115 TXLRC Timing puzzled

[Proline Mike]

Completed the maintenance items I needed to do, carb clean/gaskets, plugs,, new 10 micron fuel/water separator filter, new water pump, new driveshaft seals, lower unit lube and pressure test. All is good. Starts right up, carbs adjusted, runs pretty well. I decided to inspect the timing at idle and full advanced using the Service Manual instructions while I had the top off.

At retard (Idle) the timing marks under the flywheel are not close when at 5 degree ATDC. At full advance at 25 degrees BTDC, the timing marks are not close either? The TDC on number 1 is dead on, as well as dead on on 2,3,4 based on the flywheel marks and pointer, so I am thinking the flywheel key is not sheared. The original red theadseal on the retard screw has been broken. Setting it to where the timing marks are aligned, it will not start? returning it to where it was, runs fine. Full advance thread seal is intact, so it appears to have never been adjusted.

Am I reading the manual incorrectly, or should I just get a timing light to verify these settings at idle and WOT, once I get on the water.

Or should I punt and just take it in and have it completed. (I really dont wont to).

[99yam40]

Why do you not want to use a timing light to check what it really is firing at?

Follow service manuals procedures for sync and link after reinstalling carbs any time they are removed.
I recommend the Yamaha service manual

I found the CDI on my C40 in need of replacing as the idle timing was off due to internal wiper being defective. Set as manual showed it was way too far retarded.
Replacement brought it back to spec

[Proline Mike]

Said I did not want to take it in (to Dealer) Will verify timing with timing light. Using Yamaha Service manual and following the instructions, that's how I got here, as the timing marks on both Full Retard and Full advance were not lining up as indicated.

[99yam40]

Marks are references for initial set up , need to put light on to get it final settings.

On my C40 after making sure where the pointer was sitting at Idle and WOT with motor off , I disconnected the linkage and with motor idling on muffs with timing light hooked up I moved wiper to where they were during idle and WOT just to see what the timing with light was reading. That way I did not have to be doing it while running boat WOT on the water. It gets you a good idea of what you have and you can adjust a little , but it is a good idea to make sure all is still good after all adjusting is finished on the water under load with light also.

If the timing is way off while wiper is on the marks then you may have the same problems I had with CDI. Mine was running at 14 ATDC at idle when it should have been 7 BTDC, so throttle setting had to be raised too far to keep it running at idle.

I believe your motor is close to the same set up, but not positive

[Proline Mike]

Ok. Got timing light. At 800 rpm idle, 2 degrees ATDC. With Throttle cable disconnected, plugs removed, installed back into boots, securely grounded plugs (Verified with Ohmeter)....at WOT full advance timing is 28 degrees BTDC, adjusting the retard screw all the way in, the screw does not hit the block at all?

Of course manually advancing the timing to 5 degrees at idle, it picks up a bunch of rpms.

Now what? Any suggestions? Have service manual, hopefully between it, you guys and a little understanding I can get this thing dialed in and set up correctly.

Obviously the Full advance looks like to be simply adjust the advance screw in to 25 degrees. With so many different arm settings, lengths, etc...just gonna sit tight, read the manual 5 more times and see if anyone has suggestions... wish me luck !

[99yam40]

I do not know about your motor but on my C40 the timing at start up is advanced by the CDI until motor warms up and then it drops down to idle spec in manual.

[Proline Mike]

well, after walking into the house to type this, I realized how bad my memory and eyesight are..so I went back are rechecked at idle...I was reading wrong side of TDC...idle is now set at 5 degrees...I had to play around with the throttle cable adjustment as there seems to be a little slop in in causing it to not go all the way to the back and have the retard screw bottom out.(NEW CABLE AND CONTROLS) running fine on muffs, warmed up. Will now lower the full advance to 25 and I think all will be good. May be able wet test on the lake, Sat or Sun. (Decent Jan weather in Dallas this week)

[rodbolt17]

remember ATDC and BTDC are on either side of the piston.
your engine will idle correctly at 5* ATDC,thats on the right hand side of the TDC mark.
carb pick up timing should be about 4* ATDC,thats the point where the cam picks up the throttle roller.
WOT and it cant really be checked at cranking speed, should be 24 to 26* BTDC.
once correctly set it NEVER changes, until a backyardigan has to mess with screws . or mechanical damage occurs.
the 115 uses a movable timer base fixed to the magneto control lever.
once set the only way it can change is mechanical damage or a self inflicted wound.

[Proline Mike]

Rodbolt..thanks for the advise..I left the full advance alone, as it got dark on me. Cleaned up the slop on the throttle linkage and now the retard bottoms correctly against the block..at 5 degrees ATDC at idle. It was staying advanced at idle. Will take timing light to lake an inspect..at WOT...and probally leave there...my journey here started upon visual inspection... I understand the damage bad timing will do, especially over advanced, thats why I was "measuring 5 times, asking 4 times, re-inspecting,...sitting back and thinking....before doing anything. Will report back, hopefully Sunday with a little fish smell on my hands. Thanks again for the help...

[rodbolt17]

thats why the static timing procedures in the manual suck.
blown many an engine.
ONLY way to PROPERLY time that engine is dynamicaly.
best way is not to dink with the adjustments once set.

[Proline Mike]

Thanks for all the insight and guidance on this. After a late morning splash yesterday, Idle is set at 800, air mix screws appear set at about 1.25 out, idle retard timing at 5 degrees, Pickup at 4 degrees, and Full advance at WOT is at what appears to be 24.5 (I left it there). WOT right at 5500 rpm at 38 mph. Idle is smooth, cranks right up. Off idle in gear has a little shake at 10-1100 rpm, but at 1200 it is gone. Just going to deal with that part, no since trying to track down a gremlin that exists in only a 1-200 rpm range. Thank again to both guys, as well as this site. Just wished the fish co-operated, now i need to work on those skills!