Desperation - miracle needed

[AEB]

Help needed. I bought my bike Aug 2007 up till last week it has been my daily transport to work. Every morning rain or shine it has started first press of the button. The engine has run sweet(ish) and still does when running. It has always had a flat spot  when opening the throttle and there is slight blowing on one of the rear exhausts - where exhaust bolts to head. The bike was supposed to have had a service just before I bought it (oil / plugs etc).

Last week on COLD morning it just totally refused to start, even bump start >:(. When returned home from work it started first time ??? I left it running but it died after five minutes and refused to start again, I flattened the battery at this point rying out of frustration.  I charged the battery (volts tested OK). Day later started first time, a lot of backfires and  misses whilst running, I had to run it on full choke because as I took choke off it was going to die. Left a while and refused to start again. Put battery on master trickle charger again.

I cleaned all terminals, connectors and earths. Spark plugs sparking. Bike started again but running very erratic, I noticed that if I put the petcock on Prime the engine stabilised, back on ON and RES and the bike started to die. YES, problem solved I thought :D  Bike started again later same symptoms. Test fuel flow, no flow from tank on ON/Res and free flow on prime. I tried removing petrol cap from tank whilst running to see if any different - no difference. Left half a day again tried again, wouldn't start even with petrol on prime ???

Taken air filter and housing off and when throttle opened a nice spary of petrol being fired down into carbs. Carbs look like new inside, very clean.

I am not a mechanic, I am a novice so hope my above explanation is coherant and I've not missed something simple. As my only form of transport with little funds Its crisis to me. Any advice on where to go next here would be very much appreciated.

[Night Vision]

unless the bike is running, you will not get flow from "on" or "res". If the bike is running, and you don't get flow from "on", then I would check the vacuum hose to the petcock for leaks.

Do you have an inline filter? if you do, you may want to change that out.
If you don't have an inline filter, you should because you may have contaminated your carbs with rust or what not.

you can pull the petcock and check the screen to make sure that's clean.
you may need to rebuild your petcock....

overall, Visions do start hard in cold weather...... but it sounds like a fuel delivery problem to me.

[AEB]

Thanks Night Vision. Yes I do have inline filter which is clear and fuel can be seen through it. I will try checking petcock tomorrow (night here in UK)

[Lucky]

fuel cap vent may be clogged.., also check what the battery charges when cranking & while running & let us know

[AEB]

Since my post I cannot even get the bike to fire, I have an occasional misfire and once or twice about two seconds after cranking over I have a real loud back fire even though not cranking. I have read a number of threads on the forum and so far have tried the following but with no luck.

New set of fuses.
Carbs look clean
Petcock removed, very clean.
Good spray of fuel down into carbs when throttle open.
Yellow/Black wire cut from TCI unit
Side stand cut out (already bypassed)
With TCI unplugged battery reads 10.6v whilst cranking
Known good battery attached still exactly same symptoms
TCI opened for visual inspection, no visable signs of failure. Good spary of WD-40 before assembling.
Coils removed, cleaned, swapped over. Leads reattached. Plugs sparking with clear spark.

I found a few more terminals which appeared weak so replaced them. All electrics seem to be working fine. I have also noticed an ever so slight oil leak (one spot on garage floor) from where the starter motor enters the engine. As already said I can hit the starter and the bike turns over fine, sparks at plugs but thats about it????????

[Lucky]

--if your geting afterfire (shotgun blast out the exhaust,) your probably flooding it.
--10.6v while cranking is borderline at best.
--now that it's cold out you should be switched to a thinner oil.
--oil comming from the starter mount seal indicates the o-ring is bad.  while this won't make the bike hard to start, it is an indication that the starter oil seal (inside the starter) may need attention.  if so, your starter will be full of oil when you open it up.  (also check the brushes)

try cranking the bike off a NON running car. if she fires up easily, check the above items, one or a combination of the above will cause the conditions you describe.

--Lucky

[AEB]

Thanks Lucky.

Have tried to start it from my car battery (not runninig) but still the same symptoms as from bike battery including misfires etc. Whether it makes a difference or not but only now and again the backfire seems to fire back through the carb(s). Not sure and wouldn't know how to check or Why this would be?

