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2009 Bonnie A-1. 1968 T120R
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Discussion Starter · #1 ·
I’m in the process of trying to stop a very slow oil leak from the crankshaft position sensor grommet. My original intent was to remove the sensor, clean the heck out of it, pack it with silicone sealant, and reinstall. I have my air box still installed and, probably because of that, cannot trace the wire to its connector. I’ve tried cleaning it whilst the pickup removed from where it’s mounted, but it’s quite difficult to properly clean (man, that synthetic oil is tough to completely remove) with it dangling. I’ve soaked it (the grommet) in warm water with lots of dishwashing liquid, but results are marginal at best, and I want it squeaky-clean.
Does anyone know how to locate the connector for it? I’ve traced it to where it disappears near, but underneath, where the front of the seat slides in. I’d love to get it fully disconnected so I can do a proper job of cleaning it, or possibly replacing it.
Also, any suggestions (other than dishwashing liquid) insofar as what to use to get the oil cleaned out so the silicone will have a good chance at adherence?
Thanks!
-Sparky
 

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2008 Bonneville Black
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12,560 Posts
The connector is center under where the tank screws down to the frame. In front of the battery box. I did the job on a bike with airbox, and had to disconnect the carbs and unbolt the airbox to pull it back an inch to get at it. Without the airbox it will be easier, but you might still need to move the battery box.

Tie some string to it when you pull it down, so you can pull it back up easier.

I put some notes here: Ignition pick-up coil / Crank position sensor (nerdy AND...
 

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Spray some carb cleaner into a paper towel - mind your eyes - and use that to wipe away the oil.
You can do this in situ.
 

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2009 Bonnie A-1. 1968 T120R
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Discussion Starter · #4 ·
Thanks Rich & Driftless. Been under the weather, but got to it today. My first plan of attack is to see how well I can do leaving it wired and, if that doesn’t work out, to get a new sensor, then go the ‘drop the battery box’ route and simply replace it.
As I ride an EFI, no carb cleaner in the garage, but brake cleaner really seemed to do the job. We’ll see how it shakes out tomorrow.
I haven’t visited here in quite some time, but I sure appreciate your collective efforts. I’ll update my hopeful progress.
-Sparky
 
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I'm not actively promoting this method, but in the past, in cars, I've cut, soldered, and shrink wrapped the existing wires between a new part and the old connector, rather than expend a lot of time and effort to remove a lot of parts to get to it.

One would think that an electrical connector, by its very nature, would be located in a more accessible place.
 

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2009 Bonnie A-1. 1968 T120R
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Discussion Starter · #6 ·
Hey, Marty.
Should the leak re-emerge, I think I might consider your non-recommendation.

I couldn’t agree with you more. To drop the battery box is gonna be a PITA, in that I now have four auxiliary powered do-dads that, while neatly situated, are going to make for additional labor if I decide to go that route. I recently changed out my throttle cables, and was quite surprised at how much I needed to remove from the throttle bodies in order to gain access.
Thanks again for your suggestion.
-Sparky
 

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2009 Bonneville T100
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a very slow oil leak from the crankshaft position sensor grommet.
I had exactly this. Went to the trouble of removing the engine cover. The wire into the grommet was siliconed well but the grommet to casing was not siliconed at all (as opposed to the alternator grommet which was). :oops:
Thinking myself clever I sealed the grommet to casing and replaced the cover with a new gasket.
Made absolutely no difference.
So I got a very small syringe and shot RTV up the boot on the grommet from outside the casing, after blasting up there with carb cleaner through a straw. Has done the job but I can't understand why, it was sealed very well internally. Oh well ignorance is bliss.
 

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2009 Bonnie A-1. 1968 T120R
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Discussion Starter · #8 ·
Well I’ve had it. Bought a new CPS but don’t necessarily want to take Balto’s route, as getting rid of all the old wires feels better.
Has anyone successfully gotten to that connector crammed up in there?

I started playing around with it but even loosening the battery box did naught. I feel as if I need to pull the air box, which seems a bit drastic. If I could hear from someone who’s actually done this successfully, I’d feel a lot better digging in on this.
Thanks,
-Sparky
 

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(1) Remove the tank
(2) Remove the right side cover
(3) Gently tug the sensor wire while observing what connector moves
(4) Fish out the connector from between the opening in the frame
(5) Disconnect the connector
(6) Tie Kite string to the connector to create a drag line
(7) Gently work the sensor wire out, being cautious not to damage the connector or wire
(8) Reseal the sensor
(9) Gently tug on the drag line...while feeding the wire from under the carbs
(10) Reconnect the sensor wire, reassemble the bike

