150 gt carburetor problem

[quilter]

I have a 150gt johnson, I found all plastic bases on carbs were warped and leaking bad . I found a set of carbs on ebay off of a 1987 150, the bowls have 11/4 stamped on the carbs, my old gt carbs have 1 5/16 on them. the jet sizes on my gt carbs are 30 idle and 65 high speed. the 1987 carbs have 29 idle and 55 high speed. because of the venturie size being 1 1/4, do i need to rejet these carbs. I put a new carb kit in old carbs and the gaskets would not seal because of the warping. thank you

 

[quilter]

Re: 150 gt carburetor problem

I have a 150gt johnson, I found all plastic bases on carbs were warped and leaking bad . I found a set of carbs on ebay off of a 1987 150, the bowls have 11/4 stamped on the carbs, my old gt carbs have 1 5/16 on them. the jet sizes on my gt carbs are 30 idle and 65 high speed. the 1987 carbs have 29 idle and 55 high speed. because of the venturie size being 1 1/4, do i need to rejet these carbs. I put a new carb kit in old carbs and the gaskets would not seal because of the warping. thank you

 

[quilter]

Re: 150 gt carburetor problem

I forgot to mention the serial # for the johnson150gt. it is r08584762. I was told this was a 1990, does anybody know if that is true? thank you

 

[Walker]

Re: 150 gt carburetor problem

They should be fine jetted the way they are, but if just the bowls were bad on your old carbs why not change the main jets and use the new bowls on your old bigger throated carbs??

 

[quilter]

Re: 150 gt carburetor problem

They should be fine jetted the way they are, but if just the bowls were bad on your old carbs why not change the main jets and use the new bowls on your old bigger throated carbs??

 

[quilter]

Re: 150 gt carburetor problem

I tried to get the jets out after soaking in carb cleaner and did get two idle jets and one high speed but the other high speed striped out and i cannot get it out. I didn't try the other 2 bowls afraid the same would happen. could that one jet be drilled in the carb to .o65?

 

[Walker]

Re: 150 gt carburetor problem

Yes it can. Find a machinists data sheet and get the correct size bit for .065.
But then you won't be able to go back. Before drilling any jets I'd try the new carbs with the smaller throats and see how they perform.

 

[emdsapmgr]

Re: 150 gt carburetor problem

I have had the same experience with dried up bowls. Get a can of Bombardier Engine Tuner. Thouroughly soak the jets in the bowls. Engine Tuner will out peform carb cleaner. I would not drill out the jet. You really need to get the old jet out. Drilled jets may not perform the same as a factory-machined jet. Defintely stick with the 1 5/16" larger-throated carbs.

 

[OBJ]

Re: 150 gt carburetor problem

Qilter....are the bowls on the carbs from ebay plastic or cast aluminum? Reason for asking, the low speed jets from the plastic bowls will not fit the cast bowls. I believe the bowl change did come in 87'....production started with cast bowls and late production models used the plastic bowls. (replacement bowls from Bomby are cast.....go figure)

And post the model number of your engine if not sure of the year.

 

[quilter]

Re: 150 gt carburetor problem

They should be fine jetted the way they are, but if just the bowls were bad on your old carbs why not change the main jets and use the new bowls on your old bigger throated carbs??

I took your advice and used the carbs After rebuild on ebay. The motor sounds great. idles good after warm up and revs good on hose now for lake test when it warms up. thank you guys for your help.

 

[Dhadley]

Re: 150 gt carburetor problem

You can use the 1 1/4" carbs as they are. They'll have slightly better acceleration but maybe less capable of higher rpms. If the motor is set up at about 5600 or so, you'll be better off with the 1 1/4" carbs. If you're at 5800 or so, you probably won't see much difference on top. If you're set up at 6000+ you might be better off with the 1 5/16" carbs.