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Discussion Starter #1
Maybe you guys can help me with this one.

I got my 85 700 about 2 months ago and it has been running perfect(10,000 miles). When riding in the higher RPMS(highway, etc...) and letting off the throttle ususally results in a really loud backfire similar to a gun shot. I have been told I need the carbs sync'd so that may solve that problem. My main issue is that yesterday I was riding down some backroads with a 1/2 tank of gas when the bike started sputtering then died. I pulled over and hit the starter and it fired right back up. I made it about 2 more miles and the same thing happened again. This repeated about 5 times until I was able to get home. I have now pulled the tank and petcock and didn't see any noticeable "trash". The vaccum hose to the petcock was very cracked, so I replaced that, and I am thinking that may have been some of my problem. I was also told to drain a tube coming from the air boxs, but was unable to find such a hose.

Any help is greatly appreciated
 

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Might not be the same problem but I experience this with my 86 750: When the gas needle shows approx. ½ and I accelerate uphill, the engine most likely will sputter and die (of course depending on how hard the acceleration is). Put it on reserve and it spins again. Logical as the fuel during an acceleration will be pressed to the back of the tank. For the record mine has a great deal of popping too, especially when idling downhill at approx. 2.500 RPM, but that's another issue.
 

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Discussion Starter #4
HarveyFromOz said:
About the gunshots, I was able to reduce them by lowering the idle speed.

About the engine sputtering, this seems similar to what I have experienced. http://www.vn750.com/forum/showthread.php?t=876

Still haven't got the bottom of it.
Well I will share what my problem was:

Loud backfiring was reduced to a mild gurgle by adjusting the AIR/FUEL screws. One was set to 1/4 turn out and the other was set to 6 turns out. Now there both at ~2.5 turns out and seems to be running good except for a lot of throttle lag.

Engine sputtering and dying was solved with a new battery. It seems that the battery had dried up, and so when the bike got hot it drained the battery. It had gotten so bad that it wouldn't start at all. It would turn over fine, but just wouldn't start.
 

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backfiring on deceleration

if you have sports exhaust check the pilot jets,they should be larger than stock. it's a common cause of back fire on deceleration. A long shot is a loose coil wire.
vacuum fuel taps sure need vacuum, so the cracked hose couldn't have been good.
 

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if you have sports exhaust check the pilot jets,they should be larger than stock. it's a common cause of back fire on deceleration. A long shot is a loose coil wire.
vacuum fuel taps sure need vacuum, so the cracked hose couldn't have been good.
The guy posted this like 8 years ago so hoping he fixed it by now :)
 
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