So I picked up a 86' k100rs from a retired college professor for 250. I was shocked at the price so I proceeded to ask what was wrong with it. First off no title, bummer but that's okay, then he said other than that nothing. Was running before he started the dismantling process before covid happened and he shelfed the project when he got to electrical because it was too complicated for him. The bike was his brother's from PA  and he drove it to his house in Princeton in 2020 before half getting it to a scrambler. 

Fast forward 3 years I purchase said bike with plans on making it into a cafe. I am excited tearing it down in preparation for repaint since I don't trust said professor used the right kind of paint and want to replace the hardware and gaskets with all new or at least clean what I can. Everything comes off, everything looks good till I get to the crank case and find a very tragic site, at least that's what I currently am thinking. There was no fluid in the bike for god knows how long, there was a mouse making my engine it's living room. Definitely wont be giving this dude a cookie... So my question is, what the hell do I do? I am already out of my dept here just reading and researching what I can do get this bike to where I want and now I guess I have to tear apart and rebuild the engine? Any advice would be appreciated 

https://i.servimg.com/u/f60/20/56/25/21/img_5310.jpg

There, I made the image visible for you. It does not look good. A teardown and thorough inspection is in order.


It's '86, not 86', BTW. You're removing the 19 to make the contraction, so the apostrophe goes before the numbers to indicate removal. Otherwise you're describing an 86' (foot long) K100RS. A too common mistake that many make.

Two Wheels Better wrote:
There, I made the image visible for you. It does not look good. A teardown and thorough inspection is in order.


It's '86, not 86', BTW. You're removing the 19 to make the contraction, so the apostrophe goes before the numbers to indicate removal. Otherwise you're describing an 86' (foot long) K100RS. A too common mistake that many make.

Thank you! Appreciate the knowledge.

These engines are quite robust, and as long as it was not submerged in flood water, might only require a look-see & clean up to rectify the rust & corrosion issue. It could be a fun project, and it would seem you have not invested a lot of dosh into it so far. I say let it live!

I think I am gonna try and give it a go, I have the manual and if I can come across someone else doing it I think I will be in good shape. I was told as long as there is not much pitting I might be okay 

Ballzac

I do feel your disappointment.
You never know what you've bought until tearing it apart.

My Ecomobile has the third engine right now. Here's the story:

As I bought it, I was the third owner and the service history of the vehicle was unknown. The original engine was running fine, but guzzling engine oil like a two stroke engine. It was decided to have it replaced, as the costs of rebuilding would very probably be higher than a used second hand one.

The second engine had a damaged crankshaft and worn crankshaft bearings. I've bought that one second hand from the internet. The seller was unknown to me and I only found out after having it installed and running. That one was replaced as well.

The actual engine is w/o any fault and running strong. It was bought second hand as well, but from a very reliable source.

So my advice is:
Maybe buying and installing a used engine from a reliable source could save you the trouble and costs of having this one torn apart and being rebuilt.

PS
Unless you do have the knowledge and possibilities to do the job yourself. That would be a different story then.

It's a bit of a toss-up really - as long as you don't use a double-headed nickel. A known working engine from a reputable breakers could actually cost less than rebuilding that one. I'd want to inspect the camshaft, cylinders and big-end bearings before making a final decision. Rust in the cylinders would make me start to think seriously about looking for another engine. So, in order I'd

- check the camshaft for pitting and rust. Get a manual and check the cam follower gaps before pulling the camshaft
- if the camshaft is okay, pull the cylinder head and check the bores. One of them camera thingies you poke into dark corners isn't going to give enough information, even if it is a colour one (full disclosure: I have a high-end Bosch one with a colour camera and it's bloody useless for looking down cylinders unless there's a sodding great hole in the piston)
- if the bores are okay, check the big-end journals

If the journals are okay, start adding up the cost of new parts. At the very least you will need:

- a full gasket set
- a new set of big-end bolts (do NOT reuse the old ones because they are a stretch-fit)
- possibly all of the engine rubber parts (inlet rubbers, manifold rubbers, crankcase breather hose)
- air filter. Bet the mouse has had a high old time making a nest from that
- if you took the gearbox off and didn't secure the clutch arm first, you've probably ripped the clutch boot. We've all done it, some of us have done it multiple times

I think I've finished scaring you for today. Come back tomorrow if that's not enough in the fear department.

bad boy wrote:Ballzac

I do feel your disappointment.
You never know what you've bought until tearing it apart.

