Post by: Swampyankee on November 06, 2022, 03:53:11 PM
The tank had very little gas in it and presumably old so I put a couple gallons of fresh gas in it.
After much cranking over it would try to start and eventually got running but wouldn't idle. Then would no longer start. I noticed fuel dripping and traced it to the low point of rearmost header pipe. Felt around and thd pipe is dented and perforated, probably rusted thru. I pulled the plugs and they all were wet. I dried them and checked and got spark. Reinstalled them, but the bike is not starting.
Any tricks to bringing an old K100 back from the dead? Or is there something amiss I should be looking for?
Post by: daveson on November 06, 2022, 04:02:05 PM
If it was a small leak and not noticed by the previous owner, the sump oil level could rise over time as it gets contaminated with fuel. That's one reason the oil level wants to be below the top of the sight level glass. If it was a big leak, it could be even worse, like hydraulic lock bending a con rod.
Post by: Swampyankee on November 06, 2022, 04:26:14 PM
Now that I mentioned that, it was after that "repair" that I couldn't get it started again.
Post by: daveson on November 06, 2022, 04:34:01 PM
It might be running rich on all cylinders, and run better temporarily with the fuel pump unplugged.
Post by: Swampyankee on November 06, 2022, 04:40:39 PM
Post by: Laitch on November 06, 2022, 05:37:22 PM
I need to invest in a manual. Where does the regulator reside?There's a downloadable BMW Repair Manual in the Service Manual section of this site. That will be cost free. :laughing4-giggles: The fuel pressure regulator is behind the throttle bodies. See Chapter 13, p13.
Post by: frankenduck on November 06, 2022, 06:07:53 PM
I looked for the regulator thinking it was the reason for the gas leak but couldn't locate it. I need to invest in a manual. Where does the regulator reside?
The Fuel pressure regulator (FPR) is located on the back of the throttle bodies.
(https://i.imgur.com/adaaLUv.jpg)
You need to remove the airbox to access it.
How to:
http://www.kbikeparts.com/classickbikes.com/ckb.tech/0.ckb.tech.files/k75pa.rehab/k75parehab.htm#fuelair
Note that you don't need to take the mass airflow sensor out of the top of the airbox if you're just trying to get to the FPR.
Post by: Swampyankee on November 06, 2022, 06:44:45 PM
Post by: Swampyankee on November 07, 2022, 09:56:45 AM
I'm out of town for the rest of the week but I hope to look at it again next weekend.
Post by: TommyT on November 07, 2022, 05:58:38 PM
Did you get the ALL of the old gas out before you added your fresh gas? In my past experience just a little bit of old gas in a MC gas tank will not mix well with fresh gas and will make any bike a no start or not run much above an idle.
Post by: Swampyankee on November 13, 2022, 01:26:32 PM
20221113_132739.jpg (47.65 kB . 768x576 - viewed 577 times)I mopped out the tank as dry as I could and added some fresh gas.
After alot of turning over and purging the filter and lines I managed to start it but no better than my first attempt, and as before it would not idle nor restart. Gas is draining from the exgaust via the pinholes in the low point of number 4 header pipe. I'm beginning to suspect the injectors so i pulled them and they don't look great externally.
20221113_132708.jpg (55.29 kB . 768x576 - viewed 618 times)Is there a way to test them and clean them, or am I better off just replacing?
Post by: frankenduck on November 13, 2022, 01:55:14 PM
https://www.mrinjector.us/
He'll not only recondition them but also repaint them. I've sent him some really beat up injectors before and they came back not only working great but also looking great.
I got a K100 once that had been sitting under a tarp in Seattle rainy for so long that the water had separated from the gas.
Post by: Swampyankee on November 13, 2022, 06:15:48 PM
Whenever I get a "new to me" K bike I send the injectors to:
https://www.mrinjector.us/
He'll not only recondition them but also repaint them. I've sent him some really beat up injectors before and they came back not only working great but also looking great.
