slapping sound when starter is cranking

[pablo4953]

Aloha guys! A while back I posted a question about an exhaust for a 2000 885i (42,000 miles) I was considering for purchase, and you were most helpful. Well I bought the bike, and ordered a used 99 885i exhaust from England, which fit perfect.

The bike has been starting and running great, a real pleasure to ride. However, the other day I shut it down while fueling, when I tried to start it I heard a loud (for lack of a better term) slapping/knocking sound coming from the gearbox. I aborted the start, looked everything over, could not find anything obviously wrong, and tried again. This time I heard the same slapping noise for a few revolutions, then the ignition hit and it started and sounded normal.

I ran the bike up the street, going easy and listening for any unusal sounds, or vibrations. Everything appeared to be completely normal. I took the bike home, shut it down for about 15 minutes, then tried starting it. It started perfectly normal, which is to say it fires up smoothly after only a few revolutions of the starter. I did this three times straight, and it started great every time, so the missus and I went for about a 20 mile ride. Stopped for breakfast, and it started normal once again, and ran great on the ride home.

The next morning I went to start the bike, and got the same slapping sound. I tried it twice (only briefly) and got too spooked to continue. Considering I am new to Triumphs, and just starting to learn about the Tiger, I spent a couple hours reading the factory manual, followed by considerable reading on this great forum.

After looking at the diagrams, the only thing I can visualize it being is the sprag. So I started researching sprag problems on this site. I found some info on the Steamers having sprag problems from attempted starts with a low battery, and some info on replacing the sprag. But what I couldn't find was how you know your sprag has, or is a problem?

Although my battery is only a few months old, I put it on the charger today to make sure it was fully charged. Reinstakked it, and attempted a start, but had the same slapping noise, which is scary as hell.

Do you guys have any ideas? If it is the sprag, and I have to split the case, so be it. But I sure don't want to go that far, because of a misdiagnosis based on ignorance. Sorry for such a long post, but I am not sure how else to explain my troubles.

Any direction in troubleshooting would be most appreciated.

[Mustang]

sounds like the sprag clutch to me ..............and they are easier to do on the Girly bikes than the steamers .

[Timbox2]

sounds like the sprag clutch to me ..............and they are easier to do on the Girly bikes than the steamers .

Not on the 885 they arent, same as the steamer, engine out, crankcase split, b...tard job, sorry. 955 is the easy one, and I believe some very early steamers.

[Mustang]

:oops:  

[Timbox2]

:oops:  

Sorry Mustang, you still make the best Tiger Pegs in the world -1

[pablo4953]

In a final hope to avoid pulling the engine. I pulled the starter, and held it against the engine (for a ground). Hit the start button, and the starter turned smooth, with no unusual noise. There's no radial end play on the starter shaft, but there is a bit of axial play (estimate a couple of mm).

I pulled the engine, and split the case halves. Found a few metal chips in the sump, although nothing with part numbers on it, nor nothing alarming after 42,000 miles.

All the gears on the input & output shaft look real good (near new), and the bearings feel smooth. The alternator drive gears, and starter idler look new as well. The sprag looks new with no evident damage, turns smoothly in one direction and locks in the other. At least by hand, I can't get it to slip, nor does it make any sound at all when turning.

The only thing that does not look right to me is the starter idler gear, although snug on the shaft, it can easily move axially about 5mm. Seems like it should be shimmed a little tighter, but I am not missing any parts. Other than that, I can't find the smoking gun, and don't have a clue what could be making the noise on start up.

I'll sleep on it, and give another look tomorrow. Do any of you guys have any ideas?

Thanks!