Introduction and a couple of general sprag questions

[Klawd]

Greetings all! Noob to the TigerTriple forum.

First post is a Sprag question.  I think I know the answer - pretty sure I'm going to be pulling the engine, but I'd appreciate the wisdom of thems that have gone there before me.

I'm wrestling with my 98 Tiger, 35K miles on the odo - 5K I've put on her (with no problems), and now she's not starting.

So, should a proper functioning sprag clutch provide any friction if spun by hand? I've pulled off the starter motor, alternator, and clutch/flywheel and I'm manually turning the starter-idler-gear and the alternator drive gear.

First, holding the alternator drive gear from turning, then turning the starter idler gear, should I feel any friction? (trying to mimick the start-up phase of the sprags job, when the starter motor spins, the sprag lobes engage the outer race, before the engine fires up).

Then second, holding the starter idler gear from turning and manually turning the alternator drive gear clkwise, should I feel any friction?
Basically, at very very low revolutions, are the lobes inside the sprag fully recessed?  (trying to mimick the engine firing phase of the sprags job, when the engine fires up, and the sprag lobes fully recede back into their carriage, releasing torque from the starter idler gear and starter motor, and only turning the alternator).

I'm getting solid engagement when I turn the starter idler gear and try to hold the alternator drive gear from turning, and I get a good deal of resistance when I turn the alternator drive gear clockwise, and try to hold the starter idler gear from turning.

Thoughts?

(Mods, if you think this belongs in Steamers, feel free to toss it over there).

[Timbox2]

Basically the starter idler gear should turn freely anti-clockwise, and lock solid clockwise, well according to Mr Haynes anyway.

[London_Phil]

Hi there and welcome.  Could you provide a bit more detail on your lack of starting. Was it sudden?, was the battery low, ( a sure way of damaging a sprag, as it causes engine to kick back, forcing sprag backwards, not good) Is there a history?. Its all here in this most illuminating of forums, but the more info you can provide, the better. Good luck

[Klawd]

Thanks for the welcome Phil (on a quick sidenote - I spent a year in school just outside London - Watford/Bushey area. Gotta get back there someday - preferably by bike - see more of that beautiful English countryside).

Yeah, I searched for a similar failure - here, on TriumphRat, Advrider, the Triumph Tiger Yahoo Group, google... found lots of examples of the sprag failing with low battery power, clack-clacking noises, slow failure, then ultimately being able to only push start the bike. Doesn't match my experience. I had just put in a new battery - trickle charged. Choke on, hit the starter (no prior issues other than that diesel sound that everyone claims is normal), engine started to spin up as-usual, then high-pitched metal-on-metal sound, engine starting revolutions drastically diminished, and no start. Engine turns over, just doesn't attain necessary revolutions. I've tried push starting the bike. Skids in 3rd gear.

Again, battery was topped off, so that isn't it.
Checked the timing - wondered if it jumped a tooth. Checked ok.
Pulled the alternator - had the DAR issue - fixed that.
Pulled the starter. Bench tested it - spins real well. No side to side or forward-backward play of the output shaft. No blemishes of the starter splins. Haven't fully disassembled the starter motor to do voltometer and measurment checks - I will before I pull and crack the bikes engine, but I don't think it's the starter motor. Could be wrong though.
Did compression tests. Found a few issues - think I've fixed it with valve adjustments...
Pulled and checked the cam chain tensioner - wondered if somehow the cam-chain had gotten too tight (grasping at straws here). Seems ok.
Went ahead and pulled the cams and did valve adjustemnts - couple of intakes had zero clearance. Fixed that.
Engine spins without unreasonable resistance with spark-plugs out - both by hand (wrench) and electrically, but pinned back together, it lacks that smooth, fast, 3-cylinder spin-up sound she used to have.

Local Triumph dealers service dept has been worthless.

I get it that the sprag engages in one direction, free spins in another (like a bicycle hub with pawls, but different design - one spring, many lobes). But does it engage with the speeds attained by the starter motor - whatever that's creating - 100/500/1000 rpms? Should it engage when it's turned by hand - ie 10 rpms when I'm turning the starter-idler-gear? And should it completely disengage from the clutch side - thus my question about holding the starter-idler-gear from spinning and turning the alternator-drive-gear.

Seems logical that the sprag should only engage when the starter motor spins it up fast enough to counter-act the loop spring that holds the sprag lobes into their carriage, and that those lobes should recess back into it's carriage once the bikes engine outspins the starter motor.

Just looking to get this confirmed before I tear the bikes motor apart.

(Oh, and... any chance you could send me a nice take-out bag of fish-n-chips, wrapped in newspaper (tanslucent from the grease) with a liberal splash of malt vinegar and salt??? I think I miss that more than the libations found in the public houses - well, almost more.)

[London_Phil]

Hey Klawd,  Wasn't Watford Grammer was it?, My Kids go to School in North Watford, so my Tigger haunts your old stomping ground. Im in Harrow actually, but no top hat for me!! I suspect that the starter should "fling" the sprag into a locked condition, but what the min requirement for speed is I dont know. Cant be that high, as it will try to engage even if if the batt is low. Can you get it up on a stand and ensure the rear wheel will turn the engine when in gear?, or that the whole lot turns on the wrench, with the plugs out of course. Do you have a manual. If you had DAR, did you ensure the clutch side was ok, and the Auxillary gear  behind the clutch is ok?. Regards Phil

[Mustang]

sounds like it could be a sprag failure although the 98's have the new and improved sprag clutch ..........but shit happens

[Klawd]

Hey Klawd,  Wasn't Watford Grammer was it?, My Kids go to School in North Watford, so my Tigger haunts your old stomping ground. Im in Harrow actually, but no top hat for me!! I suspect that the starter should "fling" the sprag into a locked condition, but what the min requirement for speed is I dont know. Cant be that high, as it will try to engage even if if the batt is low. Can you get it up on a stand and ensure the rear wheel will turn the engine when in gear?, or that the whole lot turns on the wrench, with the plugs out of course. Do you have a manual. If you had DAR, did you ensure the clutch side was ok, and the Auxillary gear  behind the clutch is ok?. Regards Phil

No, I went to the US International University, up on The Ave - used to be the Royal Masonic school for boys. Looks like they're turning it into condos now - Royal Connaught. Seemed like a nice place to have a kid in school though. And not too shabby an area to explore on two wheels.

So, put the clutch and starter back into her, bikes on a lift, spark plugs out, trans in 6th gear. Turns by rear wheel and by wrench on the crankshaft. Easier by wrench. Bit of a wrestling match turning the rear wheel.
I did take a look at the clutch side of the sprag - checked the bolt holding the alternator drive gear, and checked the nut holding the sprag side of the alternator coupler. Both are solid.

I made a couple of phone calls - tried harrassing my dealer again. They seem to think that the sprag is engaged at zero revs, and dissengages with centrifugal force. Anyone care to weigh in on that?