Skip to content
View in the app

A better way to browse. Learn more.

rollaclub.com

A full-screen app on your home screen with push notifications, badges and more.

To install this app on iOS and iPadOS
  1. Tap the Share icon in Safari
  2. Scroll the menu and tap Add to Home Screen.
  3. Tap Add in the top-right corner.
To install this app on Android
  1. Tap the 3-dot menu (⋮) in the top-right corner of the browser.
  2. Tap Add to Home screen or Install app.
  3. Confirm by tapping Install.

How To Tell Diff Between Bigport And Small

Featured Replies

Hey guy I have a friend that needs a Crankshaft for her 4age and I don't know how to tell the difference between big port and small port.

I don't even know if there is any difference between the crankshafts or not.

Probely not but I thought I should ask.

small port has a 42mm bigend and the bigport has a 40mm bigend.

 

you can tell the engines apart from the size of the inlet ports, assuming someone hasn't changed the head.

what crankshaft are you after? the better one out of the 2 is the smallport being stronger.

what crankshaft are you after? the better one out of the 2 is the smallport being stronger.

One that fits the motor :hmm:

Urm, yeah the small port is better (some might disagree) but its not so better if the motor in question is the big port which would mean having to pull the motor down to swap con-rods and pistons....

 

But, yeah, as Hiro said have a look at the side of the block and see how many ribs it has - 3 its a big port 40mm big ends or 7 its a small port 42mm big ends.

But if the cranks out of the block use a Vernier Caliper or two engineers squares (or something like it) with measurements on one to do the same thing.

 

If the motor in question is a big port you could get away with the crank from a 4a-c 4a-f but you'll won't be able to use the 4a-g flywheel.

But, yeah, as Hiro said have a look at the side of the block and see how many ribs it has - 3 its a big port 40mm big ends or 7 its a small port 42mm big ends.

 

Unless it's a 7-rib bigport, which has 42mm big ends but no oil-squirters and still has the bigport head.

  • Author

Thanks for the info guys. Where abouts are the ribs located on the block?

  • Author

Thanks Hiro your a legend :y:

Please sign in to comment

You will be able to leave a comment after signing in

Sign In Now

Account

Navigation

Search

Search

Configure browser push notifications

Chrome (Android)
  1. Tap the lock icon next to the address bar.
  2. Tap Permissions → Notifications.
  3. Adjust your preference.
Chrome (Desktop)
  1. Click the padlock icon in the address bar.
  2. Select Site settings.
  3. Find Notifications and adjust your preference.