And the 640 sags continues....

[windaddiction]

So driving to work today on the bike. It stalls at the stop sign so I roll down to a flat spot and try to start it.... no luck . Battery drains insantly fast, so i try to kick it no luck. I leave it on the road and walk to work. On my way home my buddy trys to jump it off his truck. It starts runs for about 10 seconds then white and black smoke come from under the seat. It dies. I curse and push the bike 3 km up hile back to my house. Any ideas guys? I have a feeling I may have burned through a wire and shorted it out

 

[old trials guy]

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Did you recently service your air filter? Could it have been a backfire into the air box? I see a number of folks having problems with over oiled air filters causing all sorts of rich running conditions.

First thing I always do is check the spark plug to determine:

1) is there spark? If there is no spark replace the plug first and then check the cap.

2) is there any gas on the plug (is it getting fuel in the cylinder)?

3) what colour are the deposits on the plug? Normal running on a four stroke can be anywhere from a light grey to a tan colour. Black sooty appearance is a sign of rich mixture. Tiny silver beads on a light greyplug can indicate too leanmixture causing detonation.

Use a magnifying glass and flashlight to really see down into the base of the insulator to help identify plug deposits.

It is almost always spark or gas. If you have spark then check your fuel delivery system. Remove the air filter to make sure it is not the problem. If you havespark and fueldo a compression test and make sure it has sufficient compression (I doubt this is the problem but worthwhile checking if you have fuel and spark to the cylinder).



Good luck ....old trials guy

 

[windaddiction]

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I have spark. and re checked valve clearences. Could not see any damaged wires. It cranks fine but wont start. I'm going to have to go into the fel system next I guess~

 

[joker650]

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Hows the oil level?

Hows the coolant level?

Any compression?

Funny noises?

Muffler plugged?

Is the regulator mounted in that area of the smoke? Maybe remove it and see if there is any damage on the back side of it. That could have been the cause of the batterie dying fast....due to lack of charging.

 

[Island Hopper]

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Hi Dave, I would still recommend doing a thorough tracing wires and looking for short circuits....

- Check the wires going into the rectifier {next to the battery}
- pop the CDI out of its rubber retainer{under right side panel}, remove its plug in and inspect the shielding on the wires running into that plug.....
-Check all the wires under the dash mainly the ones on the outside of the clusters as they seem to be the ones that rub through....
-The wires running inside the keyswitch sometimes come loose from their soldered terminals and cause erratic faults...
-The ignition system on these bike must have good battery voltage running to it for the bike to run....It will not run without a battery and may not if some voltage is bled off to a short.....

Other things:
-Check the inside bottom of your airbox for oil as the engine will vent oil into the box if oil is overfilled or as a sign of internal damage...

- Check to see if your overflow hose out of the bottom of the carb is leaking gas...This shows when your float needle and seat have quit doing their job and is allowing to much fuel in the float bowl causing a very rich condition....

 

[windaddiction]

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Well Check more stuff

oil good
Valves good
exhuast is flowing when cranking
the plug has spark
fuel is making it to the float bowl
but it will not fire, there is also no smell of gas from the exhaust eaither....

*sigh and to top it off when I was doing the valves i drop the feller gage inside the valve cover..... so I had to take that off to get it back out! YAy


on a side note I had to work on my ford today so not much got done on the bike

 

[windaddiction]

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Pulled the carb it looks good I cranked it before I took it off and teh intake is getting fuel..... * sigh back to electrical????

 

[Mud-Ectomy]

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Just my 2c worth, if the smoke you described was from an electrical fault you should have smelt a distinctive burning electrical odor.

Did you smell anything?

 

[windaddiction]

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no.... I didn't smell it just saw it. I have the wiring diagram and i'm going to go through it step by step.... also Bearhugger said maybe the fuel pump isn't working and without that pressure the fuel may not be getting to the bike properly....

BTW thank for all the ideas guys!!!

 

[old trials guy]

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Do you hear the fuel pump when you turn on the ignition? Mine always runs for a few seconds to build pressure.

If it doesn't run check the connector, fuse and relay.

otg

 

[windaddiction]

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fuel pump is vaccum opperated

 

[old trials guy]

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Did you try the raw gas in the cylinder trick?

otg

 

[windaddiction]

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FIXED.... well tiem for test run.... I had the carb apart cleaned it checked the vaccum pump and well ti fired up woot!

 

[windaddiction]

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Test run done


Bike runs like never before... Idles like shit. I think I need to adjest the mixture screw????? anyone know which way to turn it to make idle better?

 

[Island Hopper]

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Have you got an extended mixture screw or do you have to use an angle screwdriver?

I would start at 2.25 turns out from closed and open in 1/8 turn increments if you have to use a screwdriver.... If you have the extended screw just turn it in or out till the best idle and a clean throttle snap is felt.... The screw doesn't have much effect past 3 turns out and should stall the engine when fully closed {unless your pilot jet isn't right}