The New And Improved Unofficial R65 Forum V2
Technical Discussion => BMW Technical Q&A, Primarily R65 => Topic started by: azcycle on May 13, 2010, 10:36:43 PM
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I've gotten myself thoroughly confused trying to adjust the valves this evening. Help!
Right cylinder, bike in 5th, and I have a straw in the spark plug hole to help me gauge when the cylinder is at the top. I rotate the wheel and the intake opens and closes... rotate and the exhaust valve opens and closes....
Now when I come BACK to the intake there seems to be a lot of pressure. Is THAT TDC? The straw seems to be at the top, but the intake rocker arm has a ton of play in it...I can wiggle it up and down.
Are both intake and exhaust rocker arms supposed to be snug before I adjust... no looseness or play?
When I continue to turn, there is a sudden movement, the intake opens and closes really quickly, and then I'm back to the exhaust.
Just not sure exactly where TDC is.
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TAke the rubber timing plug cover off the left side engine case by the clutch housing bell. The flywheel is visible through the hole. a SMALL bit of metal on the outer edge of the flywheel will have some stamped marks in it. We usually put a bit of white paint on them and wipe it off before it dries - to leave the white paint in the recesses of the letters to make them more visible. There will be (3) letters/marks somewhat close to each other as far as distance along the circumference goes. There is an "OT" mark that indicates TDC. A short distance from this is an "S" mark which is the timing mark that should be centered in the hole when the bike is idling at ~1000 RPM - this is about 6 degress before TDC. There is a "Z" mark which is about 26 degrees further which is the full advance point (@3500 RPM). When the OT is visible in the timing window, the engine is at top dead center, but one cylinder is on the compression stroke and the other is on the exhaust stroke. The side that is on the compression stroke will have both valves closed at this point, and there should be a gap between the ends of the pushrods and the rocker arms. There will be no tension/pressure on the pushrods and you should be able to move the rockers (at least enough to take up any gap to the pushrods). It is under this condition that you set the gap for the valves. If the valves on one side aren't both closed with some play in the rockers when the OT comes up in the window, then that cylinder is likely on the exhaust stroke and the opposite cylinder is on the compression stroke -> turn the engine some more until the one you're interested in comes up on compression stroke (or just take both valve covers off and go to whichever side is on the compression stroke, adjust as necessary, turn engine some more until TDC and other side is on compression and adjust it). After I adjust both sides I manually turn the engine through a couple more times to recheck my work - you also
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Graeme,
It may be easier to remove the spark plugs. Near your dipstick you'll find a black rubber plug. Remove it, this is your window to the flywheel markings that will show you where TDC is by a stamped tab with "OT" on it. Bump the wheel until you see the intake valve close, continue bumping the wheel until you just see the exhaust valve start to open. Bump the wheel in the opposite direction and peek through the hole you uncovered. You want the OT punch or line (which ever you might have) centered straight through the window. This should be TDC. Adjust valves for that cylinder and repeat the procedure for the other cylinder. Here's a picture of what you want to see.
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Rather than do it this way, with the straw, pop the little rubber bung off the bell housing on the left side and shine a light in there.
As you rotate the rear wheel, there are two tabs that will go by the hole in rapid succession. The first has a hash mark with a Z -- this is full advance. The second has a hash and an S below a hash and OT. The S is full retard. OT is top dead center.
When you position the motor so that the hash mark above OT points to the witness mark on the left side of the hole, one side of the motor will be at the top of the compression stroke and the other will be at the top of the exhaust stroke. The valves on the compression stroke must be closed, so if they're set right, their rockers will both wiggle some. The valves on the exhaust stroke should both be at least partially open, and the rockers will be tight.
Your description sounds like you're rotating the rear wheel too quickly. There is time for two strokes between the intake closing and the exhaust opening. However, after the exhaust opens, the intake will open before the exhaust closes (this is what's called overlap -- as the last of the exhaust is being pushed out of the cylinder, it begins to pull fresh charge in from the intake).
I just set the valves on my bike yesterday, using the method above. In 5th gear, you only need to turn the rear wheel about a quarter turn to go through all four strokes.
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The straw in the sparkplug hole will help you tell when you are getting close, but if things have somehow gotten very much out of wack and the gap between both pushrods and rockers has closed up to nil, you need to go by the "OT" mark centered in the timing hole to make sure that you're on the button. Again, the TDC on compression side should have looseness in both intake and exhaust pushrod/rockers.
I only put the bike in 2nd or 3rd gear so I can more easily "creep" up on TDC - in 5th gear it is too easy to shoot right past it. And DO take both sparkplugs out to make things easier to turn.
NICE PIC, Mike V!
