Bird Engineering Minibike

[gocartkid]

Well I acquired this from a friend of a friend (what a classic story, right?). I bought this and a brand new kart frame (see my thread in the kart section) with parts for a total of $200. Not bad, since the bike is complete and has a new clutch on it. This was bought as a kit from Bird Engineering out of Nebraska. The previous owner welded it up (NICE welds) and through a B&S flathead on it. It's either a 2 or 3 horse, the numbers are below a thick coat of paint on the shroud, so I'm gonna have to take the paint off to find out what it is. It's got no spark as of right now. Easy fix though. It has ok compression. I plan on restoring this bike to mint shape, but I don't know if I want to rebuild this engine for it or go with others that I have. I have a few choices (all of which will be built before installed): Briggs 2/3, Briggs 5, Tecumseh 6 (OLD engine, would be period correct for the 70's mini bike era), and a 2 stroke Tecumseh 3. Your input would be appreciated here. Well enough rambling on, here are the pics:

 

[Kenny_McCormic]

Either the 2 stroke or the briggs 5 with racing parts (you can build one for next to nothing, you can get a 6000 rpm safe raptor rod, stiffer valve springs(get some that float at 6k so you cant over rev), and a used cam for under $75)

 

[Russ2251]

You want fun?
Put on the biggest 2 cycle you can find.
This would be perfect.

 

[crazycart]

Want to fly?

http://cgi.ebay.com/VINTAGE-SKI-DOO...ryZ64679QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

Or you could die?

http://cgi.ebay.com/Polaris-600cc-s...ryZ23834QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

The rotax puts out around 15 hp. The Polaris you ask? 120.

 

[gocartkid]

Want to fly?

http://cgi.ebay.com/VINTAGE-SKI-DOO...ryZ64679QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

Or you could die?

http://cgi.ebay.com/Polaris-600cc-s...ryZ23834QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

The rotax puts out around 15 hp. The Polaris you ask? 120.

Either would be cool but both would require lots of fab work. I'm just looking to use what I have on hand.

 

[Walter Keller]

have Briggs will build

Just build the briggs - theres lots of parts out there for them. Seems like the easy choice.

 

[Jerryburger]

Some sort of 2 stroke! Yeah!

 

[847]

comp cam gp9530

http://www.compperformancegroupstor...re_Code=CC&Product_Code=GP9530&Category_Code=

71 bux

plus the dual spring set

for around $12 should read 110lbs when you find it

 

[gocartkid]

I'm still on the fence...but after some measurments I found out the Tecumseh 6 will stick out way far on the sides so that one's out. I'm thinking about building a Briggs 5 and loading it with performance parts and throwing it on, I want something like in the links below so the two 3 horses I have won't cut it.



http://www.youtube.com/watch?v=_7eIW2TPytg
http://www.youtube.com/watch?v=4PMgfMwZ4-Y

 

[gocartkid]

Oh, and I have a question for you guys. The brake is a rear scrub brake as you can see in the pics. I don't like that style at all and I don't want to keep replacing worn out rear tires (like what's on it now). So, what are my options here? What will work? I'm a noob in the mini bike world so any help would be apreciated.

 

[tykenfitz]

get some sweet disc breaks out of an old mountain bike

 

[sayre315]

yea, you could get a:
raptor rod
dyno cam
milled head
raptor crank
and some fancy valve springs
for around $100

 

[oscaryu1]

Raptor rod = $20 shipped

Used Dyno Cam = $30 shipped

Milled head = $30?

Raptor crank = unnecessary

And two exhaust valve springs will do. CompGoParts

 

[Kenny_McCormic]

You dont want a milled head, kills flow, unless milled means its been welded on top and the valve pockets have been milled to make it look like a heart shaped deal.

Shave the eyebrows and clean up the ports while your in there.

 

[jr dragster T]

That link with the mini drag bikes are using blockzilla's. A built blockzilla will cost around 2800 bucks at the cheapest. There is one guy on youtube that has a 3 1/4 bore engine in his bike. Just the 3 1/4 bore engine will cost you around @4500-$5000 online.

 

[jr dragster T]

And about the raptor crank. Oscar is right it is 100% not neceary. Some people at my track are running STOCK briggs cranks and running 8.30's.

 

[Roy Vanas]

Oh, and I have a question for you guys. The brake is a rear scrub brake as you can see in the pics. I don't like that style at all and I don't want to keep replacing worn out rear tires (like what's on it now). So, what are my options here? What will work? I'm a noob in the mini bike world so any help would be apreciated.

for an easy brake, try a $7.00 oil filter wrench as a band brake around the centerfugal clutch....CHEAP CHEAP

 

[Kenny_McCormic]

Yep using the clutch for a drum works great.

 

[gocartkid]

That link with the mini drag bikes are using blockzilla's. A built blockzilla will cost around 2800 bucks at the cheapest. There is one guy on youtube that has a 3 1/4 bore engine in his bike. Just the 3 1/4 bore engine will cost you around @4500-$5000 online.

Yea, I know they are. They were just representations of what I am going for on this build. I have a few stock 5 horse blocks that will be sent out to be bored. Hopefully they will all clean up, one has severe scoring. I will be building it based off of Oscar's guide in the engine section. Anyone have suggestions for a cam? I've been looking at a few, but I was wondering what your experiances are.

 

[gocartkid]

You dont want a milled head, kills flow, unless milled means its been welded on top and the valve pockets have been milled to make it look like a heart shaped deal.

Shave the eyebrows and clean up the ports while your in there.

Ok, thanks for the input. I almost bought a milled head but shyed away for that reason (it was milled a LOT). I'll clean up the casting in the head.