Recently purchased allot of early 70s Yamaha Enduros that were sitting in a barn  in the mix it looks to be a rt2 or 3 it's in pretty rough shape. allot of people on the internet seem to bash these bike saying they are grabage for some reason. in my opinion it seems like a cool bike  is there any common problems to look out or ways to get around them. From my understanding there isn't many of these bikes left and I would like to save it

The main thing to be careful of, in comparison to the smaller capacity bikes, is bad kickback when starting. This is usually caused by timing being out or the small hole for the decompression valve being blocked with carbon.

That's not so bad do you need need to pull the head to clean the orifice for the decompression ?

I think that you need to pull the cylinder to do it properly.

Once the decomp is removed you can clean through into the cylinder. But to clean down from there into the exhaust outlet you have to go from the port up to the decomp area as can't get it from above. The 'down' hole was factory drilled from the top fin then fin hole plugged with something epoxy i think. I'm doing mine tomorrow but my cylinder is off at the moment. Technically if you could get the valve out you could clean through into the cylinder with head on then poke something up from the port outlet. Probably best to pull the head to get at the valve hex with a spanner. I think there's an Oring on the valve stem itself. There's small & large valve assemblies too. The last of the "73 had a "74 big decomp. I bought a new cylinder once & discovered 'that'. "74 was a total motor re-vamp, frame & almost everything else. "74 bike in my opinion is a better stronger motor. I'm stuck with the older type but that's ok."74 also has CDI ignition so it retards to avoid kickback. With yours just be very sure the flywheel is tightened good & tight as they're pretty hard on crank keys.

Ok cool thanks for the info it's very helpful have your heard of anybody using retraining compound when mounting the fly wheel to help with the key way issue assuming it's the kick backs stripping the keys off?

Here is my advice on the 360. I have 4 '73 RT3 360s. 2 are regular riders. Also have a '71 RT1B 360. The factory decomp valve is relatively small and is prone to clog. The ignition timing is critical, if it is advanced it will be more prone to kick back. I installed a Harley Davidson manually operated decomp valve in the second spark plug hole, it has to be manually activated each time you kick. Also have a copper head gasket that is 2.5 times thicker than stock which reduces the compression ratio. They start much easier with no more kick back than a 250. As I get older I need all the help I get. I'm considering selling the 360s and get more 250s.

Yes it is a good idea to make sure the mating surface between the crankshaft and flywheel is smooth with no damage. The flywheel key does not keep the flywheel from spinning on the shaft when it kicks back, it keeps the flywheel aligned with the crankshaft while installing it. It is the contact of the tapered surface area along with the flywheel nut being tight that holds it in place.

I also have a NOS RT2/RT3 cylinder that has the larger diameter decomp valve that Yamaha put on the '74 360. Have not tried it yet.

And the 360s are fun to ride and attract a lot of attention.

No, nothing needs to be used except tightening super tight.
Now, i know i go over the top & to exptremes & ya can laugh if ya want no worries but i've seen many let go & always through insufficient tightening.
Don't ask me the torque tightness as i probably go about double but i'm not saying do that.
Never stripped the thread or pulled the thread off the crank.
I'll post a pic of mine that's been up here many times.
Just do it tight & hold it solid while you do so--so you get a good feel not a soggy tight feeling--if that makes sense.
All the 360's i've had plus this one all have damaged crank tapers & coresponding flywheel taper damage caused before i bought these bikes or motor parts but even with 'that' damage i'm happy to say mine is still hanging in there. Cheers from NZ.
Kick back is common if the timing is on the limit or a bit over.
They say 2.9mm btdc so don't go over or maybe a bit less like 2.5.
If the key lets go it'll likely not run because the flywheel will be too far away for timing but there's a danger it could be in a place that 'does fire' & either explode & blow the exhaust off the header or kick back so hard you'll be limping for a while &/or damahe kick gears & the other two into the back of the clutch.
Decomp is good to have, even if mines not working as it softens the blow.
My YZ465K "83 arrive about 15 years ago from the US with an already broken key that happened unbeknown to me & the guy i bought it off because he said he changed the stator then started it & stopped it, maybe gave it good rev then crated it to me in NZ. First #$$%g kick it kicked back so hard it broke the intermediate gear & bent teeth on the kick gear & i think on the back of the clutch too.
Seller said he'd tightened it with his rattle gun running out of oomph.
So just using that as an example.
Wasn't a happy day!!.
Ok pic on the way shortly. & sorry i know i 'go on lol'.
photos.app.goo.gl/k1jauVtE8g6nxmMZA
Sorry #7 we must be typing at same time only i'm slower lol or didn't read first & just see the question on email update then jump in to reply. Agree with all you say.

Perfectly worded. So often misunderstood.

“The flywheel key does not keep the flywheel from spinning on the shaft when it kicks back, it keeps the flywheel aligned with the crankshaft while installing it. It is the contact of the tapered surface area along with the flywheel nut being tight that holds it in place.”

#6 where you said 'retaining compound' I took it you mean loctite!! or similar. I'm guessing that might cause a real problem next time you take the flywheel off if you meant loctite on the taper?. With a good taper they're tight enough 'now'. Which reminds me, be a good plan to get the proper puller 27x1 left hand thread. Dime a dozen on Fleabay.