as an airfilter and the increase in topend from this mod was insane! Not kidding if you have that black airbox take it off now! I took it a step further by removing my base gasket to lower squish, and raised my exhaust port, but when I put my piston back in, a ring cracked-_-

THE PROJECT: Ok so me being the illogical person I am instead of spending 5 bucks on replacement rings I ordered a big bore kit. I got Sam's stage 3 headkit. He is also tapering my carb and rejetting it, and blueprinting my engine.That comes out to around $165, which is a really good price for all of that.

I have a few questions though......Sam said that running 91 octane gas was about right for 45:1 ish ratio of oil... I thought I would be running 105 octane...... Should I be? EPR I hear you run 96 with that octane booster so I will try to get my hands on some of that.... I mean 91 octane with a 15:1 compression head just sounds kind of low....

He said a stock crank was good so thats what I will be running.

I will get some blackwidow reeds from pbu because they are $22 and I have heard great things about them unless some of you guys think that the polini single green reed mod or whatever you call it is better.

I also cut my exhaust in half on the expansion chamber so I can lengthen it by a couple inches(4?).

Here are all the parts I can think of that I should get
BW reeds
HP clutch springs
Aluminum 3 shoe stock clutch with holes drilled in it
7t 3rd bearing clutch support
68t rear sprocket for now
rocket key(HELP me on this one guys haha)
aluminum pullstarter

(So thats 100 bux+165 for engine not too bad)

I sent my engine to Sam(Boosted306) on monday a few days ago so I will keep you posted.

I am going to post pics of the whole build process unfortunately I lost most of the pics I took so far but I havent done much..... Well please make some recommendations on how I can make this thing better etc. Thanks for anything I appreciate the help and love learning about this stuff haha.
 

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Welcome to the site.......I thought the title said budget....I have a 2011 cag w/1pc stock 49cc head thats modded with 3 extra boost ports and a 6 window piston....It looks like a dressed-up stock bike but thats where looks are deceiving.....I have a grand total of $85 bux into this for the pumper carb kit,,fuellines,,rocket key,,and a brand new 49cc engine from Daves for $20.00 all modded-up and race ported by me in 4 hours and its a crazy-crazy bike to ride and compared to a bone-stock bike........ its embarrasing for the bone stock bike....LOL.





The squish determines octane rating needed to burn the engine efficiently,,,are you sure it isnt .045" of squish? You can run 91 on .045"

My engines run a squish between .028" down to .024"...That tighter squish requires fuels in excesss of 100 octane.....100 octane CAM2 mixed with 108 is what I have to run in my EvilWaspCag or buy 5 gallons of VP 105 leaded and non-oxygenated ever since they pulled toluene off the shelves...............

If the squish is around .035-.030" youd have to run 93 -96 octane fuels...

Paying the extra money for the blueprinting is a best bet at getting nice power and revs...You just gotta ask him to releive the ring grooves in the piston a tad too so the rings are loose and smooth.........

Then theres my bigger more extensively modded clan of cags I built on a budget....heres one



 

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Discussion Starter #3
Thanks Cam and yes he said he will do .045" and I thought he meant 4.5mm. So would a smaller squish give me better performance? .45" sound too big but I am not sure as this is my first time with this kind of racing engine. I took alot of pictures yesterday because I lengthed and welded my pipe and also put the frame together. I also put stickers on it to make it faster,lol. I will post the picks when I get home in a couple hours.
 

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Discussion Starter #4
1st pic: lengthened exhaust.
2nd pic: spray paint muffler
3rd pic: wheel with letters highlighted
4th pic: pick of the bike
5th pic: My rusty sprocket that I rubbed paint pen paint into and it worked really well. Doesn't scratch either.
 

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Thanks Cam and yes he said he will do .045" and I thought he meant 4.5mm. So would a smaller squish give me better performance? .45" sound too big but I am not sure as this is my first time with this kind of racing engine. I took alot of pictures yesterday because I lengthed and welded my pipe and also put the frame together. I also put stickers on it to make it faster,lol. I will post the picks when I get home in a couple hours.
Of course a tighter squish will yield more power but youll need to know how to tune such a tight squish and religiously follow the same fuel always no matter how broke you are.........Pullstarting an engine with a tight squish becomes pretty crazy,,hurtful and tiresome aswell.........

