Fuel Problem ??

[Gunnypauly]

Hey Guys. I have a 86 Vmax , just got back from the Tail of the Dragon last week. Lots of fun!! Anyways, took the bike to work , no problems. on my way home, I got on I-95 and opened it up. Was in 4th gear about 7500rpm and lost power. It seems like a fuel problem . Anything above 4000 revs the motor breaks up, and bogs, but if you keep on the gas around 7k rpm it start running better, not 100% but better. If i put the choke on about 1/4 the way it seems to help . I can just cruse around @ low RPM and seems fine. Starts up fine, but you get it to around 4K and the bike will bog and miss. I checked the fuel filter. That's good, also replaced the sparks plugs. I checked the fuel pump while it was still attached to the bike. Just disconnected the out put fuel line that goes to the carbs. I'm not sure where to go from there. I'm guessing something is blocking fuel to a set of carbs , or I have trash in the carbs.. Where should i go from there???? Thanks

 

[naughtyG]

How is your fuel mpg at the moment?

A few things to try:

- check out the fuel bowl vent hoses are not pinched and routed correctly (they come up from behind and either side of the airbox
- drain your fuel bowls one by one into a clear glass or white container, that will show you if there's any shit in yer carbs
- take a good look inside your tank with a flashlight, if there's any rust (likely in an '86) you will need to treat or replace it

If none of the above is conclusive, you could try to do the 'shotgun' (search for it here) and if that doesn't help your carbs may need a good clean.

 

[MaxMidnight]

I would check the tank vent - try blowing through.

 

[sdt354]

I'd check the action of the slides while in neutral with the air box off. Are they all moving the same when you give it throttle? Or is one or more sticking? If so, inspect the diaphrams. needles and slides.
Steve-o

 

[alorio1]

I would check the tank vent and blow thru the delivery tube of the tank also. The delivery tube on my tank plugged one time and I had to use compressed air to remove obstruction, never found anything in the tank after draining it thou.

 

[Gunnypauly]

The diaphragms are good. They all move evenly when giving the bike gas. I did drain the fuel bowls just to make sure there was gas in the carbs, but I didn't check to see if there was trash in the fuel that i drained. I'll check that also. I did check to make sure there were no clogs between the fuel pump to the tank, and also checked fuel bowl vent hoses. They were good. Hey, thanks guys for the information. Guess I'll go take a look see, while there still some light left. Will keep you posted

 

[Rhoy Carter]

Make dure the airbox boots are seated good.

 

[Gunnypauly]

I didn't have enough time to check everything that I wanted to, but I did do the shotgun to the carbs, and it made a big difference. Before the bike was running @ about 50%, now its running @ about 75-80%. I noticed as I drained the bowls, rust was coming out with the gas. I flushed the bowls till no more rust appeared . After I reassembled everything, and got it running. I reset the mixtures screws, and noticed that #4 cylinder hardly dropped any RPMs once I seated the mixture screw. Guess that's a no go Houston.. #4 must still be partly clogged . How come the fuel filter didn't catch the trash??? Can you put an after market in line filter that will catch the smaller particles. Thanks Guys

 

[dannymax]

Just my opinion but I prefer OEM filters. unk:

 

[PATMAX]

Maybe I'm just pointing out the obvious but there separate "circuits" that control idle, midrange, and top end with a little overlap between one and another. It seems logical to me that you cleared out something in the top end circuits with your cleaning but maybe not completely. As far as filters go, I too used to wonder why filters seemingly did not do their job but experience and knowledge led me to understand that problems may not be particulate matter of a certain size but problems can have foundations in chemical breakdown, chemical reactions or properties such as ethanol is giving us. Fuel is passing through filtered but is affected or changed by heat, age, mixing with other chemicals (WD or Seafoam?) who knows. Shellac can build up and constrict or block orafices causing us our problems. It is to the point where I almost consider it inevitable because I don't ride enough, live in a humid climate, don't fully understand chemicals I introduce into my fuel system, cannot control my fuel supply at all times. Maybe we should shoot to become carb gurus!

 

[Gunnypauly]

Well, that puts a different perspective on the whole thing. Touche !!