engine is turning off and I dont know why

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homin

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Hey guys it's me again homin. I don't know why but my bike is turning off on me. I was wondering if it was the temperature that was turning my bike off. It was 45 degrees when I was riding. But while I was riding it, it was fine but when I slow down to first gear, the engine would shut off. Any help would be appreciated. Thanks
 
From what I can tell you it seems to me either your bike isn't charging and keeping the battery charged enough to keep it running or your running out of fuel.Is the battery weak when you try to restart?
Have you gone through your carbs to clean them?
 
The carbs been thoroughly cleaned a year and a half ago. It might be my batteries giving up on me because my horns don't work when it's on highbeam and my neutral brightness changes when I give it some throttle.
 
What the symtoms you are having it seems like an electrical issue to me,either your bikes altenator isn't charging your battery or like you said,your battery is weak and not holding charge.When the voltage from the battry gets low your power to the engines runs out.I would do some diagnostic test on the bikes altnenator and voltage regulator.Theres lots of wiring diagrams on the site and nice colorful one in my thread ignition problem.Good luck.
 
unhook the battery for safety. Test the 3 white wires from the alternator to each other for resistance on the lowest setting on your volt meter. in any combination you should get 0.72 ohms or within 10% of this give or take. also test them with body ground and they should read infinite (no connection to ground). If you are a bit off these calculations short the two meter leads to each other as most meters add some resistance of their own and this must be subtracted from your test reading. Mine adds 0.4 ohm so at 1.1 ohm on the white leads im still within spec. with the battery positive unhooked you can test your voltage regulator I believe green to brown should read 4.0 ohm + resistance added by your voltage reg is accurate also they should read infinite when touched to ground if im not an idiot (haven't figured that out yet but avoided Darwinism so far). Not sure if it applies to all model voltage regulators but testing the black wire to the black base should show 10.2 ohm resistance (plus your meter) as well, although I cant get that one to pan out myself... and the solid state rr38 shares ground and there is no black wire for vr connector clip. With the battery hooked up and set to 12v dc you should be able to see the 12v with black connector to ground and red connector to either green or brown wire on the voltage regulator. Although I would think to check one side for AC voltage which the regulator does ...convert AC to DC so your bike can be thunderstruck!

If you have power then its likely not your rectifier but someone else can tell you how to test that if needed. But the issue is likely battery, voltage reg, or the witing to the stator/field coil.... now when you cross that bridge come to the other side and help me finish my bike too!
 
It might be you have the idle set too low. Try it set about 1200 to 1300 rpms. This will help prevent some stalling and will help keep the battery charged.
Leo
 
still getting issues after riding around 15 mins. when i rev my engine, it stays on but sometime when i don't it would just turn off when I'm slowing down. going to research this situation and ill get back to you guys.
 
XSLeo said:
It might be you have the idle set too low. Try it set about 1200 to 1300 rpms. This will help prevent some stalling and will help keep the battery charged.
Leo
Click to expand...

sorry leo, I'm new to the motorcycle world and i don't know how to set the idle setting. ill be looking in to it though. thanks for your time
 
Buy a new battery and retest. If it's better after charging but still giving you problems I'm sure a cell or two is dead. I don't think the bikes charging system has enough power to keep a bad battery running for a long time but I could be wrong.
 
Its a piece of cake, should be the same on your bike, cause I can't tell what you have. Under the carb, is a knob with a spring. twist it one way, idle goes faster. twist it the other way, and the idle slows down. That is your idle control. Its the only one there.
Tobie
 
arfstrom said:
Its a piece of cake, should be the same on your bike, cause I can't tell what you have. Under the carb, is a knob with a spring. twist it one way, idle goes faster. twist it the other way, and the idle slows down. That is your idle control. Its the only one there.
Tobie
Click to expand...

I have a 1978 xs400. thanks for the help, ill do it after i get out of class.
 
It could be your battery is weak as well as it not charging well. Recharge your battery. Now hook your meter to the battery, Start the bike while watching the meter. The voltage will drop a lot while using the e-start. Down to around 8 or 9 volts. Once running it should read around 12 to 13 volts at idle, now rev it up to around 2500 rpms The voltage should rise up to 14 to 14.5 or so. Thus means your charging system is fine.
If the voltage when cranking the e-start drops below the 8 or 9 volts, charge it and take it to a place that sells batteries for a load test. This will confirm if the battery is ok.
Leo
 
The battery acid level, when you take the battery out you will see little "plugs" on the top of the battery, unless you have a maintenance free battery then it will be just flat like a car battery.
 

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