Re: fed up with 9.9 seahorse
Check the black throttle cam for a crack, the one on the mag plate. Also check the condition of the cam roller, they can wear.
This is from the sschapterpsa.com website:
(6) Throttle Position/Timing : This may not be as critical as the others, but worthwhile to check & since it is not in open view, it can slide by un-noticed. The twist grip does have a position marked as "START". This is a position where the timing plate's cam positions the carburetor arm to where the ideal setting is for starting in relationship to the flywheel magnets & points or CD sensors. This cam plate setting should not normally have to be reset unless someone has tinkered with the motor, & they unknowingly may have changed this setting.
If the twist grip is not rotated fast enough, you will have to crank all day on a cold motor, however if you advance the grip to a FAST position, it will start readily. You may have to quickly readjust the throttle to a more medium speed once it gets to running.
The throttle cam plate operates a cam roller that is attached to the carburetor. If this cam roller is cracked, broken or not functioning, it will throw the timing off. The throttle cam plate also rotates under the flywheel when you twist the twist grip. This cam plate has an arrow type mark on the front of it. This mark needs to be timed so that when you advance the throttle twist grip, that the carburetor roller is at this mark when the carburetor throttle shaft just starts to turn open. To adjust this on the earlier motors, you need the flywheel off, & loosen the 2 bolts on the RH side of the plate & adjust the cam plate to where it just aligns with the roller. To tell exactly when the shaft STARTS to move, take a small alligator clip & attach a 2" wire to the wire end of it. Clamp the clip onto the carburetor throttle shaft's Starboard side with the wire pointing UP. Twist the throttle until you see this wire pointer just move. The cam plate arrow should now be lined up. If not, loosen the 2 screws on the side & rotate the plate cam until it is aligned & retighten the screws.
Some mechanics like to set them so that the throttle arm JUST opens up a bit when this full neutral throttle is applied, I am incline to agree.
On the later motors the adjustment is different, (about 1986 or so) the timing cam plate that the carburetor roller engages is made of plastic with an adjustment screw on the rear (LH side) for fine tuning. The nature of this is that it is attached to the plate by a minimal amount of plastic on the front so the screw on the rear will allow it to move in or out for adjustment. If someone does not understand or they are poking around under the front of the flywheel they can break this plastic adjustment tail off. When this happens you will have throttle up to about 1/2 throttle, when the roller drops off the back of the broken part, the carburetor butterfly then drops back to an idle. It is usually hard to twist the speed control grip back to slow because the carburetor cam has now dropped behind this sharp broken off part.
In the photo below the red arrow shows there this cam part is broken. Normally the broken part will not be found & the owner does not know what is wrong or missing. With the twist grip at about an idle position as shown, you will see the black plastic carburetor cam roller against the cam & under the RH edge of the arrow.
I am not sure whether super glue will adhere to that plastic or not. Price of a new on is not that bad however. It attaches by 2 short round protrusions that slide into mating round holes located in between the timing plate & the timing plate base. When the plate & the base are screwed together the cam is held in place.
