Eight pump chump


XS650 Enthusiast
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Bain bent its intake valves several months ago. I have my own theory of lacquered varnished gas as the cause. I procured a nice used ebay head for substitution. But I believe my timing maybe off one tooth. Hard to start, but once started becomes a one kick machine. Is there a way to verify correct cam chain timing, by looking at the righthand side advance plate? I really don't relish pulling the motor and head again. I can't give it any type of fuel when its cold. No, choke, don't touch the throttle until it sputters to life. Which is a spit and stutter painfully slow event. Sounds like Bain has been smoking a pack a day for ages... Once running it pulls very well. Roll off the throttle and popping occurs in the exhaust...The clock had 3000 miles on it when I received it. The engine was never opened by anyone. Points, which I replaced looked original. The jetting is stock. Plugs were new. The advance rod is free. I just ran it 200 miles and two tanks of fuel. Looking for directions to travel...I'll get some timing light videos for reference tomorrow.
Yes. On the right side of the cam there's a hole machined into it for an alignment pin for the advance unit. If you remove the advance, the pin should be clocked at either 6 or 12 o'clock when the crank timing mark is at TDC.
Your choke jets may be plugged or partially plugged. If they are, the chokes won't work and cold starting will be very difficult. Here's how to check them .....

Choke Jet.jpg

If you want to check the cam timinig, this info was supplied by 5twins.

The hole for the locating pin is in the cam not the advance unit. You need to remove the advance unit to see it .....


But, there is a way to discern the locating pin's location without removing the advance unit. Above the slot for the locating pin on the backside of the advance unit, there is a retention pin pressed into the plate, and it shows through on the front .....

Advance Pin Front.jpg

But there's a good chance the notched nut that holds the advance unit on will be covering it. Still, you can discern it's location. It's on the flat side of the unit, the side behind the direction arrow, just above the bent up tab. So, looking at the pic of your advance unit you posted, if it was taken with the motor at TDC, the cam timing looks good and I don't think the chain has jumped any teeth. Your "no start" issue is due to something else.