NC29 gearbox issue

[Drunkn Munky]

My mate has a problem with his NC29 that i need to sort out before he loses all faith in it and scraps it which will be a shame as he's spent the last year building probably the cleanest bike ive ever seen.
He took it for a MOT and its first ride this week which went fine until about a mile from home when he heard a noise which he described as like the fairing was dragging along the ground, it wasnt but he got it home and discovered the rear wheel bearing was shot. Changed the bearing and got it running up on the abba stand, put it in gear and noticed the chain kinda jumps every couple of seconds or so, this is the only thing we can see thats wrong with it so are assuming its a gearbox issue. Has anyone had anything like this before? He brought the bike as a project of which the engine had been stripped and rebuilt inc the gearbox so he's convinced the previous owner missed something when putting it back together but id like to hear peoples opinions as the guy that built the engine knows what he's doing. For what its worth before the wheel bearing went it changed gear perfect so im a little confussed. He hasnt rode it since as he's convinced the chain jumping is something wrong with the gearbox and will just ruin another wheel bearing.

[tanuki]

The wheel bearing and the chain are unrelated as I'm sure you know mate.

The only way is to ride the bike under load really, NC29s have a tendancy to wear the dogs in 2nd and 6th but you wouldn't usually notice this until the top of the rev range.

I reckon he's just paranoid.

[Drunkn Munky]

Yeah hes convinced what ever is making the chain jump has wrecked the bearing but i keep telling him that bearing could be 10 years old and just waiting to go. The guy did mention when he brought it that he's replaced some parts in the gearbox and thats whats got in his head that its all related. I think i'll wait until he's calmed down a bit then convince him to take it out again.

[thunderace]

Are there any tight spots in the chain?

[Drunkn Munky]

Nope no tightspots, ive checked that along with making sure the chain, sprockets and hub are assembled right. There brand new chain and sprockets too

[cajun]

It is because he does not have a load on the engine. This is normal...

[vfr400_jon]

all bikes do it on a stand

[Drunkn Munky]

Yep well ive finally convinced him its normal and he taxed the bike yesterday so im just waiting to hear weather its ok or not.