My Ecomobile has the third engine right now. Here's the story:

As I bought it, I was the third owner and the service history of the vehicle was unknown. The original engine was running fine, but guzzling engine oil like a two stroke engine. It was decided to have it replaced, as the costs of rebuilding would very probably be higher than a used second hand one.

The second engine had a damaged crankshaft and worn crankshaft bearings. I've bought that one second hand from the internet. The seller was unknown to me and I only found out after having it installed and running. That one was replaced as well.

The actual engine is w/o any fault and running strong. It was bought second hand as well, but from a very reliable source.

So my advice is:
Maybe buying and installing a used engine from a reliable source could save you the trouble and costs of having this one torn apart and being rebuilt.

PS
Unless you do have the knowledge and possibilities to do the job yourself. That would be a different story then.

Just looking into everything as is without knowing how much rust is in there as of now looks like I'm  going to be spending close to the same regardless. If I were to purchase a used engine from a reputable site then that runs me 1600 but if I send them my engine I get some off as well. The rusting on the crank shaft looks pretty rough and might actually have some pitting so I am not looking too hopeful.

Dai wrote:It's a bit of a toss-up really - as long as you don't use a double-headed nickel. A known working engine from a reputable breakers could actually cost less than rebuilding that one. I'd want to inspect the camshaft, cylinders and big-end bearings before making a final decision. Rust in the cylinders would make me start to think seriously about looking for another engine. So, in order I'd

- check the camshaft for pitting and rust. Get a manual and check the cam follower gaps before pulling the camshaft
- if the camshaft is okay, pull the cylinder head and check the bores. One of them camera thingies you poke into dark corners isn't going to give enough information, even if it is a colour one (full disclosure: I have a high-end Bosch one with a colour camera and it's bloody useless for looking down cylinders unless there's a sodding great hole in the piston)
- if the bores are okay, check the big-end journals

If the journals are okay, start adding up the cost of new parts. At the very least you will need:

- a full gasket set
- a new set of big-end bolts (do NOT reuse the old ones because they are a stretch-fit)
- possibly all of the engine rubber parts (inlet rubbers, manifold rubbers, crankcase breather hose)
- air filter. Bet the mouse has had a high old time making a nest from that
- if you took the gearbox off and didn't secure the clutch arm first, you've probably ripped the clutch boot. We've all done it, some of us have done it multiple times

I think I've finished scaring you for today. Come back tomorrow if that's not enough in the fear department.

I got a quote from a local guy who does full engine rebuilds and he says he is looking anywhere from 3k-4k without parts so I think I am going to order a rebuilt engine from BSK Speedworks. They seem pretty fair and even give you a warranty. Hell, might even speed up my timeline to when I could get the piglet up and running. I will do my best to keep everyone updated, thank you guys for the advice and knowledge.

Swapping in another K75 engine is the way to go.

Be sure to get model year 1989 or later as 88 and earlier have the smoky rings.

Here's one in PA for $499 but you have to pick it up because I guess that the seller is too lazy to ship.
http://www.ebay.com/itm/143777171130

(I wouldn't pay that much though.)

For $3-4K to do a rebuild you could find a whole nice running bike.

Alternately, you could just buy another whole k75 to cafe and use the untitled $250 bike as a parts bike. That's what I'd do.

Two Wheels Better wrote:It's '86, not 86', BTW. You're removing the 19 to make the contraction, so the apostrophe goes before the numbers to indicate removal. Otherwise you're describing an 86' (foot long) K100RS. A too common mistake that many make.

This a motorcycle forum, not a grammar Nazi forum.

Beauty IS in the details, and a K75 engine would be less than in an '86 K100. 

I've looked on Ebay for replacement engines, there is a couple of them but I don't know what I will be getting which would/could potentially put me in the same situation that I am in now. I found a pretty reputable site but still waiting for an exact number from them.

I know where you can probably get one from a very reputable source but he's in Long Beach, CA and it'd need to be shipped across the country.

