Mark
My R25 is running extremely bad and I am trying to figure out why. Upon opening the carb I saw that the main jet (Vergaser Hauptduese) has a small piece missing (broken off) at the top end. Could this effect engine performance to such an extent that the engine hardly runs at all? I am asking this because I suppose that piece has been missing for quite some time, but the bike is only running so poor since lately.
Also I am not sure whether the main jet has to be screwed all the way in, or only partly.
Do you have any other hints what to look for when checking the carburetor? I have opened it completely but could not find any other obvious flaws.
Christian
r25 carburetor
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Mark Huggett
Re: r25 carburetor
Hi Christian,
Your description is a little vague. When you refer to main jet being broken off, do you mean the brass part of the main jet, or the zinc casting part number 13 11 0 039 127 described as “Mischkammereinsatz”? If you mean this zinc casting, the problem is quite common. Many Zinc die castings suffer from an aging problem from too rapid cooling after the casting process whereby the molecules are not frozen in situ, and slowly orient themselves to form a crystal matrix over years and slightly undergo a volumn expansion and thereby destroying itself. The parts becoming brittle and full of tiny cracks. I have seen brand new carburettors which have been laying in stock for over 40 years which one can throw away because of this problem. If this is the case, bits of the zinc casting from the part in question, can brake off and be sucked into the combustion chamber without any problem, and be expelled out of the exhaust. If the “Mischkammereinsatz” no longer has its correct form, the fuel mixture can no longer be atomised correctly and the fuel is sucked into the inlet in the form of droplets and globules instead of an atomised liquid. This mixture cannot be combusted properly and will result in extremely poor running, a black sooty spark plug and heavy black exhaust deposits.
All the jet parts have to be screwed all the way in. The needle jet should be a 1208, and the main jet should be a 100.
Best regards and good luck.
Mark
Mark Huggett GmbH
Your description is a little vague. When you refer to main jet being broken off, do you mean the brass part of the main jet, or the zinc casting part number 13 11 0 039 127 described as “Mischkammereinsatz”? If you mean this zinc casting, the problem is quite common. Many Zinc die castings suffer from an aging problem from too rapid cooling after the casting process whereby the molecules are not frozen in situ, and slowly orient themselves to form a crystal matrix over years and slightly undergo a volumn expansion and thereby destroying itself. The parts becoming brittle and full of tiny cracks. I have seen brand new carburettors which have been laying in stock for over 40 years which one can throw away because of this problem. If this is the case, bits of the zinc casting from the part in question, can brake off and be sucked into the combustion chamber without any problem, and be expelled out of the exhaust. If the “Mischkammereinsatz” no longer has its correct form, the fuel mixture can no longer be atomised correctly and the fuel is sucked into the inlet in the form of droplets and globules instead of an atomised liquid. This mixture cannot be combusted properly and will result in extremely poor running, a black sooty spark plug and heavy black exhaust deposits.
All the jet parts have to be screwed all the way in. The needle jet should be a 1208, and the main jet should be a 100.
Best regards and good luck.
Mark
Mark Huggett GmbH
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Christian Mues
Re: r25 carburetor
Hi Mark
Sorry for the vague description. The broken- off tip actually refers to the needle jet, and I have just placed an order for new needle as well as main jet. Hope the express shipment to Manila won't take too long. I've ordered part no. 100 for the main jet based on your recommendation, although I saw in your catalogue that there is one specially for the 25/3 with part no. 145.
Do I understand you correctly that the "Misckammereinsatz" cannot be replaced? How can I find out if it damaged?
Thanks for your help.
Christian
Sorry for the vague description. The broken- off tip actually refers to the needle jet, and I have just placed an order for new needle as well as main jet. Hope the express shipment to Manila won't take too long. I've ordered part no. 100 for the main jet based on your recommendation, although I saw in your catalogue that there is one specially for the 25/3 with part no. 145.
Do I understand you correctly that the "Misckammereinsatz" cannot be replaced? How can I find out if it damaged?
Thanks for your help.
Christian