Larry McDavid
Cadet
- Joined
- Sep 24, 2005
- Messages
- 11
My motor is a Yamaha 1999 40HP, non oil injected (model C40TLRX) that I bought used last fall. I swapped out the lower unit with an aftermarket jet kit. I didn't change any adjustments since the motor started, ran and idled well, although the idle was a little higher than spec. <br /><br />When I first added the jet kit, the motor ran at 5100 WOT when cold and dropped to 5000 after running for about 10 minutes. The last several times out the motor would start out at 5000 and drop to 4900. This weekend I decided to check the settings and see if I could determine the cause of the drop in RPM. <br /><br />I found that the throttle was not opening fully when the throttle control was fully forward. I started checking the settings and found that the static timing adjustment was out of spec (distance between measuring points was 25MM instead of 20MM called for). Consequently, the full retard and full advance timing were both too high. After I made the static timing adjustment, the throttle was even farther from fully opening. So I made all the checks and adjustments called for in the Clymer Manual in the Timing, Synchronization and Adjustment section for my motor, except for ignition timing and the pickup timing. I don't have a timing light and had no way to run the motor out of water to perform these checks and adjustments according to the directions. So I simply adjusted the throttle roller (cam follower) closer to the throttle arm (cam) so that the throttle would open fully when the throttle control was fully forward. Is this an acceptable procedure?<br /><br /> I plan to get a timing light and a jet drive flush kit so that I can make the checks at home instead of having to take my boat to the water every time I have to make adjustments. In the meantime, would it be OK to run the motor in the water to see if the adjustments I made helped? I don't think that the adjustments I made could cause any damage since they are closer to spec than they were, but thought I would check with the board first. <br /><br />Another couple of questions come to mind, does the throttle arm wear over time? It appears to me that mine is worn. Also, is the throttle arm moving far enough at full throttle or should it come to the very end. (See pictures)<br /><br />Thanks for any help,<br />Larry<br /><br />Linkage position with remote control at neutral after adjustments;<br />
<br /><br />Linkage position with remote control at full throttle after adjustments;<br />
