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1Back to top Go down    start, idles, revs, then dies. on Wed Apr 27, 2016 3:31 pm

desperado

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Hey guys

I tried my best to search around the forum for thoughts on this subject because I'm sure something similar has been covered before, so I apologize if I'm just missing some valuable threads on the topic.

If the bike is cold, I can start it up and let it idle. I can apply throttle and it seems to be an incredibly happy, normal brick. After about 10-15 minutes of idle with a few intermittent revs to the throttle, the bike will die.

From there, the issue gets progressively worse in what I have broken into 3 stages. The first stage is what I described above. It then gets a level where the bike will idle but any attempts to apply throttle and the bike will cut out. After a few moments of that, we get to stage 3. The only noise I can hear is starter motor and the engine will never actually start.

I've checked electrical connections into the tank and onto the fuel pump itself. I also tried it with the gas cap open to be sure it wasn't a venting issue. From various searching around the web and the forum, I've come up with a few other possible culprits: Hall effect sensor or starter motor seem the most likely. I thought about starter/kill switch but it seems less likely to me because of the progressive nature of the issue.

Anything else I'm missing?

I first encountered the issue on a recent long trip. I was up in Washington/Idaho and had ridden the bike for about 4 hours in the morning. I stopped in Spokane and explored the city a bit while stopping and starting the bike a handful of times. I then crossed into Idaho and stopped in Couer d'Alene for lunch, about 30 minutes from Spokane. As I left, Couer d'Alene, after the bike sat for about an hour, I made it about 4 miles and the bike died. A series of other adventures and tons of help from friends got me home to Los Angeles and now I'm trying to sort out my issues.

Any and all help/thoughts/links/punches-in-the-face will be appreciated.


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1985 K100RS
Los Angeles, Calif.
    

2Back to top Go down    Re: start, idles, revs, then dies. on Wed Apr 27, 2016 4:08 pm

Motorbike Mike

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If it were my bike I think I'd be taking another look at the fueling side, it could still be the pump.
Have you tried another pump?

    

3Back to top Go down    Re: start, idles, revs, then dies. on Wed Apr 27, 2016 4:10 pm

desperado

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Motorbike Mike wrote:If it were my bike I think I'd be taking another look at the fueling side, it could still be the pump.
Have you tried another pump?

Actually yes. I had the purolator ford escort mod pump in it. Put the stock pump back in today. Same issue. Should have mentioned that. I had also gone through some injector cleaner about 4-500 miles prior to the issue. Thanks for the thought though.


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1985 K100RS
Los Angeles, Calif.
    

4Back to top Go down    Re: start, idles, revs, then dies. on Wed Apr 27, 2016 4:31 pm

Motorbike Mike

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That's me out of immediate ideas.
You're obviously on the right track looking at the electrical side and would think it's a component breaking down with the effect of heat. The HES would be the next suspect as it is after all, bolted up inside a hot engine casing.

Good luck.

    

5Back to top Go down    Re: start, idles, revs, then dies. on Wed Apr 27, 2016 4:35 pm

desperado

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Motorbike Mike wrote:That's me out of immediate ideas.
You're obviously on the right track looking at the electrical side and would think it's a component breaking down with the effect of heat. The HES would be the next suspect as it is after all, bolted up inside a hot engine casing.

Good luck.

Thanks for your input. Just someone agreeing that I'm on the right track feels good. I'll try to test out the sensor and may order a few spares just to have anyway.


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1985 K100RS
Los Angeles, Calif.
    

6Back to top Go down    Re: start, idles, revs, then dies. on Wed Apr 27, 2016 5:25 pm

Beamer_Bill

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IF you are checking the HES be very careful that you get the polarity correct or have a diode to prevent component smoke ! Some one got it wrong recently and toasted them. Use of a heat gun or girlfriends hair dryer to simulate heat and freeze mist to chill would be a good diagnostic choice. Very angry was the result as they were not easily or cheaply replaced. affraid

    

7Back to top Go down    Re: start, idles, revs, then dies. on Wed Apr 27, 2016 5:36 pm

Motorbike Mike

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desperado wrote:
Motorbike Mike wrote:That's me out of immediate ideas.
You're obviously on the right track looking at the electrical side and would think it's a component breaking down with the effect of heat. The HES would be the next suspect as it is after all, bolted up inside a hot engine casing.

Good luck.

Thanks for your input. Just someone agreeing that I'm on the right track feels good. I'll try to test out the sensor and may order a few spares just to have anyway.
I think I have at least one spare part of everything (and I do mean everything) just in case.

