Crank and mains look a bit grungy...

Thanks for the update & that'd take the cake for being the rustiest & most stuck. I see the dismantled motor pics, so a bit of work to do. Not sure why they have the one rubberised engine mount when the others are solid. Had that on the top rear of the YZ250A which was only a DT1 motor on steroids & DT1-2-3 don't have. Could it be to do with frame flex--i don't know but be good if someone does. Could you spin up some solid alloy inserts--go on--tell us how it works. Could it be a vibration point, so go rubber?.

1977 IT175 also had the alloy insert mounts as I mentioned earlier... later models used the rubberized ones.

The rubber sleeved ones are still available new from Yamaha. Can be difficult to install. Alloy ones are easy and don't need that internal sleeve with the o-rings.

Ah, didn't read that. So there 'is such a thing' as alloy replacements, or as you say "77 IT175 had them.

Yes, I've used them a couple times. I made one set on my little mini lathe but finding them on ebay is easy too usually...  price has gone up though...  found them for a couple bucks a few years ago.. 

1W1-15317 engine mount insert

 

So...if I understand...if you use alloy replacements....WITHOUT the center sleeve that ALSO gets tightened when you use the rubber bushings...THEN may I assume the alloy collar transfers the tightening force from the bolt/nut to the frame tabs to the collar to the engine case? Assuming an 8mm bolt...do you stay with ~ 15 lbs of torque?

Center sleeve is there because with rubber bushings the inner sleeves of the bushings would get pushed in as bolt tightens. Sleeve between bushings is a spacer that allows solid tightening.

Alloy sleeves press on case like you said. Same torque spec as far as I know.

I remember the alloy IT175 inserts having a thinner flange than the ones on ebay... might be my memory playing tricks though.

Got it. Many thanks for all of the advice.

Could make steel one & flange will be important or it'll try to push way in unless there's a step. Could leave the spacer in & just calculate things so it matches up tight at the right time with inserts a very tight fit in the case & with the flange butting the case. Just saying.