Unstick Starter Sprag with heat?

[schrocketeer]

Does anyone have experience using heat to release a stuck Sprag on the Starter gears?
The idea is to direct heat with a steel pipe/duct, from a heat gun that can output 300 degF, or 600 degF, on to the Starter gear that engages the Primary gear on the crankshaft.

My project '85 K100RT has not been started in multiple years.
I have rebuilt and bench tested the Starter. After re-install, the Starter just free-spins without engaging the sprag.
After trying the pop the clutch rolling backwards in 3rd gear a good 30 times, I decided to try a bump-start. Since my driveway did not have the angle/distance to get my Brick up to speed, this week I loaded it up, and went to a hill where I could hit 35 mph (tested with another bike, rolling in neutral).
Feathering out the clutch in 2nd, the engine turned over some, but not even a cough or bark of running. Fuel pump did come on with the key. Also tried hitting the Starter button a couple of times on my downhill roll. Battery load tested, and fully charged.
New fuel filter. Fuel rail cleaned. Fuel injectors cleaned and tested. Half tank of 93 octane fuel, around 2 weeks old.
Spark plugs checked.
Yes, I had the walk of shame, up the hill, to get my truck and trailer, to drive it back down and load the non-running Brick. I had been hoping it would start, and I would ride it back up the hill. :-(

[daveson]

I'm wondering about the possibility that the starter motor might not have been reassembled correctly, it's happened before. In this case the starter might be turning backwards.

[daveson]

The markers need to be aligned as in the photo.


IMG_20240331_092607.jpg (27.4 kB . 432x576 - viewed 96 times)

[The Mighty Gryphon]

The markers need to be aligned as in the photo.


IMG_20240331_092607.jpg (27.4 kB . 432x576 - viewed 96 times)

+1

You wouldn't be the first person to put the starter together wrong.  I have beaten you to that honor. 

[schrocketeer]

Starter turns the correct direction, via the sprag turning only one way (counter-clockwise IIRC?) when you reach in through where the Starter gear engages. Also have rolled backwards and forwards in gear. Backwards makes the same sound my previous FYK did that I had for 4 years and almost 30k miles.
The attached photo shows the heat pipe setup I tried last night, to focus heat gun on to the starter clutch.

[daveson]

If the sprag only turns one way (by hand I'm assuming) that makes me think, yes the starter might be spinning backwards. Do the markers on your starter match those in the photo?

[The Mighty Gryphon]

A buggered sprag freewheels in both directions.  That is why it doesn't turn the engine when the starter runs. That yours only turns one way says to me that it is working.

If the sprag freewheels CCW when you reach into the engine case, then the starter would need to turn cw when you look at it from the front.  Can you confirm that?

If I understand the situation correctly, the problem started after you rebuilt the starter.

[Laitch]

Clearly my last post shows my reading comprehension at an ebb, so I deleted it.  If the starter sprags are clogged with deposts, heating the sprag clutch is likely to cement them. You're best shot is emptying the crankcase, filling to the correct level with high detergent diesel oil, taking for a hard run then finding out if that frees up the works.

Regarding the starter assembly: I'll now try a diagram  to supplement Mighty Gryphon's observation.


 

[Chaos]

from what I understand the sprag clutch gets gummed up (usually from lack of oil changes) and the starter just spins.  I never tried it but some have had success carefully drilling into the case and spraying solvent or light oil directly on the offending device

[The Mighty Gryphon]

I have rebuilt and bench tested the Starter. After re-install, the Starter just free-spins without engaging the sprag.

Did the starter turn the engine before you rebuilt it?

[Laitch]

Since my driveway did not have the angle/distance to get my Brick up to speed, this week I loaded it up, and went to a hill where I could hit 35 mph (tested with another bike, rolling in neutral). Feathering out the clutch in 2nd, the engine turned over some, but not even a cough or bark of running.

Popping the clutch in third or fourth gear around 20mph should have lit it up if the fuel, plugs, and timing were good. Feathering was polite but not brutal enough.  Persist. Running with it will build leg strength and endurance!

[frankenduck]

My project '85 K100RT has not been started in multiple years.

Fuel pump did come on with the key.

This is not how a K100 is supposed to work. The fuel pump should only get power when the engine is turning while starting or running. (As detected by the Hall Effect Sensor.)

[schrocketeer]

I've never heard this Brick run. Downside of buying a project bike. Think it's been at least two years since the previous owner had it going. Even worse than the usual cliche. It did not, "run when parked."

Thanks for the tips all. I'll swallow my pride, pull the Starter, and confirm turning direction.

New cross-fit training routine. Push a 500+ lb bike uphill. :-\

[schrocketeer]

Hmm, the metal indentations on the starter body/cylinder (attached photo) do Not look exactly like the correct-example photo above.

At this point, I would be happy to have the non-starting be due to my literally backwards mechanic'ing, so I can get my Brick on the road again.

[Laitch]

New cross-fit training routine. Push a 500+ lb bike uphill. :-\

Birmingham's the home of Vulcan the Ironman so inspiration certainly isn't lacking, despite his going downhill some the last six years. 

Hmm, the metal indentations on the starter body/cylinder (attached photo) do Not look exactly like the correct-example photo above.

Bring on the photos!

[The Mighty Gryphon]

I'm hoping it's backwards.  I'd hate to be the only one around here to have done that.

[daveson]

Spin the body around, line up the marks, problem solved.


IMG_20240402_064200.jpg (19.04 kB . 432x576 - viewed 63 times)

[daveson]

I'll swallow my pride, pull the Starter, and confirm turning direction.

There's no pride lost in asking for help. We non mechanic riders (which most of us are) can take pride in giving it a go even if we don't fix it, but I think we've fixed it to boot.

[schrocketeer]

Things work better when the Starter turns the right direction. After turning the magnet holding cylinder around, the Starters works as expected.

Thanks for help everyone. :-)

Now to work on the backfiring. I'll research the site more, then possibly start a new thread for that discussion.