Cold Weather Starting for Yamaha 150 hp 2 stroke

jimbob

Active Member
My 1996 carbed 150 hp Yami 2 stroke starts and runs like a dream in warm weather. But, in cold freezing or near freezing weather it starts easily but tends to stall out quickly (say 5-6 seconds after start up) unless I keep the RPMs way up (3000+). I am concerned about cylinder and piston damage when reving up a basically cold engine.

Does anyone have similar problems? Solutions? By the way, once the engine is warm then it runs perfectly.
 
These engines have a specific starting procedure for cold temps. You must use the choke (bump it on and off) while keeping the rpms as low as possible. It will run after a short time without bumping the choke. Let it idle at the dock...after a few minutes it will load up and slowly quit again...let it quit. Let it sit for a few minutes (5)then restart it again keeping the rpms down. It should run now for the rest of the day.
What happens is the carbs ice up...the faster you draw cold air into them..the faster they ice up. By keeping the rpms low, ice forms less quickly allowing the engine block to develop some heat. The engine may quit after a few minutes as sometimes the carbs ice up no matter how hard you try. Thats ok...because so long as it ran long enough to get the block warmed up..that heat will slowly transfer out to the carbs and prevent ice for the rest of the day.
 
I think there are anti icing kits available.Any body have any experience with them?
 
So I did some quick research and found that carbs can ice up even at temperatures which are well above freezing which suprised me but now I know. I like the idea of starting at lower rpms rather than higher rpms. Seems like that would lead to less engine wear.

My question is how long should I leave the manual choke engaged after startup? I am concerned that the engine will load up with oil and will foul the plugs and then I will have even more trouble getting it started and keeping it running.
 
quote:Originally posted by jimbob

So I did some quick research and found that carbs can ice up even at temperatures which are well above freezing which suprised me but now I know. I like the idea of starting at lower rpms rather than higher rpms. Seems like that would lead to less engine wear.

My question is how long should I leave the manual choke engaged after startup? I am concerned that the engine will load up with oil and will foul the plugs and then I will have even more trouble getting it started and keeping it running.

I wouldnt worry about fouling up your plugs in the short time you will be running the choke, once you get up and running you should blow it all out, and i know alot of guys and mechanics reccommend to run close to wot for about 30secs as you come back to dock - this leads to a near constant spark in the cylinder and burns up everything that may have accumulated in there over the day.
 
You only need to choke it long enough to get it to fire, then bump it on and off quickly just enough to keep it running. Within 10 to 15 seconds you may have to bump it once or twice if it tries to stall. After that let it quit and the engine heat will radiate out to the carbs and prevent it on restart.
 
PF's got the ticket. Your old methad was bad due to the possibility of cold seize. This ocures when a cold engine is overreved. The piston expands quicker than the cylinder can, this causes skuffing of cylinders (usually around intake ports) and possibly temparary seizing of engine.

I'm setting my priorities. I'm making time for fishing.
 
good call PF. Finally someone on here knows what theyre talking about..

untitled.jpg

Fill the dam tub!
 
I tried this time to bump the choke on and off while keeping the revs a lot lower during the starting procedure and it worked perfectly. No stalls and no high reving. Thanks for the advice.
 
Hey folks,

first time posting here....I've used the same choke-on and off running at low rpm technique on cold mornings for years with my 9.9 Yamaha 4 stroke High Thrust kicker, my buddy's 9.9 4 stroke Honda on our goose hunting boat and my 7.5 Johnson 2 stroke on the duck boat.

I mainly fish the lower Columbia River in Washington state for salmon and sturgeon, but have also fished the Strait of Juan De Fuca (now the "Salish Sea"?) for halibut in Neah Bay, outside of Victoria and west.

CW

Satisfaction: 23' Aluminum Thunderjet with Ford 460 salmon fishing the Columbia River
 
Back
Top