9.5 johnson outboard 1965 back fire

[jlbates@60]

I just bought a bet up 9.5 out board 1965 Johnson and am getting it going again , rebuilt carb,reset points new water pump, fuel pump, and new needle for low speed ajustment but am getting back fire or a buck at low speed or low idle have i mist something?

 

[flyingscott]

Open the low speed screw on the carb an 1/8 of a turn at a time until it goes away. It sounds like a lean sneeze.

 

[jlbates@60]

yes I have tryed that alot but it works for a short time (30 sec) and its right back . comp. is 75 top and bottem . maybe i should rebuild and clean carb again? have opened up needle about 3 to 4 turns and still it happens at low idle. THANKS .

 

[kbait]

It is difficult to clean the low speed chamber on that particular carb (behind Welch plug). In fact, I never figured out how, as there is a plastic piece in there.. Anyway, sounds there’s crud in there. I have successfully cleared a bunch of ‘em using the following method.
Drain carb. Air up your compressor and attach air nozzle. Attach a short length of poly tubing (about 3/16” ID) to nozzle tip. Remove LS needle from carb, insert poly tube into needle port, and shoot a few short blasts of compressed air in there. Now test run and feel the joy!
*If someone knows how to manually clean the chamber behind the Welch plug.. please post!

 

[racerone]

Is throttle plate opening too soon ?

 

[jlbates@60]

thank you all for your advise , as soon as there is light out i will try that . and plate is set good made sure to read on that alot thanks back after i try or with updates thanks.

 

[Lectro88]

It is difficult to clean the low speed chamber on that particular carb (behind Welch plug). In fact, I never figured out how, as there is a plastic piece in there.. Anyway, sounds there’s crud in there. I have successfully cleared a bunch of ‘em using the following method.
Drain carb. Air up your compressor and attach air nozzle. Attach a short length of poly tubing (about 3/16” ID) to nozzle tip. Remove LS needle from carb, insert poly tube into needle port, and shoot a few short blasts of compressed air in there. Now test run and feel the joy!

** **

*If someone knows how to manually clean the chamber behind the Welch plug.. please post!

You pretty much covered it..
The only "" Maybe Other" thing that I do with a particularly stubborn hard to clean carb.
I'm not a fan of soaking a carb.. theres not many carbs I can't clean with a can or 2 of carb cleaner and my 5-6 sets and I mean 300-400 micro bits.
{I stocked up a while back.}
But either soak it before hand and get after it with a can carb cleaner and the red straw(make sure you use safety glasses... ask me how I know.
I always have a minimum of 6 cans carb cleaner in basement.(14 right now)thanks Wally.
But typically if the combination of all previous and above don't work,.. then
you probably have another or different problem.

 

[Crosbyman]

first ...read leroys article 3-4 turns on the ls needel indicates a problem

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the carbs need to b 100% clean

check utubes

utube 9.5 carb - Search Videos

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utube 9.5 carb - Search Videos

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[jlbates@60]

ok, have watch alot of utube on this so i will redo this thanks. the kit i got this time came with to port covers and have found vido and repair manual that show how to replace these. back after Ive do all that thanks again for all your knowlege (cant spell to save my life hehehe).

 

[Crosbyman]

btw remove the lower bolt below the ls needle ... you should see light peering into it ... the HS jet is at the rear if need be pusha 2-4 pound monofilament to clear any crud ...

reflush and air spray

 

[jlbates@60]

thank you I will try that first.

 

[Crosbyman]

keep in mind this a necessity not necessarily the cure ! your version may not have the vibration dampeners on each side of the block...

see leroys

those engines do shake a lot at idle sometimes enough to push the choke knob out and kill the engine.

btw how were the coils new or cracked ?? did you replace condensers ??
secondary HV resistance to grd should be 4-8 kohms from boots to engine frame.

also try running with th cowl OFF the engine.. if ok it is likely sniffing it's own exhaust fumes due to a bad seal in the lower housing

 

[racerone]

Agreed ----Many ( not all ) motors had a vibration dampening kit installed.----The 64 and 65 models had that issue with shaking at idle.

 

[jlbates@60]

always run with out cowl. and thanks for the exhaust tip ill look into it. I want to thank you all for your help really thanks.

 

[jlbates@60]

ok sorry for the wait rebuilt carb (very clean) tested boot to ground and got 3-4 so maybe coils next oh still getting buck. runs ok at higher rpm but low get bad buck even with ajustment. it goes ----------^^^-----------^^^-----

 

[racerone]

When lean sneeze happens , open low speed needle more.----If it does not improve the carburetor low speed circuit is not working.----At idle the carburetor must be closed.---So check that adjustment.----Were coils cracked ?------Remove coils and see if one is burned through on bottom and grounding to the plate.

 

[jlbates@60]

thanks I will take that apart and look and double check carb.

 

[Crosbyman]

post#8... did you adjust per instruction.

 

[jlbates@60]

Yes I did and it idles on low now a little ruff but with a little fine tune should be good. coils show a little curotion so have some new ones coming. thanks everyone out there for your help!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! I stopped today its raining out and right now thats where Im working on it at, again thanks.