Author Topic: Reviving K100LT (Read 8827 times)

cgdan · « **on:** August 24, 2016, 01:25:00 PM »

Hi,

I have been given (yes, for free) a 91 k100LT. Full luggage, weird BMW map light the lot, 11000 genuine miles. The reason for this incredible good fortune is that it's been sitting in my father in laws garage for 9 years and my wife had finally persuaded him that he is never going to get it going. Apparently it was mint and serviced when it went in the garage but she isn't looking so well now. Various things have been lent up against/dropped on it etc. Lots of scratches and broken lights and all sorts.

I have quite a lot of experience working on jap bikes but nothing European. Anyway, after picking her up in a van a mate and I stripped off the fairing (can't believe how well made it is). Stripped fuel tank, replaced pump, filter and gauze thingy and fixed fuel sensor/ball cock. Changed coolant and oil, primed her (at first without plugs earthed, whoops, but only for a few seconds, still getting lovely sparks). Oh yes, new battery too. Can hear new (second hand but guaranteed form motorworks) whiring when I turn off after cranking, so pretty sure that is working.

Fresh fuel and she wont go, plugs appear to be dry after much cranking. Do I have to clean injectors next? Or am I doing something stupid (not unknown!)

Any ideas and guidance would be much appreciated.

Cheers

Dan

Laitch · « **Reply #1 on:** August 24, 2016, 04:40:51 PM »

Welcome, cgdan. Put your bike's model year in your profile so we'll see it in each post.

You need fuel to and from the fuel pressure regulator so you should check that. Replacing the fuel lines would be a good strategy as well as cleaning the injectors. First though, you need to verify that fuel is reaching them at the correct pressure.

Martin · « **Reply #2 on:** August 24, 2016, 04:56:43 PM »

Check the 4 pin connector to the fuel pump under the tank, notorious for bad connections. Can try cleaning it if it is bad, but it is best to replace it with a waterproof one. Can you hear the pump working?
Regards Martin.

cgdan · « **Reply #3 on:** August 24, 2016, 05:28:49 PM »

Many thanks for the prompt replies. Pretty sure pump is working as I can hear it Whiring as soon as soon as I stop cranking the old girl over. What's the best way of checking the fuel is getting to the injectors?

On another note is there a cheaper way if getting injector o rings? I have seen lots of alternatives but they all seem to be USA. Anyone had any success in the UK using BMW car ones?

Martin · « **Reply #4 on:** August 24, 2016, 05:34:11 PM »

I've used BMW cars ones in OZ.
Regards Martin.

Laitch · « **Reply #5 on:** August 24, 2016, 05:46:31 PM »

Quote from: cgdan on August 24, 2016, 05:28:49 PM

What's the best way of checking the fuel is getting to the injectors?

One way is by disconnecting the discharge ends to see if fuel is released. You should just replace the hoses because you can't determine their interior condition by their outside appearance. You should still check incoming and delivery pressures at the fuel pressure regulator. Once that's sorted then the injectors are next.

Fuel under pressure delivers a mighty stream, so go slowly. You are working with a manual, right?

Brad-Man · « **Reply #6 on:** August 24, 2016, 08:05:15 PM »

If you have VOM/Multimeter you might check to see if your injectors are getting a signal to fire.

If not then a good round of cleaning all contacts w/deoxit would seem to be called for - and should be done anyway.

Pay particular attention to the connection to the computer under the toolbox.

cgdan · « **Reply #7 on:** August 25, 2016, 05:03:02 PM »

Martin, do you know what model of BMW car injectors fit? Or is it the whole range from the early 80s? Will check fuel is getting to rail tomorrow and change lines. I guess if they have anywhere near the rubbish the tank contained and have degraded like the ones in the tank they could be real problem too. I will report back :)

Martin · « **Reply #8 on:** August 25, 2016, 09:08:05 PM »

I had my injectors cleaned by a BMW car specialist ( Non Dealer) just after I got the bike, he cleaned them on the spot and supplied the new "O" rings. If you take an injector with the "O" rings they should be able to supply. I would imagine any fuel injector workshop would be able to sell them to you. A bit of rubber or silicone grease on the "O" ring helps when fitting them, they can be a bit tight.
Regards Martin.

cgdan · « **Reply #9 on:** August 26, 2016, 08:01:12 AM »

Thanks, I think I am on the case now. Just done some digging on the interweb during my lunch break. BMW car ones were a bit of bust as parts shops here seem to always require a reg number. But at least I could get the metric sizes of a BMW 3 series website. Anyway decided to utilise the advantage of living in an industrial city and contacted a bearings shop, who have the right size and spec in stock! Drag the cg out this afternoon and pop down there.

