1953 Crank sprocket... Compensator Alternative?

[EKHKHK56]

If the starters are breaking nose gears or whatever that is indicative of a battery, connection, timing or tune up problem. 99% of engines in the world have a direct drive starter to flywheel. BIG question. Where can we find 52-53 primary sprockets??? I'm short 1 and know 3 people looking... Erik K

[sportsterpaul]

...that is indicative of a battery, connection, timing or tune up problem.

Yes, too much advance will also cause the Bendix to crack. Its not the gear itself, but the over-running needle sprag clutch that allows the engine to start without back-driving the starter motor to excessive speeds.

And what is the rational for only using the compensator only on electric-start bikes? I think that the Sportster transmission is so over-designed, it can take the shock loads from a direct connection, but the compensator would make the bike smoother and quieter, and I assume Harley was willing to take the weight and cost hit for the more "refined" XLH model. I suspect they tried the cheaper hard sprocket on the 1967 XLH, but the cracked Bendix meant that was a no-go.

Note 99% of engines either have little springs in the clutch plate that do exactly what a compensator sprocket does, reduce shock loads to the transmission, or a torque converter, that has the same effect. What Iron Sportsters have is a large displacement, high-compression, two-cylinder starting load, with a disadvantageous starter gearing, up until 1982. What my mechanic pal told me is that as the battery gets weak, the 45-degree advance means the engine would kick back since it was not turning fast enough. We have all heard an electric-start iron Sportster go grrr-grrr-grr-thump and stop dead even though our finger was still on the button. That is the event that supposedly would crack the Bendix clutch if the bike did not have a compensator sprocket.

Agree that at partial loads the compensator does reduce the peak torque, but that is for steady-state noise and smoothness, not the other function of protecting the drive-train. I stand by my warning that a 53 and 54 K was designed and tested by the factory to use a compensator, and welding them up creates a risk of damage to the tranny.

Hard to say where we can find more early compensators. We could always look at an adapter spacer to run the Sportster compensator in the 53-54 sprocket shaft, assuming the primary cover would still fit.

[JerrryR]

Hi Erik,
What does the 52-53 primary sprocket look like? I'll check my stuff.
JerryR

[55panman]

The one thing that will benefit any early Harley is to wire the starter so that you have an ignition cut out. A switch to keep the ignition turned off until the engine turns over a couple of turns and then flip the switch and turn on ignition to fire engine. Lot less drag on that starter and no chance to break the gear.
Use on many Shovelhead and my Bonneville Panhead to great results. On the Panhead with high compression don't even need the compression releases.

[sportsterpaul]

What does the 52-53 primary sprocket look like? I'll check my stuff.

See page two of this thread, the good Dr has posted the extension shaft and sprocket. I assume it takes a big spring, cam, and the T-head similar to a late-model, only sized for the smaller setup.

55panman, that is a great idea. I had heard about compression releases to help an electric start bike get going, but I could see how just turning off the ignition until the flywheels are spinning would work great too.

[55panman]

Sportsterpaul, Compression releases work great but you have to take the heads off and machine some fins to get access and drill a hole into the combustion chamber. When I had a 1989 Super Glide I pumped the engine up & had Axtell's slant top pistons with .035 squish & about 11 to 1 comp. The starters then were notorious for kicking back on compression and breaking the bendix. Mine was really bad, I'd have to put it in gear and back it up on compression like a dirt tracker before I hit the button. I was at the Sturgis drag races and watched Mike Roland start his Fuel Sporty and they'd spin it before hitting the ignition, I thought I should do that. Resoldered the wires on the handlebar switch and never had a problem again.

[sportsterpaul]

Makes perfect sense. The starter gets the wheels going past the first compression stroke, but get a goodly percentage of speed is returned as the unburnt charge pushes back on the piston, now driving the flywheel. Meanwhile the starter keeps cranking away, making sure there is even more RPM going into the second compression stroke.

But tell us, once you click on the ignition, isn't there sometimes a huge backfire when the raw charge in the mufflers get lit off?

[55panman]

Disn't usually get a backfire. I wouldn't touch the throttle until the motor fired though, so it didn't load up from the accelerator pump.

[sportsterpaul]

Technique is everything, no wonder you race Bonneville.