modified 66cc Ht bicycle engine in bmx

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dylan1024

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Oct 29, 2010
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Re: modified 66cc Ht in bmx

i guess we will have to test :D on paper it makes a difference.. so far all the paperwork for the weedbike has been spot on, but pipes dont always behave the way we plan them to. ill keep you posted.
 

dylan1024

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Oct 29, 2010
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Re: modified 66cc Ht in bmx

witing for us to pick them up at the shop.

plastic wheels so we can machine and bolt adapters straight on
 

LS614

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Dec 22, 2009
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Re: modified 66cc Ht in bmx

That's a really cool bike! A whole bunch of things told me you were somewhere else in the world! My guess was Australia, but South Africa makes sense too :D As for running on methanol, go for it, but remember these are cheap crappy 2 strokes we play with, not racing engines, so don't be surprised if something fails on you :D Happy riding!
 

CalzHT

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Jan 25, 2011
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Re: modified 66cc Ht in bmx

I see, plastic rims should be spot on for the application!
Avid Juicy brakes??

Found a wicked aluminium spec in one of the catalogues at work, CEN 3500, if I can recall. Used for cyl. heads and the like. Wonder how much it is!
 

dylan1024

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Oct 29, 2010
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Re: modified 66cc Ht in bmx

11/11.5:1
it was all designed and measured in CAD so should be spot on

thanks
 

dylan1024

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Oct 29, 2010
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Re: modified 66cc Ht in bmx

walbro is way, way, way easier to tune compared to the chikuni

high and low needle and thats it, no lifting of needles and clips.

i come from a model aircraft background and have lots of experience on the walbro style carbs
 

sketchman

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Mar 23, 2011
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Re: modified 66cc Ht in bmx

walbro is way, way, way easier to tune compared to the chikuni

high and low needle and thats it, no lifting of needles and clips.

i come from a model aircraft background and have lots of experience on the walbro style carbs
Sounds good. I wasn't looking forward to using the stocker partly because of that. I wish the walbro part numbering "system" made at least a tiny little bit of sense. I see they are dirt cheap, though. Cheap and easy. Nice.
 

dylan1024

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Oct 29, 2010
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Re: modified 66cc Ht in bmx

chain seems happy for now, modified the old Vbrake arm as a chain guide/tensioner

also running the heavy duty chain instead of the bmx chain

will post speeds when we get time to go out to the racetrack
 

dylan1024

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Oct 29, 2010
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Re: modified 66cc Ht in bmx

Thanks man

We topped out at 66km/h

The motor is choked up though.

It needs an exhaust port of about 30mm dia.
Biggers we can grind to is about 24.

Needs bigger carb and I need to lower the transfer ports by the 4mm we raised the jug by.

Bigger inlet also

Just been too busy
 

577-Jersey

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Mar 23, 2013
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central western nj
Re: modified 66cc Ht in bmx

Once you get that little china girl tuned in,,that thing is gonna rip man,,i want to see more vids,,they where really fun too watch!

Good times..

Tom :)
 

Moto

Member
Jan 7, 2012
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Re: modified 66cc Ht in bmx

THAT looks like a sick ride!
Try a dellorto PHBG carb - you can get a clone on ebay for a little over $60 and the midrange-top end boost they give is insane! So fun. Im running a 19mm one. Pipe also looks cool, you can try a moped header for bigger ports. if i were you i would put on a bigger sprocket. One that small may never take affect because you will simply never be going fast enough for the tall gearing to really matter. For example my friends bike pulls 45mph and he is running a 38t sprocket. sweet build! -moto xct2
 

dylan1024

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Oct 29, 2010
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Re: modified 66cc Ht in bmx

Thanks guys. It's good fun

Moto, we have the big carb but the inlet in the jug needs opening up. It's the restriction. As is the exhaust port in the jug. The pipe was designed for 8k and we are getting just under that so the gearing is happy. Remember small wheels affect the gearing hence the small sprocket. New pipe will be for 9k and will be the correct size all the way to the jug.