I got a K100 once that had been sitting under a tarp in Seattle rainy for so long that the water had separated from the gas.
Thanx for the referral. For what its worth I just went ahead and ordered a set from Mr Injector.
BTW, the bike you mentioned sounds alot like the condition I got mine in. Lots of weather on frame and alloy parts.
Post by: Swampyankee on November 19, 2022, 02:10:06 PM
At this point I'm completely miffed. Maybe this is the real reason the PO was selling it, even if he did play up the saying goodbye to an old friend bit.
I will get some new plugs and see if that would improve the sparkulation. Any other suggestions??
Post by: frankenduck on November 19, 2022, 02:24:51 PM
http://www.kbikeparts.com/classickbikes.com/ckb.tech/0.ckb.tech.files/k100tshoot/K100.Troubleshoot.Start.2018.pdf
First things I would check:
Resistance across ignition coils. Page 15
Also check the water temp sensor resistance between L-Jet pin 10 and ground.
http://www.kbikeparts.com/classickbikes.com/ckb.tech/0.ckb.tech.files/tempsensor/tempsensor.htm
Post by: The Mighty Gryphon on November 19, 2022, 02:31:24 PM
Post by: frankenduck on November 19, 2022, 02:50:45 PM
http://www.kbikeparts.com/classickbikes.com/ckb.tech/0.ckb.tech.files/ccb/ccb.htm
Post by: Swampyankee on November 19, 2022, 08:23:03 PM
What kind of spark plugs are in it? NGK D7EA are pretty common and work well, BUT they need the terminal nut on the end to make a good connection to the BMW plugThe plugs are Bosch but I did not take note of the type. They do have the caps on them.
Post by: Swampyankee on November 19, 2022, 08:27:08 PM
There's a good chance that your crank case breather hose is shot and needs to be replaced.I can check that but explain how that contributes to a no start or hard start condition. I should mention again that gas is overflowing a enough that it dumps out the exhaust. Of course the only reason I know is it drips out of the pinholes in number 4 cylinder header pipe.
http://www.kbikeparts.com/classickbikes.com/ckb.tech/0.ckb.tech.files/ccb/ccb.htm
Post by: frankenduck on November 19, 2022, 09:31:19 PM
I can check that but explain how that contributes to a no start or hard start condition. I should mention again that gas is overflowing a enough that it dumps out the exhaust. Of course the only reason I know is it drips out of the pinholes in number 4 cylinder header pipe.
If you're over-fueling that much then my first suspect would be to check the water temp sensor resistance that I referred to above.
Post by: Swampyankee on November 19, 2022, 09:35:28 PM
Post by: Laitch on November 19, 2022, 10:03:27 PM
1)The crankcase breather hose is allowing so much unmetered air into the system that the mixture is too lean to ignite and injected fuel is not consumed and dumped into the exhaust system.
2)There might not be enough air in the mixture to permit combustion.The air snorkel could be clogged or the air filter could be clogged. The fuel mixture is too rich to ignite; fuel is dumped into the exhaust system.
3)The coils might be damaged so not providing hot sufficient spark for ignition to consume fuel.
4)The primary coil wires might be loose or corroded so the coils cannot supply sufficient spark to ignite the fuel.
5)The plug wires might be degraded enough that they cannot provide sufficient energy spark for ignition so fuel isn't consumed.
6)Degraded throttle body connections are leaking unmetered air into the system so the fuel mixture is too lean to ignite.
All the un-ignited fuel is being dumped into the exhaust system.
Post by: Swampyankee on November 19, 2022, 10:09:02 PM
One thing to add - when i pointed out a pair of wires with bare ends the PO said he thought they had been chewed through by a rodent. I traced them to the temp sensor at the bottom of the radiator. I pulled the connector and soldered the wires back together and heat shrink tubed over the splices. But it looked like the mouse had done a very clean job of cutting and stripping the wire ends... think. The other thing was the pair of wires were the same colors - purple and yellow IIRC. Since I couldn't tell them apart I assumed it didn't matter which went where. Am I wrong there??
