R25/2 Timing Chain Stretch

[Kurt in S.A.]

I'm taking apart my R25/2 engine for overhaul.  Got the timing chain cover off.  I'll obviously replace the chain, but is this amount of stretch bad?  The bike has unknown mileage on it.  Also, I understand I can retrofit a tensioner...did that first show up in the R25/3 engines?

Thanks...Kurt

[Kurt in S.A.]

[DanMay]

Kurt, I believe you can retro fit the tensioner to the R24 and the R25.  When I rebuilt my R24 engine, I added a tensioner.

Richard Sheckler did the motor work, so he would have the details.  If I recall, it was an easy modification.  I bought the chain and tensioner from Uli's, so Uli's probally can help you with the modification also. 

Daniel

[Kurt in S.A.]

Dan -

Thanks...you and I are on the same side of the world...everyone else is asleep!!  Interesting, the R24 and R25 had tensioners, but they dropped them for the R25/2??  Strange.

I've decided to have Vech do the work.  I'm trying to get the engine down to bare block and will take all parts to him for evaluation and update.  I know that Richard is great with the singles...but he's too far away.  I want to physically take the parts to someone...I don't trust shipping it.  Vech is a little over a day away by car.

Kurt

[Rütz]

...did that first show up in the R25/3 engines?

No, it did first show up in 1963(!) for R27 (look here: http://www.beemergarage.com/documents/198.pdf).
But can be (and was recomended to be) retrofitted on all postwar singles.

If you replace the timing chain today, the tensioner must(!) be installed. Because nowadays the timing chain is no longer available in three different lengths, but just one.

Ruetz