I wanted to share an experiment I did to prevent the ever present back snap or "Ankle Breaker" effect when kicking over an RT1 (especially the 1970 model.) I recently restored a 70 RT1M and posted it here on the forum. What I didn't share was a little experiment I tried at the end of the build. As I was looking forward to the initial start and shake down cruise, I was not looking forward to kicking it over and having it kick back. So I made a manual compression relief valve that you just screw into an extra spare plug hole if your bike is so equipped. This, by the way, will work on any bike. There are the two parts I bought on eBay:

This image is hidden for guests.
Please log in or register to see it.

And this is what it looks like together and finally installed.

This image is hidden for guests.
Please log in or register to see it.

This image is hidden for guests.
Please log in or register to see it.

This image is hidden for guests.
Please log in or register to see it.

It is very sensitive and with it installed kicks more like a 250 then a 360. You only need to make sure to depress the plunger each kick as the plunger will close if you get even a pop of ignition. If you want more details on where I got the parts, PM me or post a reply to this post.

YAMABOB

Thanks Bob! I have seen those for years and always wondered if they would work on the big bores!

(Never had a chance to try one because I get in enough trouble with the smaller displacement bikes.. I'd be a certifiable hazard on a big bore! )

The valve itself is a 10mm thread designed to be installed in a Harley head after a machine shop properly bores and threads it. The alloy adapter mates the valve (10mm female) to a male 14mm plug thread that you just thread into your spare plug hole. Easy, and reliable. So far anyway. I think both parts cost me about $35.00.

YAMABOB

I have a buddy that would be interested Bob. Send me a pm please.

I still rely on the starting drill to start either of my RT1s. the compression release on my 1971 RT1B Enduro is not hooked up for now.

when cold, gas on, choke on, bring it to TDC and throw all the leg I have into the kick and follow it all the way through.

when warm open the throttle a 1/4 turn,bring it to TDC and throw all the leg I have in it and follow it all the way through.

setting the ignition timing to 2.9 on the 1970 RT1M took a lot of bite out of the kick back. it was like trying to kick a landmine when set to 3.4 mm BTDC.

3.4 is actually called for in the Yamaha specs for the 1970 RT1M and the 1971 RT1 MX.

thanks for this big tip that makes our 360s easier to start and save on potential broken bones and ruined kick start parts Bob!

Steve F. may be looking for something like that....

Looks cool.... tell everyone it is a nitrous injector.

DEET is correct
wifey may like this system better for starting her DT250A, very simple & CLEAN
Thanks for posting this info,

You bet. Like DEET, I think it looks pretty cool. And the nitrous injector...hmmmmm I never thought of that.

YAMABOB

Scootern29 did you receive the PM I sent?

YAMABOB

sign me up.... I have a 70 and I'm 60...