Originally Posted by wfopete
I finally got around to timing my 465G. On the bike's maiden voyage, the motor ran fine down low but once in the midrange or higher it rattled and clanked something awful. It also, required 20+ kicks to get fired up hot or cold. So I really didnít know if I had a jetting, timing or a possible vacuum leak problem. For those of you not familiar with timing this beast, itís a bit different than most other bikes. Most bikes of that era had the timing set statically. Wouldn't you know it; starting with the 465's, Yamaha specifies that the timing be set dynamically (engine running, using a timing light and tachometer). Yamaha recommends 16 degrees BTDC at 2000 rpm. This requires using a 12V battery to power the timing light. The Yamaha timing marks are not like the big ďTĒ and ďFĒ found on the flywheel of Hondas. The marks are relatively small and likely covered with a little grime. Also, there are three areas where you will need to locate timing marks; the flywheel, the crankcase and the stator plate. I marked the flywheel and crankcase timing marks in red color so they would show up better. Big thanks to Kevin for his assistance in the location of the procedure of this whole mess. First, I set the static timing at factory specs (2.0mm BTDC) using a dial indicator. This required the partial removal of the engine as the frame interfered with my dial indictor. Of course you get to pull the flywheel each time you need to make an adjustment too. I had removed the stator plate for cleaning so I canít tell you what the original timing was set at but I believe it was too far retarded, which is as bad as having the timing too far advanced. Guess what? The bike started great, like 4th kick after sitting for a month.
Then, with the engine runnng, I checked for any seal/gasket leaks by spraying WD40 around the ignition side crank seal, base gasket, carb intake and reed gasket areas. A spray bottle of water works well here too. I didnít get any indication of a leak. Then I put the timing light on and had a look at the marks (kinda takes a knack the first time or two doing this); hmmm, not far off. I shut the bike down and restarted while it was hot and it started in three kicks. Adjusted the idle and the air screw and ended up advancing the timing just a wee bit more. Then I took the 465 out for a ride on a long steep uphill gravel road. Power was smooth on the bottom then started coming on hard at about 1/3 of the way through the RPM range. Iím using a 3.5 slide in the carburetor that probably helps smooth the low-end power. Found a flat hard packed section and the front and came up easily in fourth gear (I didnít try fifth). The engine noise that I experienced on a MX track at Diamond Don's was gone. Plug was tan/brown. This is one of the cleanest running big bores Iíve ever seen. Iím running Maxima Castor 927 at 40:1; back in the day Yamaha recommended 20:1. So I think Iím in the ballpark. There will be more adjusting & fine-tuning needed. For one thing Iím not happy about itís cold starting, as it seems to be a bit of a moving target. This could be my technique or a mechanical issue, for one I probably will bump my PJ from a 40 to a 45 but until I can get it out on a track for a more extended eval, I'm calling it good.
Thanks for the very nice writeup on setting ignition timing using a timing light. Always nice to get someone's 1st hand experience.
And great that your bike starts so easily now. I am sure it will be much more enjoyable. With all the energy you will be saving from not kicking so much you will probably move up a couple of positions in your next race
As I mentioned to you, last weekend my IT490 started in 3 kicks cold after sitting for 3 months, then just 1 kick when hot. Who says these are hard starting bikes???
Thanks again, this Mikkola is for you!