Siebenrock 800cc to 1000cc kit, is it really worth it?

[Mal S7]

Hope it works out. I reckon it will be a good thing. Keep us informed.
Cheers

[Foxy]

i fitted 1000cc Siebenrock kit to my 72 R75/5. Not sure i would do it again. Pistons did not match cylinders. One would slide down bore (without rings fitted obviously) and the other needed to be pushed through. Siebenrock said they were "within limits". Crap. I had one cylinder lightly skimmed prior to fitting. Yes you can skim nikosil bores. Special equipment required.
Bike has little bit more power. Clutch began slipping so had to replace that, so i guess it does put out more power/torque.
Had no issues with pinging, just used standard base plates. 98 octane fuel available in Aust. Apparently its OK to use no base plates. Left carbs etc completely standard as advised. Bike starts and runs well with this set up. Plugs perfect brown color.
The bike has just developed a pretty bad leak from the timing chest. Not the front cover, the one behind that. Anyone got any clues on what may case that? Is it just the gasket? I have never had that area disassembled.
As I said, not sure i would use Siebenrock kit again, perhaps just rebore and fit 800 pistons. Not a lot cheaper than the kit in the end though. There is a significant weight saving with lighter barrells with the kit.
Cheers

[nicholas]

i fitted 1000cc Siebenrock kit to my 72 R75/5. Not sure i would do it again. Pistons did not match cylinders. One would slide down bore (without rings fitted obviously) and the other needed to be pushed through. Siebenrock said they were "within limits". Crap. I had one cylinder lightly skimmed prior to fitting. Yes you can skim nikosil bores. Special equipment required.
Cheers

Hi Foxy, thanks for the note and that is a surprise. I have not fitted anything yet, hopefully start tomorrow or Thursday, but I have to say after opening the kit, I am really impressed with the quality, everything seems to fit perfectly. Mine came with Sibenrock pistons, you need their pistons and rings as the bore on their 1000 is larger than the standard 100, again mine did fit quire nicely. Did you buy the kit new or used, perhaps they shipped the wrong pistons?

Yes, I did hear you can use aluminium oxide to hone Nikasil cylinders, but you'd want someone who knows what their doing!

The oil leak sounds like you need a new gasket, the timing chain, crank and cam sprocket are lubricated in this area.

Check out this website, great breakdown of parts, should help you figure out what you need to replace.

http://www.maxbmwmotorcycles.com/fiche/PartsFiche.aspx

[Foxy]

Yeah bought kit (including pistons and rings) new from Siebenrock. As I said one piston slid down bore under its own weight, the other had to be pushed through.
If yours are a good fit you should have no trouble.
Thanks for tip re timing chest. Removed it today, gasket looked ok but hard to tell. Will replace duplex chain, tesioner, seals and gasket.
Cheers

[nicholas]

Yeah bought kit (including pistons and rings) new from Siebenrock. As I said one piston slid down bore under its own weight, the other had to be pushed through.
If yours are a good fit you should have no trouble.

Oh, well fingers crossed mine are OK. I only looked at one barrel, I'll take a closer look when I am back in the workshop.

Best of luck with the task, I've heard the duplex chains are a PIA! I have to do my 1978 R100S....will leave it to next year.

I think there is an oil seal behind the crank sprocket that you might want to replace (unless this is what you were referring to). But oil should be entering this area via the pressure relief valve to lube the chain and sprockets, so it must be the gasket, unless it is coming from somewhere else?