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Discussion Starter #1
Hello everyone, I need a little help, I have a 1993 750 and when I start it, the front cylinder seems to be the only one working, If I rev it up then the rear cylinder seems to work. but at idle the rear stops working. I can pull both the plug wires off the rear when it is idleing and it will continue to run, but if I pull the front plug wires off it kills. At idle the exhaust from the rear cylinder is cold until I rev it up then its hot. I pulled the plugs from the rear cylinder after it has been idleing, and both of them are wet and smell like gas, so i dont think its a fuel problem. when I am driving down the road it seems like I feel a little "chug" or a miss. I dont know what area to look into next so I would appreciate any help or ideas anyone could offer. thanks
 

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Sounds like the pilot jet for that cylnder is clogged.

You can try soaking it in SeaFoam overnight.... Drain the rear carb, and then full the float bowl with SeaFoam and let it sit, then try running it. If you're lucky you won't have to pull the carb to clean it.
 

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X2 plus if you haven't got them put iridium plugs in, mine did the same until i replaced the plugs with iridium. :smiley_th
 

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Discussion Starter #4
Thanks Knifemaker I will give that a try, I just recently purchased these carbs off of e-bay from a guy that says he has been rebuilding carbs for years and years. I have contacted him to see what he says. Hello swagman I guess I am a rookie to iridium plugs why are they better?
 

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ass hole extaordinaire
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iridium plugs simply create a better stronger spark than copper the material is a better conductor of electricity
check the voltage at the rear coil it may be low at idle but when revving you are sending more voltage to it you should have at least 12 volts to both coils with the key on engine off if that is the case check out the thread on the ignition coil mod
 

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1986 VN750
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The plug part numbers are in my signature. Definitely get them. The idle jet in the rear could be clogged, or the carbs are not synced.

The carbs have to be synced with the bike running, so the front carb could get getting most of the vacuum, and thus most of the fuel.

Wet, gassy plugs mean you're running rich.
 

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Based on your symptoms, I would investigate carb sync first. It sounds like you have fuel, compression, and spark, but if your rear carb is shut all the way there's not enough airflow to fill the cylinder and fire. If you can crack the throttle and the cylinder comes to life it is your most likely culprit. If not check voltage to the rear coil as new_rider said.
 

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Discussion Starter #8
cool Thanks for all the input guys, I am going to check the rear coil. The guy that I got the carbs from says he stands behind them 100% he even told me to send them back if I am not satisfied and he will check the jets for free.
 

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ok I checked the coil on the rear cylinder, and I have 12.35 volts at the battery and 11.93 at the coil. didnt think that was bad at all. I am picking up some iridium plugs in about an hour or so. we will see if they help.
 

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well I put the plugs in and no change in the idle. you can kind of hear it fire once in a while but not all the time. When I take it for a ride and it warms up it seems to work then. I really dont think its a fuel problem btu Im not sure seems to be getting the fuel it needs but doest fire. could it be the coil? or plug wires?
 

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1986 VN750
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well I put the plugs in and no change in the idle. you can kind of hear it fire once in a while but not all the time. When I take it for a ride and it warms up it seems to work then. I really dont think its a fuel problem btu Im not sure seems to be getting the fuel it needs but doest fire. could it be the coil? or plug wires?
I'd do a carb sync. Search on the boards here if you need to make a tool for it. I just went the lazy route and eBayed the tool for $50.

After the sync, you may be better. You can check/clean the idle jet without removing the carbs from the bike. There are a few posts on that as well.

If you are seeing good spark @ idle in the rear, but no ignition, then it's most likely lack of fuel, or too much fuel. I'd do a sync, and maybe visually inspect/clean the pilot jet. See if that solves it.

Issues that just won't go away start to get really annoying :hitanykey
 
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