Well, got into it today and found that the flywheel woodruff key was sheared into 2 pieces. got a new one on order.

I'm [mostly] sure that was the source of our issues. when we set the timing last time, it started easier than Bill expected. But there was a third on-looker [distraction] there, and i think in the process of wrenching and bull5h1tt1ng and entertaining, we didn't torque down the flywheel nut.

when we were putting around on the street, i bet one good twist of the wrist sheared that key right off, and that's when we pushed it back into the shop.....

looks like there was some unfortunate damage to the tapered crank end and the inside of the flywheel mating surface. looks like mostly sheared keyway steel that got pressed/gouged into the 2 surfaces. hopefully it can be resolved with some emery cloth.

I recommend getting some valve grinding compound at your local parts store and apply to the crank taper and inside flywheel and work the flywheel back and fourth to make a good seat. This was recommended to me on here which I did to my RT1B. Over 400 miles on it and holding solid. Be sure and torque the nut down pretty good when done. I think I used 60 ft lbs and then another little tug.

BTW...that's a really clean looking flywheel and stator!

we do good work when we aren't shearing woodruff keys!!!

good tip on the valve lapping compound. i have some on the shelf.

So the thing runs now. video below.
a few interesting notes to share:

1) new woodruff key installed. polished and brushed the crank and flywheel to get it reasonably smooth, then used that lapping compound mentioned earlier. it worked a treat. be sure to clean it all off with brake cleaner etc before final assembly... they mated up beautifully with the new key and without being able to find a torque spec in the manual, torqued it to about 40 ftlbs.

2) timing the motor was manageable with two sets of hands. bill held the motor in place with the special tool (motionpro clutch holder locking vice grip tool) and kept an eye on the dial gauge, and i worked on setting the point break and holding the motor in full advance.

::::A POINT OF NOTE FOR FUTURE TIP-SEEKERS USING A DIGITAL MULTIMETER::::
this info can be learned elsewhere on the site, but here's my synthesis of it... measuring when/where the points open is a tricky operation with an inexpensive digital meter. i have a "klein tools" meter that does just fine on most things, but its still just a cheap multifunction meter in a slick looking plastic shell. it's not particularly sensitive, and the display refresh rate is exceptionally slow. an analog gauge is better in this task, but i didn't have one. OK so use the smallest OHM setting your meter has. mine was set to "2".
both sides of the points are always electrically in contact, so unfortunately, for this task, you cannot use the continuity buzzer setting. we are looking for a very small change in resistance when the points open and close. on my engine (and it will likely differ a bit on each engine), the difference was .5 OHM. half an ohm. small. i attached one lead to a good engine case ground, and the other to the spare black timing lead coming from the wiring harness. with the points verified closed, i had a measurement of 2.3ohms +/- .1ohm. when the points were verified open, the resistance measured about 2.8 ohm. with the slow refresh rate on my meter, it was difficult to measure exactly when the points broke open, but by turning the flywheel very slowly in both directions and watching the meter closely, it could be determined where that resistance change of about .5 ohm happens. depending on where you clamp your meter leads, and the integrity of your particular set of points, your .5 ohm could be a different value, as could your initial open/close measurements. you're looking for the value to jump up/down by a consistent gap. determine what that difference is first, then set the timing to that little jump in resistance. hope that makes sense. if you had access to an analog needle-sweep ohmmeter with enough sensitivity, that would be much easier to read the spike as it would read instantaneously on the meter.

ok anyways:

this motor did have the timing tab and the flywheel notch, so i was able to have a rough reference there, but it seemed like just using the timing marks would give not very precise results. the range of what i would have called acceptable when just sighting the flywheel, measured to be a variance of at least a few tenths of travel @ the piston crown. no big deal, it seems. we used the guess-and-check method of setting point gap, and were only able to get the points to open at 2.5mm BTDC. better to err on the side of retarded timing, in the interest of easy starting and ankle saving. kicked it and verified spark, but it would only start and run when using a short shot of starting fluid. carb issues....


took the carb apart, there was a bit of varnish in there, but nothing terrible. squirted it, hit it with compressed air, cleaned it well enough, and put all the OEM jets back in. some extracurricular reading on the forum related words of caution about using the jets and needle from aftermarket carb rebuild kits, which i had done a while ago. still kept the old ones, so put those back. the MJ has lost it's marking, but it was likely a 220? the PJ is a mikuni 30. the jet needle is a mikuni 6FC1.

