One explanation for a problem I'm having with oily spark plugs and tail pipe (Sunbeam) in a newly rebuilt engine (600 miles so far) is that the rings have not bedded in and are not oil-tight. I had the cylinder bores deglazed during the rebuild but I have to admit to being rather gentle with the engine during the run-in period. The engine had new rings and the valve guides appeared good.
Is there a fix for the problem of glazed bores that does not involve having the bores deglazed and starting from scratch?
This answer will engage a lot of response, wait and see. I've been working on all kinds of cars and bikes all my life. 32 years to be precise. In 1955 when chevy came out with the 265 they had similar problems with rings seating. Now here was there fix without taking engine apart to deglaze. 1/2 a teaspoon of bon ami down sparkplug holes to rough up surface to seat rings. It worked then and it will work now. Yes I know I wasn't working on 55's when new but did that trick myself and a lot of old timers at the chevy dealership where I worked did it. 396's had a lot of those problems when new and it did the trick. There were even service bullitins from chevy confirming the procedure. Now, I have never tried it on a motorcycle but I don't see why it would not work. Just cut back on the bonami. Maybe a 1/4 teaspoon. Or de glaze cylinder and assemble dry with just a light coat of wd40 to ensure break in. Tom
Re: fix for glazed bores?#44296 09/19/051:41 am09/19/051:41 am
I've heard that from an older mechanic (now deceased) who did Rolls engines, Allison, etc. Just remember that the rings are frequently as soft as the walls, so even though the seal is improved the life span is reduced. I'm not sure an oil change will get it all out, and mineral particles are not what I want in my rod bearings.
Re: fix for glazed bores?#44298 09/19/0512:57 pm09/19/0512:57 pm
panic, how about running the engine "total oil loss" for a few minutes after warming it up normally to lube the top end? If you took out the drain plug and let the bon ami splash out the bottom, you could maybe get rid of the vast majority of it and the metal particles.
"Beer is proof that God loves us and wants us to be happy" - Benjamin Franklin
Re: fix for glazed bores?#44300 09/19/052:02 pm09/19/052:02 pm
Interesting - I never heard of using Bon-Ami for break in, but it reminds me of a break-in technique I read about on line a year of so ago. Essentially the idea was to get a new engine warm, then rev it to about red line under load in 2nd or 3rd for 4 or 5 times (forget the exact details). The proponent of this technique said that "easy" break in would cause the rings to never seat. It seemed a little radical to me but I have no experience one way or another. This guy had a web-site which advocated several non-standard ideas, such as "high velocity porting" whereby one made the port cross-section smaller then the valve diameter. Anyway, do any of you racers break in your engines this way?
Re: fix for glazed bores?#44301 09/19/055:15 pm09/19/055:15 pm
The reasoning behind the 2cnd and 3rd gear redline is to move the piston all the way to the top. When someone babies a break in for an extended period of time the first time they really do tach it out the top ring used to break from the ridge at the top of the cylinder.
Re: fix for glazed bores?#44302 09/20/0512:43 am09/20/0512:43 am
I would be interested to know what oil you used during the first 100 miles. Modern car engine oils have some super slick chemical additives that would not allow your rings to seat no matter how you rode it. In the USA these are found in oils rated by the American Protroleum Inst (API) for SG, SH, SJ, SK, SL, etc. You should find some oil rated for SC, SD, or SE for break-in. These will most likely be non-detergent oils for air compressors or other such.
SE was the very best you could get in 1970. That's more of a sign as to how far engine oils have come since these engines were designed and manufactured. Therefore your ring seating/ smoking is not a comment on your engine builder.
So try 500 miles on some low grade oil before doing something weird with abrasives through the carb.
Don't hide 'em, Ride 'em !!
RF Whatley Cornelia, GA
"Shop Boy" at Rodi British Bikes
Re: fix for glazed bores?#44304 09/20/052:54 pm09/20/052:54 pm
Good advice Redneck. If after 500 miles the smoking doesn't stop it is time to take it apart. I assume you used original grey cast iron rings, and not a modern steel or ductile iron ring (like Deves). Given that you have grey cast iron rings you must either use the SC-SE generation oil from the start or a dryer ring assembly technique: Every thing is oiled, except the cylinder is washed in hot soapy water and then the bore rubbed with a slightly oily rag. Then oil the thrust faces of the piston and leave the rings dry. Assemble motor, verify oil pressure, and run the bike up to 4 or 5,000 briskly in a couple of gears. Then break in as usual.
It is important to remember that grey cast iron rings require a 150 to 220 grit cylinder finish. They are not manufactured round at the factory and require a rather coarse cylinder finish to file the rings round. Using a finer grit stone, as used for ductile iron or steel rings, will almost insure the motor will smoke unless a lot of other details are covered.
It is possible to use a glaze breaker to prepare the cylinder for grey cast iron rings, but it is tricky. Unless it is done properly, and assembled with SC-SE oil, there is a good chance the motor will smoke. This would not be my first choice, but if the customer insisted I would explain that it might not work and he would be responsible for doing it again if the rings didn't seat.
The typical stone used for these rings is an Sunnen AN220 which will give you a 150 to 220 grit depending whether you do it dry or wet. 30 years ago these stones were marked as FINISHING. Today the box is marked ROUGHING. You would never use an AN220 stone for a ductile or steel ring.
