New GS Project! Has Starwalt's Disease :(

Wondertwin · November 17, 2006, 08:39:32 PM

I was pretty excited to get my new Craiglist find for such a good deal, though I didn't have any illusions that it wasn't going to be a project. It's pretty rough looking, and the guy had a loose starter he'd gotten on eBay, and said the starter clutch idler gear was missing. Fair enough, I could probably scare one of those up! Of course, once I got the generator cover off (which had a hairline crack from someone prying on the front without taking off the countershaft sprocket cover) and found the starter clutch gear was locked solid, I figured-out the rest of the story...

Not to be detered, I made a "rotor puller" out of whatever I could scare-up in the garage. In this case, a RD350 front axle, a large washer, and a heavy donut-shaped bevel gear. Put the axle through the washer, then the gear, thread into the rotor, and whack with the gear! Off it comes, easy as pie

At any rate, once I got the starter clutch apart, there was galling on the thrust faces between the shim and the large gear, and the other end of the large gear and the crank. I cleaned-up all of the burrs with a rotary stone, then lapped it with emory cloth. Everything fit pretty smoothly and turned okay... until I tightened the rotor back to the crank! When I was spinning the gear to check for freedom of clockwise motion, I thought I detected about 1/16" of axial runout on the large gear at the outside area.

This lead me to conclude the probable cause of this case of Starwalt's was that someone had tried to pry the rotor off by the gear and bent it. The bent area was interfering with the rotor and causing it to hang-up. Then I thought about it some more... It's also possible that the problem had have developed already (thus the galling on the thrust faces of the large gear), and someone bent the gear trying to remove the starter clutch/rotor with a crowbar rather that the "cough" proper tool.

Long story short, I need to order a new starter clutch assy to get the big gear (even though the dogs/springs/housing are still good). What I was wondering is if anyone else had any speculation about the causes of this affliction. I'd hate to fix it only to have it recur. I thought about the oil hole, but it isn't clogged. Maybe someone ler it run low on oil, or let it sludge-up? Hmmmmm....

GeeP · November 17, 2006, 11:32:02 PM

First off, welcome to the circus!

Quotegalling on the thrust faces between the shim and the large gear
burrs with a rotary stone, then lapped it with emory cloth
1/16" of axial runout on the large gear

Anyone who uses those words and has large bevel gears in the garage is different. Not quite ready to say machinist because the fraction.

I don't have many helpful comments about your problem other than to say your analysis sounds good to me. If they managed to crack the generator cover trying to get it off I have no doubt they could have been inside it with the same prybar.

As to the failure mode, I'd have to look at one. I do know this is a fairly common GS problem, I remember reading that Starwalt's locked up tight enough to frag the starter armature. Your hypothesis relating to the starter dogs sludging is a good one, common to aircraft engine starter clutches and radial engine supercharger clutches which are similar. However, I haven't had an in-service failure of the GS starter clutch to oogle at. Any pics by chance?

Wondertwin · November 18, 2006, 12:10:34 AM

Thanks for the welcome! I've got an engineering background, thus all the dry verbal meanderings. I'll do my best to keep it entertaining, but it may be a bit difficult with this subject matter!

Anyway, the galling on the gear face (and shim plate) looks much like the gear in Starwalt's original post (scroll down a little): http://gstwins.com/gsboard/index.php?topic=13774.30

However, mine has galling on the backside as well where the gear and the ridge on the crank intersect (from the ID to about .10" or so out; total thrust face on this side is about .25"). Technically, my crank is damaged as well, though I carefully used emory cloth wrapped on an ignition points file to knock down and smooth the burrs as best I could. I think (hope) it should be okay. For lack of a Cadillac gage (height gage) and a surface plate, I need to put the gear on a flat surface, take a scale, and see what kind of variation I get as I rotate it. My guess is it'll be substantial, but 1/16" was only a guess (.063 would imply false precision

). One way or the other, I know I have to buy some new parts though...

Also, I'm pretty sure this problem fragged the starter on my bike as well, as there was no starter (or idler gear) mounted when I bought it, and the previous owner gave me a Katana starter he'd obtained to go with it.

My comments on sludge didn't have anything to do with the dogs in the lock-up mechanism; that all seemed to be in pretty good order. I was thinking along the lines of sludge blocking an oil gallery and starving the little oil hole of its lubrication (thus siezing the big gear). Though the engine seems a bit gunky inside, it's pure speculation on my part. Heck, the dogs could have been glued in place, but sprung free when I tapped the gear off the rotor.

GeeP · November 18, 2006, 01:06:12 AM

Ahh, I see. I haven't seen those photos before. Interesting how narrow the thrust face is on the side facing the shim!

Quote(.063 would imply false precision ).

The fact that it was missing the starter certainly suggests that the P.O. was in there with his prybar. I might be inclined to check the runout on the crankshaft stub before I put it all back together. Although it's doubtful that they managed to bend it, you never know.

I would try to get that crankshaft shoulder as smooth as possible, which it sounds like you have done.

Let us know how it turns out!

sledge · November 18, 2006, 08:05:26 AM

Wondertwin?
I will go along with that comment of Geeps. A keen but inexperienced PO not familiar with tapered fitments has got out of his depth, realised he has screwed something up, not been able to fathom it and decided to offload the bike as a result ........a little knowledge can be a dangerous thing. You sound like a guy who knows what he is doing and I am sure you will sort it out.

