Yamaha Virago 750 Carb Problem?

Question

I'm a good mechanic with injection stuff, but fall short for carbureted stuff if its more advanced than a lawn mower. My recently bought 1993 Yamaha Virago 750 has been running wierd lately. When I first bought it, it ran rough cause it sat around. I used Mechanic-In-A-Bottle which fixed it, but recently the choke needle got stuck in the partial choke position, and ever since I fixed that, it stumbles when I try to accelerate. It idles fine sometimes, but anything below about 2,300 rpm, it falls on its face like it misses a few firings here and there. I pulled off the intake boots and cleaned the inside, and also cleaned some gunk out of a small diaphram on the side. Afterwards it seemed to run fine, but after a short ride it started happening again, only it got a bit worse. Any ideas as to what can cause this? I've put a new air filter on, the hoses and lines seem good, and the fuel and fuel filter is good.

Answer 1

Before you go to do anything with the carbs. if i were you and it was my bike i would just go and spend the money on a carb. rebuild kit due to the age of the bike because i gurantee the bike has several worn carb. parts ans seeing u have no experience with carbs. ur not going to know what's a passable part or if it's to worn so get the exact service manual n go through the entire carb. and replace all jets,needles,diaphrams, gaskets, imualtion tubes, etc. the rebuild kit would be called something like the MASTER REBUILD KIT dont get just the regular kit. I would also replace all cables like throttle cables n choke cables and make sure that your air/fuel screws are set correctily but u can't forget if it is modified at all everything will be tuned diffrently..also DO NOT DO NOT seperate the carb.s if they're in a bank if u do it will be very tedious to put back together



well your on the right track def. a fuell/air issue..with carbs. there is SEVERAL diff. tiny little parts that can cause this kind of problem so you have to narrow it down the reason why the bike won't idle or run properly is because of a few things clogged fuel jet (pilot jet's or main) or a fuel circuit inside the carb. what you need to do is remove the carbs. and remove the float bowls (CAREFULLY) then remove the jets they will be removed with a flat head screw driver then carefully look through the jet holes (ALL OF THE HOLES SOME WILL BE ON THE TOP ON THE SIDES ETC BE VERY THOROUGH) u MUST be able to see the light through the holes they're very small so take you time looking just hold it up to the sun to see the light (USE CARB CLEANER THROUGHOUT ENITRE CARB SPRAY IT THROUGH EVERY JET AND EVERY CIRCUIT PRETTY MUCH NE HOLE YOU SEE IN THE CARB)



ONCE u've checked all the fuel jets and fuel circuits then you can move onto all of the air circuits and jets which are located around the throat of the carbs (the openings from the air box to the intake) now do the same steps u did with the fuel a good way to clean the jets n circuits is to spray carb cleaner in all holes n then use compressed air to blow out the holes with an air nozzle.



NOW since it is a much older bike the next thing i would be looking for is worn out parts..such as the rubber diaphrams u must be very careful removing those the rubber tears extremely easy n then allows to much air causing the bike to fall on it's face which can also be caused by to much fuel as well..look for worn out float valves and seats check to see if the floats have cracks or not you should even check the size of the holes in all of the jets ive had customer's drill out the hole of a jet due to it being clogged but they drilled the hole way to big and due to the age of the bike im sure a million ppl have been in those carbs. so who know's what they could have done.



Okay i've typed enough if u need to know more just ask becuase there is alot more to be told about carbs. but all this should be enough to get you started just pay attention to your SERVICE MANUAL





IF ALL ELSE FAILS I WOULD SOAK THE CARBS. IN A BIG BUCKET OF CARB CLEANER IF U DO THAT JUST BE SURE TO REMOVER ALL RUBBER CARB. CLEANER MAKES RUBBER EXPAND AND WILL AFFECT RUNNING CONDITION

Answer 2

Yamaha Virago 750

Answer 3

I have a 94 Yamaha Virago 750 ,very low miles 4000 . After sitting in the garage all winter ,i started the bike and gas started pouring from what looks like a over flow hose but a also see gas coming from the upper part of the carb .Do you think the float is sticking and do i need to rebuild the carbs

Answer 4

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RE:

Yamaha Virago 750 Carb Problem?

I'm a good mechanic with injection stuff, but fall short for carbureted stuff if its more advanced than a lawn mower. My recently bought 1993 Yamaha Virago 750 has been running wierd lately. When I first bought it, it ran rough cause it sat around. I used Mechanic-In-A-Bottle which fixed it,...

Answer 5

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