    

8Back to top Go down    Re: start, idles, revs, then dies. on Wed Apr 27, 2016 9:15 pm

Holister

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Certainly sounds heat related.

Faulty temperature sensor. You can check this easily by removing the FICU plug under the seat and measure the resistance between pin #10 and any earth (pin #13 on the plug) counting ALL pin spaces from the lead end of the plug. Ignition is OFF. Do this for cold (about 20oc) and operating temp (about 80oc) after 15 mins of idle. You should be reading 2.5k ohm at cold and around 300 ohms at operating temp.
There are instructions and a temp scale for this on the 'Trouble Shooting' page off the portal tab.

If that's ok, check your HES with a hair dryer to warm them up while the engine is cold. Don't use a heat gun as you may destroy the wiring insulation. Alternatively, and a better method imo, when the symptoms appear, whip the timing cover off and spray the HES with a can of freeze. Symptons should disappear.

Its also worth checking/cleaning all your connections like the FICU and ICU plugs. These can come loose. Earth connections need a good clean. Frame under the tank, gear box and the starter motor brushes and mounting bolts provide an important earth as well. Make sure your battery is good.

Cheers


__________________________________________________
1988 K100RT VIN No. 0094680
1989 K100RT VIN No. 0097367 (naked)
1996 K1100RS VIN No. 0451808
Fuel: 95 Octane
Engine Oil:Nulon Full Synthetic 15W50
Gear Box Oil: Nulon Synthetic 75W90
    

9Back to top Go down    Re: start, idles, revs, then dies. on Thu Apr 28, 2016 12:54 am

Point-Seven-five

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My money is on the Hall Effect sensors. A bad temperature sensor will make the engine run rich when hot, but I doubt that it would prevent it from starting and idling. In all my years working on engines the only parts of an engine that don't work better when hot is the electronic stuff. If they don't fail outright, they will be intermittant at high temperature.

A problem that appears after some running time and then goes away after the engine cools down usually points to electronics. The electronic devices closest to the heat with the least cooling on a K bike is the Hall Sensors. That's where I would look first.


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Present:
1994 K75RT
1994 K75S
1992 K100RS

Past:
1982 Honda FT500
1979 Honda XR185
1977 Honda XL125
1974 Honda XL125
1972 OSSA Pioneer 250
1968 Kawasaki 175
    

10Back to top Go down    Re: start, idles, revs, then dies. on Thu Apr 28, 2016 4:55 pm

desperado

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Looks like it is the hall sensors that are causing my troubles. Temp sensor seems to be working ok. I tested with freeze spray on the sensors and the back would gain back a few minutes of correct behavior. I got out my infrared temp gun and it seems that the sensors stopped functioning forrectly at 120-125F. I sprayed it down with freeze spray to get it down to 95F and then the bike would behave normally again until I got towards 120F.

I've seen elsewhere on the forum that www.hallsensors.de is the choice for new sensors. I guess I'm going to grab a couple from them, model CYHME56C. Any one else have other input on that? I'm guessing while I'm at it, I should check the shielding on the wiring and such.


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1985 K100RS
Los Angeles, Calif.
    

11Back to top Go down    Re: start, idles, revs, then dies. on Thu Apr 28, 2016 6:44 pm

Holister

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There are two options.

  • HES from hallsensors.de will need to be riveted onto you timing plate and the leads spliced into the HES loom. There is a link to instructions on the forum. Just do a forum search for HES. You'll find the info if you haven't already. An easier option to riveting would be to screw them on with ss bolts and nylock nuts. I've not done this but it's been suggested here. BTW, you won't need the CYHME56'C'. They're for heavy duty industrial applications where interferance may occur.

  • If you want the easier replacement method but more expensive, you can purchase the complete timing plate with HES and shieldied harness with connector from EME. The connector under the tank will need replacing with parts supplied with the unit.


Refurbish the old one and keep as a spare.



Last edited by Kaptain Holister on Thu Apr 28, 2016 11:14 pm; edited 1 time in total


__________________________________________________
1988 K100RT VIN No. 0094680
1989 K100RT VIN No. 0097367 (naked)
1996 K1100RS VIN No. 0451808
Fuel: 95 Octane
Engine Oil:Nulon Full Synthetic 15W50
Gear Box Oil: Nulon Synthetic 75W90
    

12Back to top Go down    Re: start, idles, revs, then dies. on Thu Apr 28, 2016 6:54 pm

Motorbike Mike

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I can get a new and complete HES set but they are 195!!

Gulp. 😥

    

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