Excessive smoking

[doors67us]

Hey guys, got a question my 1971 Johnson 25 horse seems to be smoking more than it should, the oil mix ratio is correct it also seems to be loading up when it idles pulled the plugs they look like it's running a little rich, carburetor rebuild with a Sierra kit new fuel pump new plugs, I realize they do smoke more so at idle than they do at wide open speed but this one seems like it smokes a little more than it should and also the loading up bit not sure what's up with that, I've adjusted the low speed it seems to idle without coughing or sneezing

 

[flyingscott]

Float set right? low speed set correctly?

 

[doors67us]

Yes float is level with the carb body ,carb needle adjusted to 1 1/4-1 1/2 turns out approximately

 

[flyingscott]

Checked the fuel Pump?

 

[doors67us]

Checked the fuel Pump?

Brand New Sierra pump as of today

 

[Crosbyman]

new to you motor ?? running in cool cold temps.. ???

excessive smoking can sometimes be traces to the purge valve /passages being blocked and may cause fuel oil puddling in the crankcase.

 

[doors67us]

new to you motor ?? running in cool cold temps.. ???

excessive smoking can sometimes be traces to the purge valve /passages being blocked and may cause fuel oil puddling in the crankcase.

Not new to me ,it ran well this summer,the temps here are in the high 50's low 60's ,where is the purge valve located? Never heard of it,just stumped as to why,it ran well earlier this summer and now it's doing this, especially after the repairs I've done

 

[rolmops]

Smoke is usually a sign that the fuel/air mixture is a bit too rich. Is your choke hanging up maybe?

 

[doors67us]

Smoke is usually a sign that the fuel/air mixture is a bit too rich. Is your choke hanging up maybe?

That's what I was thinking too, about the mixture being to rich,and no choke is wide open

 

[flashback]

Maybe a different brand of oil?

 

[doors67us]

Maybe a different brand of oil?

I'm using pensoil marine

 

[F_R]

Turn the low speed needle in till it sneezes, then back it off till it stops sneezing.

Part of the purge system was eliminated on that model to reduce water pollution. We got lots of complaints about poor idle, smoke, and fouled plugs as a result.

Hey, remember how lousy the 1970's cars ran with "Smog Control"?

 

[doors67us]

new to you motor ?? running in cool cold temps.. ???

excessive smoking can sometimes be traces to the purge valve /passages being blocked and may cause fuel oil puddling in the crankcase.

What's the likelihood of the purge valve being defective? Can one clean out the purge valve?

 

[doors67us]

Turn the low speed needle in till it sneezes, then back it off till it stops sneezing.

Part of the purge system was eliminated on that model to reduce water pollution. We got lots of complaints about poor idle, smoke, and fouled plugs as a result.

Hey, remember how lousy the 1970's cars ran with "Smog Control"?

Ok I'll give it a try. Well according to the parts diagram there's a drain valve,I'm assuming it a purge valve? #9 in the diagram

 

[F_R]

That is the purge (drain) valve. Wanna history lesson? Go back a few years and there were two drain valves (actually one double-ended one) #14 on this diagram. Those drained more areas of the crankcase. And the drained oil was dumped straight into the lake. Around 1968-ish, the drainage was dumped into the exhaust stream, hopefully to evaporate some of it, then still into the lake. Then 1970-ish it was modified again, now draining still fewer areas of the crankcase and the drainage was routed to the upper cylinder to be burned instead of being dumped. Yeah, right, All that did was flood the upper cylinder with extra gas making it richer than the lower cylinder, and harder to adjust for somewhere equal mixtures. As I indicated, we got lots of complaints, especially from customers that traded in older motors. that ran so much better than the new ones.

Symptoms of plugged purge valves aren't plugged at all---they just do not exist as they did in the past.

I was there in the dealer's shop in those days, trying to satisfy those customers.

 

[saltchuckmatt]

I'm using pensoil marine

A few things to look at or try....do you have a new set of champion QL77JC4 ? Try a better oil preferably synthetic....I'm running mine at 75 to 1 and I know guys running 100 to 1 especially if your idling or trolling a lot. There's a service bulletin about running a little more advanced (1/4 to 1/2) on the timer plate but not sure that applies to your older one, I'm sure others will chime in......did wonders for my 87 30.

What are your compression numbers?

 

[jimmbo]

What you consider Excessive Smoke might be perfectly Normal. Myself, I like and want that Smoke as it keeps the Skeeters away, and I love the Smell of Burnt 2 Stroke Oil. It is one of the Finest Scents ever created.

 

[doors67us]

A few things to look at or try....do you have a new set of champion QL77JC4 ? Try a better oil preferably synthetic....I'm running mine at 75 to 1 and I know guys running 100 to 1 especially if your idling or trolling a lot. There's a service bulletin about running a little more advanced (1/4 to 1/2) on the timer plate but not sure that applies to your older one, I'm sure others will chime in......did wonders for my 87 30.

What are your compression numbers?

Compression # 125 both cylinders,and never considered leaning back on my oil ratio,yes new plugs ,new everything

 

[saltchuckmatt]

Compression # 125 both cylinders,and never considered leaning back on my oil ratio,yes new plugs ,new everything

Does the cam on the timing plate under the flywheel (the thing that contacts the roller on your carb) have two lines on it? Where you match up on the link and sink?

New plugs but are they champions?

Those engines where designed with oil not nearly as good as today's modern oils. Even "Plain Jane" oil today, TCW3, is improved over stuff from the 70's. I'm using synthetics and have been using less oil and I am not having any issues with the motor. I zoom full throttle and then troll for hours and for the most part the smoke is minimal.

 

[doors67us]

Does the cam on the timing plate under the flywheel (the thing that contacts the roller on your carb) have two lines on it? Where you match up on the link and sink?

New plugs but are they champions?

Those engines where designed with oil not nearly as good as today's modern oils. Even "Plain Jane" oil today, TCW3, is improved over stuff from the 70's. I'm using synthetics and have been using less oil and I am not having any issues with the motor. I zoom full throttle and then troll for hours and for the most part the smoke is minimal.

Yes the timing Marks/link and sync are where there supposed to be,plugs are ngk b8s ,it ran fine before just confused as to why it doesn't run as before, perhaps I should try some synthetic oil