Starter issues

[swingman3]

I think we already have the evidence that shoots a hole in the drippy injector theory: Once the bike is running and has warmed fully up to temperature, if you stop the engine and then immediately try to start it again, it does not turn over fast enough, correct? At least that is what I have inferred your testing protocol was thus far.

Since this is before the alleged leaky injector has had any time to do its drippy deed, that rules that theory out.

Not quite. It was the CG boats that had a drippy injectors. My symptoms are this: I shut off the bike, I fuel (or do something else for 2-3 minutes), hit the starter button. Engine turns over a quarter turn and stops, battery flashes. I shout out some profanities, hit the button again and it starts easy like pie.

My theory does not require a leaky injector, because no matter when you shut down the engine, there will always be a piston starting it's power stroke. So we need a) a piston at the bottom of power stroke, B) two closed valves, c) freshly injected gasoline in the cylinder that is atomized and expanding from the high heat, d) possibly relatively weak starter system. All of these things come together to give us the scenario I describe above. The reason it might not happen EVERY single time is because there might be some variation in how low the power-stroke piston is when the engine stops, i.e. less compression, or something else that doesn't put too much resistance against the starter motor while it's trying to start from stop (overcome inertia.)

As I've already exhausted my limited electrical and mechanical knowledge, from here on out I will watch from the sidelines and hopefully you guys can figure out what the problem is. If you identify an issue with the starter, or wiring harness, I will follow in your footsteps in the quest for a more perfect motorcycle. I'm just saying I have this issue and it feels mechanical to me. And the compression lock theory seems as good as any to me right now.

Swingman Sends

 

[MotorToad]

I don't think the vapor thing is what's going on with Walter's bike, I just meant that it does sound like it's trying as hard as it can to turn it over. I think the problem is either a combination of a couple of minor details, or its Walter's utter refusal to dance with chicken bones.

Easy test for the vapor theory, though. Carefully click the bike into 4th or 5th and push it a couple of yards. It'll tell you if a cylinder is harder than another, and it'll vent any pressure.

 

[RadioHowie]

Let's revisit the leaky injector theory for just a moment.

Say you DO have an injector that has an enlarged prostate and is dribbling. Go with me on this one.

Walt, there would be an easy test....warm up your bike to normal op temps, go for a ride, whatever, ride home, raise the tank, let it sit for 10 minutes while it's good and hot, pull the plugs one at a time and attempt to crank it.

If you DO have a leaky prostate, you may be experiencing hydrolock on a cylinder and you'll know when raw gas comes shooting out one of the plug holes.

I wouldn't pull ALL the plugs at once for this test, since you'd be eliminating any cylinder pressure and even a marginal starter should spin over a compression-less motor.

And doing it one plug at a time could narrow down the problem, if it really is a leaky injector, to which hole is the culprit.

 

[Fred W]

I think we already have the evidence that shoots a hole in the drippy injector theory: Once the bike is running and has warmed fully up to temperature, if you stop the engine and then immediately try to start it again, it does not turn over fast enough, correct? At least that is what I have inferred your testing protocol was thus far.

Since this is before the alleged leaky injector has had any time to do its drippy deed, that rules that theory out.

Not quite. It was the CG boats that had a drippy injectors. My symptoms are this: I shut off the bike, I fuel (or do something else for 2-3 minutes), hit the starter button. Engine turns over a quarter turn and stops, battery flashes. I shout out some profanities, hit the button again and it starts easy like pie.

Sorry, I should have made it clear that I was talking about wfooshee's bike in particular.

Yours may be a different issue.

 

[wfooshee]

Further thought experiment (can't wait for the weekend so we can get back to physical devices!):

If it's a leaky injector, it would be dribbling into the intake manifold, not the cylinder. Granted, if the intake valves are open it will dribble into the cylinder, and the valve will close at it turns over, but what chance does it have of stopping at that same cylinder every time?

As for cranking with one plug at a time removed, that would show me if a cylinder was tight for some reason, but I'd rather not shoot explosive vapor out from a hot engine in my garage. If you know what I mean.

 

[RadioHowie]

As for cranking with one plug at a time removed, that would show me if a cylinder was tight for some reason, but I'd rather not shoot explosive vapor out from a hot engine in my garage. If you know what I mean.

Then do it in your mom-in-law's garage. :lol:

 

[swingman3]

Further thought experiment (can't wait for the weekend so we can get back to physical devices!):
If it's a leaky injector, it would be dribbling into the intake manifold, not the cylinder. Granted, if the intake valves are open it will dribble into the cylinder, and the valve will close at it turns over, but what chance does it have of stopping at that same cylinder every time?

As for cranking with one plug at a time removed, that would show me if a cylinder was tight for some reason, but I'd rather not shoot explosive vapor out from a hot engine in my garage. If you know what I mean.

