Are 4 strokes cold blooded when first started?

[salmonking]

Hi fellas,
I have a 50hp 4 stroke Yammy, about a 2000 which I am the new owner of, and I am new to 4 strokes as well. When I first start it it appears to run rough like it is cold blooded. Trolling it runs fine, high speed it runs fine. When coming off of a idle speed and slowly bringing the throttle forward, it acts like it is running very rough. Then when I go all the way forward on the throttle it runs great again. Any ideas???

[Chrome Bumper]

Six year old motor, have the carbs ever been cleaned? Teardown, wash with carb cleaner and use a wire to poke out the tiny passages and blow dry. $2 for spray cleaner and some for any gaskets that go south taking it apart.

[NeedaFlyBridge]

I know it is a much different motor, but I have a 2005 Yamaha T8 4 stroke, and it is the best starting and running motor I have ever owned, hands down. Even after sitting for 3 months, it starts instantly and runs great right away, as long as I use the choke as I'm supposed to.

Jon

[MattPark]

Any 1 year old engine should run perfect, carbureted or not.

6 years is plenty of time for a carburetor to get crapped up. The good thing is, pulling them apart and cleaning them out is easy.

[zipper]

Interesting.... my 2005 T8 Yami is as cold blooded as any motor I've ever owned. Once warm it runs like a swiss watch but those first few minutes are definitely rough.... my big Johnsuki 140 is just the opposite. It starts right up and idles perfectly every time in any weather. :cheers: zip

[reelfine]

Interesting.... my 2005 T8 Yami is as cold blooded as any motor I've ever owned. Once warm it runs like a swiss watch but those first few minutes are definitely rough.... my big Johnsuki 140 is just the opposite. It starts right up and idles perfectly every time in any weather. :cheers: zip



I'd agree. My 2005 T8 starts right up, but if don't give it a little gas for a couple minutes before trying to troll down to idle, it'll sputter and die everytime.

[timinthegorge]

Like what reelfine said..... I've got an '03 9.9 Merc 4stroke, and it requires two pulls to start (unless it's Really warm out) and runs rough for a couple of minutes. I make sure to give it gas too, change rpm's during warm up, and then it'll troll down all day without a burp...

Best of luck with it.... :cheers:

[1pump]

Sounds like the carb is having trouble making the transition from the low speed circuit to hi speed.

[Chrome Bumper]

Yes what one-pump said...... Cleaning the carbs should clear the problem. Leaving the engine with gas in the carbs a few times will leave varnish when it evaporates, disassemble and clean. Take all the brass bits out so you can get into the tiny passages with a fine wire to break the varnish up. If you can reuse the gaskets it will take an hour or so to get it running like new. Running the gas out after each use or draining the bowl will reduce the problem in the future.

Went down that road with my 6 year old honda after many hudred hours and a barrel of fuel, tore down the carb, scrub every thing clean and runs great again. Run choked a few seconds, fast idle a few seconds and it is ready for slow idle, on cold mornings fast idle for a minute or two to get the engine block warmed up. Alot more stuff to warm up then in a two stroke. Water in the float bowl makes it crappy too, there is a drain screw for that.

[Tom E]

My 06 Yamaha 60 starts quick and runs smooth, even after three weeks. Maybe I'm just lucky. Smoothest and quietest I've ever owned.

[Draggin' Bait]

I have two four-strokes -- a 2004 Yamaha 115 and a 2003 Yamaha 8 hp (manual). The 115 electric starts immediately every time; the 8 starts on the 2nd pull of the rope every time. Very impressive engines. I also had a pair of two-stroke Merc 40s -- one manual (1994) and one electric (1996)start. Sometimes the manual was cold-blooded. Now my old two-stroke Sears 8 hp and Chrysler 9.9 -- they were seriously cold-blooded in the morning. (But they sure warmed me up trying to get them started!)