1983 R100RS Remove Engine Top End

[@andymueller82]

Finally found your channel Brook! Great stuff, this will be invaluable down the road! Great stuff!

[@BrooksAirheadGarage]

Thank you Andy. 🙂

[@malcolmnash5850]

Fantastic Tutorial, I have just got myself my first BMW a R100RS.

[@BrooksAirheadGarage]

Malcolm, Cool beans. I hope you enjoy that bike. I'm glad to hear another airhead will be out on the road.

[@moddude101]

Thanks for the good explanation and the clear view of sight of the video!

[@BrooksAirheadGarage]

You're welcome moddude101.

[@64faffi]

Great video with useful tips - thanks! Subscribed.

[@BrooksAirheadGarage]

64faffi, Thank you. I also posted one on how I install the top end.

[@hoopdedoop1001]

I watched a different video of the same task on an older R90, but they did not remove the connecting rod, which I need to do to change the conrod bearings. They pulled the cylinder out just far enough to remove the "gudgeon pin" from the piston, then continue to remove the cylinder with the piston still in it. Seems like a time/step saver, not dealing with the piston rings. I am inclined to follow your excellent instructions, but was curious about this. Good idea?

[@BrooksAirheadGarage]

Hi John, If you don't need to replace the rings, leaving the piston in the cylinder with the rings compressed by the cylinder is safer and a good idea. I point that out in the write-up I link to in the intro to this video at the top of the page. I'm replacing the pistons and rings on this project to boost compression to 9.5:1, so I remove them from the cylinders.

[@mwtraining4310]

@@BrooksAirheadGarageWill this boost in compression increase the horsepower too? Im having oil leak on my cylinder base, the bike is a -78 R100rs, is it the same cylinder with the big o ring? I found two variations, one with the O ring and one without. Thanks for always so good instructions Brook. 🎉

[@BrooksAirheadGarage]

@@mwtraining4310 I'm not sure when the O-ring was introduced. When you pull the cylinders you will either see or not a groove for the large o-ring.

[@BrooksAirheadGarage]

If you don't need to replace the rings, leaving the pistons in the cylinders is a good idea.

[@mwtraining4310]

@@BrooksAirheadGarage thank you very much

[@steeltownbarbercompany9741]

Can you still buy the 12 o’clock and 6 o’clock studs? Everywhere only seems to sell the valve cover side studs, unless they are the same? But the 13 and 6 look thicker.. I’m going to do a top end rebuild as my right cylinder seeps oil along these 2 studs.

[@BrooksAirheadGarage]

Dean, Yes you can get them at any BMW dealer, although they likely will have to order them for you. Part# 07 12 9 908 174 STUD BOLT - M10X50 (from 08/80). I show how I install them here: brook.reams.me/bmw-motorcycle-rebuilds/1983-bmw-r100rs-rebuild-project-index/11-bmw-1983-r100rs-install-push-rod-tubes-head-studs/

[@Te4mUp]

Hey... question... so let's say I loosed the 8 stud nuts and 2 top nuts like I should have but totally forgot about the bottom nuts... About how bad might I have fucked up?

[@BrooksAirheadGarage]

FrodoLoggins, You're okay, unless you used a crowbar to try and remove the cylinder heads :-)

[@lastairhead]

hey! thanks for the info. I will replace all my o-rings and gaskets and it is so nice of you to share all this valuable details. Why you don t like the silicone gaskets? I have ordered silicone gaskets for my carburator bowls because I heve replaced them twice (with original gaskets) and one (right) keeps leaking after very short time. I hope that the silicone will stop this leakage.

[@BrooksAirheadGarage]

Hi Last Airhead. I'm pleased this material has helped you with you project. My comment about not liking silicone valve cover gaskets is based on the fact that If there are leaks, then the mating surfaces are not flat. So, it makes sense to fix the original problem rather than apply a band aid. When I had the heads rebuilt Randy Long at Long's Mechanical Services in Pennsylvania, he machined the valve cover mating surface in the head so it was flat. I suppose, for a short term fix, you could use the silicone gasket to try and keep the oil from leaking, but at some point, you ought to address the actual cause.

