Author Topic: 1980 CB650 Strange overheating issue? (Read 5255 times)

curemode2002 · « **on:** June 06, 2011, 01:51:32 PM »

So I finally got my CB650 back out on the road after a rough year of electrical gremlins. Ran great for the most part but after sitting in traffic for like 10 minutes I pulled into the lot at work and she died on me. When I tried to start her again the motor would barley turn over, and I noticed the motor was really hot (hotter than I remember it being its only 75 here today). After being outside in the breeze and cooling off she starts right up. Oil is brand new with a new filter and I popped one of the cam covers and she is oiling the upper end. Also checked the voltage on the battery after all my electrical crap last year just wanted to be safe and she is at full voltage.

Could the issue be my slow jets running lean at idle or am I barking up the wrong tree?

c(b)hris · « **Reply #1 on:** June 06, 2011, 02:08:51 PM »

i might be wrong but i think mine was stalling because it was starving and overheating.
what do your plugs look like?
airscrews too lean? stuck floats? clogged idle jet? clean carbs/tank?

curemode2002 · « **Reply #2 on:** June 06, 2011, 02:17:05 PM »

Plugs looked okay last time I pulled them but I will check. Air screws might be the issue as I just adjusted those maybe she wasn't warmed up enough or something I will check that tonight along with the plugs, carbs just got cleaned up same with the tank so I am good there.

c(b)hris · « **Reply #3 on:** June 06, 2011, 03:36:43 PM »

tuneup? I think tight valves makes it hot.

Frankenkit · « **Reply #4 on:** June 06, 2011, 04:03:40 PM »

If it's valve clearances, somewhere on here Hondaman has a recommendation for 650 valve clearances, a bit greater than the Clymers and honda service manual recommends because these bikes had a tendency to burn valves.

curemode2002 · « **Reply #5 on:** June 07, 2011, 07:40:29 AM »

I checked the plugs last night and it is definately running lean I adjusted the air screw to run a little rucher at idle and she burbles and misses a little but that is normal from what I am reading in Hondaman's posts. I still need to look at my needles though will do that this weekend. And I did just finish my valve adjustment per the manual so I will go with the .005 that Hondaman recomended and see if that helps too.

P.S. does anyone know where to get a resonably price petcock for the CB650 all of them I have found are over 100.00+?

Frankenkit · « **Reply #6 on:** June 07, 2011, 08:21:37 AM »

here

ebay also has rebuild kits for $20ish and a bunch of other petcocks for around $65.

Pinhead · « **Reply #7 on:** June 07, 2011, 12:13:35 PM »

I honestly doubt you're experiencing anything out of the ordinary. 10 minutes at idle with no airflow is enough to cook these bikes.

Look up the CB650 "Hot Start" thread...

Frankenkit · « **Reply #8 on:** June 07, 2011, 04:56:45 PM »

Guh. I hate that thread.

The summary of that problem [for me] was actually the black cable that ran from the starter solenoid to the starter under the aluminum side cover by the front sprocket. It was kinked and crappy, and when it got hot (because the motor had gotten hot) the increase in resistance was just enough to keep it from cranking decently when the bike was at operating temp. Once it had cooled down some 10 minutes or so, it'd crank fast enough to start the bike. Combining that with an alternator that wasn't putting out quite as much juice as it ought to, I really needed a miracle to get the bike to start (within 10 minutes or so) if it ever died on me.

With the new cable, it spins the starter wicked fast, and when hot, well... I dunno how it spins. The bike always starts before I can hear the starter motor spin much at all.

TwoTired · « **Reply #9 on:** June 07, 2011, 05:39:34 PM »

You need to do some isolation.
Not turning over at hot start can have several causes.

Current limited getting to the starter. (Cable cross section area restriction)
Starter weak from low voltage. (Battery in poor state of charge.)
Starter bearings worn and armature scraping the motor frame (causes huge current draw. Can see the voltage drop from good, to severely low while starter engaged.)
High resistance to the engine turning when hot. As in, the pistons swelling too much and fitting tightly in the cylinders.

One thing fairly easy to isolate is engine friction. You don't have a kick start to feel kick over. But, you do have top gear and can push the bike with the clutch in and then let it out to feel the engine drag while pushing it (spark=off). Get a baseline reference by doing this when cold. When you encounter a hot start issue. Do the push test again. If it is way harder, you have piston drag, which is not good.
I use a synthetic blend for those cases where it is impossible to keep air flow over the engine, as the synthetic will still do the lubrication thing at a higher temperature than ordinary refined oil. (Sorry, to do it, but I just gotta mention oil. Hot engines can damage oil.)

