is the timing correct on this 200hp yamaha?

[stackz]

ok, so my neighbor went to florida and bought a used engine after his old one finally bit the dust.

he went from a 1986 175hp yamaha with 150hp carbs on it (old DNR engine), to a 1993 200hp yamaha. we got it mounted the other week and cranked it up after tossing new plugs in it. ran fine but sounds like it doesnt want to redline (I think it does, he doesnt).

anyway, you could tell the top carb was recently either rebuilt or replaced. he popped off the other carbs and rebuilt them, the middle one was kinda clogged up. tossed them back on after rebuilding them and it sounds just the same. It cranks instantly and idles fine, part throttle seems good, but the high rpm doesnt sound like his old engine did.

he doesnt have the manual yet for the new engine so we just used the one for the old engine. obviously not sure if the specs are the same but it was saying for the 200hp engines you want timing at ~7ATDC with the side lever pushed in (cant remember what its technical name is).

On the new engine, there's a mark at around the 20* point. anyone know what this is for? is this where the timing should be set? also, that is the ATDC side? there's no markings other than a couple "TDC" points.

anyway, we cranked it up and let it idle and checked the timing. these are while it was idling.

without the side lever pushed

with the side lever pushed

if the first pic with the little paint arrow is correct with that side of TDC being ATDC, then the third pic tells me the timing is definitely off. If not then it looks pretty spot on to me.

any help would be great, thanks!

and yeah, I'm trying to get him to get me the model info from the new engine but we're both working right now.

 

[stackz]

Re: is the timing correct on this 200hp yamaha?

also, he's been looking online today, as have I a little and he said earlier that some threads suggest it could be the fuel pumps?

 

[99yam40]

Re: is the timing correct on this 200hp yamaha?

Do you understand that the A in ATDC (retarded) stands for after and the B in BTDC would be before right?
the motor would have to be turning counterclockwise for the 20 to be ATDC

I would think the idle timing would be ATDC and the WOT timing would be BTDC and around 20 something


What no compression #s or RPM reading from tach?
That and the boat and prop may give someone an idea of what you are playing with.
Measuring fuel pressure and vacuum would be a good test to make sure pump is working properly, but never hurts to have new pumps

 

[stackz]

Re: is the timing correct on this 200hp yamaha?

yes, I do know that. those pics were on flash, it was getting dark out and I honestly had no clue which way it spun when not running as I didnt pay attention. and all his compression #'s were 110psi. rpm reading cant be taken, his tach is busted. lol.

whats a good vacuum reading for the pumps?

 

[Capt Ken]

Re: is the timing correct on this 200hp yamaha?

Timing is 7 ATDC plus or minus one degree and WOT is 20 BTDC plus or minus one. If one of the fuel pumps was out then the motor would fall on its face a half throttle.

 

[stackz]

Re: is the timing correct on this 200hp yamaha?

yeah, it doesnt fall on its face at part throttle at all. I wanted to take video last night but it was too dark. wont get another chance till next tuesday as I'm leaving town tomorrow. just wanted to get him some info to help him chase the demon while I'm out of town haha

 

[stackz]

Re: is the timing correct on this 200hp yamaha?

just fyi but we got it running right. lol, you wouldnt believe me if I told you...but I'ma tell you anyway.

got back in town early monday and helped him. we were testing all kinds of stuff. 2 different sets of factory manuals, multimeters galore, blah blah. got a lot of stuff cleaned and updated/fixed. While I was away he tore the carbs back down a second time and found more stuff clogged up, etc.

yesterday I was helping him reset the jets on the carbs and was working on the port side of carb #2 when I noticed the oil level was low in the reserve tank. Then it hit me, his controls have been buzzing since the engine was mounted. His mark was also below the bottom arrow mark... I popped the sensor out and had him turn on the key, then moved the sensor float up and the buzz went away. :doh:

added oil to the tank and cranked it up and it ran perfect and revs the way it should, idles better, etc, etc. low oil level was putting the engine into safety mode lol. never dealt with this before as all previous engines were bypassed, etc. I guess you learn something new everyday haha.