Im having trouble timing my 9.5 Johnson to my carb

[JimO1948]

My 9.5 Johnson spits and backfires on the bottom cylinder when I time the carb to the mag according to specs. I have to advance the timing in order to stop backfiring. Any help?

 

[boobie]

Re: Im having trouble timing my 9.5 Johnson to my carb

Have you got the low speed idle mixture adjusted properly ??

 

[JimO1948]

Re: Im having trouble timing my 9.5 Johnson to my carb

Yes. When the timing is advanced it idles fine. If it is timed to the mark, it backfires on the bottom cylinder.

 

[HighTrim]

Re: Im having trouble timing my 9.5 Johnson to my carb

How do you know it is backfiring on the bottom cylinder?

Don't feel bad, these 9.5s can be troublesome to get tuned perfect.

Im assuming you are adjusting the linc n sync? Or are you referring to points timing?

 

[nwcove]

Re: Im having trouble timing my 9.5 Johnson to my carb

...im curious also as to know about the misfire on the bottom cyl?

 

[JimO1948]

Re: Im having trouble timing my 9.5 Johnson to my carb

Im referring to the cam on the magnita and the cam follower to the carburator. You are supposed to adjust the throttle to contact at the mark on the cam bolted to the mag. When I do this it runs with it spitting and backfiring. When I pull the power from the bottom plug, the top runs without sputtering. When I adjust the throttle about a quarter of an inch off the cam it runs pretty good. I think it should run better and higher rpms wot.

 

[racerone]

Re: Im having trouble timing my 9.5 Johnson to my carb

Will spark jump a gap of 1/4" or more with ease?--Have coils been inspected ?

 

[JimO1948]

Re: Im having trouble timing my 9.5 Johnson to my carb

What is the linc and synch?

 

[JimO1948]

Re: Im having trouble timing my 9.5 Johnson to my carb

I have changed out the bottom cylinder coil. The old one looked good. No signs of failure. The spark appears the same on both cylinders. I don't know about 1/4"though

 

[HighTrim]

Re: Im having trouble timing my 9.5 Johnson to my carb

It is what you were describing, syncing the mag plate with the throttle valve to open throttle the proper amount as timing is advanced.

Move tiller handle until center of cam follower is aligned with index mark on armature plate cam. The cam, follower, and nylon roller on throttle lever should all be in contact and throttle valve should be completely closed! If clearance exists, or if throttle valve has started to open, loosen the adjustment screw and move the throttle lever until slack is removed and throttle is closed. Then turn tiller handle to FAST and check to make sure that throttle valve is fully open.

In addition to this, ensure she is adequately sparking on both cylinders. 1/4" gap with a bright blue ZAP!! Does it? Have both coils been done?

What is the compression?

Will putting your hand (choking) over carb inlet smooth it out some?

 

[racerone]

Re: Im having trouble timing my 9.5 Johnson to my carb

Test the spark for a 1/4" gap.----Laying plugs on the block is not a good test !!

 

[JimO1948]

Re: Im having trouble timing my 9.5 Johnson to my carb

When I time that way is my problem. I have to have the slack. Both coils appear fine. The compression is the same on both cylinders. About 75. The spark is not blue, but reddish orange. I just purchased a carburator off ebay, and it was already adjusted as I said. That is how I found out.

 

[JimO1948]

Re: Im having trouble timing my 9.5 Johnson to my carb

And yes putting some choke helps.

 

[racerone]

Re: Im having trouble timing my 9.5 Johnson to my carb

Spark should jump a gap of 1/4" with a loud snap you can hear.

 

[JimO1948]

Re: Im having trouble timing my 9.5 Johnson to my carb

I will try that tomorrow. How would that affect the timing.

 

[HighTrim]

Re: Im having trouble timing my 9.5 Johnson to my carb

You are not affecting timing per se. Timing is fixed with the flywheel key.

What happens if you pull the top plug wire while running?

If choking it smooths it out, it is too lean. What is the low speed needle set at? Have you tried backing it out? They can leak from a number of locations, throttle shaft, welch plugs, or plugged crank drain issues.

What was wrong with the original carb?

Im not sure why moving the roller a touch would smooth it out though. Perhaps throttle plate was not quite closed like you thought?

 

[JimO1948]

Re: Im having trouble timing my 9.5 Johnson to my carb

Riching the fuel only affected it a touch. I replaced the old carburator because of the skip, which seemed it could be a fuel issue. The new carb is from a 73 year. It ran smooth as soon as I installed it. Then I called myself timing it to the mark and low and behold, the skip came back. When I pull the top plug wire the engine stops running. I am wondering if the adjusting cam is different. Otherwise why was the new carb adjusted to run. I am wondering if I am losing some power since the timing is different ant it doesn't to rev too high while running on the lake.

 

[racerone]

Re: Im having trouble timing my 9.5 Johnson to my carb

If it stops running when you pull the top wire , then you may not have strong spark on the bottom cylinder.----- A reed valve issue ??

 

[JimO1948]

Re: Im having trouble timing my 9.5 Johnson to my carb

Then why does it run with the spark advanced, as the carb was adjusted to when I put it on?

 

[racerone]

Re: Im having trouble timing my 9.5 Johnson to my carb

I have 40 + years of experience on these motors , And own about 10 of these 9.5 hp models.--You appear to not want to do a proper spark test , not sure why ?