Cheers,

curemode2002 · « **Reply #10 on:** June 08, 2011, 07:22:38 AM »

Actually I took the time to go through Kit's thread yesterday and I think I am looking at either a starter issue or cable issue. My ground line is pretty mangled and the battery end is quite corroded thanks to the PO leaving an old battery in it for five years. I have actually done the bump test you mention TT by accident I inadvertently hit the kill switch trying to bump start the bike, when I realized my problem she started right up no issues. So out of curiosity I tried it cold felt the same to me so I think I am good there. But the synthetic is a really good idea what brand and weight do you recommend?
Oh by the way battery is at 13.2 volts cold, 13.1 hot so I think my charging is okay I will test the starter draw tonight.

TwoTired · « **Reply #11 on:** June 08, 2011, 11:54:05 AM »

Quote from: curemode2002 on June 08, 2011, 07:22:38 AM

But the synthetic is a really good idea what brand and weight do you recommend?

The oil weight is whatever the owners manual states, since I believe Honda made a pretty good engine, knew what they were doing, and I am running factory tolerances. In my climate, that's 10W-40. (I have tried 20W50 on occasion back in the 80's, but only in the very hottest summer months and changed it every 1000 miles. I don't do oil changes that rigorously anymore, since I switched to semi synthetic.)
I figure Honda's own HP4 without moly is a safe bet and use this regularly.
I have also used Spectro Golden 4 10W-40 (Motorcycle oil).
Red Line 10W40 Motorcycle Oil (Spendy)
Amsoil 10W-40 Advanced Synthetic Motorcycle Oil (inconvenient to obtain)
I wouldn't mind using Rotella brand in synthetic or blend for diesels, as long as it doesn't say "energy conserving" on the label. However, I don't trust Shell branding practices (or any of the market dominant brands, for that matter).

The problem with all the brand names is that they have no obligation to keep the same formulation inside the brand label. If it doesn't say it's for wet clutch motorcycle use, what worked fine last week may not work well next week when they change the blend going into the container for any reason they chose. They don't have to tell you the ingredients or proportions that are in the bottle. And, they don't have to tell you when the contents, ingredients, or proportions have changed. Unfortunately, you don't stuff the label inside your engine, which may be the only thing consistent from batch to batch of production. Further, as the applicable standards evolve, so do the oil blends inside the container, whether the label changes, or not. Pretty much like tax forms, the system is designed to confuse the user/ consumer/ payer.

Sigh. I suppose an oil "discussion" is inevitable.

Cheers anyway,

curemode2002 · « **Reply #12 on:** June 08, 2011, 12:54:32 PM »

Thanks TT that points me in a good direction, I have used the Rotella blend for the last two changes and it has worked well but maybe that is part of my hot start issue. I will see if I can get a hold of the HP4 from Honda.

curemode2002 · « **Reply #13 on:** June 09, 2011, 08:12:10 AM »

Went to start her last night and the battery was low (11.6) she would not start so it looks like my charging issues are back. I will run through the starter, cables, solenoid, stator and connections and let you all know what I find out.

curemode2002 · « **Reply #14 on:** June 10, 2011, 07:35:57 AM »

Okay here is the skinny I cleaned all of the connections for the starter, positive, ground, stator, Reg/Rec, Starter Solenoid and anything else I found along the way. She actually started up at 11.6 volts so I did some testing, cold at 4000 rpm I get 12.8 volts and hot I am getting 12.4 volts. I left the meter on over time as well to see if it was trending up or down. At 4000 cold or hot it held steady, after cleaning everything up at idle cold she climbs on 100th of a volt every 20 sec or so, before cleaning it would drop one 100th ever 5 seconds so the clean up definitely helped. So I decided to measure the resistance on my rotor, I am just barely getting 4ohms we I say barely it reads at 3.96 ohms then climbs just a little to 4.0ohms so it looks like my rotor is toast. But the stator measured out at 1.1ohms on the coil connections does that sound right or wrong?

Frankenkit · « **Reply #15 on:** June 10, 2011, 08:13:48 AM »

The stators rarely go bad in these bikes, but the same is not true for the rotors. Sounds like it's shorting internally so you're right on about that, but I'm not sure about the stator reading.

for $80, this guy does good work.
http://www.tpe-usa.com/

curemode2002 · « **Reply #16 on:** June 10, 2011, 08:32:39 AM »

Thanks Kit! that is like 40.00 cheaper than anything else I have found.