I just replace my sensor for the second time in 20 years three days ago. Takes less then an hour to do start to finish
 

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(1) Remove the tank
(2) Remove the right side cover
(3) Gently tug the sensor wire while observing what connector moves
(4) Fish out the connector from between the opening in the frame
(5) Disconnect the connector
(6) Tie Kite string to the connector to create a drag line
(7) Gently work the sensor wire out, being cautious not to damage the connector or wire
(8) Reseal the sensor
(9) Gently tug on the drag line...while feeding the wire from under the carbs
(10) Reconnect the sensor wire, reassemble the bike

I just replace my sensor for the second time in 20 years three days ago. Takes less then an hour to do start to finish
I recently replaced this sensor. Below is a detailed description of the process from another, older thread on the subject. Depending on your level of skill it may be helpful. It was vital for me.

My experience replacing CPS/CKP on 2014 T100 EFI - long and ELI5

Hey folks,
Long post warning - buckle up, I'm verbose by nature. This thread has been hands-down the most helpful for me in the past few years, and saved me hundreds, if not $1000, in repair bills. I thought I'd relate my experience narrative-style replacing my crankshaft position sensor on my 2014 Bonneville T100 EFI as it took me a few days to piece together the right info, and somebody out there may have to go through the same thing I did, so here goes. First things first: your mileage may vary depending on your bike. I'm mildly okay with DIY repairs, so this was a big deal for me, and I'm kinda proud of myself. I'm going to use ELI5 language for others like me.

Symptoms: after a noticeably hot day riding, my bike wouldn't start the next morning. Would turn over (i.e. engine would crank), but wouldn't start. Plenty of gas, electrical seemed fine otherwise. Knowing problems like these are usually fuel or spark, I checked my spark plugs by pulling the cap off, plugging in a spare one, grounding the thread to the engine, and turning the engine over. No spark on either side. (never do this with a pulled plug from the engine - you could ignite gas vapor). I plugged in my handy dandy OBD-II sensor (pulled the seat off, plugged in to the cable), used a free app on my android tablet called Torque (Lite), and found error code P0355. You'll need an OBD-II and this app later on to clear the check engine light, so don't skip this step. I bought a wifi one off Amazon for $15 or so. Those two things led me to the crankshaft position sensor (referred to as the CPS or CKP. I'm going to use "CKP"), which led me to this thread.

I learned, slowly, that this CKP was inside the alternator housing. Scary! Dealership said it was a 6 week wait for a repair appt., so I decided to do this myself. They never did give me an estimate, so I have no idea how much it would've cost. So I ordered part T1296505 (EFI bike, 2014... this part is different for olders bikes as this thread has detailed) and a new gasket for the alternator cover T1260968. Total cost was $100 after tax and shippping. Both parts were needed. I also learned that measuring the gap on the sensor installation was important and needed to be 0.8mm, so I picked up a feeler gauge at the local auto parts store for $5 that went up to 1mm. I was ready.

While I waited for my parts, I decided to test the resistance on the suspect CKP. This turned out to be hard to figure out. I knew the CKP was in the alternator, and the cable I could clearly see coming out of the case (pictures included below), but the cable went down under the bike and up the center of it and disappeared. So, here we go. Seat off, battery out, wires out of the way, plastic side covers off (both). I also took the gas tank off, but not sure that was really needed for this job. Anyhow, the cable routed back up by the back wheel, through the frame in front of the air filter housing, and then back under the frame right near the positive battery cable. In order to get to these wires, I had to remove the four screws from the plastic housing holding the battery, loosen the band clamps and and disconnect the shorty hoses from the throttle body (I think that's what it is). This allowed the air filter housing to drop down about an inch and I could access the wires. Three of them came out, all wrapped around each other: one with three yellow wires, one with a gray and white wires, and one with skinny black wires. The gray/white was the one I wanted. I disconnected the wire and hooked up a multimeter to the sensor side to measure resistance and it read "1", meaning open circuit (I think). When my new CKP arrived, I did the same thing and it measured the expected 210 Ohms (again, different bikes have different parts and may have different resistances).

