Topic: Think I might have overheated my bike

[hyde7278]

I have a 77 CB550 with stock airbox and 4-4 exhaust. I was letting the bike run for a while with some seafoam in the oil so I can change the oil and change to my 4-1 exhaust. It was running maybe 15 minuted at an idle of about 1200 rpm. I switched the HI beams on the light flickered and caused the bike to stall out (have to go through the wiring harness and clean all the connectors) After the bike did I hit the starter button and the bike just cranked and wouldn't catch. I know I have spark to 1 and 4 as I could see #1 end cap arking to the motor and when I went o move it while cranking I felt a shock also felt a shock on #4. Didn't check 2 or 3.

My question is do you guys think the bike was just overheated and that's why it wouldn't catch or possibly something else. Up till I switched on the high beam the bike was running quite good. The bike has a new Battery and a full tank of gas.

I haven't done any work on the bike as I just picked it p from the PO who hooked up the battery backwards. The only thing I have done was replace the electronics panel and rectifier because of the damage caused by the PO mistake.

On a side note when the bike idles below about 1200 RPMS there seams to be a rattle from the motor as the RPMS are increased it goes away. It doesn't change when I pull the clutch, could it be a misadjusted cam chain or is this normal on these motors.Sorry for being long winded but wanted to give as much info as possible

Thanks for any help in advance

Sean

[Bob Wessner]

Fifteen minutes of standing idle is a long time. You should use a fan directed at the motor. At only 1200 RPM, you weren't charging anything and it was running off the batt.

[hyde7278]

I kind of figured that, Im going to give it a chance to cool down and see if she will restart. The battery had plenty of juice to turn the bike over but it just wouldnt catch.

[TwoTired]

Bike won't run at idle with a depleted battery and lights on.

Check the voltage.  Might still have charging issues.  But, the battery runs in depletion mode at idle.  Extra electrical loads run it down faster.

After you change to the 4-1, *then* expect overheating.  (Unless, you change carb settings.)

Also, remember its an air cooled motor.  Stationary running doesn't cool it very well at all.  Box window fans help that a great deal.

The kick start sometimes works when the electric start doesn't.

[hyde7278]

TT thanks Ill try the kicker

Ill go out and check the battery voltage right now

Im definitly going to re jet after the exhaust change but thanks for the heads up

After it died the battery still had plenty of power to turn the motor over easily If this has any revance

[TwoTired]

After it died the battery still had plenty of power to turn the motor over easily If this has any revance

I'd that was a good sign.  And overheated motor usually seizes pistons.

Check battery.   ...And the fuel level in the gas tank.

[hyde7278]

Just checked the bike after it sat for awhile. The battery voltage was 12.11v alittle low I think, I was able to get it started and the bike reved with no problem. The headlight was alittle dim. So Ill charge the battery and make sure I have a fan on it when letting it run in the garage.

TT
I knew I didt seize the motor I thought I got it to hot that it either possibly vapor locked the fuel or the motor was to hot and may have been pre detonating causing the motor not to run.
Also as I stated I had a rattle for a better word at low RPMS that went away when I reved it past 1500-1600 was wondering if this is normal or is it possible its a misadjusted cam chain tensioner

thanks again for the feed back

[TwoTired]

The rattle may well be trans gear clack or the clutch basket.  If it changes sound when you pull in the clutch, that's probably it.
Carb sync and peaking the tune up items can affect this, too.  You need to have every cylinder making the same power pulses at idle or the crankshaft changes speed, speeding up a bit then slowing down, which changes which side of the gear teeth are engaged in the trans. Clack-clack unless all cylinder fire evenly.

Cheers,

[hyde7278]

It doesnt change when I pull the clutch, hopefully it will clear it self up after I do the 3k service and get the carbs synced. Have to change the oil,plugs,set the valves and the plug wires as I was able to see them arcing to the head as it was running in the dark.

[phil71]

if that battery was hooked up backward once, it could have fried the rectifier diodes.
Then it wouldn't charge at any RPM.

[dave500]

you might need to replace the plug caps,the wires are part of the coils,if the caps resistance has gone high the voltage can sort of back up and come out the easiest place it can.

[hyde7278]

Phil
I put in a good rectifier from a partsbike I have. I think it was because the bike was idleing and these bike dont charge below about 2500 mfrom what im told. The rectifier definitly got fried when hooked up backwards

Dave
Im going to replace the caps but Ill prob change the wires also theres a few treads about how to cut into the coil and replace the wires.

[dave500]

the wires are actually solid wire and dont really go bad unless they suffer some physical damage,id try doing just the caps first as your probably just making work for yourself and comprimising an otherwise good set of coils for no gain,can you get hold of a multimeter and check the old ones?a cheap digital meter will do.

[hyde7278]

Dave

Have a real nice multi meter, was going to check the resistance on the caps when I get a chance. How do I check the wires with it?

[TwoTired]

With the caps off you check end to end through the coil.  They are about 15KΩ --ish.

[hyde7278]

Tiller

thanks for the sugestions, I ordered some caps from Z1. The rattle is still there when I pull in the clutch TwoTired suggested to get the bike synced up and running good and that may clear up the rattle so im going to do that before getting farther into it. The PO didnt want to go through the electrical after hooking the battery up backwards that why I was able to get the bike for $750 (running,titled with about 7000 miles on it) Ive replaced the rectifier and all the wiring and connectors ant the electonics panel and checked the rest of the wireing for burnt wires (non found) Im sure the engine is fine from idleing it was just odd that it wouldnt catch after getting hot, thought maybee the fuel was vapor locked or the engine was hot enough to pre detonate and keep the bike from starting. After leting it sit and cool down it started up and the headlight was dim but thats because the battery was only at 12.1v from not being charged at the low RPMS.

[nsargeant]

hyde,

I that that rattling noise that you are hearing is normal.  mine does it as well.  You can only hear it on mine when it is idling at a lower rpm than it is supposed to.  It goes away for me when idling at 1000rpm or higher.

nathan

[hyde7278]

Thanks Nate mine goes away if i bring the RPMS up to 1500 or so

Sean