Hello, I believe the pressure plate of the clutch is contacting the inside of the right side engine cover. The bike makes a jingle sound with the clutch disengaged, and slight markings on the inside of the cover confirm this.

I'm a little confused at how this could happen, hoping for someone wiser than me to point me in the right direction

Post the year, model, etc. maybe some photos too.

More likely to be clattering of primary gears or clutch drum play on the internal cush rubbers but only a guess & look forward to knowing the model of bike. If it 'is' touching then have you got some odd ball clutch lever with a high amount of lift. Have seen levers with quite a distance from pivot point out to the cable nipple hole. All that's pretty unlikely though. Only other thing is if there's something odd going on to let the complete shaft move over then adjustment on cable been taken up to compensate. On second thought --third thought--has the clutch center nut come undone?, all quite unlikely events--but!!. On some models there a quite fat Oring that fits over the clutch drum gear & drops down between drum & gear & dampens out any rattle or chattering at idle. Not realy do do with when clutch pulled in but more just sitting idling. Of course i don't know ya bike & i'm woffling more about DT175 etc.

Apologies for the lack of details in the original post. The bike is a '75 DT400. I installed new EBC plates with my rebuild. I don't quite follow the clutch adjustment procedure in the service manual, but I have tried to follow it as close as I can.

If the clutch cable is adjusted to how I would normally (little play in the lever), when you pull the lever down you can see the engine side cover bulge out. I let out the cable and now it only touches at the extreme when the lever is pulled in, but the clutch is slipping slightly at that point.

I was just wondering if maybe I missed something obvious. I will probably pull the side cover and clutch and make sure I have not messed up.

I will take what you say into account when I go back through the clutch @RT325. I'll keep you both updated here

Ok, thanks for the update. I'm in NZ so too far away to help. If you let the cable adjustment back off "you say" the clutch slips-- i'm thinking you mean its dragging, just hanging on a bit from only just lifting, so no worries there. You've done that to see if it will lift enough to operate without touching the cover. Sounds like you're going to have to pull the cover & see what's going on. Are the new plates stacking up a lot thicker overall. Those don't have an adjustment screw in the pressure plate unless it's been swapped for a different model at some stage & the screw is reaching the cover, so not a likely issue. The left side adjuster purely lifts or lowers the lifter arm & the shape of the lifting part is tapered to get closer or further away to set the clearance to the pushrod... Best to back off the cable then take up the clearance on the adjuster as much as you can then adjust cable. But i'm sure you're way ahead of those tricks You only get a half turn of adjustment to lift & lower the arm. If you keep turning it clockwise it'll lock up so have to find the half turn so the adjusting pin is well engaged but not too deep. Ok, i'm woffling on about that but the problem's the other side. Is the clutch assembled right. Is the complete assembly somehow spaced over to the right side. Can't see how it could be & then the clutch pushrod would be too short to reach & have the lifter arm touch. Better go, cuppa tea time.

www.partzilla.com/catalog/yamaha/motorcy...clutch-250b-c-400b-c

Yes, right now the lever has a lot of freeplay, and when I draw it back fully, the clutch is dragging slightly, and the pressure plate is just barely contacting the inside of the side cover at that point. But the freeplay is necessary, or else the right side engine cover will bulge out when you pull the clutch too hard. I'd rather have the freeplay than let that happen right now!

I have little experience working with the clutch pack (could you tell?? ). Is it possible the new plates are just slightly too thick and will get worn down with a break in? In that case, I think the clutch will end up doing its job properly... maybe!

When assembling the clutch, I followed the diagram, and there were no surprises. I am wondering if I mixed up #14 and #16 (if that is even possible?). Maybe their thicknesses are different and would set #3 out farther than it should be? I am grasping at straws here

To me, it almost seems as if the side cover is just too close - I started wondering if gasket thickness could be playing into it... but that seems extremely unlikely!

Thanks for your help (and moral support) RT325! I will keep you posted if I find anything of note

In no way should any clutch parts be in contact with the inside of your case. If it is, it is shaving metal into your gearbox & clutch so I would not advise running it like that. You may have assembled the clutch housing incorrect? Something has moved your complete clutch pack to the outside. I'm not familiar with the 175 but on the 250 the back of the clutch housing pawl must align with the gear behind or it will stick out enough to strike the case. I do not think your clutch plates are causing this
You might want to take that apart & check the distance. Good luck!

Might have to try it minus one fiber plate & one steel, or if it doesn't sit high enough to stop the pressure plate bottoming out before compressing the plates then try adding two steels together, which is ok like that. Clutching at straws sorry & just trying to reduce the stacked height of the pack. Does the clutch & crank gears line up pretty well, like not 'way out' of line!!. If you 'do' try that you'll then have to be sure there's enough room to back off the arm adjustment on the left which will be with the arm lowered to the max by memory.

You mentioned "gasket thickness".

So my question is if you have installed the cover with sealer and without the factory gasket? If so, that might be the problem. Yamaha designed these engines to be as slim as possible so just that little bit of thickness could lead to an issue.

P.S. On the CT1 175 the engine will "lock up" if you try to install and tighten the clutch cover without a factory gasket. The tolerances on the tach drive gear spacing are that tight.