Skip to content
View in the app

A better way to browse. Learn more.

Trials Central

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.

Ty250a Piston Size And Cylider Removal

Featured Replies

Hi All

I have a ty250a with the piston stamped 25. Does anyone know if that is the first oversize?

Also trying to remove the cylinder, one of the recessed bolts has been nicely rounded by a previous owner. Any ideas on how to get it off please? Thanks for any help you can give me.

Yes 25 normally means 0.25mm oversize which is first oversize.

The bolts that hold the cylinder on are aluminium nuts and usually cause problems if they have never been off before but your being first oversize may be less frozen in place. The main problem is usually corrosion product and dirt between the OD of the nut and the cylinder. If there is no way to grip the nut or loosen it, you can drill the stud away and fit a new stud and nut. A simple cylindrical steel drill guide that fits neatly in the hole through the fins will allow you to keep the drill on track.

As David says its First oversize. Removal of the nut can be difficult but do make sure you have all the crud off the head. Sometimes the combo socket will work on rounded nuts or in the past I have used an open ended spannner between the fins to gain access (level with the top of the reed ass) but this can be a knuckle buster! Look on ebay for the replacement bolts.

Tony

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

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.