Top end rebuild

[greg the pole]

Greetings.

I finally caved and tore into my motor. Folks in the know, please chime in. High def. pics here: https://flic.kr/s/aHskQgPES5

The motor has 80k km on it. Original owner. Started using oil at 50k. Puffs blue off high throttle application. Not while on the throttle.

Comp check prior to tear down read (cyl 1/ cyl 2) dry: 62/70, with oil 72/88. Yam spec is 84-108 PSI. Bike uses 1L of oil every 2200-2500km. I didn't have a leak down tester, so didn't do that.

I haven't checked ring gap yet, will do it tomorrow, but they seem very loose, so likely not in spec.
Valves, guides and seal will need to looked at by someone competent. Will take the head to my buddy so we can pull the valves, check the valve guides, valves, springs. I will replace all valve seals, gaskets, both pistons, and rings. Yamaha says to replace the head studs. Should I bother, or reuse the old ones?
The bore looks spotless. It still has the cross marks in it from new.

Cylinder head update!!

Jan 14th 2014, head work is done.

Nothing shocking found on the head and cylinders.
Rings and scraper ring were done. Valve seals were hard and done as well. Otherwise, head, valve seats, valves, and guides were all perfect.
The pistons were basically brand new. Well within allowable. Ports were decent. Some casting marks, but nothing to write home about.

The parts list will be small.
I'm hoping I can use 2014 rings with the 2012 pistons. It be a shame to leave them on the shelf.
I've added pics to the flickr account.

https://www.flickr.com/gp/97730749@N03/743WiP

 

[Don in Lodi]

The head bolts/studs have a stretch tolerance built in. You need new to get that stretch tolerance back for the new torque application.

 

[greg the pole]

Thanks Don,

noted. Thoughts on the patient?

 

[Don in Lodi]

Valve guides/seals or ring(s). It's against the odds, but I've read that if the gap in the rings should all line up she'll consume oil, but you'll also get a whole bunch of blow by. (engine case pressure) All engines have some blow by, that's why they vent to the airbox/intake. A broken ring could score the cylinder wall enough to burn oil... and lower compression. Just oil consumption I'd see if some stem seals can be used. Low comp...

 

[Xt1200zsupertenere]

Sounds " to early " to be needing rebuilt ? What engineoil do you use ? ( if it can be the cause to early wear ? )
What airfilter ? Drive mutch dirt ? ( if leta in microscopic dust and get early valveseal wear ? )

Just thinking

 

[Harry Dresden PI]

On car engines I always did a compression test and if low, a leak down test before tear down to check where the leak was.

Also if it was burning heavy level of oil, have someone ride behind you and watch for when if any blue smoke was seen. Blue on acceleration means rings leak blue of deceleration means valve guides leak.

However given cat converters and how little you may be burning, perhaps none of the above are valid for the S10 motor.

Best of luck and thanks for posting

 

[EricV]

Your motor looks about like mine did when mine was torn down at 82k miles for the CCT failure. I had not been using any oil at that time. I think you're on track for what work you plan on doing.

As to cause... that's a sticky wicket at this point. My FJR starting using some oil and was running very rich on NO with low compression numbers, poor leak down numbers, etc at around 98k miles. Turned out that the root cause was the hose clamps from the air box to the TBs had been left loose by the tech that did the 78k valve check service, (yes, I know you don't need to remove the air box on an FJR to do that service, but they did due to a Jr tech w/o supervision). Anyway, running the bike in all conditions for 20k+ miles essentially sucked in so much dirty air that it prematurely wore the valve seats and rings. The bores were fine, looking as you describe, but it would have needed a full head job and rings/pistons. II opted for a low mile replacement motor and swapped that myself since Yamaha didn't want to give me any love under YES, which was still current at that time.

Funny thing was that during the period of use after the 78k service, the bike ran great, never any problems or indication of issues. I only took it to the shop at 98k because the CCT was getting noisy, (replacement #3), and they discovered the O2 sensor was bad, replaced that and tossed it on the exhaust gas analyzer, then discovered the NO readings way off. They even swapped the ECU, thinking that was an issue, before doing the comp test and leak down. Despite no one ever seeing early ring wear on an FJR, ring wear is specifically not covered by the YES, so no love.

You might cost out replacing the engine with a low mile unit from a wrecker Vs what it will cost for you to do the work to rebuild yours. The low mile replacement will have some advantages in that everything else will be low mile too.

 

[hogmolly]

Really looks like the oil loss is through the intake valves.

 

[RED CAT]

Holy crap Greg. Thats low milage for a Yamaha rebuild. You've got brass ones tackling that yourself. Best of luck and keep us posted.

 

[BWC]

The one thing that I noticed looking at your pics is the dark coating on the inside of the engine castings. So yes, it looks like it has had leakage by the rings for awhile causing blow by and darkening of the engine internals.
I think the parts list along with the cylinder head studs as mentioned would be the piston and ring assemblys from the 14+ model as it looks like these are listed as the parts to be used in our 12-13 bikes. When looking at the valve assembly's you might want to ask if there's any benifits to changing to the weaker exhaust valve springs that are used on the 14+.
Having said that, and pricing out all of the parts needed, as Eric mentioned it would be a good idea to see what's the price and availability of a used engine.
Good luck and let us know what you find.

 

[WJBertrand]

Looks like the bike has seen a lot of off-road use. I too would be interested in what oil was used, how often it was changed and what air filter was used. Good luck with the refresh.

