Author Topic: is this what happens when you over heat? (Read 5070 times)

Flying J · « **on:** June 08, 2009, 08:46:33 PM »

I think my bike is running lean. I just got it running for the first time last week. (cb550) Still havent synced the carbs but it fired up fairly easily so i rode to my parents house. About a block away. Shut it down hung out for 5 min then headed back. On the way back i got on the throttle. A turn or 2 later it began to sputter and lost power. I tried to keep it running but any load would bog it down and then it just died. 100' from my house. Wont start. This happened last week after a few trips around the block and the next day it fired up just fine.
What happened? Am i over heating from running lean? To correct the situation should i jump straight to bigger mains and raise the needle or is there something else i should do first?
I am running a kerker 4-1, foam pods, and 110 mains in a 78 carb.

Frankenkit · « **Reply #1 on:** June 08, 2009, 08:54:29 PM »

could be a heat-soak problem with your pulser generator for 2 and 3 since you're having 'interesting' spark issues with those two anyway. The 550s and 650s seemed to have issues with those. This would namely be the one with yellow leads, I think.

seaweb11 · « **Reply #2 on:** June 08, 2009, 08:57:28 PM »

What do the plugs look like?

Have you done a plug chop?

Mdub · « **Reply #3 on:** June 08, 2009, 09:00:32 PM »

Sounds lean.
Pull a plug and look at the color.
Should be tan/coffee color.
If it is whitish it is too lean.
Blackish is too rich.

Frankenkit · « **Reply #4 on:** June 08, 2009, 09:02:51 PM »

here's his build thread. Lots of plug pics.
http://forums.sohc4.net/index.php?topic=51902

Hush · « **Reply #5 on:** June 08, 2009, 09:18:17 PM »

My bet is it's running lean but not from any electrical or tuning fault, sounds like you are running out of gas, check for blocked tank filter.
You said you hadn't had it running for a while, well suddenly you are asking it to perform and that takes gas, rubbish in the tank/filter/carbs will block it running temporarily, leave it for a while and the pressure to deliver gas goes away (bits float away from filter etc) then she will run sweet again until you ask for more effort.
I'd check fuel delivery before anything else, sound slike gas starvation to me.

But that's just me and I'm cheap...always looking for the simple inexpensive solution.

alltherightpills · « **Reply #6 on:** June 08, 2009, 09:23:55 PM »

To do a plug chop on the main circuit, ride the bike at WOT up a hill through as many of the gears as possible. At the top of the hill, pull the clutch and kill the engine, and come to a stop. Then check the plugs. This will tell you what is happening at the exact time you killed the engine. I don't recall off the top of my head when the main circuit takes over, but I think it's at around 2/3 throttle. Doing a plug chop at less throttle will tell you what's happening with the idle or pilot circuit.

Also, I don't know how much of a difference this will make (TT could probably tell you better than I), but the 78 carbs were lean burn for emissions and I don't know what kind of can of worms get opened when they are put on an earlier bike. The stock main jet in the 78 carbs is 90. I have a similar set up on my 78 550k and I am running 105 mains and it runs like a champ. If the bike was a 78, I'd say you were probably running a bit rich with 110's, but who knows what all gets changed when you put those carbs on another bike.

Flying J · « **Reply #7 on:** June 08, 2009, 09:25:55 PM »

here are the plugs. Im going to pull the petcock and see what the filter is looking like.

martino1972 · « **Reply #8 on:** June 08, 2009, 09:29:19 PM »

sounds more like fuel starvation to me....

If it dies,open the gas cap,see if it's under vaccuum..

Is the petcock filter clean..

does fuel run out the tank fast when you open the fuel valve without a hose on it..

seems that fuel can't get fast enough to the carb's when demand get's little higher....i would check your fuel cap first...

martino1972 · « **Reply #9 on:** June 08, 2009, 09:31:21 PM »

you posted the pictures as i was typing my first reply,

those plugs look lean.....very lean..... but that could also be from fuel starvation at the carbs...

TwoTired · « **Reply #10 on:** June 08, 2009, 09:46:34 PM »

Freakin' pods with the 550 PD carbs, and low back pressure exhaust mean pretty serious changes for carb jetting away from stock. Not just the main but the slide needles, too.

When the bike died, could you spin the engine with the kick start? Could you spin the engine? If it is overheated, the engine will seize. If the engine wasn't seized, then you have issues with spark or fuel supply.

bucky katt · « **Reply #11 on:** June 08, 2009, 10:11:03 PM »

sounds like tank vent to me too. when i first got this motorcycle in 2005, it had a blocked tank vent. i fought it and fought it. i had never had this problem with either the ironhead sprotster or any of the brit bikes i owned.

