Big Bore Twins, how big can you go before........

[DOCO794]

it gets really difficult to kickstart?

you need a billet case?

[locogato11283]

I kick start at 24DM in billet.

[trickedcarbine]

I hesitated for years because I was scared to break stuff. However, there are lots of 10 mil motors being  ridden reliably in several applications. And I'm glad I made the plunge. 

[bluebanshee98]

The bigger motors 10+ are not really that bad to kick over. You just gotta do it correctly. It's not like a stock motor where you can kick it over carelessly without even paying attention and half ass it with flip flops on


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[pp13bnos]

First get use to starting old CR500s, or LT500s, then starting a 10mill is a piece of cake.  Honestly a 10 is pretty easy. 

[RagunCajun]

i can kick start my 521 with crocs on. My purse doesnt even fall off my shoulder.

[n2otoofast4u]

Don't kick like a pussy and you can start big motors.

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[JTmachining]

I kick with Vans on

[kawa110]

All about that compression stroke.

 

Dad taught me how to kickstart his vintage pan head Harley when I was 14...(if you can start it you can ride it type thing).

 

That think jacked my ankle and tossed me around until I figured it out.

Cr500 ain't nothing after that.

[DOCO794]

I know it's not quite as bad on a quad but what about the vibration? (assuming bar weights, aftermarket engine mounts etc are used)

Do you think a heavier billet case would help with the vibes?

[n2otoofast4u]

.

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[JUSTWANNARACE]

21 minutes ago, DOCO794 said:

I know it's not quite as bad on a quad but what about the vibration? (assuming bar weights, aftermarket engine mounts etc are used)

Do you think a heavier billet case would help with the vibes?

If the crank is built correctly and pistons are weighed and balanced you shouldn't have any more vibration than a stocker. Usually don't start getting vibration that I've seen until you get to about 85mm bore and above and still isn't half as bad as say a cr500. Most bikes vibrate like a mofo from poor balancing and counter balancing(single cyls)

[locogato11283]

Build a 24DM. They're smooth off idle all the way to the upper RPMs.

[DOCO794]

7 hours ago, locogato11283 said:

Build a 24DM. They're smooth off idle all the way to the upper RPMs.

Wouldn't it be be better(shorter stroke) to use a DMX instead and just lower the ports with thinner base gaskets to make them less peaky since they're normally for dragging?

[locogato11283]

Wouldn't it be be better(shorter stroke) to use a DMX instead and just lower the ports with thinner base gaskets to make them less peaky since they're normally for dragging?

Probably. DMX are super reliable too.