77RS hard start!

[RDG]

New to the scene here. Thank you, thank you very much...

My 77RS with @170K, strong runner, dual plugged, Boyer E-Ignition, is having cranking/starting probs. I use to know the answer to this, and I even dreamed about it the other night, but forgot!

On a fair weather day, 60-70 F, I've usually pinned the "choke" halfway, cranked the motor a few seconds, and it fires right up. Idle for 30 seconds, ride off, close the "choke", it's good. Lately, the motor doesn't even want to crank on choke. It cranks sluggishly at a touch of choke, but will eventually start while carefully feathering the throttle...It won't fire at all without a touch of choke...This is only from a cold start.

The timing is right. Plugs look a bit dark, but always have. Carbs clean and adjusted. The valves have always been mostly right on every 5K adjustment... I haven't checked lately, but I'm thinking the ex valves might have closed up, leading to hard crank/starting.

Anyone out there concur? Anyone experience the same problem? Advice? Comment?

[Armaguidon13]

ignition timing is OK ?

[SteveD]

Two simple things.

Remove the float bowls. Check for: 1. water in the bowl. 2. The gasket is well seated.

Motobins list the gaskets as a known cause for poor cold starts.
The holes in the gasket adjacent to the choke pickup tubes become oval. That may allow entrainment of air from the float bowl instead of drawing fuel up the tube into the choke mechanism. Using the choke will worsen it because of too much air in the system.

I hope it's that simple.

edit: pictures from advrider.
Blue line = air
White line = fuel


This is what happens with ovaled gaskets


This is what should happen

Then there's the battery ....

[RDG]

Thanks for the tips! Keep em' coming!

Ign. timing is spot on. I've even played around with a few degrees of advance/retard. Nuttin'.

Batt is ok. It's a fairly new Panasonic gel with plenty of cranking power.

Never thought of the float bowls, they haven't been off in a few years and many miles...will check those out along with the valve adj. this weekend.

[Garnet]

I think Steve was refering to the enriching (choke) housing gasket. They tend to suck in with age and the circut looses vacum and won't suck up enough fuel to start.

Edit: Sorry just reread Steve's post. So if your floatbowl gasket is OK move on to what I said.

[Jean]

Cranking sluggishly implies either a weak battery OR a starter that needs some love.
Cranking action ought not be affected by using the choke. Brand-new battery does not guarantee "good". We've all had some bad experience with that sort of thing!
You may have more than one thing giving you problems.
And DO check the valve clearances. That helped my R100s a lot, for quick starting. On the other hand, a rebuilt starter did the rest of the job. Snappy response for cranking (starter) AND a Quick start (carbs and valves)for the past 3 years.

[SteveD]

Ensure the small brass jet at the bottom of the enrichener well in the float bowl is clear.

Is the timing correct?

Are the choke cables operating correctly? Do they pull the whole way, do they return the whole way?

see my edited post further up for a couple of nice pix.

[Duane Ausherman]

Check logic first.

Tight valves will allow easier cranking, not harder. Your problem is most likely related to the cranking, not the timing etc.

You could have a poor battery, or a starter that drags and is taking more current. This will drop the voltage down quite a bit and may not have enough left for the ignition. I would test the battery by jumping from a known good one, such as your car battery.

If you had a volt meter on the battery posts (not the terminals) while you do this slow cranking, what does it show?

Suspect your battery terminals and the crimp inside the terminals.

This isn't related, but any time that one suspects a lack of fuel, just add a few drops directly in the spark plug holes. That is an instant test.

Let us know what you find.

[Armaguidon13]

Good point for the starter dragging too vuch voltage or bad batterie. I've had the same problem with a 1959 Beetle : half broken starter forbid the car to start correctly, the same car start in 2 meters of pushing it.
Try to push your RS ?

[Jean]

I'll vote for some sort of battery problem. Electronic ignitions are a lot more sensitive to low voltage than the old points/coils. Weak battery = lower voltage when cranking (due to excessive current) = less voltage to the electronics = hard starting.
If it starts smartly when jumped, that's the problem.

"Suspect your battery terminals and the crimp inside the terminals."
by all means check this before spending big bucks...