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Hard Starting When Hot

Started by turbosteve84, July 16, 2016, 10:27:28 AM

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turbosteve84

I can see the eyes rolling, but I DID read all the posts I could find on this problem but I think it would be easier to explain MY problem here and hope for the best.

With a few twists of the throttle the bike starts EASILY with very little or NO choke (a clue?) and runs, but will not idle without my hand on the throttle for long (another clue?) It eventually dies and will not restart for about 10 minutes even If I try the restart immediately.

No, I haven't checked the plugs yet, but I'm suspecting it's burning rich. Haven't synced the carbs dynamically yet either. Just looking for other areas to check.

Steve
Steve
saddlebums.tumblr.com

Walt_M.

Well, you are correct about it being rich. First thought is pilots but it could be float level is too high. Is it on the center stand or the sidestand? My '83 would not start if I rode it until warm and parked it on the sidestand. I decided it was float level but since the carburetors were such a pain I just never used the sidestand. Rode it that way for nine years.
Whale oil beef hooked!

turbosteve84

Center stand. The fact that I need little or no choke has me thinking about something in the choke valve (?)

Steve
Steve
saddlebums.tumblr.com

QBS

Do you do your throttle twists with hot or cold engine?

Walt_M.

The choke is actually just a richening circuit that is either blocked or open. The way it is designed, it is more likely to be blocked, off, than open, on. I think it might still be float level unless you have changed the pilot jets.
Whale oil beef hooked!

turbosteve84

Minimum choke (half way), a few twists of the throttle, hit the starter button and away she goes. Sometimes I'll need to twist it a couple of times while it's cranking. Shut off choke immediately.

Stock pilot jets.

Steve
Steve
saddlebums.tumblr.com

Rikugun

I have a difficult time keeping track of everyone's Vision and what stage of being sorted it is. Is this an old problem or new? Have the carbs been sorted or this still a work in progress? A bit more patient history would be nice but I'll happily throw out some guesses.

The Silver Vision I bought last summer I'm only now beginning to sort out but it does run good. Having said that it starts easier cold than hot as did my black Vision.

The process you described sounds more like a cold start procedure what with all the gas required from multiple throttle squirts and partial enrichener. Have you considered maybe it's lean? Beat throttle shaft seals could be a problem as well as a leaking YICs if still in place. Getting away from carbs, tight valves could also be a contributing factor.

It is far better to grasp the universe as it really is then to persist in delusion, however satisfying or reassuring.  Carl Sagan

fret not

Also the condition of the air filter should be checked.  A dirty one will cause rich running.
Retired, on the downhill slide. . . . . . . . still feels like going uphill!

Walt_M.

Ok Steve, you seem to have some conflicts here. The title says hard starting when hot but you say you are using the choke and hitting the throttle. As this would be giving it extra fuel which WOULD make it hard to start if it is jetted correctly and the carbs are clean with no intake leaks. Will it start hot if you just crack the throttle, 1/4 or less and hit the starter?
Whale oil beef hooked!

turbosteve84

Partial choke ONLY on initial startup. I should have made that clear.

Figured out a workaround. If I twist the throttle all the way to the stop -- ON A HOT ENGINE -- it re-starts.

So now I can fill it up at the gas station without waiting for the engine to cool down before re-starting.

Yay!

Steve
Steve
saddlebums.tumblr.com

Walt_M.

Okay, that sounds exactly right and, if you don't mind doing it you should be fine. You may be getting a little vapor lock, gas boiling in the carb and flooding the engine and a common Vision problem.
Whale oil beef hooked!

QBS

My experience with my '83 and my long time riding partner's '83 when starting from hot is: Bike vertical, enrichner totally off, no throttle twists, hand off throttle, push starter button,  let bike idle for a few seconds, and off you go.

auto

Been sorting my 82 vision for my son.Had this bike since new,and been through a lot with it.It was having a hot start issue.I reset the valve on the loose side,also pulled the carbs and layed in a SS foil heat shied.It goes from the F valve  cover across the intake boots and up the rear cylinder. Of course you have to cut holes for the intake boots to stick through and the vacuum line for the fuel pump.We've been having some nasty hot weather here in SJ.This mod seems to be working,bike is restarting in this hot weather.

Rikugun

This sounds interesting but some pictures and or details would be helpful. How thick of material? Attachment points? etc...

On a side note, it's nice to know I'm not the only Visionary in NJ.
It is far better to grasp the universe as it really is then to persist in delusion, however satisfying or reassuring.  Carl Sagan

auto

You know me,I bought the 125 Bultaco from you.

Rikugun

Hey, how are you, I didn't recognize the screen name - you need to visit us more often.  :). Did you ever restore that bike?
It is far better to grasp the universe as it really is then to persist in delusion, however satisfying or reassuring.  Carl Sagan

auto

yea fixed it up nice,but sold it.Selling off most of my vintage dirt bike right now.As for the heat sheila it is .003 ss heat treating foil wrap.We use it at work.Not the too clear in picture,but you might get the idea.As for the vision I'm letting my son get into street riding with it.When it would not start I could see his frustration,had to try something.Really haven't rode the vision in a good 5 to 10 years.Did drain the carbs and kept the gas tank full.Pretty much started right up with a new HOT battery.Maybe look you up for a ride next time we go north.

QBS

Auto, your red V looks like it could be the basis for a good Sport Touring bike.  How does it run?

auto

Like any other vision,don't look at the tach and just ride it! When it was new I rode it to yellow stone from NJ,but we both had less mileage on us then.

Rikugun

Thanks for the pics, that's a sharp Vision. I like the Euro rear fender.

Is there a typo in your post - from the looks of it I'm guessing it's .030" and not .003"?
It is far better to grasp the universe as it really is then to persist in delusion, however satisfying or reassuring.  Carl Sagan