First off, hello everyone, i"m In need of some advice. I got a ds 650 from a dude for real cheap and it wasnt working properly. was revving to 4000 and cutting out and spitting back through the carb. first off i thought Valve adjustment. when i got into it i noticed the cam lines would never exactly line up(like a tooth off). I adjusted the cam chain to the point where they are almost perfect, though they seem to just be a tad (16th of inch) off now. im just wondering if maybe im not exactly at TDC? i have the locking bolt and i tried putting the straw in the plug hole and when looking through the hole on the right side of the machine when the straw just hits the top of piston stroke its in between 2 notches on the flywheel. is this correct? Valves were way off and i got new shims and they are now about .005. im just kind of scared to start up the machine and maybe hit the piston off a valve and cause way more problems. sorry for the long post. Im really a 2 stroke guy as myy family and children all have them. first time working on a 4 stroke. thanks alot in advance, looking forward to helping and being helped as much as possible.

 

That is correct. At TDC your lobes will face opposite one another and your index lines will be very close. There is a slight bit of slop. Ensure that your cam chain tensioner has movement and is not frozen closed. Should spring back out after being compressed.

 

thanks for the reply. next question is, what would happen if the cam chain jumped the bottom sprocket? i watched a you tube video that said even if you had it at tdc with bolt in it could possibly, but not probably jump timing at the bottom. well me being a newb to this, forgot to put the tensioner back in and flipped it over with the starter. cams on top were not the same, but the notches on the flywheel were. so did i jump the cams only? or would it matter as long as bike was at TDC? i feel like a stupid *** on this. worked on 2 strokes for years and have a mechanic background. thanks for any info i can get.

 

It's possible but not probable. Even with the tensioner removed I don't believe the cahin would clear the teeth. Then again I have never tried it!
Lock everything back at TDC and adjust accordingly. Put the tensioner back in. Then check your gaps. Enjoy the ride. Very reliable and comfortable bike.
Welcome to the forum.

 

Thanks so much for the help. i should be driving before i know it .

 

SO, bike has more power and runs awesome. well almost awesome. when i first start it, it still spits back through the carb. i have it set at 4 and a half turns out on the mixture screw. give it gas and it goes like hell, but runs better with choke on. i cleaned the carb 8 times. once it warms up. no spit. and it goes like hell. is my timing off?? set valves and are fine at cold. got dyno jet kit, but didnt come with pilot jets, just mains and a needle. maybe timing is off?? works great after quarter throttle and great at full range just boggs at first quarter till it warms up.. after that it goes awesome. any ideas

aceisback thanks so much, these bikes will go. just hoping to get past this bump.