[@lastairhead]

@@BrooksAirheadGarage I totally agree, but I can not find the problem with my carburator bowls.

[@jupiterjohnson7191]

Just subscribed, question for the studs that are holding the cylinder; there are rubber bushings. I saw that there were only two. The two at the top; should there be four.

[@BrooksAirheadGarage]

Hi Jupiter, You should read the complete procedure which I include a link to in the video summary under the viewing screen. I explain all the details of the work in those links. In short, no, there are only two o-rings (not bushings) used on the two top cylinder studs. The holes for the studs act as oil passages for lubricating the overhead valve assembly. The o-rings seal those passages so oil does not leak out.

[@jupiterjohnson7191]

Brook's Airhead Garage thank you! Just visited the blog/website, wealth of knowledge

[@ragazzi25]

My R50/5 needs new piston rings, anything I need to pay attention when doing the work?? Reinstalling the parts is pretty straightforward or??

[@BrooksAirheadGarage]

Hi Terry, I document how to to that work on my site, brook.reams.me. Here are two posts that show how I do that work. Removal (R75/6 but same procedure as your R50/5): brook.reams.me/bmw-motorcycle-rebuilds/1973-bmw-r755-rebuild-project/02-bmw-r755-general-tear-down/#Remove_the_Engine_Top_End Installation (R75/5 but same procedure as your R50/5): brook.reams.me/bmw-motorcycle-rebuilds/1973-bmw-r755-rebuild-project/11-bmw-r755-install-engine-top-end/ I hope that helps.

[@NotJooob]

Is it necessary to removal the whole piston to replaced reseal the top end?

[@BrooksAirheadGarage]

Hi Chau, Yes because you have to install a new cylinder O-ring and remove the old sealant and apply new sealant on the engine block and the base of the cylinder. You can remove the wrist pin and keep the piston in the cylinder which is the best method if all you are doing is replacing the cylinder O-ring and the push rod tube seals.

[@DmitriyGolovinov]

Thank you for this, very informative

[@BrooksAirheadGarage]

You're welcome Dmitriy.

[@dullbrass]

Great tutorial. Thank you!

[@BrooksAirheadGarage]

You’re welcome. Thanks for coming by.

[@albeenamelast6620]

Have you ever seen a R 90 S push rod? I think they are machined from one piece of steel. They are a nicer rod than what you have there ! But what you have is better than a /6 push rod. Not that I know much, just an observation!!

[@BrooksAirheadGarage]

Alan, there are two versions of the push rod, the earlier part# 11 32 1 259 607 and the later part# 11 32 1 262 907. The "S" and all /6 bikes used the "607". The "907" is lighter putting less stress on the rocker assembly and has better heat transfer keeping the valve train cooler. I installed the "907" when I raced my 1975 R75/6 as I bent a "607" push rod when I blew past the red line on mistimed down shift. I never bent the "907" when even though now and then I blew past the red line.

[@albeenamelast6620]

@@BrooksAirheadGarage When gas went to unleaded back in the 80's I was trying to regain to power that my R75/6 had when it was new (I could take it to red line and still have throttler left , the bike was doing 125 mph) I decided to do dual plugs. I also up dated rocker arms to the ones with needle bearings I did R90S push rods and also after market light weight wrist pins. I do remember that the push rods were one piece machined rod witch would have been a lot of money to make. They did look like your "907" and I bet when BMW was designing the R100/7 motor that they redesigning the"S" push rod for manufacturing purposes now that they were putting that push rod in all of there motors. My guessing that your 77 and your 83 have the same push rods. I wish I new someone with a R90S to confirm this but I have lost contact with everyone that I new that had one. The R90S had 7 more horse power than the R90/6 but I don't know why the push rods wouldn't have had anything to do with it!