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Carb replacement

Kenger

Member
Has anyone ever tried to mount a 787 carb on a 657x motor? I have a 1995 gtx that I can’t seem to get running right. I think it just sat way too long and it’s time for new carbs. I can’t buy carburetors anywhere for the 657x motor, but 787s are everywhere. Has anyone ever had this issue? Or mounted a 787 carb on a 657 engine?
Thanks
 
Yes, I’ve rebuilt them many times and it still floods. I can get it to run alright for 2-5 minutes. Eventually it will just quit. I’m pretty lost as to why this is happening. I’ve had a few other knowledgeable people go through them and neither can find an issue
 
Did you use genuine mikuni, set the high and low speeds? Also have you ever replaced the needle and seats?
 
Has anyone ever tried to mount a 787 carb on a 657x motor? I have a 1995 gtx that I can’t seem to get running right. I think it just sat way too long and it’s time for new carbs. I can’t buy carburetors anywhere for the 657x motor, but 787s are everywhere. Has anyone ever had this issue? Or mounted a 787 carb on a 657 engine?
Thanks
Have you ever changed the spring for the lever in the carb? Apparently those are no longer available so if you haven’t, don’t. Have you checked the pop off? And looked for leaks past the needle or seat while doing the pop off? Have you checked the carb to see if it will hold pressure after it’s back together to be sure the lever is not holding the needle out? Maybe someone’s been bending the lever? Trying to achieve proper pop off?
 
Has anyone ever tried to mount a 787 carb on a 657x motor? I have a 1995 gtx that I can’t seem to get running right. I think it just sat way too long and it’s time for new carbs. I can’t buy carburetors anywhere for the 657x motor, but 787s are everywhere. Has anyone ever had this issue? Or mounted a 787 carb on a 657 engine?
Thanks
Also worth checking the fuel tank relief valve, perhaps it’s not opening causing a positive pressure in the tank forcing fuel into the carburetor? I can’t remember what pressure it’s supposed to open at? I think it’s 3 ponds for the relief valve and 1.5 pounds for the valve that allows air back in, but best to check. There should be a slightly positive pressure in the tank but not more than 1.5 pounds or so.
 
Yes, I’ve rebuilt them many times and it still floods. I can get it to run alright for 2-5 minutes. Eventually it will just quit. I’m pretty lost as to why this is happening. I’ve had a few other knowledgeable people go through them and neither can find an issue
Are you sure it’s flooding? And not starving for fuel? Have you taken the plugs out after it’s died on you to look at the Color of them? Is it dying at higher throttle or while idling or no difference? Will it start right back up after dying? Does pulling the choke help when it’s about to die out?
 
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