So I'm getting ready to reassemble the engine on my first RD250 teardown and rebuild and am wondering if it is a good idea or not to use an anti-seize thread lube on any nuts or bolts either on the cases, or various shafts, countershafts etc.
The manual also vaguely implies to install the bottom case nuts before the upper half bolts and it mentions following the order of the numbers on the bottom of the lower case for installation but says nothing about the top bolts or the order to install. Is that the way people here do it, bottom nuts first then top? I would be inclined to just follow the same basic order on the top bolts if not specified.
(https://i.postimg.cc/k2FQF997/Screenshot-2025-05-27-154456.png) (https://postimg.cc/k2FQF997)
There is an assembly torque order.
(https://i.postimg.cc/cKYPj5q3/torque.gif) (https://postimg.cc/cKYPj5q3)
I know its small, but it's what I could find easily marked. Typically, the large bottom nuts for the crank are torqued first. But, start by installing the upper case bolts on top and just finger tightening them. The case will stand up on the flat back and you can then do the torque for the bottom bolts and finish everything in sequence.
I wouldn't worry too much about using anti-seize, unless you have seriously rusted up threads. just clean them well on the wire wheel before you install them and run a thread chaser down each one. You can find a decent metric set on Amazon for around $40.
:thumbs: yup
Thank you Striker (and m), exactly what I was looking for. My manual does not seem to have that page or diagram so this is perfect.
When I was the 'Engine Mechanic' at the CycleSprings Yamaha in Florida during the last century, I never used anti-seize on any of the motors from YamaHoppers to V-Max's. If you torque the case-bolts to the recommended values (it sure seems light at the time), you should be golden. I never had a comeback for a leak, and only found stuck bolts on rebuilt motors that had been severely over torqued or stored underwater.
WW
I used a bit of anti seize on the cylinder studs and just a wee bit. I did it just as an after thought and I had it in my possession. I had such a hard time getting the old studs out to replace with longer studs doing my 250/350 conversion. I figured what could it hurt? That and with no bolt head you really need the proper tool to grab onto the stud, finally learned that later on. Sometimes I have found that aluminum and steel just wanna stick together also.
Agreed - cylinder studs tend to stick, and that would be a good application for Anti-seize. I have a stud-puller which has saved a lot of struggling; a solid hit with the brass hammer usually helps too.
W
Studs into case are oversized M8's
Made for interference fit.