Wondertwin · November 30, 2006, 10:43:25 AM

Well, I ended-up replacing the starter clutch shim plate ($5) and reassembled everything, and the mechanism seems to work as it should now. My guess is that the old one was warped pretty badly when it was galled, and cleaning the burrs off really didn't do the trick on that thin part. The runout on the big gear doesn't seem to be as bad as I'd estimated, and the starter turns it easily, so that should be okay. I JB welded the crack in the engine cover (it was pretty a pretty small hairline affair), and everything is ready to go back together... as soon as the gasket I ordered at the dealer comes in next week!

Then the real fun begins in trying to get it to run! It fired on ether whin I bumped it (to make sure it was worth fixing the starter clutch) and I've cleaned the carbs (raised the needles with a washer and installed 127.5 mains, have stock pilots for now as I didn't have any 40's laying around). My guess is I cn get it to run okay, but I need an airbox to really get it tuned-in. The bike didn't come with any kind of filter/airbox assembly on it.

Mandres · November 30, 2006, 01:43:03 PM

since you've already got the (slightly) larger main jets in there it might be a good idea to just grab one of the $30 K&N lunchbox filters. I have a set of the #40 pilots you could buy and then you wouldn't have to fool with the annoying stock airbox at all.

The Buddha · November 30, 2006, 02:09:36 PM

On this savage I was working on, some genius installed its starer clutch backwards. Somehow in spite of that it had broken teeth on the gear, making me think that they thought they were doing it right - remove it, then re install the same broken sheite back ... and go like its worse than before ... WTF.
Cool.
Srinath.

Egaeus · November 30, 2006, 05:40:18 PM

Quote from: Mandres on November 30, 2006, 01:43:03 PM
since you've already got the (slightly) larger main jets in there it might be a good idea to just grab one of the $30 K&N lunchbox filters. I have a set of the #40 pilots you could buy and then you wouldn't have to fool with the annoying stock airbox at all.

You never used them?

Wondertwin · November 30, 2006, 09:15:31 PM

Quotesince you've already got the (slightly) larger main jets in there it might be a good idea to just grab one of the $30 K&N lunchbox filters. I have a set of the #40 pilots you could buy and then you wouldn't have to fool with the annoying stock airbox at all.

I've got a selection of larger jets, but didn't want to get too crazy with it right off the bat. However, without the airbox on there...

My thinking is also that the lunchbox would be the best alternative, especially since an eBay airbox shipped ends-up being at least $20... 40 pilots will be a must (how much do you want for them?), but like I said, I'm going to make sure the thing will run decently before I buy any of that stuff. I'm assuming the starter clutch is what caused the bike to be parked, but I want to make sure it's not otherwise FUBAR'ed first

Mandres · December 01, 2006, 08:02:53 AM

Quote from: Wondertwin on November 30, 2006, 09:15:31 PM
Quotesince you've already got the (slightly) larger main jets in there it might be a good idea to just grab one of the $30 K&N lunchbox filters. I have a set of the #40 pilots you could buy and then you wouldn't have to fool with the annoying stock airbox at all.
I've got a selection of larger jets, but didn't want to get too crazy with it right off the bat. However, without the airbox on there...

My thinking is also that the lunchbox would be the best alternative, especially since an eBay airbox shipped ends-up being at least $20... 40 pilots will be a must (how much do you want for them?), but like I said, I'm going to make sure the thing will run decently before I buy any of that stuff. I'm assuming the starter clutch is what caused the bike to be parked, but I want to make sure it's not otherwise FUBAR'ed first

PM sent

Quote from: Egaeus on November 30, 2006, 05:40:18 PM
Quote from: Mandres on November 30, 2006, 01:43:03 PM
since you've already got the (slightly) larger main jets in there it might be a good idea to just grab one of the $30 K&N lunchbox filters. I have a set of the #40 pilots you could buy and then you wouldn't have to fool with the annoying stock airbox at all.

You never used them?

I somehow ended up with 2 extra sets, lol. The bike's previous owner must have stuck a set in there also.

Wondertwin · December 07, 2006, 10:05:03 PM

Well, my gasket came in yesterday, and I got the bike all buttoned back together! I changed the oil and filter and decided to switch to a set of 140 mains in the carbs due to my lack of airbox. I hooked-up my auxilliary tuning "IV" tank, hit the switch, and it fired right up! It's pretty cold natured with the 35 pilots and no airbox, but it did seem to run pretty well for no longer than I ran it (keep in mind Indy is COLD right now, and I didn't want to asphixiate myself in the garage while the wife cooked dinner). At least that gives me the confidence to order the K&N lunchbox so that I can do further tuning once I get the 40 pilots.

I had no apparent problems with the starter clutch, as that all worked properly and didn't make any weird noises. I'm guessing that keeping good oil in it at the proper level should keep the starter clutch gear from starving for oil and siezing again. My theory is a sludged-up or low-oil condition could lead to the Starwalt's Disease problem, but that's just my educated guess...

Now I can start getting the misc. parts I need and begin making it look pretty.

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New GS Project! Has Starwalt's Disease :(