Hi guys, I'm new here. Just picked up a 300ex yesterday for $300. The previous owner said the the engine knocked, so they had a "mechanic" put a new top end on it. When they got it back it still knocked, so the "mechanic" said it must be the rod bearing, but the kid said he just rode it that way until it quit running. I brought it home and charged the battery and it turns over, makes good compression, good blue spark, and I don't hear any horrible noises. I sprayed starting fluid into the carburetor, then took the carb off and sprayed it directly into the intake but it doesn't try to start. I can see the valves are moving through the intake.

Keep in mind the "mechanic" was an 18 year old kid. I haven't heard the noise, but my guess is that the noise they were hearing was the cam chain, and he rode it until it jumped time which killed it and now won't let it start.

Anybody have any other ideas of what may be wrong with it? Is there an easy way to check the cam timing on these engines? I can't see an quick/easy access to the cam sprocket or the flywheel. thanks for any input.

 

take the valve cover off and the TDC plug(the small one) and make sure its lined up, and that your valves are in spec. good luck

 

Can you give me a little more details on where this TDC plug is and what exactly I'm making sure is lined up? I'm guessing from this TDC plug I will be able to see when the engine is at TDC, then there will be a mark on the cam sprocket, but what do I need to line that up with? What is the best way to turn the engine over slowly to get it to TDC? Put it in 5th gear with the spark plug out and turn the rear wheels? thanks

 

Ok I found the TDC plug. I got the timing mark on the flywheel lined up. But I'm stuck on what I need to line up at the cam sprocket. Heres a pic of the cam sprocket when I'm on the t mark. Does this look right? And what is the valve clearance supposed to be? .003?

 

Anybody out there? Nobody ever worked on a 300ex?

Well I adjusted my cam timing (it was off 1 tooth), set the valve clearances, and cleaned the carb. It acted kinda like it wanted to start but wouldn't. I'm getting ready to go get a new spark plug. Any other suggestions?

 

Ok, I got the new spark plug and still doesn't run. Somebody Help!!!! I've got compression, good blue spark, cam timing right, valves adjusted, and a clean carburetor. It sounds like it's about to start sometimes, but never does.

Is ignition timing adjustable? Do you think the valves are bent from the timing being off 1 tooth? What else can you think of? I really what to get this thing running.

 

get a true compresion test. make sure that you are getting fuel to the carb and that none of the jets are plugged up. make sure its not old gas, it won't run off of bad gas. good luck

 

get compression test, if its within spec it cant be gettin gas or cant be firing correctly.like the other guy said, make sure it aint old gas..good luck

 

If it jumped a tooth you have a bent valve . From the looks of it you jumped more than one . Do a compression test . If I had to guess I would say who ever rebuilt it didnt line the timing marks up . Or maybe the timing chain tensioner is bad ?

 

i have this 2002 300ex, and i rode it for about 20 minutes (sat for a couple day in garage)
but i parked it in the sun after riding it and 30 minutes later tryed starting it and it didnt start, it turns over, and has spark, its also getting gas, im baffled with it, what could it be? any suggestions?

thanks