So this weekend going to whip the injectors out and see whats going on. Fingers crossed.......

jay1622 · « **Reply #10 on:** August 26, 2016, 09:12:22 AM »

I declare the OP full of it, and just yanking our chains! Nobody gets anything for free, especially a brick in near mint condition.

Just kidding of course, but us jealous types would love to see a picture of it.

cgdan · « **Reply #11 on:** August 26, 2016, 09:29:28 AM »

Strictly speaking, it wasn't free, over the years I have put up fences, installed televisions and married his daughter. Pics to follow....( I must stress it's not aesthetically mint, front fairing is looking particularly sad)

jay1622 · « **Reply #12 on:** August 26, 2016, 09:34:47 AM »

Touché Sir. You've surely paid your dues!

Oh...
"...and married his daughter. Pics to follow..." :hehehe

Sorry... I couldn't resist.

As I am sure you have seen at this point, there are endless resources and information on this forum. Let us know if you need anything, and best of luck with it.

cgdan · « **Reply #13 on:** August 27, 2016, 06:53:31 AM »

I thought that as soon as I posted it! Anyway, cleaned the injectors using a little rig consisting of a can of carbcleaner, a battery and some fuel hose. All injectors seem to work. So then connected all the rail and injectors and left them dangling over a piece of cardboard. Again, they seem all to work, 4 nice squirts of fuel. Then put it all back together with my new 40p o-rings. Fired up first time!

By the way for all European people the o rings I used were 7.52mm x 3.53mm 203 viton o rings. Same as a BMW E30 car. Was putting fairing back together this morning but it has just started raining, the famous British summer! I think I still need a pair of new tyres and the bump stop on the shock replacing (as that has perished).

Aus BMW · « **Reply #14 on:** September 08, 2016, 09:24:05 PM »

I feel your pain...I too was gifted a K1100LT and thought you beauty! ........ lots of pain and transporting on a trailer every week or so to my local guru. a BMW wrecker near me with a truly gifted mechanic brought the fuel injection back to life { beyond epic tale in its own right...} and after re building everything it will cross fingers,be alllll ssorted....maybe.!

cgdan · « **Reply #15 on:** September 09, 2016, 02:00:56 AM »

I have to say I am very fortunate to only about an hour from Motorworks (and it is an amazing ride to get there, even on a 125). So between this forum and some advice from them things are looking good....now where did I put that gearbox?

ewing · « **Reply #16 on:** September 13, 2016, 07:07:31 PM »

Sounds like a good 'revival'
I've recently done an '85 K100RT.

You will need to replace the vacuum hoses, if you haven't already. There is one from the fuel regulator which tucks around the corner of the number 4 cylinder throttle body to the vacuum take off there. They go hard. If you can just lift it off its takeoff with no pressure, it's gone hard and must be replaced. It will be leaking. Earlier models like mine have a second one off Number 1 cylinder (front one) for a vacuum switch but your model may not.

If the fuel is getting round the fuel pipe or rail but there's no sign of moisture on the plugs, the injectors will be glued shut. A screw-driver or punch on the steel body of each injector with a good clip from a hammer--WATCH OUT FOR THE PLASTIC! DON'T CLIP THAT---can free them and get things going.
Having the injectors cleaned after all this time will most likely Be A Very Good Thing (tm).
Injectors are Bosch 0-280-150-210's. (I think ... my memory ain't what it used to be)

Replacing all bevel drive (rear drive unit) oil seals (pinion seal, crown gear output seal and O-ring) will save a small fortune in oil and prevent leaving puddles everywhere.
I had to do this last year to revive the RT and I changed the g-box output seal at the same time, just in case. These seals seem to be more age-dependent than mileage.

Hope this helps.

cgdan · « **Reply #17 on:** September 14, 2016, 04:16:34 PM »

Cheers for that, bike now on road. I think I need to replace that breather pipe as it looks very perished. First 150 miles, all good, but quite vibey. Between 3200 revs and 4000 revs feels a bit like a high-speed cement mixer. Outside of those revs smooth as anything.

Brad-Man · « **Reply #18 on:** September 14, 2016, 04:47:13 PM »

When you have the time and wherewithall, check your valve clearances and then balance your TB's.

That should reduce vibes to a tingle...

Martin · « **Reply #19 on:** September 14, 2016, 05:02:33 PM »

Might help, in the library in the Other section. Topic: Curing Early K100 Vibration Problems ~ author don eilenberger (Read 1053 times)
Regards Martin.

cgdan · « **Reply #20 on:** September 15, 2016, 02:32:34 AM »

Thanks for that, will have a look into implementation next week

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Author Topic: Reviving K100LT (Read 8827 times)