Author Topic: HELP! Aggressive riding and my bike won't idol. Makes different noises now. (Read 3979 times)

MotoLion · « **on:** August 21, 2014, 02:46:08 PM »

Hey guys,

Yesterday I was cruising around town on my '73 cb500 and I was in an aggressive mood so I was aggressively accelerating and shifting. I was in first or second gear and reaching the mid to upper rpm range when my bike bogged out and died. It immediately sounded different and wouldn't idol. I have almost no power... and can really only go in first gear at full throttle... otherwise it dies. My initial thought... something inside has snapped while I was gunning it... I need to know where to start / how to diagnose it...

Check out this video:
The password is "cb500".
Not a valid vimeo URL

MotoLion · « **Reply #1 on:** August 21, 2014, 03:26:26 PM »

The bike was hot when the video was made. It idols great when the bike gets to running temp. I know what the cam chain sounds like when it's loose and I am confident that it's not the case. I will take the valve covers off and give it a look see.

Is it possible that a piston got messed up?

As per the carbs... I know that the bike is running really rich... I also find gas on top of the crank case on most mornings due to a leaky petcock.... but it only leaks from the 3rd carb. 3rd carb going from left to right while seated on the bike.

ekpent · « **Reply #2 on:** August 21, 2014, 04:03:19 PM »

Yes check that all 4 pipes are getting hot. Touch them all with a wet rag and compare the sizzle.

Retro Rocket · « **Reply #3 on:** August 21, 2014, 04:54:17 PM »

More than likely you have got some small rubbish from the tank into a jet...

bjbuchanan · « **Reply #4 on:** August 22, 2014, 10:02:07 AM »

Quote from: Retro Rocket on August 21, 2014, 04:54:17 PM

More than likely you have got some small rubbish from the tank into a jet...

Bingo, you stirred the craps up and now your pilot jet is clogged

MotoLion · « **Reply #5 on:** August 24, 2014, 01:51:00 PM »

So I took the carbs apart and cleaned them. They were actually ver very clean already. Though it did not solve the problem... the bike DID idol. It still makes a dull slapping sound and it's coming from the crank case. Something is loose broken. Suggestions??

Tews19 · « **Reply #6 on:** August 24, 2014, 02:15:23 PM »

Pull the clutch in and listen to see if the noise stops. From what you describe I'm thinking cam chain as well.

lucky · « **Reply #7 on:** August 26, 2014, 07:10:10 AM »

Quote from: MotoLion on August 21, 2014, 02:46:08 PM

Hey guys,

Yesterday I was cruising around town on my '73 cb500 and I was in an aggressive mood so I was aggressively accelerating and shifting. I was in first or second gear and reaching the mid to upper rpm range when my bike bogged out and died. It immediately sounded different and wouldn't idol. I have almost no power... and can really only go in first gear at full throttle... otherwise it dies. My initial thought... something inside has snapped while I was gunning it... I need to know where to start / how to diagnose it...

Check out this video:
The password is "cb500".
Not a valid vimeo URL

Sounds like it got hot seized.
Stock intake and exhaust?

lucky · « **Reply #8 on:** August 26, 2014, 07:13:02 AM »

Quote from: calj737 on August 21, 2014, 03:40:32 PM

If you're comfy that it's not the cam chain, my strong suspicions would be valves. Maybe blew an adjuster loose? Or two? Remove the tappet covers first, then if you're concerned, lift the rocker cover.

As for carb 3 leaking, is the float stuck? Is it leaking from the bowl gasket, o-ring or overflow tube?

Now, you divulged something interesting: you say it's running really rich. Have you perhaps fouled your plugs badly enough after your spirited riding, and coupled with a carb or two, not providing fuel, have a dead cylinder? Pulled the plugs yet?

If you start the bike, do all 4 pipes get hot quickly and evenly? (Check this after inspection of the tappets, and do this FIRST).

"Maybe blew an adjuster loose"
Tappet adjusters very rarely "blow" loose. Almost never.

lrutt · « **Reply #9 on:** August 26, 2014, 10:21:50 AM »

did you check all 4 pipes, are they all hot? If you're missing one jug it could make weird noises down low from the primary chain slapping. Make sure you're hitting all cylinders good first before doing a bunch of other crap.

MotoLion · « **Reply #10 on:** August 30, 2014, 08:24:33 AM »

Okay, so only the 1st and 4th pipes are getting hot. I replaced the spark plugs and made use the battery was at 100%. When I removed the plugs 1 and 4 were black. 2 and 3 were black and wet.

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Tews19 · « **Reply #11 on:** August 30, 2014, 09:10:08 AM »

Pull the spark plug wires on 2 and 3. Put a spark plug in each one to see.if you getting spark. Easiest way to check then go from there.

MotoLion · « **Reply #12 on:** August 30, 2014, 09:20:43 AM »

Nice! Good idea!

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MotoLion · « **Reply #13 on:** September 01, 2014, 10:25:29 AM »

Okay... So I switched the lead wires for the coils and put the 1 and 4 spark cables on 2 and 3. I got no fire. Now that I think about it... Maybe u should have switched plugs too... 2 and 3 are probably wet. A wet plug will cause it not to spark right?

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MotoLion · « **Reply #14 on:** September 01, 2014, 11:12:42 AM »

Okay, I switched the plugs. Same result... 2 and 3 give me no spark... Even with the coils and lead wires switched. Spark plugs are all new.

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MotoLion · « **Reply #15 on:** September 01, 2014, 11:52:42 AM »

It's aftermarket new.

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MotoLion · « **Reply #16 on:** September 01, 2014, 11:56:53 AM »

I'm not sure. Coils are old... Possibly stock. Wires are old but are not detachable from the coils.

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Dimitri13 · « **Reply #17 on:** September 01, 2014, 01:07:00 PM »

So did you take the tappet covers off or what?

Possible you could've overrevved, missed a shift, etc. and floated a valve, and knocked the adjuster loose. I managed to do that and it blew the nut right out a hole through the tappet cover.

MotoLion · « **Reply #18 on:** September 02, 2014, 06:31:34 AM »

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MotoLion · « **Reply #19 on:** September 02, 2014, 06:32:35 AM »

Yes I removed the tappet covers. Nothing exciting going on there.

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setdog · « **Reply #20 on:** September 03, 2014, 05:06:43 AM »

my experience is limited, so im really just guessing here but,

is it possible your cam chain jumped (or stretched as mentioned in an earlier post) and is now causing a misfire? maybe get a timing light gun, and check the timing, see how thats doing.

MotoLion · « **Reply #21 on:** September 03, 2014, 06:16:54 PM »

OKAY! Check it out...

I have a fully charged battery.
I can start the bike and it runs on 1 and 4 with the coils and wires where they should be going.
I switch the yellow and blue wires and moved the 1/4 spark plug cables to 2/3. no fire.
I noticed that my 2/3 cables were now getting spark. So both of my coils work!
The issue must be in the blue or yellow lead wires?

Tews19 · « **Reply #22 on:** September 03, 2014, 06:49:17 PM »

Swap the blue and yellow wires from the electronic plate. Near the airbox. See if this helps

MotoLion · « **Reply #23 on:** September 03, 2014, 06:59:53 PM »

Whelp... That shorted out my bike...

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Tews19 · « **Reply #24 on:** September 03, 2014, 07:02:49 PM »

Oops sorry meant to state make sure the top ones are back to matching. Do you have another fuse?

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Author Topic: HELP! Aggressive riding and my bike won't idol. Makes different noises now. (Read 3979 times)