Had a leak at the pushrod seals, hence their replacement. I thought that my pushrod tubes' seals melted, when I saw a mess of black at the base of one. After removal of the seals and pushrods, it looks like this: Looks like the PO used silicon to seal bases of the seals, to either forestall leaks or to patch one. Good or bad idea? Necessary? Here's the heads and pistons: Left side: Right side: Anything I should worry about from what you guys see? I plan to remove the carbon and see if that improves my high fuel consumption, reinstall stainless covers and new seals.
everything looks good (heads, clyinders, pistons) I wouldn't recommend using gasket seal for the pushrod seals... They work fine without it. Granted you use bmw parts, I heard there are some aftermarket ones that tend to crack with hardly any use
Do NOT use silicone on the push rod seals. a) They work fine w/out the goop, b) you end up with a mess (as you've found) and 3) how will you ensure that a bit of silicone won't spooge out into the oil galley and subsequently block oil circulation. There's no need for silicone goop (and make sure you keep the remains of the PO's mistake out of your engine). As for removing carbon to improve mileage, I don't think you'll see much of a change. Much more inportant is what was your compression before disassembling? Healthy compression plus well tuned carbs will have the biggest impact in a stock motor. Nice work.
Yep. I've got seals from Motobins on my bike right now. They're about 5 years old and getting ready for replacement. Worked fine so far. I don't know if they were BMW parts 5 years ago or now.
I just did that exact same job on my '78 R100S. It looked as though the PO had goobered silicone on the seals to try (unsuccessfully) to stop the leaks. I would recommend taking the heads apart to check the valve guide clearance, also it will allow you to do a more through job of cleaning them. I got my parts from Hucky.
That's a nice, healthy-looking piston crown, typical of Nikasil bore bikes. Have a good look at the rings for wear and pull the lifters and inspect their faces.
Good call on the lifters Bud. At least half of the lifters I've pulled out of my airheads have pitting and damage on the faces, even though the cam journals look perfect. Worth double checking and replacing if necessary. dc
If you have to replace a lifter, soak it overnight (at least) in motor oil. They are cast iron and absorb oil, just as an iron frying pan does. Whether you are replacing them or not, smear the faces with cam assembly lube, or if you don't have this ass'y lube, get some CV Joint grease from the local auto parts store. The first minutes of use for lifers and cam are the most critical in their lives.
I ALWAYS check the lifters when I have a cylinder off. If they are flaked at all, I replace the ones that are. No need to replace the set. I think an old one that hasn't yet flaked is more likely to not flake in the future than a new one. It's already been flake tested! CV grease? I think lithium is fine. I never soak them either. I agree with bmwrench that the first seconds is most critical but our cams and lifters do just fine without pre-soaking them and lithium grease. Cams that need that much special attention say exactly what they need in the instructions. If I was installing a cam in my friends wingless sprint car, I would follow that lumpy mofo's instructions to the T!!. Personally, the best thing I think you can do for the lifters in our bikes is to run motorcycle specific oil in them and not automotive oil but that is for a dreaded oil thread. Boy have lifters gone UP in price lately! I think Motobins sells a lot of stuff that isn't BMW from what I can tell. They seem to be like Capital Cycle only different? I would only use push rod tube seals from a BMW dealer myself but I am not down on the dealers like a lot of people are. The rings look like they have sealed real well from the looks of the piston crowns. I would only clean off the piled up and caked carbon. There is NO need to clean it down to bare metal. If you do, a carbon layer will be back in no time so why do it. DON'T gouge the stuff cleaning it. IMO, the rings won't be worn but the top side of the top ring groove might be. If you clean the heads with the valves out be careful and don't ruin the valve sealing surfaces. Do not wire wheel the valves or the pistons. Some people put oil on the push rod seals. I install them dry after I clean the mold release from them and have had good luck. My own seals right now don't even weep and they have been in there for nine years and about 65,000 hard miles.
Yeah, what's all this shit about buying seals from Motobins? bikecat, where are you? There's nothing in your profile that says where you are. If you are in the USA, WHY would you buy $2.00 seals from England???? Do you own stock in a shipping company or something? C'mon folks, lets get real here. Once in a while there's a deal to be had at Motobins, but for fuks sake, let's check a US dealer first, (if you are in the US of course.) Max's has current prices listed on their catalog.
Dude, it's not like I shipped $8 bucks in push rod seals across the pond. It was $1,000 bucks in parts that would've cost nearly double from my BMW FLAPS. Trust me, next time I need push rod seals and don't need cylinders and pistons, rings and bearing shells, etc. I'll be shopping locally. Peace. Love. Harmony.
Hiya, just insert my location, sort of. I'm in Singapore. I used to have a great relationship with Jason of Hammersley until they stopped the BMW bike parts business recently. Now it is not as easy to get US dealers to ship international. An order from Hammersley typically takes 3 to 6 weeks to get to me (I suspect based on parts availability), while Motobins takes about 7 to 10 days, great for getting urgent spares and parts. I do deal with US eBay sellers and other traders, like Joshua Buck and EUBMW. Motobins, however, does not carry all parts; for non-available parts I have to turn to the local overpriced BMW agent. :) Eh, noob here .. what is a "lifter"? Thanks for the tips, guys.
By lifters do you mean pushrods? I can see this turning out to be another good learning thread. I am a noob learning about my R80GS & although I ask my friendly mechanic lots of questions, they unfortunately don't have a spare airhead handy to show what things should look like. Is it possible for any of you experienced guys to post some pics of any bad looking lifters, valves, pistons, bores etc vs an used but still good condition ones? Pics are so much easier to comprehend than descriptions.
Good sealing rings will have uniform, dry carbon on the piston crown all the way to the edge and all the way around. A lot of pretty good sealing pistons have a little oil wash on the bottom. I use mostly chop sticks. I will very carefully use a wide bladed Exacto knife on a stubborn chunk. I don't use scouring pads. There is no need to remove the thin layer of carbon, just the cake. The only way to deal with worn ring grooves is to get new pistons. It's critical if you want to fix it. Rings seal on the cylinder wall but they also seal on the piston. A lot of people forget this fact.
No. I actually buy them specifically for shop use. I get good ones and sharpen them into this or that shape for this or that use. Wood is softer than metal!
