Starter chain XJ750 '83

I have seen the posts about starter clutches and cam chains, but it seems no one has ever managed to chew up a Starter Chain. I dont know how I did it, but I have been fishing bits out with a magnet.
Got the sump plate off and the end driven gear out, but undoing some of the star screws etc to split the crank case halves is a nightmare.
I'm not even sure where I am going. Has anyone gone in to just change a starter chain?

 

The chain runs more than the starter.

You need a manual; there are a lot of little "details" to reassembling an XJ motor. Miss one, and the mill won't last.

 

I have split two XJ750 (82 and 83). You WILL need a manual. I read through the procedure about a dozen times before doing it. I did not change the starter chain but I replaced the chain guide, by the way you might want to replace that while you are in there. They get hard over the years and break apart.

The manual takes you through all the steps to replace the chain and guide. Take your time and be organized and it should go smoothly. Take lots af pictures to help you remember where everything goes (and to post for us to see what you are doing and to help others who may need to do the same thing). Good luck and ask lots of questions.

 

Save your alternator and find a low mile (KM) engine.
Your Police engine may have been abused (alot)

Get back on the road with another motor, then do a complete teardown, replacing the cam chain and guides, shifter springs, rings, valve job, and clutch, and starter clutch. Good as new.

 

Hmm, Thanks for the comments. I found the Haynes manual and the CD parts diagrams frustrating because they only show the chain (which I see is called the Primary Chain) as a ghost outline! I will keep on trying without busting more bolts/screws.

 

The chain is (was) "endless" you have to lift the crank out of the cases to replace it.

If you have the Haynes 650/750 book (the one with the red Seca 750 on the cover) look on pages 64, 65 and 66; reassembly is rather poorly covered on pages 87 and 88 then through page 93.

There are a LOT of things to be attended to, in order, upon reassembly. I would read pages 61-93, CAREFULLY, before beginning reassembly.

 

A thought: Are you 100% sure it's the starter chain that disintegrated, and not the oil pump chain?

I just remembered about the dumb little "dedicated" chain that drives the oil pump, you sure that's not what failed?

 

Yes, it is the Primary Chain. The oil pump chain is good. Some bits of Primary chain on the filter though!
We did some reconnoitering today and will try for a replacement either the bottom end or a whole motor. I dont want to waste the new rings, gaskets and cam chain!
I could see that it is a closed chain hence my confusion about how to actually address a problem with the chain itself, which the manual does not really describe as a maintenance issue.
The 4 Torx screws holding the bolts holding the Driving Gear seem about impossible to remove and even the Allen bolt holding the Ignition Reluctor has so far withstood as much force as I dare put on it for fear of stripping the bolt head.
Just as worrying as all this is the question of how DID that chain get into the state shown in the picture???

 

By the way,
Surely its time to go beyond Haynes and into the DVD video era? What about a video showing how to do these tricky jobs with comments explaining why the clever Yamaha engineers chose some of their design features?

 

THAT one's easy. The bike sat long enough under poor enough conditions that the chain rusted, internally, in at least one spot, if not a whole section. Rusted enough to "compromise" some of the pins, so that once it was run again, the chain soon failed.

I've seen it happen with final drive chains on more than one occasion.

Said failure, if at any RPMs at all, would have generated the shrapnel you found.