See full version: Setting valves on a 4 stroke yamaha outboard motor
225TLRS: I had been trying to adjust the air adj screws and was advised to set and forget trying to dial them in. I had been trying to adj at idle but could not notice any change in rpm. so I set them all at 1 1/8 turns. AM I wrong??
On my FI'ed motorcycle, 4 banger (Yamaha BTW), you do your throttle sync using 4 air screws. This engine has two, "two barrel" throttle bodies. It does have one sync screw for the butterfly shaft (all TB's are in a straight row) however that screw is preset at the factory and is a no no to adjust. [links]
The Quadrajet had main jets, secondary jets that the butterfly needles inserted. I don't know if the holly knock off Q-=jet had those air screws, I'd think so.. more
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+++ Clean (if applicable) or replace.
• Please refer to your owner’s manual or consult with your authorized Yamaha Marine dealer for specific requirements of your engine.
•• After each use, especially in salt or brackish water. here
+++ Clean (if applicable) or replace.
• Please refer to your owner’s manual or consult with your authorized Yamaha Marine dealer for specific requirements of your engine.
•• After each use, especially in salt or brackish water. more
The most accurate and specific maintenance interval information for your particular outboard will be found in your owner’s manual. We’ve also included basic charts (above) to help give you an overview of what needs doing, and when (indicated by yellow boxes). To determine when service is due, keep your eye on your hour meter. If you don’t have an hour meter, it’s easy and inexpensive to install one. Or, many Yamaha gauges already have this functionality built in, allowing you to set reminders at various intervals, and helping to keep you on schedule. You can also utilize the Yamaha Outboards Mobile App on your smartphone. here
Yamaha provides easy-to-understand information about how, and when, to perform proper maintenance. Yamaha also offers approximately 2,000 authorized Yamaha Marine dealers from coast-to-coast, specially trained and equipped to handle most of your outboard’s maintenance needs. So whether you get the parts from your Yamaha Marine dealer and do it yourself or have them do the work for you, you’ll rest assured knowing you’re doing your part to help protect and preserve your Yamaha outboard.
REMEMBER to always observe all applicable boating laws. Never drink and drive. Dress properly with a USGC-approved personal floatation device and protective gear. This site contains many of Yamaha’s valuable trademarks. It may also contain trademarks belonging to other companies. Any references to other companies or their products are for identification purposes only, and are not intended to be an endorsement. [links]
Fuel for a 2-stroke engine has a small amount of oil mixed into it. It is called a “2-stroke” because just one up and down movement of the piston—the 2 strokes—performs the full cycle of intake, compression, combustion and exhaust. No intake or exhaust valves are used and instead, small holes called scavenging ports in the cylinder wall are used for drawing in air and expelling exhaust. Because combustion takes place with each revolution of the crankshaft with a 2-stroke, this format puts out more power than a 4-stroke engine and the power has more instantaneous delivery. This are some reasons why 2-stroke engines have a long history of use on many different types of motorcycles.
However, concern for more environmentally friendly performance grew and 4-stroke engines are now the norm because they inherently have better fuel economy and less exhaust smoke. As of 2019, the only 2-stroke motorcycles Yamaha makes are for closed-course competition and some models for export. Nonetheless, Yamaha 2-stroke products have a simple, lightweight construction and comparatively easy maintenance, and their high reliability keeps them popular in many regions. Today, Yamaha 2-stroke snowmobiles are used to traverse the icy cold environment of Russia, and our 2-stroke outboard engines are widely used across Africa for fishery. And, many motorcycle enthusiasts continue to love 2-strokes for their punchy, breathtaking feeling of acceleration.
As for 4-stroke engines, they run on gasoline without any oil mixed in and the piston goes up and down two times for every combustion cycle, hence it’s called a “4-stroke.” However, 4-stroke engines require valves for both the intake and exhaust that must operate with high precision, making this engine format more complex, heavier and other disadvantages. But they provide stable power delivery, good fuel efficiency, cleaner emissions and more. This is why almost all two-wheelers, from big motorcycles to small scooters, use 4-stroke engines. here
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