RT-2MX/YZ360A Hybrid

[firko]

Does the Jones Mag cover have the oil filler hole?

I always thought that they did but it doesn't look like it in these photos although that could be a filler directly below the oil feed bolt on the barrel on the bottom shot.
 
                                                                                                       
                                                                               

[Iain Cameron]

I always thought it was through the tacho blind plug on the YZ . Iain

[Tahitian_Red]

Looks like the YZ cases just had the tach drive hole tapped for a threaded plug.

[Davey Crocket]

100% correct Red.

[Tahitian_Red]

I have the opportunity to buy an RT2 Works cylinder, but it has a chrome bore and not sure where I could find a cast iron ring to fit a 360 piston? 

Anybody know if one (iron ring)  exists?

[farmpro]

There are plenty on Ebay over here in the US.It is part # 365-11611-70.It is available for buy it now of 24.95 USD and 8.99 shipping to Australia.
The 70 designates it is a cast iron ring for a chrome bore.



Bill Davis      Texas Vintage Racing Club

[Tahitian_Red]

Thanks Bill !

Which 360 models came with the chrome bore?

[Davey Crocket]

YZ360A....all GYT cylinders...the 70 on the end of the part number means it a cast iron ring.....Bill, Reds one of your countrymen.

[OverTheHill]

I'd love to see [& have] a chrome 360 cylinder. Only ever seen chrome on the 250A & B cylinders, 360A & B down here had a thin liner allowing two oversizes. I have a 360B cylinder [& i have a plan--just not happening], mine is on .25 over so one bore left to go if necessary. Does the GYT kit 360 cylinder mean it's a chrome job!! as opposed to the original cylinder on A & B? Cheers.

[firko]

I recently bought a YZ-A cylinder from an Irishman living in Canada that's got an iron liner on 2nd oversize. He sold it because he wanted his bike to be 100% standard right down to a chrome cylinder so when he found one in usable condition the iron version got the flick. His quest for perfection is my gain . I'm using it with an ACK head on my DT2MX bottom end with YZ clutch cover and YZ clutch basket and 'Crockett Racing Conglomerate' YZ style sprocket cover/clutch actuator. It'll be my counterfeit YZ250-A  

[farmpro]

All of the YZ 360's (A & B) that I have seen over here in the US had the thin steel liners that could only be bored a couple of times.The only 360 cylinders I've seen over here were RT1MX.There must have been some MX360A cylinders too as their prefix is 364  like the ring but I've never seen one.
I do have a couple of chrome bore PDV cylinders.I just recently ported one of them to YZ 360 specs and had it Nikisiled but haven't fired it up yet.
I have a NOS YZ 360 liner and a couple of YZ 360 cylinders if anyone needs one.

Hey Firko,I have a Jones Cover on one of my PDV's and it has no oil filler.
I tapped out the Tach Drive hole to 3/8 pipe as I recall and have a brass plug in it.

[farmpro]

Just read my last post.It should have said the only chrome bore 360 cylinders I've seen were non reed Rt1MX.

[firko]

There must have been different specifications for different models Bill.....Aussie YZ-A & B were chrome bore (I'm  presuming all of them) and my new besty in Canada told me that the YZ-As they got were "Euro spec", whatever that entails. My GYT RT1 cylinder has a cast iron bore so that backs my hunch that DT1/RT1 MX and GYT cylinders are different, going against popular belief that they're the same. I've been searching libraries and the internet for years trying to find some definitive information on both GYT and MX piston port Yamahas but I've found nothing of any substance so far. My friend had a lot to do with the Yamaha factory race effort during the DT1 era and he's still got the 'factory' RT1 porting specs that he got from Don Jones back in the day. In them there are separate porting instructions for the iron barrel and the chrome version which adds to the mystery .

Bill, I'm still desperately looking for a Jones clutch cover if you ever come across another one .

[firko]

was going to use an MX250 lower clamp with a YZ100 upper, but now I have the real deal. 

What are the difference between MX and YZ triple clamps?

[Tahitian_Red]

The YZ-A clamps have an aluminum stem that is welded to the lower clamp while the DT2MX/MX/YZ-B models have a steel stem that bolts to the lower clamp.