Boxerworks.com

Hi, I am just going through the process of rebuilding my 1981 R80 engine. I took off the barrels and found the nikasil coating in one has started pitting and also found a minor score on the piston.

I decided to replace both barrels and saw the Siebenrock kit that upgrades my R80 to a super R100 with impressive claims. Just wondering how much of this is real and how much is marketing?

I am contemplating getting my barrels recoated, Richard Moore from Moorespeed provides a nikasil recoating service and I am pretty sure this is the way to go without throwing my money into the wind. He reckons I'd get more bang for my buck if I stuck with the 800 barrel and upgraded my cam... interesting!

So anyone got experience with the Sibenrock claims and the performance increases one can realistically expect?

I've already put my foot in it with the boyer blue box kit, they said my bike would feel completely different... felt just like the points after I spent a day and a half making brackets and redoing the wiring on my bike...

Any constructive advice would be well received!

No info on that particular swap, but the only complaints I've heard were from people using them on the R75/5 cases. It seems the later cases have more internal bracing. The people who were cracking the R75/5 cases were flogging them, so... YMMV

Yeah thanks, I've not heard this, only that the performance claims are not as noticeable, some people on forums say they have noticed more power and one guy stated getting 114mph, others said not much of a difference except a bit more torque.

Hard to translate what is real and what is placebo, after having spent £800 to upgrade your engine some people might be looking for that extra power, no one likes being a mug!

If the head and carbs are not updated then you're still limiting fuel supply, so it is a far stretch to overpower a R100 which comes with in the right configuration. I did see a common occurrence that the R100 power kit makes no difference, so that is questionable given the lighter pistons and improved compression.

The higher compression pistons seem good, but apparently you need to run the engine on higher quality fuel otherwise engine performance is poor...not worth the extra 8mph at the top end...my R80 does 106mph (maybe 1 more in it if I loose some weight) right now. So that is £100 per 1 mph.

Would be great if someone who has installed the kit could please stand up?

Hi nicholas
You would probably do better asking that question on the adv rider airheads forum http://www.advrider.com/forums/forumdisplay.php?f=85

They are more into modifications.

Cheers
Mal

Thanks Mal, well I am in a pickle now, running out of time (moving back to OZ) so will stick with this kit, call me a mug...

I'll update this thread once I have the motor running and give you thoughts as I'll be able to compare my rebuilt 1987 R80 with this one.

There seems a bit of doubt in your mind re: the Siebenrock, but little doubt Re: Moorehead's approach.

It seems that the Siebenrock will need more stuff to get it to go more.

More money spent to unsettle a package that is generally considered one of the better ones from BMW.

Go cheaper, go the Moorehead route. Does he offer any other tweaks or advice?

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There, did that help?

I don't know anything about Siebenrock's kit, but I have owned an R80, and I currently ride an R100, and, if I still had an R80, I wouldn't bother messing around with "performance upgrades". There is no better airhead engine for smooth operation at reasonable speeds than a Nikasil-bored R80. Get your 800cc jugs re-plated, or buy a new pair of them, but get happy with what your R80 does so well.

I've swapped between 800cc and 1000cc several times on my previous R80ST. Just used stock BMW 1000cc jugs, pistons, and heads. Dead simple, don't even need to adjust jetting on the same carbs. The 1000cc engine had more power and more vibration. The 800cc engine was so smooth, I went back to it. Depending on your rear drive, you can probably go to red line with either engine. I've been over 100mph, but..... only to prove it could be done. Don't really need to go there in my life.

Don

Thanks guys, they are good points. I need to respect a lot of these old boys here in the UK as they do make some incredible engines, but at the same time they also run a business and need to make a living...so this is why I thought I'd ask on here...

Right now I have a time constraint and need to get this R80 rebuilt, I've done the sums and this kit isn't that much more than getting the rest of the parts I need for a nut and bolt engine rebuild. I also have a great 87 R80 which I rebuilt this year, and a 78 R100S so I should be able to get a feel for what combination is best.

I love riding my 87 R80 and the R100S is nice too but feels sluggish, but I put that down to the engine needing a strip down and the heavy flywheel. My mate has a light flywheel R100 with an R80 bevel box (spoke wheels) and I absolutely love riding his bike, it is bloody smooth and powerful, very noticeable...So perhaps the gear ratio of the R80 contributes to the smooth ride? Anyway... I should know soon enough.

SteveD wrote:There seems a bit of doubt in your mind re: the Siebenrock, but little doubt Re: Moorehead's approach.

I guess Richard Moore isn't well known...but you should have a look at what he does, he builds and races BMWs and has his own line of upgrades for these bikes... So I have to respect the man and his experience. What I'll do is get my bike on a dyno and compare it with what Sibenrock are claiming... that should be easy.

FYI
http://www.moorespeed.co.uk/bmw-engine