Stock engine squish is something like .070"..Like I said I set my squishband between .028 and .024" but I need fuels with an octane rating inexcess of 100 octane..

The mods are looking pretty good...............
 

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Discussion Starter #8
I can get 93 octane the easiest where I live so I guess it is ok. Will I still get enough out of Sam's kit with that high of squish though? If making the squish smaller is a drastic change, like huge power gains, then I would have to do it but if not I think I will keep it as is.
 

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I can get 93 octane the easiest where I live so I guess it is ok. Will I still get enough out of Sam's kit with that high of squish though? If making the squish smaller is a drastic change, like huge power gains, then I would have to do it but if not I think I will keep it as is.
Like I stated stock engines operate at .070....Hes setting squish at .045..Thats a .025" decrease or the same as removing the basegasket on most 1pc heads

The hugest powergain you can get out of a cag engine is 17:1 compression[240psi comp] running methanol/alchohol race mix...Just dont expect to pullstart it too easily.......I busted an all aluminum pullstarter on my 43cc wickedly powered EvilWasp Cag

 

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Discussion Starter #10
What hp gains would you expect from a .45" squish to 5mm?
 

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What hp gains would you expect from a .45" squish to 5mm?

5mm or .05mm?

The .045" squish doubles the current stock hp.... .024" would theoretically quadruple the engines power but on alky/methanol mix it feels almost 6 times as powerful as stock power output.............

Before alls said and done see if you can get Sam if he can make the squish readjusted to .035"....Youll have to run 93 premium juiced-up a tad with 104 outlaw and some lead substitute additive...... .035" will triple the engines power output...
 

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Discussion Starter #12
I may be able to run it on alcohol.....would I need to replace the stock intake manifold since it is plastic? What else would I have to change?
 

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I may be able to run it on alcohol.....would I need to replace the stock intake manifold since it is plastic? What else would I have to change?
Your gonna have to get a better intake and also an alky carb like a Walbro pumper carb and getting the carb in tune is gonna be not easy........When you get in the 17:1 range youre gonna need a really good ignition system too like an MSD kicker CDI ignition system aswell as a tuned pipe..

if you wanna know in-depth how a racing engine is built check out Mexicanos thread"Racing engine built"
 

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Discussion Starter #14
I read through that whole thread prior to this one......to bad mexicano never got back. Ya that is a little much...... What squish should I tell him if I want to run around 98 octane? I would be mixing 93 octane w/ 104 octane booster or whatever they have near me I need to check around.
 

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I am running all my engines with 91 oct. and 1 1/3" oz per gallon of 104 Octane Boost about 96 oct, works ok for me.
 

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Discussion Starter #16
Did you change the squish from .45" that Sam did? Or did you ask him for less?
 

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i read through that whole thread prior to this one......to bad mexicano never got back. Ya that is a little much...... What squish should i tell him if i want to run around 98 octane? I would be mixing 93 octane w/ 104 octane booster or whatever they have near me i need to check around.
.035"........................mexicanos thread is a good one to know what you gotta get into just to build one right but the only thing I see missing in his thread is the modding of the piston by adding extra windows or relieving the ring grooves..When you get into race engine range things get even twitchier and the fitment of parts becomes more stringent and crucial......
 

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Discussion Starter #18
Oh I know about the finecky-ness off these engines..... I used to have some nitro rc cars. Those were a nightmare haha. Ok I asked him if he got my engine and he didnt reply and then I asked him about lowering my squish to .035" and he still has yet to reply.....im alittle worried because I sent my engine 1 or 2 weeks ago via prioty which is supposed to ship in 3 days and he has said nothing. I trust Sam and he is super helpful so I doubt its much of anthing.... Will I need a better coil for .035"? I will probably order a new stock coil for $6 and replace the crappy copper wire with an nkg one or whatever I can find at a local autostore if you guy think this would make a better spark.
 

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Discussion Starter #19
He just replied after my last post,lol. He said that he could no prob.
 
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