Hi all,

Bit of an idiot question but a quicky, when i press the starter button the starter moter spins but getting no spark from plugs. But at the minute not sure if my Sprag clutch is engaging to turn engine. My Question is does the engine need to turn over to get a spark or is that all in the electrics.

thanks john.

It's not a stupid question if you don't have any knowledge about the electronic of the K100.

Yes the engine has to turn over as the Hall sensors are mounted at the end of the crankshaft.
If the engine doesn't turn over, the hall sensors don't send a signal to the ignition computer.
In simple words, the Hall sensor monitors the position of the crankshaft which relates to the position of the pistons.
When the angular position of the crankshaft is 6 degrees before TDC, it sends a signal to the ignition computer to power the spark plug.

I'm certainly not saying it is a stupid question either, but while we're on the topic, I can think of no engine where you will get a spark without it turning over. Whether they use hall effect sensors, mechanical points or even a dynamo, all engines use crankshaft rotation to trigger the spark.

As for the starter clutch issue, it really should be quite simple: if it sounds much like any other engine (eg: car, bike, tractor, etc) cranking over and the noise stops as soon as you release the button then it is cranking. If it just sounds like an electric drill and takes a few seconds to spin down again after you release the button, it isn't engaging. If you're still not sure, pull a plug out and see if air puffs out the hole at you when you press the starter - if so, this means the piston is going back and forth = cranking. :-)

Actually, you don't even need to pull a spark plug out - you should be able to feel puffing at the end of the exhaust if the engine is cranking over.

thanks for your support in this matter. getting a nasty feeling the engine is not been turned by the starter motor.

Thanks John

don't dispair, I think its a relatively straightforward repair if not turning over. These bikes are over engineered in most areas, so something's likely gummed up rather that fatally broken.

Hi all,

I am not getting a spark from my spark plugs, what could i test next to advance my quest.

Thanks john

Mate, the simplest way to determine if the crankshaft is turning when the starter button is depressed is to go to the front engine cover and on the right hand side you will see a cover plate which is held in place by 5 screws. Take a 5mm Allen key and remove these screws. Remove the cover and gasket. The end of the crankshaft is now visible. Press the starter button (or ask an able -bodied assistant to kindly do so) while you observe the end of the crankshaft.
If it turns by the starter, you need to begin troubleshooting to find the reason for no spark. If there is no rotation you need to then look at the starter drive system sprag clutch as it may be gummed up and not gripping the hub to turn the engine.
If you are confident the engine will start, and you have sufficient gradient nearby, it is possible to run-start the bike. Remember though, if it doesn't start it will take a hurculean effort to get the bike back up the hill.
Hope this helps.

thanks Dennis,

I will try that, a nice visual way to putting my mind at rest over the sprag clutch. I have taken all the spark plugs out to see if it I could hear air poping from the holes, not a thing so you can quess what i think I am going to see or not see in this case.

thanks John

John, undoubtedly, your engine is not turning over. I would be focussing my attention on the starter sprague clutch now. Forget about compression testing as per your other thread, if the engine's not turning over it will not create compression to test.

John, reading a bit more about the sprague clutch, you're going to have to go deeper into the drivetrain to get to it. See this:

http://k100rt.aforumfree.com/t1191-spinning-starter?highlight=remove+starter

thanks all, looks like i will have to strip the engine to clean the sprag clutch as it will not run to flush it.

hmmm wonder if there would be a way to pull the starter and work the sprag a bit without the full disassembly. Can you turn the motor over manually? There is a process for doing that as if you were checking timing. Or maybe put the tranny into 4th gear and try turning it over with the rear wheel while the bike is on a center stand.

John, just some advice, but hopefully not to dampen your spirit - it appears that your engine starter sprag clutch is not engaging. Unfortunately, once this becomes a problem there is really very little that can be done in the way of tricks to remedy the problem - it will require removal from the engine and a thorough de-gumming. The unit is a precision device which cleverly grips onto a hub without marking the mating surface. Once started and running, the sprag clutch just sits there stationary. So as soon as you have the sprag clutch operating correctly, my advice to prevent any more problems is to use a high detergent oil, typically a diesel engine mineral oil, viscosity 15W40 is fine, and change the oil at 5,000 Km intervals or sooner if you do short runs. I have spoken about this in other threads, and Bert has plenty of info in here on the sprag clutch.
We're all here to help good luck, Dennis.