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Thanks for the photos... they helped. Spark plugs had been removed. Cracked open the timing cover plug, rotated the engine until I saw OT, and measured what I had done on the right cylinder. Turns out I did it right. :)
My problem was that I loosened the intake rocker adjusting nut so much so it had a ton of slack in it, and I couldn't figure out why. But I just tightened the adjusting nut and it snugged up perfectly. Measured intake .002 and exhaust .008, double-checked and I think I'm good.
Will do the left side tomorrow.
And have to buy some valve cover gaskets, as the right one tore when I removed the cover. >:(
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The intake should be .004".
And have to buy some valve cover gaskets, as the right one tore when I removed the cover.
Par for the course. The center stud came out with one of the nuts on mine, and I had a hard time getting the nut off the stud. If the gasket isn't too bad, you can turn it with the torn part up and use it temporarily. Using a bit of goop in the tear could help as well, but you shouldn't need any on the sealing surfaces.
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+1 The intakes should be at .004 inches.
Once you get new gaskets they should last you for years. Note carefully how they go on (there is a "top" and "bottom"). you will want to put them on so that they tend to stick on the head in proper position - not come off with the valve cover.
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Right! 0.004-Intake and 0.008-Exhaust will have your scoot making nice BMW music.
Monte
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Ah, .004 intake... got it.
Okay, so plugs! These plugs are OLD. That being said, the right plug looked perfect... nice and tan, perfect. However, left plug was in okay shape: Tan with some carbon deposit and the insulator has just a TINY bit of blistering on it, as does the electrode down near the base.
So, what do you all think? Go with the same plug (NGK BP7ES) and take a look after a bit of running with the new valve clearances?
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Sheesh and I've been using .006" on the intake since 1993. Must be the older bike... :o
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I'm using .006" intake and .008" exhaust on my "new" 81 R65 top end. I'm thinking I may want to open the exhaust to .010" until after break-in. Then what? The owners manual states .002 intake and .008 exhaust. Man, .002" intake seems tight to me. I'm kind of glad this subject came up. What are you guys using as a safe operating range with a broken-in motor?
I have the new lead free conversion valve seats and Swiss-made valves.
-Mike V. / 650 newby
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.002" intake seems tight to me.
BMW originally specified intakes at .002" and in a later service bulletin increased it to .004". I think you can also find .006" in print some place.
Service bulletin attached
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Barry, I think one of the guru's instructed .004" Iintake and .008" Exhaust for the 650, that seems like a good formula to me for a broken-in motor. I currently have the valves set at .006" and .008" but I may want to open the exhaust a bit for a few hundred miles.
Sorry AZ, don't mean to step on your topic here. Just curious what you guys are comfortable with and what works best...Barry, Bob, Rob, Monte, Semper, et.al.?
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I might try it at .004" and see if there is any difference in sound/performance.
The tighter the valve lash the more advance the valve opening. What effect this has on engine tune is beyond my pay grade -- but there will be an effect.
Other thing is what is good for the Goose (1981 light flighwheel R65) might not be good for the Gander (pre-1981 heavy flywheel R65)
(paging a German engine dynamics engineer who speaks english)
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When I had the heads reworked around 40,000 miles ago, San Jose BMW installed I think, stainless steel valves, they recommended a larger valve clearance, I think it was .008 in. for intake and .010 in. for exhaust, I'll have to find the paperwork that came with the heads to be sure I'm right .
So my settings aren't valid for other valve types .
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Mike: No harm done... in fact I'm learning a lot, so ya'll just keep chatting.
Oh, and whether by accident or on purpose the guy at Iron Horse BMW only charged me for one valve cover gasket. :D
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Mike, just to be awkward I set mine at .005" and .009" and notice no increase in noise level. Snowbum advises slightly larger clearances for R45/R65 models compared to other airheads but doesn't say why which is a shame because I'd like to understand his reasoning.
BTW I added the service bulletin PDF on valve clearances to my earlier post.
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Thanks for the Service Bulletin. Probably should go in the Tech section - eh wot Justin?
Barry - Why don't you send The Snowbum an e-mail. He might answer!
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The tighter the valve lash the more advance the valve opening.What effect this has on engine tune is beyond my pay grade -- but there will be an effect.
You got me thinking Bill.
The most important aspect of cam timing is when the intake valve closes which determines how much valve overlap there is with the exhaust valve. Larger clearances close the intake valve early and the cylinder builds more pressure because there is less valve overlap. This improves power at low revs. If you close it later you have more valve overlap but the engine will breath better higher up in the rev range. The amount of valve overlap is said to determine at what revs the engine "comes on song". How much difference a few thou makes I don't know probably not much but in principle larger clearances - more tractable and efficiency at low revs and tighter clearances better performance at high revs.
