NC21 Electrical Problem

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decngb
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NC21 Electrical Problem

Post by decngb » Sat Nov 09, 2019 9:24 pm

I'm still working on my NC21. It had been running mostly well, but then would occasionally lose power when warm. It would start and run again after cooling down a bit. I think I'm dealing with a couple of issues. I also have an NC24 with an NC21 engine, so I have known good parts to swap around.

We have confirmed that we have spark and fuel (I moved the good carbs over from the NC24). It was running, and in fact we got it to start today. The battery is not getting charged, even though I moved the R/R and battery over from the other bike. The voltage does not vary at all with RPM. I suspect the stator, but resistance and voltage checks do not indicate a stator problem. I want to put this problem on the back-burner until we get the other issue resolved.

Now, we can rarely even get the bike to start. I've check for spark and fuel in all 4 cylinders, checked all the wiring, swapped the CDI and more. At one point it did start today, but eventually acted like it did like time it was out for a ride - gauges went haywire and eventually the engine quit, seemingly due to low voltage.

I know I need to correct the charging system, but even with a fully charged battery this thing is not right. I'm wondering if the camshaft sensor can be a problem when warm. I'll let it cool down completely to see if it will start again.

Does anyone have any ideas?

Suzuki416
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Re: NC21 Electrical Problem

Post by Suzuki416 » Sat Nov 09, 2019 11:38 pm

Have you taken the cover off to look at the stator?

It can tell you quite a lot..

decngb
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Re: NC21 Electrical Problem

Post by decngb » Sun Nov 10, 2019 12:17 am

I took the cover off, but the flywheel needs to come off to get to the stator. None of my flywheel pullers works, so I have to order the right one for that job. Meanwhile, I'm working on the difficulty starting. I have tried swapping the cam position sensor with no luck. I cross-posted this to a Facebook group, and tight valves were mentioned as a possibility. We did a valve adjustment within the last year, but I will check them again. This is one of 4 Honda V4s we've done adjustments on, so I doubt this is the problem unless something is causing it to quickly fall out of adjustment.

magg
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Re: NC21 Electrical Problem

Post by magg » Sun Nov 10, 2019 7:35 am

"Gauges went haywire" suggests electrical. If engine cranks well, then battery must be ok. Not familiar with NC21 loom but it must have a chassis earth lug somewhere. NC30 one is located on left side of the frame in front of the ignition coil. Might be worth a look to see if it is in good condition, otherwise an inspection of the condition of the loom and the various connectors.

Suzuki416
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Re: NC21 Electrical Problem

Post by Suzuki416 » Sun Nov 10, 2019 11:47 am

PLUGS, PLUGS, PLUGS. - They love new plugs.
EARTHS, EARTHS. - Make sure the FRONT COILS are earthed (on the right side of the frame).

These bikes are REALLY intolerant of not starting.

decngb
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Re: NC21 Electrical Problem

Post by decngb » Sun Nov 10, 2019 5:31 pm

Suzuki416 wrote:
Sun Nov 10, 2019 11:47 am
PLUGS, PLUGS, PLUGS. - They love new plugs.
EARTHS, EARTHS. - Make sure the FRONT COILS are earthed (on the right side of the frame).

These bikes are REALLY intolerant of not starting.
We have a winner! It looks like the front coil ground was loose! Thanks for the reminder - this should have been the first thing I looked at since it was doing strange things since we changed the carbs. The amazing thing is that seems to have been the cause of everything including the lack of charging. I can imagine how badly grounded coils would still generate a spark, but I would have expected it would still charge the battery (while the engine was running).

We only ran it with the fuel that was in the carbs, so a test ride is in order to verify it is really better. My son will take the NC21 while I take my father-in-law's V65 Magna. We've been working on the Magna for a while since it was parked for years needing a lot of repairs. We've been through a bunch: cam chain tensioners, valve adjustment, muffler repair, clutch bushing, fork pressure balancing tube, seized brakes, all fluids, main fuse, tires, and probably other things I'm forgetting.

decngb
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Re: NC21 Electrical Problem

Post by decngb » Sun Nov 10, 2019 6:59 pm

I'm happy to report is is still running great after a 25 mile ride. I have a voltmeter installed and saw 14V at speed and down to 12.7V at idle with the headlight on. That's a little low at idle, but turning off the headlight got it well over 13V at idle.

Suzuki416
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Re: NC21 Electrical Problem

Post by Suzuki416 » Sun Nov 10, 2019 9:37 pm

The reason I mentioned the earths is that 2 months ago I'd also forgotten to do it - lol
& the annoying thing was that it wasn't until I pulled the carbs that I could check it - ha, ha, ha..
My front one was loose - attached but not torqued up.

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Re: NC21 Electrical Problem

Post by magg » Mon Nov 11, 2019 1:12 am

Headlights on at idle is mostly battery power, no battery charge hence the low voltage reading.


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