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I need help with my XJ1100
The summer before last, occasionally, when I would shift into second while ridding slightly aggressively, I would get a thunk sound and a slight lurch in the acceleration. Just for a fraction of a second. I wasn't too concerned at the time.
At the beginning of last Spring, still noticing the occasional lurch I pulled the 750 final drive and put one of my XJ drives in. There was no change, still a very occasional lurch and thump as soon as I would shift into second gear under power.
My oldest son talked me into letting him have the XJ to ride fore the rest of Spring and the Summer as I was having a lot of knee trouble and was getting a Knee replacement.
When he brought the bike back in July he told me it had stopped the thunk and lurch after shifting into 2nd. but was now doing it in first and that it was so bad that he had been starting in 2nd. gear and not using first at all. He said the thunk was louder and he was right. When I was able to ride it I discovered that the noise was now very mechanical and metallic sounding and would do the lurch and thunk repeatedly while under even mild acceleration in first, but would not do it in any other gear. The noise was now discernable as coming from the engine and seemingly from the center to the front.
After looking at the service and parts manual I came to the conclusion maybe it was the primary shaft cam damper.
Well, I just today split the case and found Absolutely nothing that I could determine as defective, worn or slipping. No chipped, missing or even worn gear teeth. The interior of the engine looked just as good as the day it was made, or at least as good as when I was in it in the winter of 2004 when I re-ringed it and replaced every bearing in the engine and the bike (except the one that's not available) and did the 2nd gear fix.
The only thing I haven't inspected is the middle gear assembly but it feels good and beside, if the problem was it, I'd have it in all gears.
Any and all suggestions for a cause will be greatly be appreciated.
Louis
The summer before last, occasionally, when I would shift into second while ridding slightly aggressively, I would get a thunk sound and a slight lurch in the acceleration. Just for a fraction of a second. I wasn't too concerned at the time.
At the beginning of last Spring, still noticing the occasional lurch I pulled the 750 final drive and put one of my XJ drives in. There was no change, still a very occasional lurch and thump as soon as I would shift into second gear under power.
My oldest son talked me into letting him have the XJ to ride fore the rest of Spring and the Summer as I was having a lot of knee trouble and was getting a Knee replacement.
When he brought the bike back in July he told me it had stopped the thunk and lurch after shifting into 2nd. but was now doing it in first and that it was so bad that he had been starting in 2nd. gear and not using first at all. He said the thunk was louder and he was right. When I was able to ride it I discovered that the noise was now very mechanical and metallic sounding and would do the lurch and thunk repeatedly while under even mild acceleration in first, but would not do it in any other gear. The noise was now discernable as coming from the engine and seemingly from the center to the front.
After looking at the service and parts manual I came to the conclusion maybe it was the primary shaft cam damper.
Well, I just today split the case and found Absolutely nothing that I could determine as defective, worn or slipping. No chipped, missing or even worn gear teeth. The interior of the engine looked just as good as the day it was made, or at least as good as when I was in it in the winter of 2004 when I re-ringed it and replaced every bearing in the engine and the bike (except the one that's not available) and did the 2nd gear fix.
The only thing I haven't inspected is the middle gear assembly but it feels good and beside, if the problem was it, I'd have it in all gears.
Any and all suggestions for a cause will be greatly be appreciated.
Louis
They are overengineered, and you have 6 dogs on 4th to spread the stress across, vs. only 3 for 2nd. As has been stated, you need to REGRIND 1st/4th and go ahead and redress 2nd/5th while you're in there, and be a bit more aggressive with the angle of the undercut. 
I have a 4H3 engine that's got rusted up cylinders out in the garage. I'll take a look at the gears and let you know how they look. If they are good I'll make you a deal on the entire secondary shaft and you can just swap it all out.
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