Author Topic: Problems when Hot (Read 2305 times)

OldSchool_IsCool · « **on:** July 22, 2006, 03:33:42 PM »

My '77 550K has problems when she's hot. I've had a few incidents where she was hard to start once warmed up. I had to play with choke and throttle, getting nothing, then a few pops, then more pops, and finally she started and purred. Vapor lock was my first thought.

Last night, I ran about 8 miles to the store. At one point, I took off from a stop light and it felt like a cylinder dropped out. I pulled in the clutch, reved, and back she came. I parked at the store, shopped for about 30 minutes. When I tried to start her, she really gave me fits! Sputtering on maybe one cylinder, gradually more and more joined in. Once started, she sounded GREAT!

Drove home and made it 7 and a half miles. I felt a cylinder drop out, but no amount of revving would bring her back. I limped home and got a half block from my drive where I had to stop for a light. She quit and I could not start her. Luckily I was up hill from home so I walked her into the back yard and let her sit.

Today, about 24 hours after this incident, I pulled the plugs (Champion RA8HC) and took this picture:

I put the plugs back in and attempted a start (full choke). I barley touched the start button and she fired up and purred!

Any thought on what my hot engine starting/running issues might be?

750goes · « **Reply #1 on:** July 22, 2006, 04:32:46 PM »

It sounds like fuel starvation.... but it could also be some clogged jets if it all of a sudden cuts out on one cylinder, then sputters back again with a hit of throttle.

I would do a quick check for fuel flow in this order -
from tank, petcock,fuel filters if installed, carbie drain screws, inspect float bowls, then the slow/idle jets...then mains, tighten all carburretor boots for leaks.

what's the recent tune up history???

by the way, plugs look fine,

eldar · « **Reply #2 on:** July 22, 2006, 04:43:12 PM »

I to would like to know about the tune up history. Plugs look good, maybe slightly rich for the 77-78 years as they are lean running by nature. Do you still run points? As the problem happens when warm, I dont think fuel flow is an issue but you never know sometimes. How old are your plugs? I would say check gap and dress your points if you still have them. Maybe check your coils to make sure there are no cracks or damage to them. Does the issue happen at higher rpm or just low? I could be fuel related in that the lows may be plugged.

OldSchool_IsCool · « **Reply #3 on:** July 22, 2006, 05:37:03 PM »

Tune up history... yea... well.. um... er.. ahem....

I got this bike last fall, buddy was moving and didn't have room for it on the van. Didn't run because of an electrical short that kept blowing the main fuse. He hadn't riden it in maybe 6 months.

Bottom line, I don't know the tune-up history.

750goes · « **Reply #4 on:** July 22, 2006, 07:59:32 PM »

Then time to bite the bullet...

do the simple stuff first, just like I posted in my first reply... let us know the results of each step, if you find some problems then these are all relatively easy to find and simple to fix in most cases.

Just complete each step as you go, then a quick test ride, no improvement, then go to the next step, don't try and do every one of them at the same time, or you may get confused by the changing or non/changing results.

Also if you document your actions, then you benefit by what you have done as you go.. always a great starting point for finding problems.

Let us know if you still have the same problems after going through those items mentioned in both replies to your post.

OldSchool_IsCool · « **Reply #5 on:** July 25, 2006, 08:58:31 AM »

If I ran her with the choke closed, that would keep the mixture artificially rich and thus keep the engine cooler. Is that correct or am I just asking for trouble? I'm just wanting to test to see if indeed it's engine temp that is causing the sudden sputter/cylinder drop out.

Any thought on what an acceptable fuel flow rate though the drain tube(s) should be?

eldar · « **Reply #6 on:** July 25, 2006, 09:48:58 AM »

You dont need much fuel flow. A trickle is about it. Heck I think a pint in a minute would be more than adequate, from the tank. Well a richer engine will run cooler but adversely affect performance but then I suppose popping and sputtering does too!

750k5 · « **Reply #7 on:** July 25, 2006, 10:50:37 AM »

I used to have an old car back in the 70's that did that, and it was a bad condensor, only when it got hot..I think you need a full tune-up

crazypj · « **Reply #8 on:** July 25, 2006, 11:02:14 AM »

number two is lean. the fuel line runs into carbs between 2&3? park bike on sidestand? dirt gets into no 2.
carb clean shold fix things. pilots may be dirty, even if they look clear push a single strand of copper wire through them (from old wiring harness/speaker wire, whatever)

OldSchool_IsCool · « **Reply #9 on:** July 25, 2006, 11:12:28 AM »

Quote from: crazypj on July 25, 2006, 11:02:14 AM

number two is lean. the fuel line runs into carbs between 2&3? park bike on sidestand? dirt gets into no 2.
carb clean shold fix things. pilots may be dirty, even if they look clear push a single strand of copper wire through them (from old wiring harness/speaker wire, whatever)

Is your statement about lean on #2 due to the pic of the plugs? Yes, they are in cylinder order, left to right. The fuel line from the tank connects between 1&2. I do park it on the side stand mostly. I'll need to take the carbs off to clean #2, right?

eldar · « **Reply #10 on:** July 25, 2006, 11:29:04 AM »

I would not say any of those plugs are lean. the 77/78 nature is lean running. granted I am using d7 right now but none of mine are half that dark and I still run too rich at idle and even at higher rpm. At 5000 rpm, I run better in the morning when the air is denser than in the afternoon once things warm up. My plugs have only a LIGHT coloring on them. I know I am running rich cause if I hit my choke at 5000rpm and push the gas a little, I get severe bogging.

I would suggest cleaning your plugs for one thing.

