This Seloc repair and service manual covers 1992-1997 Yamaha Personal Watercraft, including 650, 700, 760 and 1100 models.
Book Excerpt: 1992-1997 Yamaha Personal Watercraft 650, 700, 760, 1100 Repair Manual
SPARK PLUG EVALUATION
Remove the spark plug wires by pulling and twisting on only the molded cap. NEVER pull on the wire or the connection inside the cap may become separated or the boot damaged. Remove the spark plugs. TAKE CARE not to tilt the socket as you remove the plug or the insulator may be cracked.
Carefully examine both plugs to determine the firing conditions in the cylinder. If the side electrode is bent down onto the center electrode, the piston is traveling too far upward in the cylinder and striking the spark plug. Such damage indicates the piston pin or the rod bearing is worn excessively.
In most cases, an engine overhaul is required to correct the condition. To verify the cause of the problem, rotate the flywheel by hand. As the piston moves to the full up position, push on the piston crown with a screwdriver inserted through the spark plug hole and at the same time rock the flywheel back-and-forth. If any play in the piston is detected, the engine must be rebuilt.
A proper firing plug should be dry and powdery. Hard deposits inside the shell indicate too much oil is being mixed with the fuel.
The most important evidence is the light gray to tan color of the porcelain which is an indication this plug has been running at the correct temperature.
This means the plug is one with the correct heat range and also that the air/fuel mixture is correct.
Remove the four engine mounting bolts. Attach an engine hoist to the lifting eye on the engine. As soon as the engine weight is taken up by the hoist, move the engine forward to disengage the rubber coupler from the jet pump coupler.
If an engine hoist is not available, have an assistant help with the lifting. Two adults should have no difficulty in lifting any of the engines listed for this manual.
Remove the rubber coupler. Move the engine to a suitable work surface.
NOW, THESE WORDS...
The following instructions pick up the work after the preliminary tasks listed above have been completed and the engine is in a suitable work area.
Procedural steps are given to remove and disassemble virtually all items of the engine. However, as the work moves along, if certain items, ie: bearings, bushings, seals, etc. are found to be fit for further service, simply skip the disassembly steps involved. Proceed with the required tasks to disassemble the necessary components.
COMPLETE and DETAILED procedures to clean and service all parts of the engine are outlined in the last section of this chapter. Section 8-4, beginning on Page 8-29.
The following procedures pick up the work after the engine has been removed and is in a suitable location.
- Remove the two bolts securing the oil pump to the flywheel cover, and then remove the oil pump and set it aside. Notice the slot in the end of the crankshaft for the "spade" of the oil pump to index into during assembly.
- Disconnect the electrical lead from the cranking motor terminal.
- Remove the high tension leads from the spark plugs.
- Withdraw the thermo-sensor from the receptacle at the inside aft end of the muffler pipe. Loosen the tie-clip to permit the lead to clear.
Subject: 1992, 1993, 1994, 1995, 1996, 1997 Yamaha 650, 700, 760, 1100 personal watercraft (PWC) service, maintenance, repair. ISBN-10: 0893300446 | ISBN-13: 9780893300449 | Seloc 9602