For years I’ve resisted changes and upgrades to the R65LS, preferring instead to ride around its difficulties. If I wanted a larger or more modern bike I would at some stage have purchased one.
In April 2024 I went on a long ride with friends on larger bikes and found that I was flogging the LS trying to keep up. Probably I did more than twice the number of gear changes that they did, even allowing for their 6 speed boxes. After this I decided that it was time to purchase the 860cc upgrade.
I decided to have the heads reconditioned, forks rebuilt and rear shocks serviced as part of the job. These other items held the job up somewhat, and the bike was off the road for 3 months.
I purchased the kit direct from Siebenrock. It was available from other places, but Siebenrock offered a R65LS-specific version of the kit that I didn’t find elsewhere. Part number was 1100870. Other R65 after 9/80 are 1100860. I don’t know what the difference is between the kits, and the other vendors I checked didn’t offer both. Everything necessary was in the kit: pistons, rings, gaskets, O rings, gudgeon pins.
Installation was straightforward and could be done in a day if there were no glitches.
After installation the bike had increased power throughout the rev range and was a joy to ride. It did lack a bit at the top end, which also changed the character of the engine. Always the LS has been moderate in the range from 3,000 to 5,000 rpm, pulled really well from there to 7,000, and then ran out of puff towards the redline of 7,500 rpm. Keeping the bike in the 5 – 7 thousand range has been key to spirited riding. With the 860 kit this emphasis on keeping the engine over 5,000 rpm has gone, it pulls cleanly from much lower down and this delivery is steady through the rev range.
To fix the top end I went up 3 sizes in main jet, 138 -> 140 -> 142 -> 145. This was a guess based on the main jet sizes of different bikes in the Haynes manual: different LS were supplied with main jets 135, 138, 145 and 148, the 145 size was used on the 1982 US delivery bikes. With the increased main jet it keeps pulling strongly above 7,000 revs. The bike no longer runs out of puff towards redline.
During the run in period I had oil temperatures of 140 degrees Celsius, as measured on the dipstick thermometer. This didn’t last long, but highlights the need to be gentle during the first few hundred km and to do an oil change afterwards. I believe the high temperature to be due to the piston, rings and cylinders scrubbing each other in.
Curious three toned engine: new Siebenrock barrel; reconditioned heads; and grimy tappet cover.
A couple more notes. Some people use gasket goo of some sort to seal the cylinder base O rings and also the pushrod tube seals. I didn’t bother.
Also, the Siebenrock kit instructions included that the gaps in the piston rings be offset at 120 degrees. A more precise method is suggested by Brook’s Airhead Garage where the gaps are rotated to avoid the thrust surfaces on the cylinders. I used 120 degree spacings as per the instructions, but would probably use the more precise spacings if I was doing it again. The precise installation is at https://www.youtube.com/watch?v=1I9RI3pVZHg
I’d consider doing this upgrade on my other bikes, I’m really enjoying the extra power, and the cost isn’t too high. The main consideration is whether the bikes are kept stock or not.
The valve clearances tightened up during the run in period: it’s important to use the “first 1000 km” clearances of 0.15 and 0.25 rather than the usual 0.10 and 0.20mm.
The R86LS stickers were supplied by Gian Sticherman, contacted via https://www.facebook.com/stickersmann. The “Siebenrock 860” decals supplied with the kit were black and orange, so would stand out on neither the red fairing nor the black side covers.
The bike vibrates less, the vibration characteristic of this model at 5,000 rpm is entirely absent. This is probably due to the Siebenrock pistons being better matched/balanced than the original. The pistons I took out were 378 and 382g (using kitchen scales), had they been more closely matched the bike would probably have vibrated less.