OldSchool_IsCool · « **Reply #11 on:** July 25, 2006, 12:18:22 PM »

I'll clean and gap the plugs. Most of what I've read would indicate that most people like the NGK plugs. Should I pitch the Champions?

I'll also inspect the points. Are there any test procedures on evaluating the condensers? They are about $20 times 2. Not that it's a huge amount of $$, but I also see that ServiceHonda has a complete points assembly (sans Advancer) for under $60.

Bob Wessner · « **Reply #12 on:** July 25, 2006, 12:27:03 PM »

I doubt it's related to your lean/rich issue, but I noticed the "R" in the plug ID you are using which suggests these are resistor plugs. Are you sure these are correct for your bike?

eldar · « **Reply #13 on:** July 25, 2006, 12:28:30 PM »

Well I dont know what others say about points. I got some from partsmore.com with condensers for probably about $20 - 24. Seem to work just fine cant remember brand though. But if those are old, it maybe worth replacing. This winter i think I may save up sone cash and go the dyna s route and keep my points as backup. May be even keep them onboard just in case, need to open up a spot for them though. ok so I ramble sometimes!

With champions, I dont know if R designates resistor like it does on NGKs. Could be an issue for sure though.

Bob Wessner · « **Reply #14 on:** July 25, 2006, 12:40:00 PM »

The "R" seems to be somewhat universal, here's the Champion ID chart.

OldSchool_IsCool · « **Reply #15 on:** July 25, 2006, 12:44:32 PM »

According to the fiche on mrcycles.com, the OEM plug is a "D7EA" or a "X22ES-U" Are those NGK numbers? If so, then there is no "R" in either plug number. I think there are new plugs in my future!

Bob Wessner · « **Reply #16 on:** July 25, 2006, 12:45:42 PM »

"D7EA" is an NGK plug, not familiar with the other designation.

eldar · « **Reply #17 on:** July 25, 2006, 12:56:50 PM »

I think the other may be a champion number maybe a nippon-denso. I dont know.

OldSchool_IsCool · « **Reply #18 on:** July 25, 2006, 02:20:00 PM »

Hmmmm According to the fiche at mrcycles, I should install NGK D7EA plugs, but my Haynes & Honda Shop Manuals, D7ES Is there a significant difference? Should I follow the shop manual's gap of (.028 - .032)?

Yes, the X-22ES-U is Nippon Denso (ND). Although, the Shop Manual differs from the fiche again, calling for X-22ES (no -U)

OK, as a tie-breaker, I looked at the fiche at ServiceHonda.com which lists all 4 plug numbers. Guess I'll gap the the D7EA's and pop them in!

eldar · « **Reply #19 on:** July 25, 2006, 02:26:35 PM »

The D7ES was the old designation. The D7EA is the correct plug.

OldSchool_IsCool · « **Reply #20 on:** July 25, 2006, 04:43:07 PM »

Fuel Flow Test:

The petcock, in-line filter and fuel line can deliver 4 ounces of fuel to the base of carb #2 in 16 seconds. More then a trickle. I tested fuel flow thru all 4 carbs in parallel via the bowl drain tubes (1.5 turns out of the drain valve), and the over all flow rate was comparable to that of the supply tube figure. I also measured the rate thru carb 1 and carb 2 individually. Both would deliver the same 4 oz in 50 seconds. A little parallel mathematics and indeed, max fuel flow matches individual carb throughput pretty closely. Also, when I emptied each bowl, they all held a little over an ounce of fuel. All four floats seem to be matched, alltho they could all be wrong. I also tested the breather hole in the gas cap and could blow air through it just fine.

Spark plugs:

There is a big difference between the hex dimensions of the Champion and the NGK plugs. Unfortunately, I don't have a thin-walled, deep-well socket that will allow me to install the NGK's, so all 4 Champions are back in. I figured it better to match plugs, even if they are all wrong.

Bob Wessner · « **Reply #21 on:** July 25, 2006, 05:28:23 PM »

Quote

There is a big difference between the hex dimensions of the Champion and the NGK plugs. Unfortunately, I don't have a thin-walled, deep-well socket that will allow me to install the NGK's, so all 4 Champions are back in. I figured it better to match plugs, even if they are all wrong.

Do you have the under seat tool kit? Use that plug wrench if you do. First chance you get though, change out the Champions. Since they are resistor plugs, you are taking a double hit on the spark strength, assuming you are running stock plug caps on the wires as these have resistors in them already.

OldSchool_IsCool · « **Reply #22 on:** July 25, 2006, 05:46:38 PM »

Nope, no tool kit. I sure would like to track one down, though. It's my mission tomorrow to track down the proper socket and get the right plugs in.

TwoTired · « **Reply #23 on:** July 25, 2006, 06:01:19 PM »

I dunno if this is your bike's problem. But, I had a "cut-out-when-warm" issue some years ago.

I had some water under the points cover. When the engine got hot the water vaporized and then condensed on the points, shorting one of them out. Lose two cylinders, do not pass go, do not collect lowest time slip for the day of racing. Drying out the points restored the cylinders. A neoprene points cover gasket stopped water from getting inside thereafter.

Cheers,

P.S. If you don't have a tune up history, then the bike needed one long before you bought it, and every 3000 miles (or 6 Months) thereafter.

OldSchool_IsCool · « **Reply #24 on:** July 25, 2006, 09:15:11 PM »

Seems like a long shot, but the bike does spend a fair amount of time exposed to elements. I don't mind riding in the rain (not a Hardly rider here!). I'll definitely look for moisture when I inspect the points.

Yes, a tune-up is in the near future!

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Author Topic: Problems when Hot (Read 2305 times)

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