But what if it's not a leaky injector, just a cylinder full of atomized fuel with both valves closed and the piston at the bottom (start) of the power stroke, when the engine is shut down? If the starter is kind of weak to begin with, and the engine is hot, the fuel could expand and create a lot of pressure for the piston to push against as you hit the starter. If this is the case, it wouldn't have to be the same cylinder/injector every time, it would just have to be any one of the pistons in the right place (bottom of stroke) and a hot engine to create extra expansion of the fuel in the cylinder. With four pistons idling at 1100 rpm, it would be likely that one of them would be in that condition at shut down.

I do like your idea of rolling the bike forward in 5th gear before starting to see if it breaks the compression. All it would take is to move the crankshaft enough to crack open one of the valves a very small amount. I will try that today and post my results. If the bike starts, it won't definitively prove the compression lock theory, but I'll keep doing it over time and see if that seems to be a work around.

Like I said, my experience is that after the first failure to start, within 5-6 seconds, I can hit the starter again (bike still hot) and it fires right up. That's why I'm not convinced it's an electrical fault caused by a hot starter.

SM

 

[Fred W]

But what if it's not a leaky injector, just a cylinder full of atomized fuel with both valves closed and the piston at the bottom (start) of the power stroke, when the engine is shut down?

Ummm... How is that not 100% normal?

 

[RadioHowie]

But what if it's not a leaky injector, just a cylinder full of atomized fuel with both valves closed and the piston at the bottom (start) of the power stroke, when the engine is shut down?

Ummm... How is that not 100% normal?

+1...not to mention that vapor (gas) is compressible, while liquid isn't.

 

[swingman3]

All I'm saying is it feels mechanical to me. I'll keep watching your troubleshooting actions and if someone can solve the problem of a hot bike not wanting to start, then it's all good.

Swingman Out.

 

[wfooshee]

Swingman Out.

Sounds like baseball . . . . .

 

[dwhartwell]

Ok, I just spoke to an engineer (military-speak for a mechanic) friend of mine. Here's his thought. He says it sounds like vapor-lock.

That's not what vapor lock is. This is vapor lock and rather than me explaining it. Read all about it here. Vapor Lock

Many of the big block carb engines had this issue from time to time. Chrysler corp on their 440 and 440 Sixpack and HEMI engines solved this problem with a special fuel filter that had a bleed hole and a return hose to the fuel tank that allowed the vapor to escape back to the tank. A slick solution to the problem 40 years ago.

 

[dwhartwell]

All I'm saying is it feels mechanical to me. I'll keep watching your troubleshooting actions and if someone can solve the problem of a hot bike not wanting to start, then it's all good.
Swingman Out.

That would be one hell of a leak given that many times I've poured 1/2 cup of gas down a carb of an auto engine to "prime it" and it starts and turns over fine.

 

[swingman3]

Ok, I just spoke to an engineer (military-speak for a mechanic) friend of mine. Here's his thought. He says it sounds like vapor-lock.

That's not what vapor lock is. This is vapor lock and rather than me explaining it. Read all about it here. Vapor Lock

Agreed. I looked up vapor lock and what I initially described is not that. That's why I started calling it "compression lock". But it's a failed theory, anyway. Discredited like the Earth being flat or WMD in Iraq.

 

[wfooshee]

OK.

My starter, no load, 75-80 amps after an initial startup draw of about 120.

Loaner starter from my new best forum buddy FJRnut, 35 amps after an initial startup draw of not quite 80.

So basically half the load on the battery.

Now to assemble the bike and confirm in real life.

FJRnut, I'll be in touch by PM about arrangements for the starter.

 

[wfooshee]

Bike is buttoned up, cranks probably twice the RPM it had before. Gonna have some lunch, then go ride, get it warm, and come home to shut it off (just in case.)

Lost 15 minutes in reassembly because I had the airbox back in, then found the spring and washer for the idle adjustment screw, it was still disconnected from the throttle body. Had to take the airbox back out and take care of that. I hate being stupid! I wish it would stop.

 

[RadioHowie]

I hate being stupid! I wish it would stop.

I dunno....it's always served me well.

 

[wfooshee]

I hate being stupid! I wish it would stop.

I dunno....it's always served me well.

Good camouflage for the missus every once in a while, huh?

 

[RadioHowie]

I hate being stupid! I wish it would stop.

I dunno....it's always served me well.

Good camouflage for the missus every once in a while, huh?

Nah.....she's known me for 37 years. She can sniff out my stupidity and knows when I'm using it as a ruse.

One of her favorite sayings is "Oh, so now you're playing the 'stupid' card?"

 

[dcarver]

Oooh, stoopid, finally a conversation I qualify for!