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.

Montesa 315R 2003 Engine Knock. Ideas? (Video)

Featured Replies

Hey guys, bought a 2003 bike a few weeks ago (LOVE IT) and other than the knock it pulls like an absolute train!!

Anyway, here is the video of the knock. Some friends have suggested the small end bearing.

My dad has just rebuilt his Beta Techno and it sounds like a sewing machine compared to mine now!!

Any ideas?

Also, I live in the UK and I can't find a small end bearing/con rod kit anywhere. Does anyone know where would be best to look? I don't mind paying overseas shipping if it is this that's the problem.

Cheers :guinness:

  • Replies 40
  • Views 14.9k
  • Created
  • Last Reply

Top Posters In This Topic

Most Popular Posts

  • 100% piston slap, the piston has 3 rings and that keeps the top of the piston very stable, but the bottom of the piston when worn does move around a lot It'll still run good as the rings keep the com

  • Hey Lewis, its a simple job, the top end has to come of but its a very easy job, exhaust off, carb and reeds off, then its a couple of engine mounts and the main bolt through the swing arm drop the

  • Right, just been on the phone to Sandifords who sell the piston kit, and looks like the only option is an "A" piston and putting any larger piston in the barell is a big no no. Glad I rang because I

Posted Images

  • Author

Hard to tell by the vid, but it sounds like main bearings.

Yea, could be. It does sound like a lower tone in person.

Here is another vid:

Since it has a knock that bothers you then you need at least the head and barrel off anyway. Far better to properly inspect and measure than waste time guessing from sounds.

Sounds top end to me, either piston slap or little end.

Edited by dadof2

Take the head and barrel off I think it needs a new piston and maybe the barrel re nickasilled

100% piston slap, the piston has 3 rings and that keeps the top of the piston very stable, but the bottom of the piston when worn does move around a lot

It'll still run good as the rings keep the compression but defo worth fixing, Sandifords do a complete kit for £140

  • Author

Since it has a knock that bothers you then you need at least the head and barrel off anyway. Far better to properly inspect and measure than waste time guessing from sounds.

Sounds top end to me, either piston slap or little end.

Yea I would like to fix it. I'll do the full piston kit I think. Is there anything else that is worth replacing while the head is off.

Also, is it a hard/big job? I haven't been around bikes much, only cars. I also know that 2 strokes are a different beast.

more than likely piston slap

Thanks

100% piston slap, the piston has 3 rings and that keeps the top of the piston very stable, but the bottom of the piston when worn does move around a lot

It'll still run good as the rings keep the compression but defo worth fixing, Sandifords do a complete kit for £140

Right OK, thanks for pointing me in the right direction on parts. I'll have to keep running it as is for the moment though as the piggy bank is getting low :wacko:

Does the noise change when you pull the clutch in?

No not at all.

Its an easy job, i take the whole engine out and do it on the bench but some people like to keep the engine in the bike

That sounds just like mine and I've been told it's the top end and would be best swapping the piston while I'm on! But I'm really not keen on pulling the engine to bits!

Any tips?

  • Author

Its an easy job, i take the whole engine out and do it on the bench but some people like to keep the engine in the bike

Alright cool, I'll see how I get on cheers.

Alright cool, I'll see how I get on cheers.

If you give it ago can you let me know how you get on? Then I may set too myself!

  • Author

If you give it ago can you let me know how you get on? Then I may set too myself!

Will do. Probably won't be for a while as I just splashed out £200 on new boots/gloves/helmet haha :rolleyes:

Will do. Probably won't be for a while as I just splashed out £200 on new boots/gloves/helmet haha :rolleyes:

I may have a go first then! Hahaa

Any one know the best place to get a top end kit?

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.