I have to disagree at this point, when the sprag clutch is not engaging the first thing you do is to change the oil for some highly detergent diesel oil like Shell Rimula and go for a very long run (after having got a bump start from friends). Start with a full fuel tank and basically go for a full tankful ending back at your house without turning the bike off unless you do so at the top of a steep hill and can get a rolling start down the hill. The diesel oil often cleans up the sprag clutch enough for it to start operating again. If not go for another full tank run generally most people find the diesel oil gets it going again. Think about changing the oil and filter for a fresh lot of Rimula and run for the full service period till the next oil change. From then on only use premium oil with good cleaning power. Mobil 1 is good but so is Rimula and as we have a dry clutch, car oil is fine and diesel oil is fine because we mostly don't have catalytic converters either.
Regards,
K-BIKE

I think for the OP's specific problem here, I believe he has bought the bike as a non-runner. As such it may be difficult to bump start (roll start, push start) the bike, since the actual running condition is unknown. So any new oil in the bike is just going to sit in the sump. With that said, if it was me I'd probably get a couple of friends together and try and bump start it as it sits now (with the plugs and such reinstalled so it's ready to start). If it starts and runs, then drain out the oil and take K-bike's and Dennis's suggestion on the diesel oil trick, bump start again and go for a ride with a tank of gas. But the bike should be ready to go if it does start, meaning old gas drained out, fresh gas put in, fresh spark plugs, tire pressure correct, maybe a little starter fluid sprayed into the air intake, etc etc. That's going to give it the best chance to start and stay running.

Should also remind everyone he's working on a K1100 trike, so there may be some odd changes from the K100 series, especially with the trike conversion.

You are correct club-c it is a trike but it did run just not for me lol. My understanding is that it was in the last owners hands for three years but only rode it a few times rest of time it was in garage.

jwh01
Bump start it as you would any other bike.....if it runs then you can ride back home and remove the oil for sythetic oil...then go bump start it and give it a good old run....that will solve the sprag clutch problem matey.
Cheers Ajays

Hi all thats been helping to get my K1100lt trike running. update going to give the old girl a compete clean up. Had a good look at her and she is in the main in good condition, but as with anthing thing this old needs some TLC. so decided to srtip the engine down. I drained the engine oil tonight to find its a brown milky colour would i be right in thinking it may have been contaminated with water or is it just a lot older then i have seen lol.

john

Brown milky is not good that sounds like water contamination. If you had the oil in there I would suggest take the spark plugs out and do a compression test just to see what you get on each cylinder.
Regards,
K-BIKE

cant do a compression test just yet as it seams the sprag clutch is not catching to turn the engine. thats why i am taking her apart. just hope its a leak and not a crack letting water in. is there any other areas that may let in water other then the gaskets.

Condensation...if it has been standing.
Before getting in deep. See my comments above.
Ajays

I agree with Ajays. When the bike has been stored for some times, you can get a coat of this milky substance sitting on the top of the oil.
I once blew the seals in the oil/water pump and the oil got quickly contaminated with water (K75).
In theory, the combination shaft seal / mechanical seal should prevent the oil mixing with water but I guess when one seal went, it destroyed the other and it was free flow between both pump.
Do you have any dripping under the front of the engine? Have you cleaned the drain hole under the oil/water pump?

Had a good look at engine tonight at the 'nobody sees this bit' parts. I found that the last owner has spray painted the engine, gunk, rust and all. this was done while engine was still in bike from the masking marks. The hole you point to crazy frog was full of crap but nothing much else come out. I have not seen any drip marks on the floor of any type from this engine.
I was thinking I may do a diary of work done as i strip this beast down and rebuild her if anyone intrested,

Always handy, if not for yourself then for us, so nice please yes? And some of us are not too far away, so a quick call/help is handy.

Good point ReneZ, As you may aware this is a K1100lt trike but as far as i can tell it is a K1100 from the engine to the front so it may have interest to some. As it was some 26 years ago since i was riding on two wheels before a major crash put paid to my enjoyment, bikes have come on some way since then so help from the forum would be welcome as I learn about this machine.

Have you already downloaded a factory manual for the bike? If you do a search you can download the official BMW repair/maintenance manual, which gives good info & drawings.

The K1100lt manual is available in the download section.

There you go, how's that for a Merry Xmas?!