Flying J · « **Reply #12 on:** June 08, 2009, 10:33:14 PM »

Quote from: TwoTired on June 08, 2009, 09:46:34 PM

Freakin' pods with the 550 PD carbs, and low back pressure exhaust mean pretty serious changes for carb jetting away from stock. Not just the main but the slide needles, too.

When the bike died, could you spin the engine with the kick start? Could you spin the engine? If it is overheated, the engine will seize. If the engine wasn't seized, then you have issues with spark or fuel supply.

i knew the day would come when TT piped up, and i knew i would be introuble for having The wrong pipes and the pod fillters. TT forgive me! The pipes were on the bike and it came with no airfilter. Aside from me going against everything TT stands for i appreciate any bit of advice i can get out of you. And maybe ill stop by on a ride one day.
That said, yes i could spin the motor so tomorrow morning i will check my pet cock and check the breather..
thank you guys for all the help. Somtimes you just need somebody to point out the little stuff.
I will update as soon as i find something

TwoTired · « **Reply #13 on:** June 09, 2009, 12:32:03 AM »

Um....
You did check the oil, right?

Flying J · « **Reply #14 on:** June 09, 2009, 12:58:53 AM »

yup its got fresh oil. and my oil light works.

Treeguy · « **Reply #15 on:** June 09, 2009, 01:12:16 AM »

I agree those spark plugs look like they are very hot (ie lean), if it is a fuel starvation issue, have you tried riding around the block with a gallon or so of fuel and keep the gas cap loose to see if it still dies ? Sometimes the breather vents in the gas cap get plugged . . .

razor02097 · « **Reply #16 on:** June 09, 2009, 04:46:18 AM »

usually on these air cooled bikes you don't overheat unless you sit in traffic for a long time stop and go, Or you run them low on oil. There maybe also the filter screen in the gas tank that could be partly clogged. You would have to drain the tank and pull out the petcock to check it.

OldSchool_IsCool · « **Reply #17 on:** June 09, 2009, 05:20:17 AM »

If you have an in-line fuel filter, just get rid of it and don't tell us as that would be the THIRD mortal sin!!

razor02097 · « **Reply #18 on:** June 09, 2009, 05:24:11 AM »

Quote from: OldSchool_IsCool on June 09, 2009, 05:20:17 AM

If you have an in-line fuel filter, just get rid of it and don't tell us as that would be the THIRD mortal sin!!

Better an inline filter then a garage floor soaked in fuel

OldSchool_IsCool · « **Reply #19 on:** June 09, 2009, 05:55:13 AM »

Trust in your in-tank filter, my son. The three inches of fuel line between your petcock and an in-line filter won't produce needle jamming crud but a poorly mounted in-line WILL trap air and fuel starve your engine.

And always turn your fuel off when you park for crud is not the only abomination that causes carb overflow.

Now go forth and do good things!

JS550 · « **Reply #20 on:** June 09, 2009, 06:31:06 AM »

Quote from: OldSchool_IsCool on June 09, 2009, 05:55:13 AM

Trust in your in-tank filter, my son. The three inches of fuel line between your petcock and an in-line filter won't produce needle jamming crud but a poorly mounted in-line WILL trap air and fuel starve your engine.

And always turn your fuel off when you park for crud is not the only abomination that causes carb overflow.

Now go forth and do good things!

Amen brother! I tried an inline for about 15 minutes. And ALWAYS shut your fuel off. On my 550 I would shut it of a couple of houses away & that stopped it from dribblin gas. Are those pods foam? I read somewhere that you can coat them in oil & it helps the lean condition a little. Never tried it myself.

Flying J · « **Reply #21 on:** June 09, 2009, 05:32:14 PM »

drained the tank, cleaned the filter, flowed it and gas comes out fast. No vacuum on the tank. Drove it for a while today and it never died. Plugs look a little better. im still going to pull the carbs and move the needles. Any suggestions on what slot to put it on. Stock for the 77 was 3. Is that third slot from the top so 1 or is it 4?
   2 3
   3 2
   4 1
i also developped an oil leak.

i also was wondering if there is some trick to getting at the needles without having to separate the carbs.

scooter1 · « **Reply #22 on:** June 09, 2009, 05:37:19 PM »

Your plugs do look better, I would not mess with the needles just yet.

How many turns out are your air/fuel mixture screws???
I would try them all at 1 1/2 turns out and try that and work from there.

Flying J · « **Reply #23 on:** June 09, 2009, 05:45:06 PM »

i think they are like 4 turns out.

scooter1 · « **Reply #24 on:** June 09, 2009, 06:04:45 PM »

That might be your problem.....too lean. Try them at 3 turns out and see what happens

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Author Topic: is this what happens when you over heat? (Read 5070 times)