85 BMW K100LT

Yes I had to get it, came up on FB market place in my local area and I just had to get it. It is the LT so all the fiberglass stuff is coming off this bike. Looks like it has fallen over a few times as the cowlings were more or less messed up. No damage to the underlying bike, engine or seat.

Looks to have 28K original miles, inside of tank was much better than the first K100 I got running. This one even had gas that was not totally varnished to the bottom of the tank. Only had little rubber parts from the old fuel lines in the bank. The PO or someone has already changed out the OEM fuel pump and fuel lines in the tank, that was a big help.

The PO said the bike would just stop running and he tried to fix it. The did a good hack job of some of the controls and wires, so getting that sorted out. I have been able to bypass the wiring issues and get the bike to turn over with the starter and also see spark off the plugs. That was a really good thing to see. The PO had the battery in the wrong way and I really thought the FI brain box would have been fried.

Thinking of stripping all the wiring off and follow the YouTube vid on bear bones wiring using the M-unit. I know that is cost $300 but it seems to remove all the fuse box and relays that are needed to run the whole bike. More research is needed before I drop that much money for a project bike. Pics to come.

 

Buy a stock wiring harness and be done.

 

I know the m units are popular on customs. Revival Cycles have loads of instructional videos on them as far as I know.

As for wiring I know less than nothing so I can't comment on the merits of the m unit over stock wiring looms - they seem simpler but perhaps that's too good to be true or comes at some other cost.

 

i have a 85 rs, wouldn't even think about rewiring that thing. that computer has more wires than Bayer has aspirins.
i think i still have a "no start check list" i'll look for it

 

M unit seems to me like a huge waste of money. It's a $300 fusebox, and needs a ton of time to get it wired in. K-bikes have trouble with connectors, not with relays.

On a 2-valve K-bike you REALLY need to check valve clearances. People ignore them till bike won't run. The one I had, two valves wouldn't open at all.

It's the same shim and bucket deal as the XJ.

 

Great inputs thanks folks, always love the ideas I get from this forum. I installed both left and right new/used bar end controllers. What ever that old right side controller was messing up, the new one has fixed. The lights came on in the interment cluster, the start button even worked. I had to pull in the clutch cable as the neutral indicator is either not working or unplugged.

I have checked over the wiring and it seems everything is good. I placed all the relays back in there OEM locations, there is one spare I am guessing for the running lights that are no longer on the bike. Today I will add some fuel to the cleaned gas tank and try to start her up. I will get to the valves as soon as I know the engine is alive.

Front brakes have been flushed, cleaned out the MC fluid holder. Rear brakes today and then need to order a LED front headlight and fabricate a holder. I can see this bike changing to a cafe style or at least a standard if I keep the factory LT bags on it. They need some TLC, a little loose when attached to the bike.

 

Probably a chewed up harness or corrosion in connectors.

Dashboards on these things can be wonky, but replacing them is not trivial. There are a couple of circuits in it that make the bike run. If you pull the dash, it won't start.

Bad news - this is a classic K-bike problem. The neutral switch gets crudded up over the years and sticks. It's not super expensive, and only held in by one or two screws. Unfortunately, it's at the back of the transmission and almost impossible to get to without pulling the swingarm.

Tight valves might make it not start, tho.

I rebuilt mine into a naked. It was pretty great that way.

Personally, I don't like cafe style all that much. I think on bikes other than aircooled upright twins it mostly just looks wrong. Bags are super-useful, and minus the top case it actually looks good.

 

I was able to get her started today! Stuck a fan in front of it on the lift and watch the smoke pour out of here. When I cleaned the plugs there was a lot of carbon on them, the tops of the pistons the same. I could only guess the stuff in the muffler from sitting at least two yrs. The smoke soon faded and the bike ran very well. The throttle was hanging a bit but adjusting the throttle cable a bit has seemed to do the trick.

JPanganel, Thanks for the helpful hints on the bike. I thought that neutral indicator would be all gummed up. The oil was nasty not tar but still dirty. I have in the past been able to run enough sea foam in the oil to clean up the oil windows in some of the bikes I have done. The oil filter cap on the K was really nasty but again not tar. When I pull the valve cover off that will help to determine how clean the engine is. I still have to pull the oil filter out, I sure hope it is not factory one, but then again how would I know. I don't think this bike was very well taken care of if the engine oil window is dirty with only 28K miles on her. I should remove the injectors and see how they spay as well, have a little contraption that I use to clean them with a 9v batter and a spray can of injector cleaner. I will not be taking this bike down to a cafe, you are right they look good as a naked. Your bike looks really nice, thanks for showing me what mine could look like.

I only changed out the controls at the end of each bar. That is supper easy on these bikes, one screw and they come off the bar controls. Harder to remove and re-route the cables to the wiring harness.

 

Replacement injectors are actually really cheap, if you need them.

Couple more things you want to pay attention to:

Vacuum hose to the fuel pressure regulator - cheap, but if it leaks, you might have fuel delivery issues

Crankcase vent tube - can spew oil and cause idle problems. They are like 15 bucks, and I think still available.

