My 550 strange problem

[timbaux]

Maybe this forum needs a place where people can post if they dont know if their problem is fuel or electrical related. What if the bike dont run and they dont know why? Where do you post such an issue?

Anyway,.... I got an 85 550EF. When it runs...it runs great. It does have a slight vacuum leak, but it runs really good. I just adjusted the valves and they are all good. I changed the plugs, and the coils check out fine. The regulator rectifier allows the stator to bring the battery up past 13 volts when running at idle, the pick up coils test out at a hair under 400 ohms, even when the
"no-run" situation presents itself. I have two proven igniters, tested and working fine.

After running great for two weeks after the valve adustment, I went somewhere, turned the motor off. Spent about a half hour at the place, then got back on the bike...it spun over fine, but would not start. It does have fire, but will not start. Not even try. If i spray starter fluid in the air box, it seems to try to come to life.

All of a sudden, after sitting a while, it starts up and runs great.

I am stumped. I have to go find a compression tester, but does anyone have an idea of what this could be? Carbs are clean.

I am wondering if I have some kind of ventilation issue. I really dont know. I am going to have to make a small "IV" tank that will allow me to feed the carbs fuel with the gas tank off.

[tom203]

.."no-run" situation presents itself. I have two proven igniters, tested and working fine."

Sounds electrical......doublecheck signal coils to ignitor connections...carry your spare proven ignitor so next time it cranks,but doesn't come to life, switch ignitors and retry.

[timbaux]

I did do that and it wouldnt start. Got a small gas tank i will hang over tje bike and get my tank off so i can check to see if 2 and 3 are firing. Got fresh plugs May be the coil

[Cipher]

Are you in a place hot enough to boil off the fuel int he bowls?
If it's super hot out this seems to happen.

Have you tried to use prime?

[timbaux]

These bikes are in haittiesburg and before that in new orleans so yeah vapor lock is an issue to consider Going back outside and pull the plugs and check gap and check cylonders 2 and 3 with tank off and rigged temporary gas tank in place hanging beside bike. Deaf so i cannot hear gas cap swoosh Will let ya know what happens

[timbaux]

The bike has a manual fuel shut off. Been like this for five years. Turn gas off when not running. This is not the issue. Its possible the gas cap is not original but like i said its been running for thousands of miles like this.

it runs on prime always i changed petcocl sevn or egbt years ago new factory petcock and it wont draw from vacuum.

[Chancho196]

Not sure I understand that last post. It's an original vacuum tap? What positions does it have at the lever?

[timbaux]

Its got a vacuum petcock. One day, i was riding along about 55 mph and it lost power. Put it on prime, and it got me home. Changed to a new OEM petcock and it would not work... I tried a petcock that was working, and it still wont draw...so i installed one of those Briggs and Stratton lawnmower fuel shut offs. I leave it on Prime and turn the gas off and on, works fine. Not a problem. Been like this for years.

I thought it was not creating enough cylinder pressure and when i adjusted the valves i figured i'd try it..but it still wont pull down via vaccum.

[Cipher]

Did you ever think to replace the vacuum tube? Or to check the diaphragm?

[Cipher]

Also is prime able to flow enough at high engine rpm? And why are you tolerating a vacuum leak? Won't that burn your valves and cause poor running?

[timbaux]

I think the choke cable on the right carb is messed up. Vacuum leak is fixed. I really wanna ditch the air box and put two filters on it instead and install a jet kit. But it might be the choke. It may be squirting gas when i try to start the bike when it is warmed up.

[bobgroger]

Sounds like the vent in the gas cap is plugged to me. Does it start if you open the cap and let air in? If so take it apart, making note of where the balls go. Clean out the gunk.

[timbaux]

Ive cleaned that out already i am not sure the gas cap i have is the original but when its in "no run" mode i have tried to start thr bike after taking the gas cap off but it didnt fix the problem