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Rick, Small Engine Technician
Category: Small Engine
Satisfied Customers: 3844
Experience:  Outdoor Power Equipment technical trainer since 1990, covering eight states.
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Hi,my son has a Champion 450,148cc.,serial no.1012075111496,(also

Customer Question

Hi,my son has a Champion 450,148cc.,serial no.1012075111496,(also has CR84 printed on somewhere) & the question is:- It was very poor starting this season & then was running terrible,he asked me to have a look at it (by the way it looks brand new it is 3 years old & has hardly done any work).When I had a go at it,it wouldnt start a all & we found that a new plug was the answer,it started first go but was still running even when warmed up as tho it was on half choke.I left it running for quite a while so it was thoroughly warmed up & then had a look at the new plug,it was all black again as tho the mixture was too rich,I was hoping to see a mixture screw to adjust it but couldnt see one,am I right in thinking it hasnt got one.If we continue to use it like this obviously it will eventually carbon the plug up & we will have to replace it again.We could live with it like that but would like your advice on how to cure the problem & have it running as sweet as a nut.Over to you.Thankyou.
Submitted: 3 years ago.
Category: Small Engine
Expert:  Curtis B. replied 3 years ago.
Check the carburetor choke flap. It sounds like the choke is closed and not opening as it should, flooding the engine and causing the carbon buildup on the spark plug.
Customer: replied 3 years ago.

Hi,how do I get at the choke on this particular engine,it looks like it is pretty sealed unless I remove the carburetor,is this the case?

Expert:  Curtis B. replied 3 years ago.
I don't have a picture of the carburetor, and the model you provided does not show,usually the choke could bee seen if the air filter and adapter is removed, but I don't know this application.
Customer: replied 3 years ago.

Hi again,when you take the air filter off on this model all you can see is the vertical inlet chamber with a jet at the bottom,and the choke flap is nowhere to be seen,have you access to an exploded view of the order to ascertain the position of it,could it be on the other side of float chamber,i.e.on the engine side of the carburetor? Also there do not seem to be any moving parts on the carburetor only the throttle mechanism on the engine side of it,is there any adjustment anywhere that could affect the even running.

Expert:  Curtis B. replied 3 years ago.
it has no choke , the flooding may be due to a leaking needle valve or a bad float in carburetor. If you can get me a model number that will show, I could see. What is this, I assume a go cart or other small atv.
Customer: replied 3 years ago.

Its a Champion 450, & is 148cc.& the serial 1012075111496,& it also has CR84 printed somewhere on the body,I dont know if this is sufficient information for you.

Expert:  Curtis B. replied 3 years ago.
A Google search for Champion 450 does not show anything, What is this application?
Customer: replied 3 years ago.

What do you mean with 'what is this application'?

Expert:  Curtis B. replied 3 years ago.
Generator, lawn mower, go cart, airplane, car, chainsaw, trimmer?
Customer: replied 3 years ago.

lawn mower!

Expert:  Curtis B. replied 3 years ago.

Is this Briggs engine? With carburetor mounted on the fuel tank? Here is link to what I think you may have.----