Let me know if interested and I can hook you up.

Another option, clean it as best you can, without dismantling, a bit of lube, and give it a go. If it really has sat for only three years, that's not bad. Most of the important bits are made from non rusty stuff. Bricks withstand a lot of abuse. Compressed air helps.

That's crazy that it is so corroded inside after only a few years. Even if there had been fluids in it, if it's never run that shouldn't matter because the oil never circulates in a non-run engine but there should still be some residual oil film left on the parts.

I once bought a boatload of K stuff from a local dude who was moving and needed it all of his K stuff gone for $200. It was one of those "you have to take it all" deals so I got most of a rollable an 85 K100RS(sans fairing), an 86 K75 motor and several boxes of miscellaneous K parts. Anyhow, the 86 K75 motor then sat in my basement for another several years until I finally decided to turn it into my K75 Frankenbrick.

Being a big believer in blind faith, I just figured that it was still good and started building a bike around it. The thought of taking either the valve or crank covers off of it or doing any of the stuff the Laitch recommends never even occurred to me. All that I did was use use refurb'd fuel injectors and a clean fuel rail.

Once I had the wiring harnesses and a frame installed I'll be damned if it didn't start right up once I put a battery in it. I even did that on the old oil that was in it because I only ran for it a minute just to make sure that it would start and run.

I did eventually check the valves and along with a few different fairing iterations but it ended up going from this to this:

Before:



After:


It's been a very reliable K75 and I still have no idea what it looks like under the crank cover.

My only regret is that I built it around a smoky 86 engine but I do have a 60K 94 engine to replace it with if I ever get motivated enough.

Very strange view inside this engine. It looks like it's coated with a mix of never-drained burnt oil and coolant.
When I find such a mess when opening a case, I just spare the ignition system and throw all the rest.

Ballzac,

I have a '88lt that runs fine. Son dropped it on both sides so fairing is messed up bad. It has a good title and could be had at a reasonable price. Shoot me a PM if interested.

PS, Did that bike come from State Collage?

duck wrote:That's crazy that it is so corroded inside after only a few years. Even if there had been fluids in it, if it's never run that shouldn't matter because the oil never circulates in a non-run engine but there should still be some residual oil film left on the parts.

I once bought a boatload of K stuff from a local dude who was moving and needed it all of his K stuff gone for $200. It was one of those "you have to take it all" deals so I got most of a rollable an 85 K100RS(sans fairing), an 86 K75 motor and several boxes of miscellaneous K parts. Anyhow, the 86 K75 motor then sat in my basement for another several years until I finally decided to turn it into my K75 Frankenbrick.

Being a big believer in blind faith, I just figured that it was still good and started building a bike around it. The thought of taking either the valve or crank covers off of it or doing any of the stuff the Laitch recommends never even occurred to me. All that I did was use use refurb'd fuel injectors and a clean fuel rail.

Once I had the wiring harnesses and a frame installed I'll be damned if it didn't start right up once I put a battery in it. I even did that on the old oil that was in it because I only ran for it a minute just to make sure that it would start and run.

I did eventually check the valves and along with a few different fairing iterations but it ended up going from this to this:

Before:



After:


It's been a very reliable K75 and I still have no idea what it looks like under the crank cover.

My only regret is that I built it around a smoky 86 engine but I do have a 60K 94 engine to replace it with if I ever get motivated enough.

Gives me a little hope!

daveyson wrote:Another option, clean it as best you can, without dismantling, a bit of lube, and give it a go. If it really has sat for only three years, that's not bad. Most of the important bits are made from non rusty stuff. Bricks withstand a lot of abuse. Compressed air helps.

I think after getting a few emails back from a couple of people this is my option I will be exploring this weekend. Going to be taking off everything I can without getting in too deep, WD40 everything, use some light rubbing with some emery cloth and hope for the best.

caveman wrote:Ballzac,

I have a '88lt that runs fine. Son dropped it on both sides so fairing is messed up bad. It has a good title and could be had at a reasonable price. Shoot me a PM if interested.

PS, Did that bike come from State Collage

I did pick it up from the College yeah. I will let you know where I am at after this weekend, might take you up on it.