 

[greg the pole]

Valve guides/seals or ring(s). It's against the odds, but I've read that if the gap in the rings should all line up she'll consume oil, but you'll also get a whole bunch of blow by. (engine case pressure) All engines have some blow by, that's why they vent to the airbox/intake. A broken ring could score the cylinder wall enough to burn oil... and lower compression. Just oil consumption I'd see if some stem seals can be used. Low comp...

I'll gap the rings today, and take the valves over to a mechanic friend for dis assembly and inspection. Make the parts list from there

 

[greg the pole]

Thanks for all the replies guys.

Things used on the bike:
Mineral oil for break in, then ams oil synthetic. I gave up on the synthetic at the 50k km mark, as it was using about a liter per 2500km.
Early on for about 30k I used a K and N. I later smartened up and went back to Yamaha OEM.

Bike sees 40% gravel and muck regularly.
Rather worryingly, I saw some dirt on the tb. Not sure how that got there but I'm fairly anal about clamps being tight etc.

Not sure if this is relevant, but the bike had a full arrow system installed at about 55k (no cat)

Good idea about the motor, but having one shipped from the states to Canada would be tricky and expensive. A quote from the local guys, including all vavles, springs, gaskets, pistons, rings, pins was under $1000 cdn. I need to factor in another $100 for a light hone, and if the valves need work.

 

[tomatocity]

Sorry to hear about engine. So after this you going to be faster 8^/

$1000 CDN is cheap.

I was one of the 2012 owners that had Carbon Buildup and a failed CCT at 52,200 miles. It went to the dealership with failed CCT and Yamaha tried to blame it on the carbon buildup. The carbon was bad enough that a couple of the valves wouldn't close all the way. Yamaha eventually gave the go to rebuild the engine because of the Failed CCT. The rebuild included from the crank up to the head. Because of time the head was built locally. That machine shop would not use most of the Yamaha parts. I rode it 60 miles before trading it in on a 2015 ES. The 2012 had NEVER run that well before and I almost did not want to trade it in. End results on the trade in... No regrets. I believe (and others) that the 2012 (USA) ECU is part of the problem. Yamaha wants me to ride in the 4500 - 5500 RPM range to keep the carbon from building up. Since then the dealership has found more stock 2012's showing carbon buildup as they gained mileage.

- Did you flash your ECU to match the Arrow exhaust?
- What RPM range do you ride? (I know you ride fast)
- What is the condition of your valve guides?
- Was there excessive carbon on the backside of the valves?

I noticed that one of your spark plugs was not indexed like the other three. I have not ever indexed spark plugs but have heard of it (years ago).

 

[1954]

Since these engines have a coating on the aluminum cylinder bores rather than cast iron or steel liners, honing would probably destroy the bores and result in even worse oil consumption. I think you need to invest in a shop manual and see what the rebuild instructions are.From what I can see , there is a huge amount of carbon buildup on the pistons. I think you need a new cylinder bore assembly(because to the best of my knowledge they cannot be bored over), pistons and rings and a head rebuild. I do not have much experience with bike engines other than old 2 strokes, but from my car engine experience that is what I would do. Getting a shop manual would give you the specific knowledge you need though.There may be other bolts in the engine that are mandatory replacement as well.

 

[yz454]

I have to say it , but it was ring buy pass , probably ams oil bad stuff . The giveaway is the burnt oil above the oil ring the scraper ring not doing it's job .
I think it was a ring seat problem early on . If you have carbon build on the back side of the intake valve then it's a seal or guide . And fix the intake and ex port mismatch and especially the ex . Did mine in the frame . That's what they did in the gen two heads .

 

[~TABASCO~]

Don't you just hate when you write a post, you then go do some homework and close the screens down and erase your post............. dang, just happened... lets now start all over..



Ill throw in my two cents...

From what I can see in the pictures I would clean the carbon from the heads, valves, pistons. The cir clips are cheep so I would pull the pistons and make sure everything looks good.. If this was my bike, after pulling and checking the valves I would lap them back into the seats and replace the rings and probably go down the road. (assuming I didn't find anything funky or needing to be replaced or extra attention.

I just checked on the rings, I could not find them available for 12/13, but for 14/15/16 they are about $15 a side... Also the pistons between gen I & gen II are different part numbers and so are the rings. The gen II are cheaper. I forgot if Gen II have a higher compression.. If you find that you want to throw in two new slugs maybe gen II will pop right in and save you money. They are about $50..

When you pulled the motor down did you check valve clearance before you pulled it all down ? If so will you share that info ? Have you checked the valves at the service intervals? I'm sure you have, just thinking.

The head studs are stretch bolts, ONLY to be used once.. have to get new ones.

Your cylinders look good from the pictures. I might clean the carbon ring around the top and set them aside..

(from only the pictures) it looks like garbage on your valve seats, and ring issues.. check the valve angle, make sure the valves don't have funky wear on them and the seats look good. If they look good, lap them and re install.

If you throw in new rings they will need to be gapped from Yamaha but its easy. Check and re check, file to spec of necessary.

 

[EricV]

Since it came up, and I've been down that road, the Gen I pistons come with rings. The Gen II pistons do not come with rings. So if you go with Gen II rings, you will need to order rings too.

I just stayed with Gen I pistons. Didn't want to find out the lighter pistons w/higher compression would cause issues, plus it was warranty work.

 

[~TABASCO~]

eric,

great info, thanks

 

[Don in Lodi]

There's pictures? LOL, I just looked. Those oil rings are seized. They should float free like the comp rings did. Good catch YZ454. That poor thing was digesting a bunch of oil... in both cylinders. How long did you run dinosaur before going synthetic?
The image that shows the cams, is that just a reflection or is there something off with the two lobes upper left...