A young S10 owner

jwrands

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Jan 6, 2021
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35
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San Luis Obispo, CA
I bought my S10 two years ago for some serious adventure touring after graduating college. Been enjoying the bike and taking some long trips. Finally decided to join the forum after deciding it was time for me to rebuild my engine. I'm impressed with the extensive knowledge and history many members have with this bike. I hope I can contribute some value to the knowledge base here.
 

tntmo

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Welcome to the forum. I wish you luck on the rebuild.

I'm curious as to the cost of items to get the engine back up to OEM specs. If it was using oil, are the cylinders still good or do they need to be replaced or re-plated? Are the big end rod bearings and crank in good shape after being run low on oil? Things could add up quickly, to the point that a used bike is a cheaper option. Or maybe not, I haven't priced out any of that stuff.

Looking forward to what you find and a breakdown on repair costs.
 

EricV

Riding, farkling, riding...
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The cylinder bores are ceramic coated, you won't be boring those out, or likely need to. At 90k that wear is insignificant to the bores. Almost certainly you were using oil because of valve issues. Either out of spec, build up of carbon deposits, which is common in the Gen I bikes, or simply high rpm use a lot. Sustained running over 5k rpms on a Gen I tends to use some oil. It's blow by and some of it ends up in the air box. This is normal, not wear or indication of wear.

Unless the ring groove in the pistons has a lot of wear, just a set of rings and clean up the valve train and you're done. Anything else that isn't damage repair is wasting the money and time, IMHO.

I had my '12 apart at 83k miles due to a CCT failure. The bores were beautiful, but they wanted to replace the rings. Gen I rings are not a separate item, so you order pistons and get rings too or change to Gen II pistons and Gen II rings. Gen II rings are a separate part number, btw. I had one damaged piston and two damaged valves, fwiw.
 

jwrands

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Jan 6, 2021
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Location
San Luis Obispo, CA
Thanks for the warm welcome! I probably should have posted about my situation before tearing into the engine...

The cost in parts was about $1000, which included Gen II pistons, all bottom end plane bearings, some really expensive bolts, new clutch pack, and associated gaskets.
I ordered several parts direct from Japan which were on backorder in the US.

As Eric suggested, I think most of my problems were coming from the cylinder head, but I opted to replace everything to cover all the bases.

I took photos and video of everything, with the intention of making a write-up and video of the process.

I was really close to jumping ship and getting an Africa Twin halfway through the project, but I stuck it out and here I am.
 
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jwrands

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Jan 6, 2021
Messages
35
Location
San Luis Obispo, CA
I was burning about 1 L of oil per 1000 mi. I was surprised to find the pistons, rings, and cylinder to all be in spec despite the oil consumption. The valve seals looked OK, so I'd be surprised if that much oil was coming from the top. So how is the oil getting into the combustion chamber? Is it simply bad ring design on Gen I?

As you might guess, I had major carbon build up in the CC. I made the controversial decision of lapping the valves to clean up the seats. Ended up grinding away significant material from the valve seats and faces. In hindsight I probably should have taken it to a machine shop to get it done right, but it seems to have worked out OK. Haven't done enough riding on the rebuild yet to know if any of the problems I was having have been resolved.
 

Checkswrecks

Ungenear to broked stuff
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I was burning about 1 L of oil per 1000 mi. I was surprised to find the pistons, rings, and cylinder to all be in spec despite the oil consumption. The valve seals looked OK, so I'd be surprised if that much oil was coming from the top. So how is the oil getting into the combustion chamber? Is it simply bad ring design on Gen I?

As you might guess, I had major carbon build up in the CC. I made the controversial decision of lapping the valves to clean up the seats. Ended up grinding away significant material from the valve seats and faces. In hindsight I probably should have taken it to a machine shop to get it done right, but it seems to have worked out OK. Haven't done enough riding on the rebuild yet to know if any of the problems I was having have been resolved.
Two key questions:
Did you actually run out of oil?
Did you find damage resulting from low oil?

These are very different than just experiencing high oil consumption on a Tenere. The A-#1 most common reason owners feel they are experiencing high oil consumption - which can lead to major carbon build-up - is to trust the oil sight glass and overfill the oil. There are numerous threads around here on how to have the right amount of oil AND about how misleading the sight glass is.
 

Cycledude

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Jan 29, 2016
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Rib lake wi
I was burning about 1 L of oil per 1000 mi. I was surprised to find the pistons, rings, and cylinder to all be in spec despite the oil consumption. The valve seals looked OK, so I'd be surprised if that much oil was coming from the top. So how is the oil getting into the combustion chamber? Is it simply bad ring design on Gen I?

As you might guess, I had major carbon build up in the CC. I made the controversial decision of lapping the valves to clean up the seats. Ended up grinding away significant material from the valve seats and faces. In hindsight I probably should have taken it to a machine shop to get it done right, but it seems to have worked out OK. Haven't done enough riding on the rebuild yet to know if any of the problems I was having have been resolved.
very interesting read, never noticed any oil consumption in 50,000 miles on my previous 2013, many folks are perfectly comfortable over filling the oil but I won’t do that.
I am a firm believer in occasionally using a little Marvel Mystery Oil in the gas to remove-prevent carbon build up and keep things clean.
seems most folks love the S10 engine but I’m really not that fond of it, to me it seems like a much smoother 3 or 4 cylinder might have been a better choice.
 

StefanOnHisS10

Converting fuel into heat, noise and a bit motion
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Welcome jwrands, I am very surprised you need to do a rebuild at those miles. The darn thing is nearly bulletproof.
But thanks for sharing it here, we all can lean from your rebuild. You found nothing out of spec??

Stefan.
 

jwrands

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Jan 6, 2021
Messages
35
Location
San Luis Obispo, CA
Did you actually run out of oil?
Yes, after I cracked the oil pan, and had to ride out to get service.
Did you find damage resulting from low oil?
I saw significant particle streaks on the big end bearings, and light scoring on the journals. Not enough wear to take the bearing clearances out of spec. I assume this was from the no oil condition.
These are very different than just experiencing high oil consumption on a Tenere. The A-#1 most common reason owners feel they are experiencing high oil consumption - which can lead to major carbon build-up - is to trust the oil sight glass and overfill the oil. There are numerous threads around here on how to have the right amount of oil AND about how misleading the sight glass is.
I use the procedure in the manual for checking the oil level. I know it was burning oil because I ran it until the oil light came on. I will take a look at those threads again.
 
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