Are all pipes the same?

[kingsley]

Im looking at fitting 472cc cub cylinders to my bike. Currently i have FMF Fattys.

Do the pipes or "flange" go up in size when running the 472? or will my FMF pipes still fit?

Theres only a couple hundred more dollars to buy the 472cc kit, compared to the 421cc kits.

They are both a bolt on with my 4mm hotrod crank and rod and i can use my cool head still but with 69mm domes, that ive been told.

I know il have noticeable more power with the 472cc but will i create a list of problems with the 472 compared to the 421, apart from a larger radiator and pump?

I have 34mm carbs also.

[NYUK]

fatty pipe will choke your cub, look into, shearers.

[Screaming Yellow Zonker]

fatty pipe will choke your cub, look into, shearers.

 

X2

Those fattys are good for a slightly modified (stock) bike. But not made for the big bore set up.

[jbooker82]

Are you sure you don't have to bore the top case half?

 

The cub is a drag ported engine so it needs a set of drag pipes. Shearers, cpi's, snipers, or rockets.

 

You do realize your building a drag engine?

[kingsley]

Its claimed that the top of the casings dont have to be machined to fit the big bores in.

I was unaware that i would be building a drag engine. If i understand correctly, a drag ported motor will not be suited for dune or track work, since the power will be made mostly in the higher rev range and have less power/torgue down low in the parts where id need torque?

As far as having the upgrade the pipes, im open to do that to get the performance from it.

 

I like the idea of the big cubes to increase to lower torque...

Would i achieve that buy having a 472cc with no port work done or light work?

Or...

Would the 421 be suited better, with or with out port work?

[jbooker82]

Its claimed that the top of the casings dont have to be machined to fit the big bores in.

I was unaware that i would be building a drag engine. If i understand correctly, a drag ported motor will not be suited for dune or track work, since the power will be made mostly in the higher rev range and have less power/torgue down low in the parts where id need torque?

As far as having the upgrade the pipes, im open to do that to get the performance from it.

 

I like the idea of the big cubes to increase to lower torque...

Would i achieve that buy having a 472cc with no port work done or light work?

Or...

Would the 421 be suited better, with or with out port work?

 

By track do you mean drag strip or mx? Cubs don't have a good midrange for general riding. They are a all top end engine. You can't really detune a cub to make it more midrange friendly. If you run your fmf's on it it will only hurt the top end, and you won't get any better midrange.

 

I you need to talk to M&M about the Serval Cat cylinder. It was made for the duner's. It is the exact same cylinder as the cub only with lower port timings. It makes way better power in the midrange. It is only avalabe in 68mm bore +4mill stroke (421cc's)

 

 

M&M posted a dyno graph. It made 50ft lbs of torque and 80HP. I believe that setup was with CPI pipes, pwk33mm carbs and pump gas.

[jbooker82]

Here is the link. It would be my cylinder of choice. I haven't had a cub but I have had a 4mill drag ported engine. It is fun when your at WOT but not having a mid range sucks for general riding.

 

 

http://bansheehq.com/forums/index.php?showtopic=134580

[Nutwood 472]

Are you sure you don't have to bore the top case half?

 

The cub is a drag ported engine so it needs a set of drag pipes. Shearers, cpi's, snipers, or rockets.

 

You do realize your building a drag engine?

 

 

Yep top cases have to be bored out,I just built one and I run cpi big bore pipes,It's a beast