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1985 honda vt700 weird issues

15K views 29 replies 10 participants last post by  Trials 
#1 ·
I was just given a bike my brother was stumped about it's a 1985 honda vt700 has about 24,000 miles and is all original. The issue with the bike has me confused cause i don't know where to start. ok down to the issue. the bike will start and idle fine. When you put the bike in gear and begin to ride down the rode at about 3,000-4,000 rpm the bike will stall completely die with or without the clutch released. The lighting system stays on and never cuts out. I am thinking a relay or the coils but I would like to know if anyone has any clues :71baldboy:
 
#3 ·
Well really the only indication as to why it is stalling is the rpms are up to about3,000 to 4,000 and when it does it the bike just dies brakes are free and clear. clutch releases normally and everything is shiftting perfectly. It has to be something with the electrical system
 
#6 ·
>_< NO S***! Why did I not think of vacuum leaks? -_-; Especially since thats what plagued me with my Ford Fairmont I used to own. Same goes for the Airbox and filters. Thats something I should have thought of. I really feel stupid right now. I am willing to bet Custom really hit it on the head with his suggestion.
 
G
#7 ·
Don’t feel bad I have owned this model for 10+ years, had it all apart and rebuilt into a contest winning show bike. Yet I had a bout of very similar symptoms & circumstances this spring only to find my air filter was so degraded as to greatly restrict the air-flow. How dumb is that? :(
 
#9 ·
Thanks guys Im still working on the bike but I found 2 possible causes so far or actually 3 . 1 Air filter seems to be the original and crumbles when I touch it and 2 fuel filter seemed to be the original so I'm replacing it and Finally there is crack in the vacum hose where it connects to the carb. So I'm going to replace all three and see how my well it works
 
#11 ·
Well it still had the same issue without the air filter but after replacing the vacum hose and the fuel filter it ran good up and down the road alittle sluggish but after i trimed the fuel lines to fit the new filter better. it came to life and ran great then i went to put the tank back on got it all back together was gunna take it for a joy ride and enoy the victory. blame gas pouring out from under neath the tank. removed the tank and started it again gas was gushing from a 90 degree fuel line that goes from the main feed to the secondary carb. had a giant gash in it. So it's time to play find the part since no local shops or stores have the line. I tried just using a regular line but it kinks to much and will only let the bike idle the minute you throttle it dies. oh well back to the parts search. btw is anyone knows where i can get a 90degree fuel line 1/4 inside diamater only about inch in a half 2 inches long btw regular rubber fuel hose just curved at a 90degree.. appreciate all yalls help so far
 
#13 ·
hmmm maybe i should start another thread, but a co worker of mine has been shopping for a bike and came across an 80 cb750 with a somewhat similar problem ...

it starts, turns , and runs but unless you give it gas, the bike dies out. also, when giving it a lil throttle to keep it from dying, it idles a bit rough. so i told him it mainly could be a carb issue, but since im no bike expert, i could be completely wrong.

any quick response to this ? hehe again , sorry for not starting another thread to this!
 
#14 ·
Well the issue I have currently is there needs to be a fuel line at a 90 degree angle. bad thing is I can't find one anywhere and when i try to use a fuel hose it kinks up a bit and causes it to restrict the fuel to where i can get enough in to idle just not anything more then that so it basicly starves then dies
 
#18 ·
Well the problem is I can't seem to locate the part. The original plan for this bike was to have it up and running for Galveston tx's Lone star rally for halloween weekend. Doesn't look Like it's going to happen. I've even checked Bikebandit.com and they don't have it. Says not available. I've checked ebay looking for something similar but notta. Looks like I'm up the creek without a paddle
 
#19 ·
Ok new issue, Bike runs great without the tank. With it only running on the reserve the bike idles can wrench the throttle all i want no problems. But when I put the tank on bad issues. throttling kills the engine but will idle. Appears I have a issue with a vacuum somewhere but I don't know where to look and is there a way to adj this. Keep in mind it's a 1985 Honda shadow vt700c also i did remove the fuel lines from the gas tank and they appear to be obstruction free. Any help or possible causes would help tremendously.
 
#21 ·
I don't know if that's a vented system or not. Also, that bike has a fuel pump, does it not? How is that doing? Did you do the flow test?
I don't think California uses any vented fuel systems?
As to the parts, it will be available someplace, you just gotta find where. Maybe more Shadow owners can help.
dc
 
#22 ·
I checked no vented gas cap. I'm gonna try cleaning the tank out see if that will work. I'm thinking there maybe sludge in the tank because it has been sitting for 9 months without being started with gas in the tank. The fuel pump is doing great can't see any issues with it.
 
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