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Starting a rusty '82 KZ750

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30 Aug 2019 10:28 #810099 by loudhvx
Replied by loudhvx on topic Starting a rusty '82 KZ750
14.86v is a bit high. You will eventually want to measure the voltage drops in the path between battery and regulator. Those drops are what the regulator compensates for, but then the voltage on the battery ends up too high.

Most common places for voltage loss is the fuse holder area, then switches, then connectors.

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30 Aug 2019 11:03 #810101 by Nessism
Replied by Nessism on topic Starting a rusty '82 KZ750
If there is voltage drop between the battery and regulator that means that 14.86 VDC will be even higher once it's cleaned up. Not ideal for sure. Should be about 14.5 VDC at the battery as the max. That's what I get with a SH775 R/R.

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31 Aug 2019 09:35 #810141 by loudhvx
Replied by loudhvx on topic Starting a rusty '82 KZ750
Once the voltage loss is cleaned up, the voltage will be lower on the battery.

Normally, the regulator senses the system voltage through the sense line and assumes it is the same as the battery voltage. The regulator will increase output to the battery (if it can) until the sense line reaches the desired voltage and then hold it there. If there is a bad connection in the sense line path, the sense line voltage will be lower than the battery voltage. Thus the regulator increases output to the battery until the sense line is at the desired voltage. The result is that the voltage on the battery is too high.

Once the bad connection is cleaned up, the sense line and battery will be at the same voltage, so the regulator will no longer have to overcharge the battery to get the sense line voltage up to the desired value.

So the symptom of overcharging the battery can be either a bad regulator or a bad connection on the sense line.
If the regulator does not use a separate sense line (and uses the output wire as the sense line) then that only leaves the regualtor as the culprit. Most Kz's have the sense line (brown wire on the regulator), but not all.

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31 Aug 2019 10:13 #810145 by Nessism
Replied by Nessism on topic Starting a rusty '82 KZ750

loudhvx wrote: Once the voltage loss is cleaned up, the voltage will be lower on the battery.

.


Okay, I forgot that most of the stock Shindengen R/R's used a sense signal. On a more conventional R/R that won't be the case though.
The following user(s) said Thank You: loudhvx

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06 Oct 2019 21:18 #811952 by Tvag06
Replied by Tvag06 on topic Starting a rusty '82 KZ750
Hey folks. FYI I sold this bike and will be working on my '80 440 project. Thanks for all your help. Enjoyed the 750 but sold it and bought a 04 Suzuki DL650 with a gas leak. Looking forward to getting the 440 on the road.

'80 KZ440D - Stripped for rebuild - kzrider.com/kunena/11-projects/611352-st...ng-a-rusty-80-kz440d
'04 Suzuki DL650 K4 V Strom

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10 Oct 2019 14:59 #812199 by Tvag06
Replied by Tvag06 on topic Starting a rusty '82 KZ750
Funny thing. The guy I sold the bike to called me and said his carbs were greasy. So I went down there, cause I know the guy, and I take a look. Sure enough the carbs have an oily film on them. A little bit had even dripped down onto the starter cover. Looks like motor oil. Thoughts?

'80 KZ440D - Stripped for rebuild - kzrider.com/kunena/11-projects/611352-st...ng-a-rusty-80-kz440d
'04 Suzuki DL650 K4 V Strom

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11 Oct 2019 07:05 #812242 by loudhvx
Replied by loudhvx on topic Starting a rusty '82 KZ750
Maybe the vent hose is plugged and a leak is spewing oil on the carbs?

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11 Oct 2019 07:21 #812245 by Tvag06
Replied by Tvag06 on topic Starting a rusty '82 KZ750

loudhvx wrote: Maybe the vent hose is plugged and a leak is spewing oil on the carbs?


I like it! I'll put that on a list of things to check. I did not know that even was a thing.
I also will see if the valve cover is weeping. After reading up on the forum some more maybe it needs to be re-toqued. I only torqued it once and now realize it needs a re-torque.

Still learning.

'80 KZ440D - Stripped for rebuild - kzrider.com/kunena/11-projects/611352-st...ng-a-rusty-80-kz440d
'04 Suzuki DL650 K4 V Strom

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11 Oct 2019 07:37 #812248 by loudhvx
Replied by loudhvx on topic Starting a rusty '82 KZ750
A clean gasket install on the valve cover shouldn't need a re-torque, but I don't think it would hurt to check.

I'm not sure what you did with the clean air system and the vent pipe that came from the crankcase to the airbox. If it's all stock, it probably won't get plugged. If there is a vinyl hose on the breather, sometimes the vinyl can kink and cause the crankcase to start to build pressure which would really push oil out of the seals.

If the vent was just left wide open, it will spray a bit of oil upward and air circulation will spread it over the carbs.

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11 Oct 2019 09:21 - 11 Oct 2019 09:22 #812252 by Tvag06
Replied by Tvag06 on topic Starting a rusty '82 KZ750

loudhvx wrote: A clean gasket install on the valve cover shouldn't need a re-torque, but I don't think it would hurt to check.


Ok. That's what I thought but after reading some posts I think its worth a look. I can't recall anything about the breather except it didn't stand out to me. There wasn't a wide open hole as I would have noticed that. Maybe the hose is cracked or free. Won't be able to see for a time since I don't have the bike. It's bugging me now tho!

'80 KZ440D - Stripped for rebuild - kzrider.com/kunena/11-projects/611352-st...ng-a-rusty-80-kz440d
'04 Suzuki DL650 K4 V Strom
Last edit: 11 Oct 2019 09:22 by Tvag06.

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