[Kenny]

    I have had similar problems with the Yellow 83 I rebuilt a couple of years ago (loud backfires while starting) last fall I could not get it started & found I had no spark. My t/s led me to a u/s side stand relay & a clutch switch that was intermittent.
   No more loud backfires & it starts within one revolution.
      If you have the rich odour of fuel out the pipe you probably do not have spark or enough spark- check out your relays and switches.
                           Cheers Ken S. ;)

[Rick G]

I  have removed the side stand switch  on mine , because of the age and degradation of the switch . Everything has to be  in perfect condition to start a Vision in cold weather (below 45 deg f,)  each vision will vary, but to start mine when cold , I put the petcock on PRI  wait 30 seconds , activate the accelerator pumps by twisting the throttle rapidly , twice, set the choke on full and crank it . The second it fires I reduce the choke from 1/4 to 1/2  and hold the throttle at about 1/4 for 2 min. turn choke off and continue to hold 1/4 throttle for 2 more min. By then it should idle OK . But, I don't idle it long, I get moving . Just don't work it hard until its fully warmed up.
What ever you do don't start it and leave it  idling with the choke on full.

I believe  you flooded it. Gas doesn't vaporize as well at cold temps  and its easy to flood it .
If you can park the bike in a garage , remove the plugs over night . If its out doors don't do this, just leave them out for as long as you can. The idea is to let the excess gas evaporate to dry the engine out, so you can start from scratch.
"Experts " will tell you that , if an engine has gas, spark and compression  it will start , but engines will also go from too lean to too rich,with out going through just right, when there very cold.

[louthepou]

Just adding to the "backfire = weak spark" team.

Lou

[Night Vision]

Everything has to be  in perfect condition to start a Vision in cold weather (below 45 deg f,) 

so true.. we had a devil of a time getting my brother's V woken up this spring... his is one of those "hard starters/hard runners"  ::)

He had yamalube 20/40... I had Syn Mobil VTwin 20-50... neither were really willing, but mine took less effort...
I drained the carbs, he didn't.... I had my mouth full open, then backed it down to half, he didn't  ;)

[Rick G]

Night , it sounds like your on the the correct formula, for holding your mouth while starting a Vision, in cold weather,  half mouth sounds about right!! :D :D :D :D :D :D :D

[jasonm.]

If an engine only runs while the choke is on....THEN it's either a vacuum leak or a clogged pilot gas jet. The jet clog is likely on most bikes. BUT having the YICS leaking(vacuum) is just as likely on a Vision.

[Coil Coyle]

I left it running but it died after five minutes and refused to start again, I flattened the battery at this point rying out of frustration.  I charged the battery (volts tested OK). Day later started first time, a lot of backfires and  misses whilst running, I had to run it on full choke because as I took choke off it was going to die. Left a while and refused to start again. Put battery on master trickle charger again.

Spark plugs sparking.

Plugs can be wet fowled and look dry. Try again with new clean plugs that are pre-warmed as hot as you can with a hair dryer. Work fast.
Careful heating of the electrode to just dull red; done slowly in the natural gas flame of a stove burner, can save a wet fowled plug but you can also pop the ceramic if you hurry.

$0.02
;)
Coil

[inanecathode]

Right, heres what you do.

Connect a good battery source (jump it with a non running car)
Open the throttle ALL the way, keep it all the way open, all the time
Turn the choke off (dont need it right now)
Drip raw fuel down each of the carb throats (about 4-5cc worth)
Crank it for about 10-15 seconds

It'll do one of the following:
1) It'll start right up and rev crazily, then sputter out and die
2) Backfire erratically, never really get started
3) Do absolutely nothing (no firing AT ALL)

Most likely it'll do number one. This means your carbs are dirty. Theres no way around taking them off and cleaning them VERY throroughly. They may look clean on the outside, but if it wont start or stay running after it consumes the fuel you manually put down the throats, its clogged.

If it does number two you have fouled ignition. Either the plugs are fouled (either clean the electrode/ground very thoroughly on each or replace the plugs, best to replace it), or the wires are bad. Spritz water over the plug wires whilst cranking in the dark, you'll see the voltage leak out quite easily. This tells you if theres an exterior break in the wire. There still could be an interior break. If you plan on keeping the bike, you should just replace the wires anyway, you will once you get it running.

Number three means both of your plugs are either totally fouled (it does happen, happened to me actually), you've got astoundingly weak coils, a dead tci, two bad wires, or no compression in both cylinders. You're pretty much hosed at this point diagnostically, and you'll have to check each individually.


I'd bet money it'll do number one. The ignition on these bikes (aside from the crappy safety relays and questionable rev limiter circuit) is pretty bullet proof. That leaves your most likely problem with fueling, ie dirty carbs.

[jasonm.]

looking at the original post. It is Normal for gas NOT to flow in "on" and "res" positions. UNLESS vacuum is applied to the small hose going to the front intake manifold. That is why they call it a vacuum petcock. Check to see if by sucking on the hose while in RES... the gas comes out when the hose to the carb is disconnected...it should really flow and make a mess. Next thing to check is the fuel pump...these are also vacuum operated by the front intake. LIKE I SAID, it's either lack of gas or vacuum leak. These are very common issues on older bikes. Remember , start with the easiest thing that can be checked first. I have given you a few easy ones.