Post by: frankenduck on November 20, 2022, 10:07:45 AM
(https://i.imgur.com/vkuuUbM.jpg)
Post by: Swampyankee on November 21, 2022, 10:19:00 AM
Post by: The Mighty Gryphon on November 21, 2022, 10:50:49 AM
The good news is that there are many here who have restored Bricks that were in pretty bad shape and documented their work here at Motobrick.com. There isn't one job on these bikes that hasn't been documented somewhere here.
The most important thing you need is some patience. Take your time and our advice and you will have a machine to be proud of.
It looks like you have a decent place to work, so it shouldn't be too hard to do this as a winter project. I would strongly suggest that the first thing to do right now is to remove the bodywork and do a good clean on the frame and the wiring before the weather gets much colder. Working on a dirty bike can really make even nice jobs suck.
My favorite cleaner for this step is S100 which you can get at any Harley dealer and a lot of other motorcycle shops. Once the frame is clean, keep it by your laundry tubs to clean parts as you remove them to be worked on. Clean parts and a clean bike make this work a lot nicer.
Post by: Swampyankee on November 21, 2022, 01:57:57 PM
Post by: Laitch on November 21, 2022, 02:04:00 PM
I'm piecing together my understanding of the operating system on this bike.This manual explains how it all works. You could have downloaded it from the site but I've saved you a step.
Post by: Swampyankee on November 21, 2022, 05:42:03 PM
Post by: The Mighty Gryphon on November 21, 2022, 05:45:03 PM
I did download it but I'm one of those that refer to the instructions as a last resort :idunno:
Probably not the optimum way to go through life. :idunno:
Post by: frankenduck on November 21, 2022, 06:07:11 PM
I did download it but I'm one of those that refer to the instructions as a last resort :idunno:
Here's part of the owners manual you should read:
(https://i.imgur.com/NWVLsCx.png)
Post by: Swampyankee on November 22, 2022, 07:21:57 AM
So excuse me if I ask too many questions. Just looking for moral support as much as knowledge....
Post by: Past-my-Prime on November 22, 2022, 06:42:11 PM
Post by: Swampyankee on November 23, 2022, 08:49:30 AM
This manual explains how it all works. You could have downloaded it from the site but I've saved you a step.
I assumed your link was to the Repair manual. Now that I'm on a computer and not the tiny screen of my phone, I see what you have provided here, thank you. I did not see that in the downloadable content, or did not recognize what it was. It provides the description of the operation of the FI system that I was looking for. As I go through the steps, I am leaning toward problems with the ignition/spark rather than the injection system. Given the amount of fuel I see being passed through, I would think the bike would start readily, even if it did run poorly and die from a too-rich mix, as long as a good strong spark was present. It does not want to pop even when initially cranked. The other thing is, when I pulled plugs and grounded them to the block checking for spark while cranking. It was pretty weak at best, and jumping across from the side of the center electrode to the base of the prong as opposed to jumping from tip to tip as it should. When I did have it running and idling, the removal of #2 plug wire made no change to the idle, which tells me #2 wasn't even firing.
I plan to check resistance of the coils and if ok, see if a new set of plugs would provide a solid spark. Hopefully I have the same easy fix as this guy. http://www.motobrick.com/index.php?topic=14612.0 (http://www.motobrick.com/index.php?topic=14612.0)
Could corrosion of the hall sensor also be causing poor ignition response? As mentioned earlier, the bike has seen some weather.
Post by: Laitch on November 23, 2022, 09:26:09 AM
Given the amount of fuel I see being passed through, I would think the bike would start readily, even if it did run poorly and die from a too-rich mix, as long as a good strong spark was present.If the fuel/air ratio is too lopsided the mixture is unlikely to ignite regardless of spark.