TwoTired · « **Reply #17 on:** June 10, 2011, 08:54:51 AM »

When the alternator is asked for full power output, a 4 ohm rotor will draw 3.15 amps., a 5 ohm rotor will draw 2.52 amps, and a 6 ohm rotor will consume 2.1 amps of it's own output.
If the rotor has shorted windings, the full alternator capability is reduced from standard value.

When noting trend voltage data, it is important to know what the alternator rotational speed is.

Stators rarely go bad without some physical abuse. (Crash, axe, 50 cal, connecting battery backwards, etc.) Further, reading very low resistances, requires impeccable tester technique, and highly accurate test equipment. A digital display is not an indicator of accuracy, btw.

Cheers,

Frankenkit · « **Reply #18 on:** June 10, 2011, 09:02:00 AM »

Quote from: TwoTired on June 10, 2011, 08:54:51 AM

When the alternator is asked for full power output, a 4 ohm rotor will draw 3.15 amps., a 5 ohm rotor will draw 2.52 amps, and a 6 ohm rotor will consume 2.1 amps of it's own output.
If the rotor has shorted windings, the full alternator capability is reduced from standard value.

Sorry to be dense, TT, but how does one go about testing the amp draw of an alternator, then?

TwoTired · « **Reply #19 on:** June 10, 2011, 09:29:44 AM »

Quote from: Industrial Kit on June 10, 2011, 09:02:00 AM

Quote from: TwoTired on June 10, 2011, 08:54:51 AM
When the alternator is asked for full power output, a 4 ohm rotor will draw 3.15 amps., a 5 ohm rotor will draw 2.52 amps, and a 6 ohm rotor will consume 2.1 amps of it's own output.
If the rotor has shorted windings, the full alternator capability is reduced from standard value.
Sorry to be dense, TT, but how does one go about testing the amp draw of an alternator, then?

By inserting an ammeter in the path between regulator and slip rings.
But, it's the same information you can get by measuring the resistance, voltage applied, and applying ohm's law.
I = E/R , 12.6V/4Ω = 3.15A

Cheers,

Frankenkit · « **Reply #20 on:** June 10, 2011, 10:02:15 AM »

Thanks, TT!

curemode2002 · « **Reply #21 on:** June 10, 2011, 01:16:32 PM »

Yeah I kinda just did an informal test to see if the cleaning was helping. And in regards to the damage you spoke about TT the PO did burn up the top end once and rebuilt it as well as crashed it twice on the left side so it has definitely been beaten up quite a bit. Also I noticed that some of the varnish is flaking off of it as well.

curemode2002 · « **Reply #22 on:** June 10, 2011, 01:31:26 PM »

Sorry that is the rotor the stator looks good as far as I can tell I will check the amps.

Duh!

curemode2002 · « **Reply #23 on:** June 13, 2011, 07:57:37 AM »

Okay cold running at 12.6volts I was reading 3.23amps on both rings, hot it got up to 12.6volts and 3.07amps on one and 3.19 on the other. Well as best I can tell as I only have one meter so I couldn't see the voltage at the battery at all times. I did check the resistance on the lines to the slip rings and there was no measurable resistance. So looks to me like the rotor is on its last leg. Also in the process I found the starter is still cranky with good voltage so I am going to rebuild that in the process.

curemode2002 · « **Reply #24 on:** September 12, 2011, 01:31:33 PM »

First things first the thank yous!

Industrial Kit: Thanks for turning me on to Tim Parrott http://www.tpe-usa.com/ !

TwoTired: Thanks for all for all of the testing know how and advice!

Tim Parrott: This guy does awesome work with Stator Coils and Charging Rotors if you ever need a rebuild check him out http://www.tpe-usa.com/ ! He is also one of the nicest guys I have done business with for quite a while.

All of the Other Folks who offered advice and support that is what makes this Forum Great!

I thought I would throw out an update just to cover what my problems were as the search pulled back some info that was helpful but not each piece I needed in one place. Industrial Kits thread "The Ever-Popular CB650 bad charging 'issue', formerly hot start 'issue'" http://forums.sohc4.net/index.php?topic=42826.0 is awesome not my particular problem but lots of great info. Now on to my solution.