As an aside the R60\series airhead is notorious for pinging because it has modest low overlap valve timing compared to other models. This results in a higher effective compression ratio at low revs hence it's more prone to pinging on modern fuel even compared to other engines of the same nominal compression ratio
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Barry, awesome. I just realized your attachment after your reminder. Thank you. That's another link I have in my favorites I always forget to refer to; the SB's.
I think I'll open the exhaust to 0.010" for break-in then run them at .004" intake and .008" exhaust after a few hundred miles checking them often.
Good info here guys, thanks.
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Barry - Why don't you send The Snowbum an e-mail.He might answer!
I might just pluck up the courage to ask about this on the airheads list one day. Perhaps I should come up with a plausable theory first.
I also have 3 other service bulletins I can post if wanted :-
Clutch adjustment
The front wheel recall (not applicable to us)
pre-delivery inspection
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Wow. I don't have the owners manual for my bike, I'm just going by what I found in the Haynes book, which I've also been using for my R90S. Haynes just says .004 and .008 for all Airheads.
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I'm with you Darryl, that sounds like a healthy and safe combination. Even though I've experimented with my /7 I've been tempted to decrease rocker gap to get rid of noise but as soon as I adjusted the rocker axial play the noise went away completely. Not so much an issue with the 81 R65.
Been riding that R52? Gawd what a beauty!
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OK, I was just gonna leave it alone but what the heck...
Overly loose valve valve lash settings can hammer the crap outta the valve stems. And obviously, yes, larger lash settings do alter performance at different rev ranges. The bigger gap also permits the valve to remain on the seat for just a nano second longer thereby transferring additional heat from the valve to the head and away.
I do believe the 0.004" and 0.008" settings to be a good all-around choice for the R65.
As for Mike V's engine break-in period, I'd suggest not opening up the gap but instead check the valve lash frequently until the engines is 'settled'.
Monte
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As for Mike V's engine break-in period, I'd suggest not opening up the gap but instead check the valve lash frequently until the engines is 'settled'.
Jump on in Monte! Interesting suggestion. I mean we're talking about ±.002". I may just leave it as is for 50 or so miles as you suggest and check often.
Ok az...back to the original scheduled program thread.
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I have been running mine at .005 and .009, I think that it might be slightly noisier but have not observed any issues with power or pinging - engine seems pretty happy and pulls well. My primary reason was to increase the time for heat transfer from valves-to-seat as I'm still running the original valves &seats. With newer replacement seats&valves I'd go back to stock settings. I might still consider going back to .004/.008 if the tap-tapping gets any louder, thouch I definitely did improve things in that area by snugging up the axial play in the rocker support blocks.
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I'm with you Darryl, that sounds like a healthy and safe combination. Even though I've experimented with my /7 I've been tempted to decrease rocker gap to get rid of noise but as soon as I adjusted the rocker axial play the noise went away completely. Not so much an issue with the 81 R65.
Been riding that R52? Gawd what a beauty!
Actually, I took the R52 out for a ride last week, with a friend riding the R51/3 along with. Did about a 60 mile loop out to the Corralitos Smokehouse to buy some sausage, and then back along the Monterey Bay. That's a lot of work on a hand shift, no twist grip machine with 3 thumb levers to manipulate. We also had the R60/2 out for a putt.
But I've put a couple hundred on the Free Bike (the R65) since rebuilding the forks, again -- had to helicoil the drain plug on the left side and put new caps and felts on. When I got it apart, I had rubber chunks with goop on the damper feet, so I needed new rubber donuts. Then I did an oil change and valve adjust, which leads me to this thread.
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Not to divert attention from this thread again but...you have one of the most impressive stables I've seen, dripping with envy and wondering if you charge admission for visitation rights. Your collection is a brilliant display of time and beauty. Searching for my next restoration project...
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Hey Barry,
I suspect Valve lash has to do with the camshaft installed on the bike. On Map Cycles catalog they list a bunch of different camshafts from stock to racing for Triumphs and BSA's that list different lash for each cam.
Did the camshaft change from the 1980 and earlier to the 1981 and later bikes?
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Update.... valves adjusted (they were all very tight) and new plugs installed. Wow, what a difference!
However, now she seems to idle a bit high. I don't have a tachometer (do have a Crafstman "engine analyzer" that has one.) So I'll hook it up and see what rpm she's revving at.
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Did the camshaft change from the 1980 and earlier to the 1981 and later bikes?
No I don't believe it did which makes it all the more curious why BMW kept changing recommended clearances.
Just to summarize what I've seen in print:-
78 -80 owners manual inlet .004" Ex .006"
81 owners manual inlet .002" Ex .008"
Mar 82 Service bulletin inlet .004" Ex .008"