Hi, my '84 XJ 750 Seca stuck in 1st gear, refusing to change. Removal of lh side gearbox cover and a light shone into the selector drum area clearly shows a part of the 'rubber' alternator drive guide residing on top of the selector drum. Moving the remnant allows the drum to work properly. Obviously I have to remove the remainder of the guide and replace it. The question is, is it possible to replace the drive guide by removing the alternator; is there sufficient access? I've 'heard' the remedy is to remove the engine from the frame, split the cases and remove a lot of the internals to do this. :( I hope that is not necessary. All advice gratefully received.

Wish I could help but I could send you the Service Manual for the XJ750RL Seca (84) from the XJ CD. It's has lots of detail and inside pictures etc...

Hey CT, thanks for the offer, very good of you, but I have a workshop manual on it's way to me. I think my evenings will be occupied with the internals of the motor - unless I can find a good runner for a decent price!!

Oops! That's not the alternator buide but the primary drive chain guide and the cases have to be split to replace it. However , you can break up the remaining piece and blow the bits out with an airhose. I have heard of guys driving for another 20 or 30K miles without any other bits jamming up the works. BTW any small bits that fall into the crankcase will dtay there. The screen on the oil pump won't let them get intothe oil passages.

Thanks for that Blue Maxim - at least I know where I stand now. As the rest of the motor is good, I think I'll remove the offending piece of guide and put the casing back on - and hope!!

Glad I could help. This happened to my XJ 750 K. I let it sit in my garage for 4 years and then repented of my neglect. I weighed my options and respective prices of repairing rebuilding or replacing the engine. I opted to replace. I got an engine out of an '82 Seca for $300 USD. It would have cost $800 to rebuild.
Of course my engine had over 60K miles on it and rebuilding meant replacing rings, micing the head, replacing valve guides/springs, lapping the valves, replacing the clutch plates, camchain and guides, primary guide etc. etc. I was happy to get a running engine with only 22.5K on it that meant only rebuilding the carbs. That left me money to rebuild forks, calipers, front wheel bearings, part of the elec system and a custom paint job. I have been riding it all year and have put about 5K on it.
I will have to pull the head this winter to replace a leaking oring on the left side oil passage. At the same time I will replace the steering stem bearings with raced ones and the rear wheel bearings. This is practically a new bike now. I rode it all the way to Dallas in June for a carb clinic which was a 400 mile ride. It ran flawlessly. Now I have a bike that needs no bike shop which wouldn't know how to use a colortune anyway. They wouldn't have Mike Oberle's excellent YICS too either. Just some inferior Yamaha tool! Yea.....I'm happy!