Engine smoking left side only

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Snakeoil
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Re: Engine smoking left side only

Post by Snakeoil » Wed Sep 18, 2019 7:35 pm

First, agree with pretty much all that has been said. When you said no smoke at idle or revving, my first thought was rings. If bad guides, you'll fog the car behind you when you take off after idling.

My guess is your new rings never seated. End gap is not believed to be as critical as it once was. Hastings supports that theory.

How did you break in the new rings? If you started up the bike, let it idle while you tinkered with carb tuning and other stuff, that probably was the cuprit in the rings not seating. I'm a firm believer of hammering the engine on the first start. I actually suit up, and as soon as it fires up, I'm down the road hitting redline in every gear. Rings always seat. Only had one set not seat and am convinced it was a mechanical issue. Either the rings were not round (had polished high spots on both compression rings and other areas that never seemed to touch) or the jugs were not round. My shop put the hone in the jugs and only took off a few tenths. The rings were Riken and my shop ordered a new set of Hastings rings and GAVE them to me. So, I suspect they were wondering if they had screwed up, too. Engine was a T120R Triumph. New rings seated perfectly.

You did not happen to use synthetic oil for your break-in oil, did you? I know of one instance where syn oil prevented proper seating. It is very slippery stuff and has great film qualities. Happened to a good friend who is 50 years in the business and probably rebuilt more air cooled motorcycle engines than all the members here combined have owned. Engine was a Trident and the rings were also Riken. And they also looked just like mine with polished high spots. We use the same machine shop. Break-in oil should be straight weight, cheap oil because you will dump it after the first 100 miles or so. Some engine builders say sooner.

Yes, you can try to run a hone, a GOOD hone, not one of those Kmart POS ball hones, thru the bore and put in a new set of namebrand rings. Call Terry Crawford, I got my 650 rings from him. If it were my engine, I'd take the jugs to a proper machine shop and ask them to put it in their honing machine and take off as little as possible. And yes, a 180 grit stone would do the trick.

I would be interested to see what your rings look like when you get the jugs apart.
Regards,
Rob
Proud member of the Peanut Gallery
2000 Ural Tourist
40 Pilots, 122 Mains
Before you say something stupid, always ask yourself, "What would Harpo say?".

URALNUT60
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Re: Engine smoking left side only

Post by URALNUT60 » Thu Sep 19, 2019 9:32 am

Thank you for your input Snakeoil, machine shop did my cylinders, 20-50 4 stroke castrol or valvoline whatever is available no synthetic, upon start up checked timing with light, maybe guilty of babying the first 200 miles, will carefully inspect rings, have a cross hatch done at machine shop, will close end gap to whatever .004× cylinder bore on 1st ring, .0045× cylinder bore on 2nd ring, Cayetech says he runs his oil control ring at .006-.008, I will run it harder this time forcing the rings outward to seal

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Lmo
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Re: Engine smoking left side only

Post by Lmo » Thu Sep 19, 2019 12:35 pm

My R75/5 top end job was assembled with no lubricant, per Butler & Smith specs.
Lew Morris
Dnepr w/ '06 Ural Drive Train
C5 Power Arc
125/42 jets
Drilled slides/
.030" shims

1973 BMW R75/5 (original owner)
1947 HD FL (long gone, forever regretful)

URALNUT60
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Re: Engine smoking left side only

Post by URALNUT60 » Thu Sep 19, 2019 4:57 pm

Guy up in Michigan builds British bikes and turns his cylinders upside down and sprays WD 40 lightly leaves pistons and rings dry

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Snakeoil
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Re: Engine smoking left side only

Post by Snakeoil » Thu Sep 19, 2019 6:39 pm

Yup, I agree. No lube on rings. I rub some oil on the piston skirts with my fingers. After scrubbing the cylinders with hot soapy water and a brush, I dry and then rub motor oil on the cylinders to prevent flash rust since the motor will probably not run immediately, followed by several dry wipes with paper towels. I basically scrub the walls with dry paper towels to remove as much oil as possible. Essentially, the only oil remaining on the cylinder walls is probably at the molecular level. Oiling the jugs is probably not necessary in a commercial shop where the engine will get built and started within 24 hours in most cases.
Regards,
Rob
Proud member of the Peanut Gallery
2000 Ural Tourist
40 Pilots, 122 Mains
Before you say something stupid, always ask yourself, "What would Harpo say?".

URALNUT60
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Re: Engine smoking left side only

Post by URALNUT60 » Sun Sep 29, 2019 10:43 am

Disassembled motor this morning, Both pistons had light gaulding both pistons, facing up and underside of both sides, w@$#ed cylinders and smooth, will take to machine shop to clean up any glazing, to better understand reason for gaulding/ overheating was broken ring on both sides, being oil ring gapped at .030 instead of .006 that may have caused this? Lack of lubrication? All input appreciated! New end gap settings will be 1st comp ring 3.073×.004= .0122 2nd comp ring 3.073×.005=.0153 oil ring .006 will remove pistons to inspect and scotchbrite

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Tomcatfixer
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Re: Engine smoking left side only

Post by Tomcatfixer » Sun Sep 29, 2019 3:53 pm

Scratches on the upper and lower piston skirts are not unusual. Looking forward to seeing images.
- Chad

Gordonsville, Virginia, USA

Current rides:
2015 Ural cT "Mobile Chernobyl", 2001 Ural Patrol "Little Red Bear", 1999 Ural Tourist "The RPOC", Mid-Nineties Ural Tourist "The Heap", 1994 Honda VFR750F

Previous rides:
2007 Honda VTR1000 FireStorm (Super Hawk in U.S.)
2001 Buell Blast! - - - - - - - 2005 Yamaha FJR1300
1993 Honda CBR600F2 - -1984 Yamaha FJ1100
Two different 1986 Yamaha FZX700S Fazers

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