1st gear clutch issue - disengaging while riding

[Fingerscrossed]

Hi all, thanks to everyone who has helped me with the bike so far! I’ve done a lot to it - had to rebuild the engine a few times and worked through a lot of issues. Recently I rebuilt the engine because the head stud thread stripped just after rebuilding it… I took it on a long run the day before that happened and it was running perfectly. I also found a broken cush spring in the clutch so I replaced that and put it all back together. It’s run pretty well for a while (maybe 200kms or so) but now I’m having clutch issues. One thing I noticed is that I had no problem finding neutral before but now I can’t get neutral while the motor is running.

I first noticed something when I shifted gears from first gear to second gear there was a big grinding sound/feeling for about a second. This was after 5 mins of driving. I pulled over and slightly adjusted the clutch free play and it was fine although I kept thinking I could hear something from the clutch when it was pulled in while in first gear. That ride was about 20kms.

I took it out yesterday and all of a sudden just after taking off in first it’s like the clutch was pulled in - so it’ll take off, then rev hard and engine brake for an second and then keep going normally in first gear. It’s now doing this same thing every time. I don’t think it’s doing it in other gears but I have been pretty cautious because I don’t want it to engine brake hard when I’m turning a corner or something… I just took it around the block and it now also feels way underpowered in second. Like there’s a rev limiter. I found a thread where it was that the dogs had worn on the gear teeth but they seemed fine when I took them out last.

It has new friction plates and the rebuilt cush springs - I’m not sure why it would only be first gear. There were maybe 2 or 3 metal flakes in the oil maybe about 3mm long. I’ll pull the clutch again but I’ll need to drive it to the workshop first... Any ideas on what it could be?

 

[Wingedwheel]

What kind of oil did you use?

 

[Fingerscrossed]

Penrite 20w50 mineral oil

Going to drive it the 15 mins into the workshop today and have a look. Hopefully not too rough...

 

[Fingerscrossed]

Ok, here we go... I guess that was the loud scraping/grating sound I heard/felt and the reason for those metal flakes.

That happened on the 4th ride or so after rebuilding it, so I'm not sure why it took so long or what would have caused it. I used the kit to rebuild the clutch basket, but it looks like a nut has scraped the inside of the case and potentially loosened/bent something so now the clutch is slipping in first gear (although the slipping didn't start straight after the sound when I assume the nut hit the case). It had both washers on before the basket.

It's a 256 basket - everything else is 447, could that be the issue? should I use file the nut down?

I now am guessing that something else is causing the slipping - the force from the nut grinding through the case has bent or loosened something. Hopefully, it's only the pushrod or something easy like that but I have no idea...

 

[bosco659]

I’ve seen quite a few motors with this spot missing material. Does it matter? I know the crankcase is very thin in this spot. Just curious.



On a separate note, it looks like some metal bits are lodged in the gear teeth. Or is it just a deceiving picture?

 

[Fingerscrossed]

I’ve seen quite a few motors with this spot missing material. Does it matter? I know the crankcase is very thin in this spot. Just curious.

On a separate note, it looks like some metal bits are lodged in the gear teeth. Or is it just a deceiving picture?

View attachment 343980

I have no idea about the first question but am interested too.

I think the light is bouncing off the metal but I’ll double check there are no flakes when I’m back with the bike. I found the screw that holds the star on the shift cam was loose (maybe from the vibration of the basket on the case) so that was potentially my issue and would explain it gradually happening - more vibration = screw getting looser

 

[bosco659]

Waiting to hear from the wise OG’s on post 5, 1st pic.

 

[gggGary]

Waiting to hear from the wise OG’s on post 5, 1st pic.

Still looking, here's one

 

[gggGary]

#2

Might have to slog out the SOIR tomorrow to find anymore pics, not a view that gets shot all the time.

 

[gggGary]

Three more from the web. But like you say the aluminum casting over the steel shell is thin there, prolly OK Mebby someone pried against it.

 

[gggGary]

One more, for now...

 

[gggGary]

several from the motor shelf in the SOIR

 

[bosco659]

Thx @gggGary. Some I’ve seen look like your second last pic above. It almost looks like a casting deficiency (red lines) vs a piece broken off. If it’s that thin there, does it serve a structural purpose?

Is the yellow line pointing to the steel bearing retainer in the case?

 

[gggGary]

Pretty sure yes, the steel insert is placed in the mold the aluminum cast around it. Like you say that's a thin slot to squeeze aluminum into, cold cast flaking away is going to happen now and then.

 

[bosco659]

Pretty sure yes, the steel insert is placed in the mold the aluminum cast around it. Like you say that's a thin slot to squeeze aluminum into, cold cast flaking away is going to happen now and then.

K thx. I guess no need for alarm then.

 

[Ratranger]

Sounds like worn drive dogs and probably a failing shift fork. Mine did it where you'd take off and it would jump out of gear then pop back in. On tear down I found a heavily worn shift fork. The fix was to undercut the drive dogs and get a new shift fork.

 

[Fingerscrossed]

Still trying to sort this out... I think the 1st gear slipping was a loose screw on the shift cam assembly that happened after the basket scraped the case. That's fixed now, but when I'm sitting in first with the clutch pulled in it wants to bog down and die. The bike doesn't roll forward, it also doesn't matter if I take all of the free play out at the perch. Could it be that there isn't enough pressure to disengage? I'm just thinking this because it doesn't seem to matter how little free play is in the lever, it still doesn't feel like it's disengaging properly.

It's got 5 original steel plates and 1 new steel plate (which I sanded to remove the burrs) but I noticed the new steel plate isn't flat like the original ones. It's one of these plates, does anyone have any experience like this with these? Or any other ideas to try?

The rest of the clutch is together correctly. There is a new actuator arm, single push rod, friction plates, and thrust bearing washer.

Not sure if this is related but I was riding and the clutch cable came out from the actuator arm (engine side). I put it back in and closed the tab to make sure it won't come out again but that was weird