Hello there, 

my 1973 Yamaha RT3 that I’ve been restoring (first time) is making my hair fall out. After the first few times kicking it over, it started for about 2-3 seconds then died. This was at 9pm or so, so I figured with the amount of exhaust smoke and noise I should hold up until the next day to avoid the neighbours calling the fire brigade. 

the next day, I kicked it over again and again, and it sounded like it wanted to start but didn’t. Slowly going backwards , away from progress it seems. 

it’s had spark the whole time, and fuel. I’ve adjusted the ignition timing to spec, float levers in the carb to spec, even followed the instructions on which needle , pilot jet, main jet to use etc (because I used a keyster kit before that) and I have a slide with a 3.0 cutaway now instead of the 1.5. 

still nothing :/ the condenser and contacts are old and haven’t been replaced , but would that stop it from starting now?

now when I kick it over , every 5th kick or so it pops kind of, like air is blowing out of somewhere (exhaust?) or some extra fuel is igniting. 

any tips from the pros would be greatly appreciated , it’s snowing today in Canada here and I wanted to have it running at least once before winter ! 

Thanks in advance everybody. 



 

I hate to ask but have you tried a new spark  plug

I'll say crank key, then i'll wright a story. 
Ok, add story. You say set the points & timing but was that before or after this event as could still be crank key if points etc was before running it. But as run103 says there--have you tried a new plug.
Add more story--running for only a few seconds would be pretty unlikely to eat a crank key but check it anyway. Did you hold the flywheel solid while tightening. I had a bike once at work that has a sliver of almost invisible metal bridging the points wire screw across to earth.

The flywheel key is a good catch  because they kick back so hard.  that flywheel has to be torqued on as per specs.  I have 2 of these and it should run good if the timing is where you say.  is the exhaust pipe plugged with carbon and oil 
Doug

I've had a crank key shear on a big bore with a mild kick back...  wasn't my bike and flywheel possibly wasn't tight...  but it happened surprisingly easy.

One thing I want to add is more of a question...  you say you are restoring but my guess is maybe this engine hasn't run in a long time and has not been taken apart recently?  

Bottom end might just be full of oil from the oil leaking past the pump check ball over years...  and it may have popped a crank seal.  Pull the exhaust pipe and see if it has a lot of oil in the bend and/or if it spits oil out the port when you kick it.

Well I'd put the correct slide in it and rebuild the carb using correct parts and settings. Next, run the idle screw in a little more so you know the slide is up. Run the idle screw in plenty so you know it's not letting the slide be bottomed out.  Won't start at idle if too low.  You always start the bikes cold with your hand off the throttle. That's why important to get the idle up on a complete teardown. Good luck.

Indeed I have, a few just to be sure! They were fouling

Actually there is a bit of oil in the exhaust pipe , dark stuff. Not a ton but a bit. Also I never checked out the inside of the exhaust either for carbon etc 

Could try a super hot plug like a B6ES & bring the revs up slowly not a handful as fires all the oil that 'might' be in the crankcase up into the plug. Oil won't stop it directly but when it gets sooty & baked on to the insulator it'll 'then' go to earth. I've often forgotten i've left a hot plug in mine & race of down the farm but luckily not going hard enough to kill it or melt holes.
Yes i remember my 490 arrived with a broken off key & just about broke my leg first kick plus broke kick gears. Guy had replaced the stator just before crating the bike up but not mentioned it. Said he only ran it for a minute so that's all it takes.

I’ll give it a go with the B6es spark, see if it starts after that. I’ll also check the wood ruff key, is that what you’re referring to? 

thanks!