If I did the motor, and it smoked, I would fix it... I don't think it is unreasonable to expect that the motor will not burn oil - meaning smoke (you can expect to use a quart every 800 to a 1000 miles ) All this stuff isn't magic... talk to you engine builder. Bonami, in my opinion is for people who are lazy or don't know how to do it right in the first place. john
Re: fix for glazed bores?#44305 09/22/055:33 am09/22/055:33 am
I have heard of the Bon-Ami procedure but the pots on a Douglas are presumably easy to remove ?
We have bore glazing problems with diesels fitted to fire pumps, they go straight to full fuel from cold and no load unless you can return a bunch of pump flow back to a storage tank, centrifugal pumps suck most horespower at high flows.
Generally a hard run against lots of load for 45 minutes to an hour cleans up the exhaust smoke, I would warm the Dougie up on hot plugs, change 'em quick and then flog the engine hard.
My diesel fitter, who is a pretty smart bloke, reckons that they never come back 100% but much cheaper than an engine strip.
1969 TR6R 7.62 x 51 is not a maths puzzle.
Re: fix for glazed bores?#44306 09/22/058:11 am09/22/058:11 am
In answer to your question Sid, I believe most racers do run-up their engines very early on in their life. In fact the first time many race engines are run on a paved surface after a rebuild is on the race track.
In my case, as a humble Proddie racer, I had intended to do about 100-200 miles or so on the road before racing my Triumph, after doing a recent rebuild, including rebore and new pistons. However this plan came to naught due to several unanticipated problems including one of the cylinder stud hole threads stripping out.
I had installed MAP pistons that have steel rings. As the rings are steel the bore was originally finished to 400 grit and platuae (spelling) honed. However, after one of the subsequent strip-downs during which time I installed gapless rings in the second groove, decided to rough the bore up a bit with a a store-bought hone. Then took the bike for a brief 10 mile ride running it up to about 5500rpm before setting-off on the long 15 hour drive to the Sandia AHRMA event.
At the track, kind of took it relatively easy for a couple of laps in practice allowing th bike to rev freely, before opening the throttle wide. From then on it was flatout reving to 7000 or so. Compression remained great and no smoking according to a couple of the spectators. They also told me that it sounded great.
One thing I maybe should mention is that Sandia is a short track with short straights (only got up to 82mph max). Maybe on a longer track I might have experienced problems. Anyway, now believe that my Triumph is well and truly broken-in after about60 miles or so of hard track time.
BTW Bore clearance is 0.055" compared with 0.042" called-out by the manual.
P.S. I believe that it is generally accepted practice nowadays that the inlet port dia just upstream of the port opening into the cyclinder should be about 80% of the valve diameter.
Re: fix for glazed bores?#44307 09/22/0511:51 am09/22/0511:51 am
Chrysler's instructions for non-warranteed drag race cars used to read: Preparation 1. Start engine and bring water temperature up to 160 degrees rapidly, do not permit engine to idle 2. Make 1 full-throttle pass shifting at 4000 RPM. 3. Make 1 full-throttle pass shifting at 5000 RPM. 4. Make 1 full-throttle pass shifting at 6000 RPM. 5. Race car.
Re: fix for glazed bores?#44308 09/22/0511:52 am09/22/0511:52 am
As far as I remember I used 50 weight non-detergent oil for the first 250 miles after the rebuild of the Sunbeam. One thing I didn't mention is that although the plugs looked oil-fouled rather than gas-fouled, and the tail pipe gets a coating of black oily stuff, there is no indication of any smoke production, either white, black or blue.
I would not fancy bon ami down my bores why not try an Italian tune up its amazing how often it improves running when a bike has been having an easy life. Does the bike start easily.If it does"nt smoke there cannot be much wrong.A good neck wringing may cure the problem
Re: fix for glazed bores?#44312 01/19/0812:59 am01/19/0812:59 am
Ajax, Bon ami or spic & span? I've tried a lot of things but putting powdered abrasives in a non-cage vehicle is sounding darn near torture like! I have seen HD guys pull the head and use a can with a cloth wrapped by 400 grit de-glaze in an afternoon so there should be no risk of sediment that way. A very agresssive revving ride may also help change the surface finish? Bikes snorting powder through carbs? sounds like a TV series sketch. Takes my single 300-500 miles before the rings bed in, I rev full out after 200 or so and downshift brake after 300-400 say.
The 441, most versatile BSA of the 60's
Re: fix for glazed bores?#44313 01/19/084:50 am01/19/084:50 am
Deglaze with a 220 hone THEN fifteen seconds with a Brush hone, 220 grit and soapy water, clockwise, reverse the drill and fifteen seconds with soapy water counterclockwise. Wipe clean and refit immediately, no lube. Clean piston and rings, fit with compression end gaps 180 degrees apart, oil gap at 90 degrees, no end gaps in line with thrust or with wrist pin. Dry start, blip the throttle to fifty percent of redline. Don't run more than thirty seconds with fans on fins. Repeat and this time blip several times to seventy five percent of redline for another thirty seconds. Repeat with a couple of full rpm blasts. By now, oil will be finding it's way into the bores. Start life with a good synthetic, that kukai about it not letting the rings bed is certainly a load. I have NEVER had an engine, and I have done a bunch, not seat properly except in the case of one where the owner insisted on GTX and keeping the chrome rings of his big bore kit. I pulled it down, put in iron rings and Mobil One, and all was well. Run the bike with vigor, but keep it cool and don't lug it. Slightly rich is better than lean. I currently am using Royal Purple 10w-30 and don't see any reason to change, although I am open to better oil whenever it comes along.