C85TLRT timing specifications.

[Reidak16]

Good morning,

I have a 1995 Yamaha 2-stroke C85TLRT. I found the listed service manual for this engine on the Yamaha website; however, when I went to buy it, the manual was for a CV85E. Two different engines. I rechecked the LIT #'s and found that Yamaha lists the same service manual for these two engines.

Going forward, I was having the timing checked at my Marine mechanic shop. The CV85E manual specifies 2 deg BTDC Idle and 24 BTDC Full advanced. However; on the fly wheel, someone painted a white glob at the 7 degrees ATDC and 24 degrees BTDC. He stated it was probably marked like that from the manufacturer and he set the timing to 7 ATDC and 24 BTDC. I really want to see what the idle timing specifications are for my specific motor. I'm not feeling that comfortable about the white painted globs on there since I really dont know when they were put there and they differ from whats specified on the service manual. But, again the service manual seems more generic and not specifically for my motor.

Anyone that could help me find the Idle timing specification for this motor? I wasn't having any luck finding any stickers on the engine that mentioned that, unless I'm just blind.

Thank you.

[boscoe99]

The manual is the bible. But the idle timing is not critical IMO. If the motor starts, idles, accelerates and runs well I would leave well enough alone.

[Reidak16]

Thank you.

Referencing that; The idle is perfect as is 7 ADTC, but there is tons of room to play, especially to lower the idle. The Yamaha has a clear Idle Adjustment screw on that keeps the throttle linkage of all 3 carbs in sync. Turning this screw slightly opens all of the butterfly valves to increase rpm. But, advancing the timing on the idle screw bumper also increases the idle. Honestly, it runs the same, idle wise if I slightly raise the idle timing from ATDC to BTDC the same is it is to turn the screw and slightly open the butterflys to increase idle. Any difference on how the idle should be adjusted?

[99yam40]

When I bought my C40TLRX used many years ago it had many problems and one was the idle timing was not to speck and I could not get it to spec without jacking the idle theottle open ing to spec.
then the pickup timing was off( when the timing advancing happened)., while following the procedures in the manual.
spec was

7 ADTC, but do not remember what it was sitting at, but think i was a ot more retarded than spec

I would look at other motors around that age close to you HP just to confirm they agree with you manual
A 90 would be good I think

[Michael B]

I have the same engine on a 18ft Glasspar fishing off San Diego. It's got 1100 hrs and runs like a champ. It's not the smoothest idling engine however.