Now: removing the bad CKP. With everything loosened up, I set out to pull the bad cable back down through the body of the bike. Dirt and grime made the cable stick to everything, and two muthaflippin' zip ties embedded deep in the hard to reach areas had to be clipped. I found the CKP cable also stuck to the engine next to the back tire, which makes me think this is why it failed, but only a guess. With everything really loosened up, I could pull the cable down and through, taking pictures to remember the routing. Removing the alternator cover was pretty easy - each bolt was easy to remove, and it took some smacks with a rubber mallet to free it from the gasket, a distinctive change in sound made that obvious. The alternator magnetism held the cover on, so it takes a little finger muscle to get the cover off. That other cable with the yellow wires ran to the coils on the cover, so I had to be careful with that. I did not drain the oil at all - the bike was on the kick stand - but oil dribbles out, so I kept a rag on the exhaust pipes just underneath to keep things clean. Now the fun part: removing all the caked on gasket. I used Goo-Gone and a sharp razor blade. Took me a good hour or so to scrape it all off. And yes, you must scrap it all off on both sides.

Anyhow, removing the CKP was a breeze - some people have commented on how hard the screws were to move, but mine were no issue at all. A tooth on the sprocket needs to be lined up right under the sensor in order to measure/set the gap, so make sure you do that. To move it, put the bike in 5th gear and just push it forward a few inches (while in gear), it'll move. Takes a bit to line it up just right, but is simple enough. Careful with that cover that's just dangling there with the yellow wire. The existing gap was easily 1.0mm or more. Putting the new CKP was simple - I put a little lock tite on the threads per a suggestion. Feeler gauge helped set the gap at 0.8mm, pressing down on the CKP while I tightened the screws. Double check the gap, route the cable (referencing my pictures), careful with the sharp metal edges, and set the little rubber grommet thing. I used some black RVT silicone gasket maker in the hole the rubber grommet goes in as that's a common leak point. Same with the entry point for the other yellow wire cable. That stuff needed 12-24 hours to dry, so I knew it'd be a day before I was ready to ride. The housing gasket back on, the cover goes on, and tighten things back up. Easy peasy.

Routing the cable back up through the bike was easier than I thought it would be. I used a long spare wire to route down, tape to the CKP end, and pull it back up. Don't try to push the cable up through the holes. Zip tied back where I could reach. Back up top near the battery, I took my time to fit the wires back in where there would be room - don't just stuff them in. The air filter housing needed to go back up an inch, and the positive battery cable needed to move a bit, and things are very tight. Tucked back in, the two shorty hoses connected back up easily, tighten the bands, and put the four screws back in the air filter housing, which was oddly quite challenging. Battery back in. Time to test the spark again using my spare plug. This time, I got spark on both sides. Hooray! Now stop - don't put the seat back on. I put my gas tank back on, and fired up the bike. Check engine light was on. Remember the OBD-II sensor, hook that back up and use Torque (Lite) to clear the error code. Now you can put the seat back on, let the gasket sealant set for a day, and get back on the bike. After a 10-15 mile ride, I checked for oil leaks (none), and now I'm all done.

Pictures are worth a 1000 words, so I'm including some of the main pictures below for reference. Sorry for the length of this post - hope it helps some of you!

Images:







Attachments
 

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2009 Bonnie A-1. 1968 T120R
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Discussion Starter · #11 ·
Hey Big Mike.
Me? I like the long and detail-ridden explanations, probably because I’m of the long-winded, detail-oriented ilk.
I want to sit down and digest what you’ve been kind enough to regurgitate for me, and will do so soon. But I can’t sit around not knowing what something you said at the very beginning of your post means: I presume you were referring to what followed when you said “long and ELI5”. I know the meaning of ‘long’, but what ELI5 means is beyond me and, choosing not to Google it, look forward to your explanation, which will likely be short & sweet. Thanks, and I hope this to be a done deal in the very near future.
-Sparky
 

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Hey Big Mike.
Me? I like the long and detail-ridden explanations, probably because I’m of the long-winded, detail-oriented ilk.
I want to sit down and digest what you’ve been kind enough to regurgitate for me, and will do so soon. But I can’t sit around not knowing what something you said at the very beginning of your post means: I presume you were referring to what followed when you said “long and ELI5”. I know the meaning of ‘long’, but what ELI5 means is beyond me and, choosing not to Google it, look forward to your explanation, which will likely be short & sweet. Thanks, and I hope this to be a done deal in the very near future.
-Sparky
Sparky,
I can’t take credit for it. The post was by fellow member Beestung. I would have forwarded the entire thread but, being tech challenged, I simply cut and pasted that post taken from a long thread. I learned from it that ELI5 means “explain it like I’m 5” which aligns perfectly with my intellect. A career of working around engineers has taught me that people with deep knowledge of technical matters often have trouble simplifying things and I was very pleased to stumble upon Beestung’s post. Good luck on your repairs. Mine went pretty uneventfully with the help of Beestung. Cheers!
 

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2009 Bonnie A-1. 1968 T120R
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Discussion Starter · #13 ·
Well thanks Beestung wherever you are.
 
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