First: Clean, Clean, Clean and Clean some more....

I took four hours, three cans of electrical connector cleaner, a package of steel wool and half a tube of dielectric grease to clean every connection on my bike. Take your time doing this disconnect your connections one by one I pulled everything apart in my headlight bucket at once and it took a good hour with the wiring diagram to get it all back together.

Second: Testing 1, 2, 3, 4...

Buy a decent multi-meter and test everything! I could have saved money and time had I just invested 30 minutes testing the first time around! :

Here are the big ones for me.

Battery - On the CB650 if you use the stock or OEM battery you should have 12.6 volts to 13.6 volts fresh of a good charger. If you don't stop now!

You may have a bad battery and the rest doesn't matter until this is good!

My battery had good fluid levels and always ran about 12.8 volts fresh off the charger.

Negative Battery Cable (Ground Cable) - This cable goes from the negative battery terminal to a frame mount, this cable should be 0 Ohms make sure you clean it well along with the mounting points, also it is a good idea to test cold and hot as temperature combined with corrosion can add resistance. My Cable read .9 Ohms on my meter once it was all cleaned up hot or cold (my multi-meter reads .9 Ohms test lead to test lead).

Positive Battery Cable - This cable goes from the positive battery terminal to your starter solenoid, this cable should be 0 Ohms make sure you clean it well along with the mounting points, also it is a good idea to test cold and hot as temperature combined with corrosion can add resistance. My Cable read .9 Ohms on my meter once it was all cleaned up hot or cold (my multi-meter reads .9 Ohms test lead to test lead).

Starter Cable - This cable goes from your starter solenoid to the starter, this cable should be 0 Ohms make sure you clean it well along with the mounting points, also it is a good idea to test cold and hot as temperature combined with corrosion can add resistance. My Cable read .9 Ohms on my meter once it was all cleaned up hot or cold (my multi-meter reads .9 Ohms test lead to test lead).

Charging Rotor - This is the spinning part of your stator setup and is very fragile on the CB650, the rotor should read 4.4 Ohms to 5.6 Ohms from slip ring to slip ring for the LD119 part number. My old rotor would read 3.96 Ohms cold and .9 Ohms hot so my rotor was shorting out when hot!

Charging Rotor Brushes and Lines - From the stator cover you have a connector running off of five lines, the White and Black lines run to the rotor brushes, these lines to the brushes should be 0 Ohms (usually there will be minor measurable resistance in my case with my .9 Ohms on the meter 1.1 Ohms). Make sure when you test the brushes you depress the brush I have one set that reads good until you depress them then they read over 100 Ohms!

Stator Coils - From the stator cover you have a connector running off of five lines, the three yellow lines are your stator coils. From connector to connector you should have 0 Ohms (usually there will be minor measurable resistance in my case with my .9 Ohms on the meter 1.0 Ohms). I have two stator coil sets on bad and one good measure yellow 1 to yellow 2 and then yellow 3 now switch to yellow 2 to yellow 3. They should all be the same if you have any measurable resistance the coils are bad.

Charging Rotor Line to Line with the Stator Cover in place - These are the White and Black lines we measured to the brushes in this case we are measuring through our charging rotor, we should get roughly the same resistance. In my case my rebuilt rotor reads 4.7 Ohms slip ring to slip ring with the cover in place I get 5.2 Ohms hot or cold.

If you have any resistance clean your slip rings and brushes again or check to see if the brushes are worn past the reference mark (a simple line molded into the graphite brush).

Three: Take your time ask questions if necessary I could have saved a ton of time and a pocket full of money!

Here is what I found out from all the testing and help. My Charging Rotor was shorting out at operating temp which pulled extra juice from the battery to try and charge the bike (see tt's posts above for info on what is happening). This in turn fried my first and second Regulator/Rectifier replacements. Also when I fried the second R/R it seems to have fried one of my two Stator Coils as well. I had a boat load of dirty high resistance connections causing issues from here to the moon just a bit of cleaning solved some other weird issues the bike had.

Here is what I replaced:
Rebuilt Charging Rotor - Tim Parrott Enterprises http://www.tpe-usa.com/
Used Stator Coil and Like new Cover - feebay
New Solid State Regulator/Rectifier - Willies Cycle http://www.williescycle.com/

I hope someone can learn a bit from this and if you want to add anything post it because it's awesome to have any new info that can help someone else!

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Author Topic: 1980 CB650 Strange overheating issue? (Read 5255 times)