cb 550 3rd gear

[gary123]

What is the most likely cause of a 550 not engaging 3rd gear fully. It chatters and wants to disengage all others are ok.

[Bryanj]

One of the gears, cant remember which, is known to ocassionally shear off the locating dogs.
Drop the sump pan and see if any bits in there

[gary123]

One of the gears, cant remember which, is known to ocassionally shear off the locating dogs.
Drop the sump pan and see if any bits in there

Its not mine, Im asking for a friend. Ill pass on all suggestions and probably help with any necessary repairs.

[Oddjob]

Engine out and split job I'm afraid.

Check the primary chain etc whilst you're in there.

[gary123]

oh pooh, didnt want to hear that.

[Bryanj]

Thats to fix it, just sump off to find out then that stays off to remove lump.
Only need bottom case off if primary chain ok

[gary123]

So, we removed the sump and found nothing. Removed clutch and all looks good with the mechanism.
It runs and rides great, snicks in and out of all gears just as it should and even runs in 3rd until you put some load on it. Then it slips and sounds as though the gears are hardly meshed so Im thinking a selector fork is not sliding it all the way across. Does that sound feasible? Looks like engine out :'(

[Bryanj]

More likely dogs rounded but still engine out.
Remove sump, top breather cover and oil filter to make it easier

[Oddjob]

It could be a combination of a worn selector fork, rounded dogs on the 3rd gear and even the corresponding gear it's engaging with.

I think the problem will be 2nd/3rd combination gear, 23431-374-000 and it's engagement gear either 23450-390-000 or 23480-390-000. All still available to buy NOS. If it's the selector fork, I suspect that's the middle one on the drum not the rods and that's hard to find new. 

[gary123]

I have a complete 550 gear set in my spares stash so hopefully should be able to sort something out.

[davidcumbria]

I recently replaced my 550 gear cluster that is driven by the clutch. Only one of gears was damaged so if you need anything off there it's yours for postage costs only.

[gary123]

I recently replaced my 550 gear cluster that is driven by the clutch. Only one of gears was damaged so if you need anything off there it's yours for postage costs only.

Thats great, thanks. Ill bear that in mind.

[gary123]

The engine is out and it looks like 3rd gear is just not sliding over enough to engage. Compared to 2nd gear it could go another 2mm at least but it just wont. The gears look ok but show evidence of slipping, the dogs are polished as is the gear it engages with.
The fork that moves it fits snug in the groove but looks well worn, do you think thats it? [ Guests cannot view attachments ] [ Guests cannot view attachments ]

[Johnny4428]

Just a thought Gary, the selector drum that positions these forks when the gears are selected could also be worn and make a difference. Also the levers that rotate the drum.

[K2-K6]

Fork looks bent sideways, only supposed to touch on either side of the two pads out at end of fork.

Looks like a half moon witness mark at base of semi circle that's been rubbing where it shouldn't.  That will probably account for the error you're seeing in travel.