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Discussion Starter #1
Magnum was running fine. Parked up for a month. Won't start as I don't get fuel from carburetor into chamber. Pulling my hair out.... Have spark, fuel from pump to carburetor, fills reservoir where float is, but doesn't carry on from there to cylinder. What could have gone wrong? Cheers in advance
 

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Can you get it to pop and fire if you spray starting fluid into the carb? Are you using a fuel with ethanol in it? If it will pop and fire with the starting fluid then you have a carb problem. Most likely need to go into it and clean everything out. With the ethanol fuel it could have plugged up a jet. Even without ethanol fuel you probably have a jet plugged up in the carb. Time for a cleaning. Not that bad to get off and not really complicated to clean and repair.
 

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Hello and thank you for your reply. I should have mentioned that it fires if I pour petrol into air intake of carburettor, the engines runs until the petrol is used up. I have cleaned all jets except the pilot jet, hope that's correct name. This is the jet located near the float chamber on the bottom of carburettor. Unfortunately the head is stripped on that particular jet. Wouldn't it be crazy funny if that is the problem? Cheers
 

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The carb needs serviced - gums up from gasoline varnish and algae due to evaporating fuel - when parking for more than a week, the carb needs to be drained (either by shutting off the fuel and running the engine till it uses all the fuel in the float bowl or by draining), the petcock needs to be turned to the off position, stabilizer needs to be added to the gas in the tank or the fuel tank needs to be drained. If using non ethanol fuel, only the carb needs to be drained. Remember - ethanol blended fuel needs to be used within 21 days or dumped into a daily driven vehicle.
 

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Discussion Starter #5
Hi thank you for reply. Supposedly there is no ethanol in 91 grade petrol added, here in NZ. I have checked all jets, except the pilot jet(?), it's on the underside of carburetor next to float chamber. The head of the jet is stripped and I'm not sure how to remove, or should remove that. In your opinion and expertise is there a way to test the carburetor on a bench? I have all the hoses, petcock etc. I just want to see if fuel gets through to the cylinder inlet. The bike is unfortunately at the holiday bach 300kms away. Any suggestion is appreciated.
 

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The pilot jet is in the float bowl in a well next to the main jet. The screw on the outside accessed from the bottom is the pilot screw. It fine tunes the amount of fuel drawn through the pilot jet for a smooth idle.
 

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You can spray carb cleaner into the jets as they are installed in the carb and see that it goes through the passage to where it is supposed to. That is pretty much the only way to tell if the passages are open and clean.

How is the compression? Has this been sitting for a while? You could have a compression issue or the compression release stuck.
 

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Discussion Starter #8
The pilot jet is in the float bowl in a well next to the main jet. The screw on the outside accessed from the bottom is the pilot screw. It fine tunes the amount of fuel drawn through the pilot jet for a smooth idle.
Do I take it that if that pilot screw is too tight, there will be no fuel going to the chamber where the butterfly valve is, which is controlled by the accelerator cable?
 

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Discussion Starter #9
You can spray carb cleaner into the jets as they are installed in the carb and see that it goes through the passage to where it is supposed to. That is pretty much the only way to tell if the passages are open and cle'an.

How is the compression? Has this been sitting for a while? You could have a compression issue or the compression release stuck.
Bike was running a month ago. Parked up at beach house. Spark is fine, pouring fuel direct into carburettor when air intake is removed, will run until fuel is used up. Float chamber fills and I can drain with unscrewing drain screw. No fuel gets up from float chamber.
 

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Yes - if the pilot screw is all the way in it will get no fuel at idle, but it should still start using the enrichener (choke)

I think you need to clean the carb - I'm sending a manual for your reference
 

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Have to second what Latebird said. First, he knows his stuff! Secondly if you are getting fuel into the carb but not into the engine, you have a carb problems.
 

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Discussion Starter #12
Yes - if the pilot screw is all the way in it will get no fuel at idle, but it should still start using the enrichener (choke)

I think you need to clean the carb - I'm sending a manual for your reference
Thank you. Have received the manual.
 
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