1979 Yamaha XS400 Starter Marbles

[mixelpix]

Hello,
Half the time my starter fires up just fine from sitting cold. The other half the starter spins round and it sounds like there are a handful of marbles rattling around in the crankcase. At first I thought it was the starter itself, but I am beginning to suspect the starter clutch. Anyone know what the culprit might be and how to fix it? I have read varying accounts from riders and from Yamaha on how to fix this issue on the 650's, however, they have fairly different starter assemblies and I am no engineer. Before I tear apart my spare motor this winter and try and figure it out, I would love to hear from anyone who has encountered this same problem with these smaller bikes. Thanks! Patrick Kennedy

[John]

I don't have any XSperience with the 400 but from what you described, it is the sprag (overriding) clutch that is driven by the starter, but is always engaged to the engine. It will spin along as long as the engine is running. There are springs, and rollers that disengage from the starter gear when the engine reaches a certian RPM. Do a little research on a Spragclutch. A Chevy starter drive is an example of sprag clutch.

[mixelpix]

thanks John! I'll write back with what I find out. -pdk

[mixelpix]

Hello, I did some web research about sprag clutches. I'm not sure if the '79 would have been using that principal or not. Any chance you could take a look at the yamaha schematic and tell me if I am looking in the right place?

(works best in internet explorer)

http://parts.yamaha-motor.com/

Specifically, this is for a 1979 Yamaha XS400F.

Thanks again for the tip!

-Patrick Kennedy

[John]

Thats the right place. Items 6,7,8 and 9 are the sprag clutch.

[mixelpix]

Thanks John! I appreciate the confirmation - I am not nearly as fearless a mechanic as I used to be... Will let you know what I find in there.

On that note - is there anything in particular I should be looking for? I assume that parts will be worn and potentially there will be springs which I can try to re-tighten?

Appreciate the help!

-pdk

[John]

I don't know what you'll find when you get in there. Do you have to split the cases to get to the starter clutch? The springs I imagine will not be servicable, they will probably need replacing, as will the rollers. Try Bikebandit.com . They may have it.
Good Luck.

[soccer4m]

starter

Hi, I have a 1100 and my son has the 400. The starter has a chain drive from the starter motor to the crank and it is a very sloppy, loose, fit. Just pop off the starter cover, maybe one hour and you can see real quickly if the chain is slipping or too loose. His starts but it does rattle at times. Probably taking out a link in yours is hopefully the problem.....good luck,,,,,Mike in san diego