[Jtee]

Hi,

Son's 2013 R125 seized last week 5 minutes into journey. It was travelling at approx. 60mph and then revs dropped and it died and now wont start

Mechanics said it had seized due to no oil and to fit a donor engine it would cost £1000. It has little/no compression.

I have removed cam cover and it does turn.

I would really appreciate some advise as i intend on fixing myself. I know this is not uncommon so dos and donts would be good. I have time so thats not an issue.

Specific questions include, how do I know if it is big end or cylinder/piston etc.? Do i have to remove engine? Will I be able to see damage from removing camcase?

Cheers guys.

 

[anthonysanc32]

Welcome


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[NorthCust]

>I would really appreciate some advise as i intend on fixing myself. I know this is not uncommon so dos and donts would be good. I have time so that's not an issue.

This is a potentially much bigger job than is sounds. Anything including the words "bottom end" is even more complex and likely requires a press too. Don't get me wrong it's 100% doable, I've just done a full rebuild (inc crank split/rebuild) on mine and it's awesome but damn that was a lot more work than it looked and a LOT more learning than involved as well as making 2 separate tools to be able to do it.

If it's "seized" then it's hopefully the cylinder that has seized and your bottom end may be ok (normal wear and tear for the miles). In that case you would likely only need to change the cylinder which I have done videos on (see my sig/youtube), which may mean you don't need to split the cases and take the bottom end apart.

Unfortunately on the engine I just rebuilt I got it thinking it was only a seized piston but removing the seized wrist pin scored the bearing surface of the con-rod, and to put a new con-rod on you need to split the cases and the crank itself which is a whole different thing.

> Specific questions include, how do I know if it is big end or cylinder/piston etc.?

mk1 eyeball. The order you'd have to take it apart in would indicate whether it's the piston or not which is seized.

> Do i have to remove engine?

much easier to do all these bits with the engine out. That is literally the least challenging part of this.

> Will I be able to see damage from removing camcase?

cam-cover? no, cylinder head? hopefully. Ideally I'd want to see some nice scrapey lines and some obvious damage in the cylinder bore (which is getting fully replaced either way). Be very careful removing the wrist pin if stuck, since score that bearing surface on the con-rod and it's a whole new world of hurt (and cost).

Honestly if you want a running bike then just buy a replacement engine with a warranty, sell the seized engine on ebay as it is. . If you want to learn how to build engines or want to do very specific modifications then have at it DIY. Imho there is no cost or time advantage in DIY but there is definitely knowledge/experience advantage.