Oil filter - there are two types of these filters, they both look the same, but one is painted and the other not. You want the unpainted one. K bikes have the filter inside the sump and outside is bathed in hot oil. Paint can flake off and clog stuff. Also, heavily recommend the filter with the little hexagon for the wrench. BMW filters have an oddball number of dimples and very little clearance between the case and filter, so 90% of normal filter wrenches don't work. You need a special BMW one.

Oil filter gasket - a common problem is old gasket staying put on the tube when you remove a filter. If you put a new one over that, oil system won't build pressure.

Valve cover - same setup as XJ, rubber gasket and mushroom seals under bolts. Goes bad in the same way.

Parts catalog to look up part numbers. : https://www.realoem.com/bmw/enUS/select

 

before too many miles check the engine side of the drive shaft splines, if they go you don't move and you mess up the internal splines in the transmission, $$$.
all that smoke can happen anytime you park it on the sidestand, try to use the centerstand or don't worry about it, it's normal.
how do you like that sidestand clutch gizmo?
don't put much faith in the odometer, the whole cluster is flakey and a lot of times just gets replaced with another used one

 

books are good
https://drive.google.com/drive/folders/1aQRPfUYm2arr7y75sNVWGhuYIwRweG30?usp=sharing

 

One more thing.

Keep an eye on the centerstand. Early K-bikes have ones that are hollow tubes with the upturned end, and water can collect inside, leading to internal rust.

If the bike starts leaning on the centerstand, it might be weakened.

Late-model K-bikes have a solid metal centerstand which is a direct swap.

 

All great advise and links to good information. Looking back to the issue of starting and the power drain when hitting the starter. I think the keyed ignition needs to be removed and cleaned. I would guess this was the initial problem the PO had and just didn't trouble shoot it.
http://www.eilenberger.net/K75S/IgnitionSwitch/
Today with the nice winds in my area, I might take this project on and see if that takes care of the rest of the issues.

 

Got the oil filter removed today, it was the OEM BMW filter and either it was the original and never changed or they used BMW parts. Did the rear brakes today, there seems to be something not right about the rear brake. I am not too sure if it needs to be rebuilt or just flushed more. The ignition swx came out with little effort, the center pin was black and the original grease was brown and very sticky. I thought it would be worse. I took brass brush to all the solid parts and cleaned everything else off. New grease and put it back together. Seems to work much better and not lack of power when pushing the start button.

Guessing I should take the valve cover off and take a look at them. Same size shims I think as the XJ's. Need to get a LED headlight, I think I will measure the OEM one and go with one the same size. I need to get a bracket for the front forks or fabricate something else for the new headlight.

A good cleaning of the throttle body area and checking the rest of the hoses in that area.

 

5 of the 8 valves were out of spec. Not huge but need to go down in number on shim. I was lucky and could mix and match what I had in the bike and only had to order two 2.35mm for the exhaust side.

 

The temps are going up and this bike is one that I will keep. Being it is a 1000cc and FI. I had it running down the road but no way is it firing on all 4. I would guess I will have to pull the injectors out and clean them up. Bike does feel good doing down the road, trying to avoid ice spots still in shady areas. These bikes stripped down are not too heavy and do not have the top heavy issues the Air head BMW's have.

 

If the injectors are really bad, they're are the same as most Ford passengers and trucks from the 90's. Cheap and plentiful at part stores and junkyards.
I had a K75s a few years ago, if it continues to overheat later on it you may need to replace the fan. The factory electric cooling fans are GARBAGE! You can get an $18 Ebay low profile 7" fan that moves ~800 CFM (claimed) and it will do a great job. I installed one in Tucson, Az and never had an overheating issue even sitting in traffic on a hot day.
I also needed to replace the fuel pump. If you ever do need to do it again, save your money, don't get the high priced BMW part. I replaced mine with one for a Ford Escort or Tempo for ~$30 from Autozone.

 

Thanks Steve,
I didn't know about the injector from the Fords, good to know. On another BMW project I did have to replace the fuel pump. I did go with the mustang fuel pump and it worked great. I had to get some fuel tank racing foam and cut it so the pump would fit in the OEM spot, but once that was done all good. I hope to get back to this project soon. Thanks for the good information. It will be nice to have her running for the riding season.

 

Best of luck with it! When all dialed in, those bikes are like riding a sewing machine. If you do get the Ford injectors, get the newest versions. They atomize the fuel much better and give you a little more power and much better throttle response.

 

The throttle body vacuum plugs were leaking. Put the sync tool on it yesterday and got it dialed in. I still think I will get the new Ford injectors as the bike is not spinning up as fast as I think it should. It is firing on all 4 now and runs very smooth. Made new vacuum plug caps and need to run some Techron through it and hope that also helps. I know this bike has set for a long time, so maybe the new Ford injectors would help her out. I would guess modding or changing to a K&N filter would also help. The nice thing with these is you don't have to keep the air box like the CV carbs. Was thinking of just putting a car size K&N on it as I will not be running this in rain ect.