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61
The Motobrick Workshop / Re: K100RS running hot
« Last post by Filmcamera on May 03, 2026, 07:31:47 PM »
Well, the thermostat is fine.


In fact it seems maybe the old girl just need to clear her lungs after a year or so off the road,


I have done a few more rides and the temperature is fine, runs normal when cruising, gets kinda warm when pushing but nothing I can't deal with by easing off the pace for a bit





62
The Motobrick Workshop / Re: 1985 K100 RS ... lower crankcase removal - engine out?
« Last post by Duckbubbles on May 03, 2026, 10:06:19 AM »
Are we talking about the crankcase/crankshaft cover bolts?
If I remember correctly they go into a blind hole in the crankcase and no way it should end up inside the engine.
The engine serial number is stamped into the lower crankcase/oil sump and is a matched set with the upper crankcase and may not match up correctly.

Frank
63
Welcome To Motobrick.Com / Re: New rider from the Netherlands
« Last post by Bmwsquirl on May 02, 2026, 07:59:54 PM »
welcome
64
The Motobrick Workshop / Re: 1985 K100 RS ... lower crankcase removal - engine out?
« Last post by Laitch on May 02, 2026, 07:03:51 PM »
Timing cover = Crankcase cover. Got it!   :laughing4-giggles:

However likely that might be a widely accept translation, I still can't visualize how a fastener with 8Nm of torque requirement mounted through a rubber bushing can be broken—unless it was a victim of 'roid-rage—then fall into the oil sump of the engine and follow up by causing an ominous bang, but I will admit I don't have much imagination. Others are sure to chime in with clarification. Please keep us in the loop and try to provide photos as you go.
65
The Motobrick Workshop / Re: 1985 K100 RS ... lower crankcase removal - engine out?
« Last post by Sticklebrick on May 02, 2026, 05:45:46 PM »
Sorry I should have made it clear, it was the right hand crankcase cover that I removed to replace the gasket. It was the top left pesky bolt on that cover, when I remove the sump cover I hope I'll find it!

My theory is it was whipped up by the flywheel and whacked the side of the crankcase housing, causing a shockwave that broke the gasket seal and maybe worse. But any damage done should be confined to the lower crankcase housing (which I have a replacement for).
66
The Motobrick Workshop / Re: 1985 K100 RS ... lower crankcase removal - engine out?
« Last post by Laitch on May 02, 2026, 03:02:26 PM »
Thanks for the reply. Are you referring to the Hall sensor cover gasket? It could be too early to diagnose a broken screw shaft to be at fault, given your description of the timeline between starting and the banging. A short screw shaft fallen to the floor of the sump probably would stay on the floor, especially when the motorcycle isn't being ridden. Like daveson implies, it would be easier to remove just the crankcase cover and sump for a diagnosis.
67
The Motobrick Workshop / Re: 1985 K100 RS ... lower crankcase removal - engine out?
« Last post by Sticklebrick on May 02, 2026, 11:09:27 AM »
Excellent question... I removed the cover to replace the weeping gasket but can't think of any other work I had done on the engine. I over-tightened that cover bolt but didn't hear anything drop, I just heard the bang. Should have used a torque wrench
 Be advised everyone... those bolts snap off quite quietly and can cause disaster.
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The Motobrick Workshop / Re: 1985 K100 RS ... lower crankcase removal - engine out?
« Last post by Laitch on May 02, 2026, 02:12:29 AM »
What work—besides replacing the cover gasket—had you completed before this happened?
69
The Motobrick Workshop / Re: 1985 K100 RS ... lower crankcase removal - engine out?
« Last post by daveson on May 01, 2026, 08:09:12 PM »
Quote from: Sticklebrick on April 30, 2026, 05:15:46 PM
When I started the bike after replacing the cover gasket there was an almighty bang followed by an oil leak of equal and continuous pressure around the edge of the lower crankcase where it mates with the upper part of the engine.



So to sum up my question ... as I need to remove the lower crankcase to inspect, do I need to remove the engine to do this or can it be done with the bike supported upright or on its side?


That sounds like a tall order, but you're in a position to try it and update the forum. But you might not have to remove the lower crankcase for inspection. You might find the problem by removing the crank cover (or the cam cover, depending on which bolt broke) or the base plate of the sump.

Good luck, it's not sounding very good, an almighty bang and leak. You might be lucky, you might not need to dismantle it, hopefully it's something simple.
70
The Motobrick Workshop / Re: Luftmeister upgrades on my bike?
« Last post by Duckbubbles on April 30, 2026, 05:58:43 PM »
No pun intended, just came out like that.
A friend and I had a lot of dealings with Luftmeister back in the day.  I built a hot rodded 8 valve K engine in the late 80's using their services.  I  spent a load of money with them and was mostly happy with that.  A mod that I liked the most was a 7%-11% gear change in the transmission.  It raised 1st through 4th by 7% and 5th gear by 11%.

Frank
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