one other issue to solve on this one was a real stumper... get this:
carb slide had a weird issue where the slide would get stuck up at 3/4 throttle and you'd have to open the top and push it back down with a tool or something. figured that the issue was a backyard carb repair problem from the past... the nylon guide inside the carb body bore had been broken off at some point, and epoxied in it's place was a little piece of metal that seemed to do a decent job, but also maybe was the reason that the slide was hanging up. we brushed the slide and the bore, filed away tiny amounts of extra epoxy, lubricated it and it seemed to be working better on the bench. install it back to the bike, and the first twist of the throttle makes it hang up again. take it off the bike, re-inspect, re-clean, verify that it's working okay again in our hands... reinstall and it hangs up again.... turns out, it was the torquing of the intake manifold nutsonto the engine, apparently deforming the carb body just slightly enough to cause the slide to hang up. when the slide did hang up, i used a wrench, and loosening one of the intake nuts by like 1/12 of a turn caused the slide to drop back down. crazy.

RT1 VIDEO LINK
(how do you embed a youtube video?)

here's what it looks and sounds like today.
it runs okay, still needs some help.
it ought to be able to wheelie really easily in first gear by smackin the throttle, i would assume, but it seems like it kinda dogs out, or just has a slower delivery of engine power to the wheel.
gears 3, 4, and 5 seem to have smoother power delivery while already cruising, but going from a start... forget it!

i wonder if it's clutch related.

Just paste the link without any fancy changes.

Yep, the slide sticking on those old type carbs has been a problem over the years & can be damn dangerous. Don't run an Oring 'too fat' to be easily compressed in the groove or the ears will warp & seems to pull the slide body out of shape. Think face of the fiber block gets out of shape from years of overtightening the carb, then the flange gets bent ears.

It breaks parts too if the kick back is really violent. I set my 1970 RT1M and 1971 RT1B respectively, 2.7 and 2.9 mm btdc with the advance blocked open. the points cam is worn on the RT1M between the cam weights and the points cam so I have to play with it some when setting the timing. the RT1B itself is easier. along with the dial indicator and Buzzbox I remove the head and use a dial Indicator stand for setting the timing.

Congrats on getting it running!

I'd go to to at least 50 ft-lb on nut.

Cheap digital meters make the timing task hard to impossible. One thing is that with points closed ohm reading should be 0.0. Points closed should be a solid ground. Could be your meter or dirty contacts or bad ground connection or... at least you got it to work well enough to show a difference.

Hopefully you didn't set the point gap... not sure what was meant by that comment. Important thing is to get points to open at right time, not the gap. I mention because manuals are confusing and you wouldn't be the first to "adjust the gap" after timing and mess up the timing in the process.

I've never seen a nylon guide in an old Yamaha carb... or new one for that matter. What you have sounds original. Warped flange from overtightening or using wrong oring is an extremely common reason for slide sticking on the flange mount carbs. You'll probably want to pull carb and make sure flange is flat... it's almost certainly warped.

Im back
Last time i posted, we got it running, i appreciate the feedback on the carb flanges... a mystery to me at the time, good to know it's nothing to be overly shocked about.

Tomorrow I go back to trying to extract more power from it. Where should I be looking?

Today we had to use some ether to get it running again for the first time in a few months, it quit firing up for me back in january and it languished in the shop.  I had intended to get a strobe light on the timing marks, but it wouldnt start and i got deflated.  today I verified with the strobe gun that the timing is set "well enough" i think.  The red timing mark on the flywheel is lining up almost right on the timing tab while strobing.  perhaps the flywheel mark is a few "minutes" later (clockwise.. as read on a clock) than the timing tab. I assume that is slightly retarded timing. I think at this point i will search towards carburetion for any performance gains. 

Bill makes a good point, that this bike, in proper running condition, ought to be able to hop the front wheel up onto a modest log with ease.  It will not, at this point, without some dedicated effort with the throttle and clutch.  FWIW, Bill put a totally new clutch on the bike, it's apparetly unlikely to be a slipping clutch that's limiting the power to the rear wheel. Should I try to retime it a bit more advanced?? that was my idea back in january, but the strobe looked ok, and i don't wanna do any damage to it.

the motor kicks over pretty easily when it wants to start.  Bill said he remembers it being a bit of a dangerous game to kick it in years past, danger of kickback etc.  there seems to be very little threat of that these days.  a clue?

will report back with results of what i experiment with.
Going to try different jet needle heights to see what changes it makes.