Running problem

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I have a 74' 850 Roadster that after 2 years is fully restored but will not consistently run. It will start when cold and go for about 5min, then get erratic rpm and shut off. Haven't updated any of the electronic components (new harness though) and it has a stock ignition. I'm so close to the dream being reality, please help.
 
Maybe choke stuck or left on.
Check plugs to see if wet maybe.
If Mikuni "choke" (enricher circuit) on when lever is up.

Bob
 
If you really want that stone to roll you will fit electronic ignition with a strong battery. It's surprisingly easy.
 
It does sound like a fuel delivery problem.
Check tank vent and fuel tap flow.
But yeah, it could be a vent problem.
 
G'day rolling_stone, can we call you Mick.
Do you still have Amals.
Tricky little suckers, could be lean or could be rich.
Does the bike start up again, straight away, after it stops, or do you have to tickle again.
If so it may have a slight blockage in the supply to the float bowls.
Firstly, check the plugs, they should tell you something.
Are they dry or wet, black or white. One ok but one wet.
If they are dry then it may be short of fuel. Give the bowls a tap with the handle end of a screw driver
while the fuel is on, this might help with a sticky float.
Remove the fuel lines from the taps, and check for a good flow, then check further along, (inline filters ?),
undo the lines at the carbies and check for flow, if it's all good so far, hook them up and then undo the
removeable plugs on the bottom of the bowls. If the flow is slower than before, then the float needle
and seat may be gummed up.
If the plugs are wet, (flooding), then the floats or a float may be sticking. TAP TAP.
Will the engine rev ok untill it stops. if so probably fuel shoetage.
It's all good fun, so close but so far away, eh.
AC.
Hey Bob,.. On my Mikunis, if there is no lever, only a knob, then up is on.
If there is a lever, then down is on. heheheh.
 
6 V coils ? see if there boiling when it dithers .The insuklationcan not work when hot , the anodiseing on the wires inside .
condensors also questionable if original fitment.

Though ' the points ' can wear in so close the gap . If its closed a way can get awkward when hot .Set correct should be satisfactory .
 
Hi there

Has it got a fiberglass tank it could be the resin has degraded and gumming up the carbs this happened to me when i put my f/back back together (i hadn't drained the tank properly)
 
Check you charging system. Put a meter on the battery and run it up to 3000rpm. If all is well, 14 vdc (ish), then do a load test on the battery. You may have to take it to the auto part store to use their load tester. Even a new battery can be bad.
 
Rolling_Stone said:
I have a 74' 850 Roadster that after 2 years is fully restored but will not consistently run. It will start when cold and go for about 5min, then get erratic rpm and shut off. Haven't updated any of the electronic components (new harness though) and it has a stock ignition. I'm so close to the dream being reality, please help.

I had similar symptoms that turned out to be a corroded kill switch. The resistance was there when cold but seemed to increase as it heated up till it was enough to the kill the motor. It can happen at any switch or connection but kill switches are notorious for getting corroded. New harnesses have been known to have problems too. Try running a jumper from the battery to power up the ignition. All this is after you've checked the tank vent :)
 
Appreciate all the replies, started the bike for the first time 6 months ago and since then it's be a different challenge at every corner. The prize goes to rpatton, I took apart the kill switch and cleaned it up and now the bike seems to run fine. It keeps a consistent rev going and doesn't shut off involuntarily. Where should I mail the beer?
The funny thing was as soon as I realized it's been fixed it started to rain, can't wait to get it on the road though. Thanks again!
 
let's meet at your house. The rains are back. In some places people have moss on the shady sides of their trees. Here we have moss on the shady sides on our houses, cars, people who don't get around much...
 
Hey Bob,.. On my Mikunis, if there is no lever, only a knob, then up is on.
If there is a lever, then down is on. heheheh.[/quote]

Right you are AC. I've got a cable to mine and choke level on bars and got backwards on it.

Bob
 
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