Don't get into the Hall Sensor itself yet. First, clean all ground connections, including the main one under the tank, the hall sensor plug connection, the four-pin tank connection to the fuel pump, the Jetronic and ignition control unit plugs including their respective terminals, and the coil and plug wire terminals themselves unless they are new. The cleaner recommended by many here is DeoxIT D5, often found in music stores selling electronic instrument, sometimes sold in auto part stores and easily found online.
Brick engines are dependent upon good electrical connections. A disused Brick left out in the weather can be stubborn to start and if electrical connections are not thoroughly cleaned up, starting and running might occur but will likely be undependable.
Post by: The Mighty Gryphon on November 23, 2022, 09:37:00 AM
Considering that the bike has been out in the weather for a while, have you gone through and cleaned all the electrical connections? There are a couple connectors under the tank that carry ignition signals from the Hall Sensors. A little attention with Deoxit may help things along. Also, if you haven't already, you should clean the ground connections, especially the one under the tank on the frame backbone. You should be sure that the coil connections are clean and tight as well. Over the years here, I've seen many bikes come back from the dead from cleaning the electrical connectors.
I think you are correct to be installing new spark plugs. If you don't know how old the originals are, they are definitely worth the relatively small expense to be sure you have good ones.
Post by: frankenduck on November 23, 2022, 09:54:04 AM
(https://i.imgur.com/v8gFTfN.jpg)
If you can find the newer coils on Ebay or wherever they are interchangeable with the early coils.
Post by: Swampyankee on November 23, 2022, 11:06:18 AM
I use Deoxit for cleaning scratchy pots on my guitars and music gear, and I've already used it on the 4 pin connectors for the fuel pump, so I'll check the other connections you mention. Looks like I'll be pulling the tank again. It'll be a bit heavier this time with the 3 gallons of fresh gas I put in. LOL
Post by: frankenduck on November 23, 2022, 11:09:30 AM
Post by: The Mighty Gryphon on November 23, 2022, 11:51:30 AM
Post by: Swampyankee on November 23, 2022, 04:46:49 PM
Post by: Swampyankee on January 09, 2023, 08:25:03 AM
Moving on, I tried bolting the crash pad back where I found it but it sat way too high. I checked on line and found that the C pad is different than the RS pad, in that the RS pad bolts to the 2 cap screws at the back of the handlebar clamp bases. Looking for an alternative to ordering an RS pad on eBay, I thought maybe I could modify mounts on the one I have, by straightening the brackets and possibly re-drilling holes where needed. Upon closer inspection I noticed someone had enlarged the holes in the brackets and had bent the brackets to mount on the clamp bolts. The pad was the original RS pad, modified to mount higher for C 'bar clearance. Straightened the brackets and they lined up perfectly with those 2 cap screws at the back of the clamp bases, albeit with slightly larger holes. Problem solved.
After routing the replacement throttle cable, I installed the ends and tried adjusting the excess slack out, but even with the adjuster at full extension there is still too much slack - as much as 1/4" (?@@??). Is there a spacer I'm missing, possibly down by the throttle bodies? Hint - I bought the cable on eBay. Although the ends are correct, could there be a different cable that requires the extra inner cable length?
The last straw was when I reinstalled the air filter and spring clamps on the air box. The loop in the spring clamp that contains the pin just split, discharging the pin !@#$%! As one of the clamps were already missing, I'm down to one holding the box together. Looks like I'll be looking on eBay for a couple clamps along with a new air filter element (don't ask why!) and a clutch-side handlebar control.
And I still haven't installed new plugs, troubleshot the coils or other electrics to get this thing running! Did I say 1 step forward and 2 steps back??
Post by: daveson on January 09, 2023, 03:38:40 PM
Post by: Swampyankee on January 10, 2023, 08:59:51 AM
Meanwhile, anyone have a spare clutch-side lever perch?
Post by: Swampyankee on February 18, 2023, 07:09:05 PM
After getting flakey "warm" ohm readings from the temp sensor, I went ahead and ordered a new one. Still waiting for it to arrive.
Can't wait to get it installed and get this thing sorted mechanically so i can move forward with putting the fairings back together.