81 cb400t will not start

badluck

badluck

81 CB 400t
ok...here I am again having solved the below issue with the help of the trusty forum here!!! Thanks again gents!

http://www.dotheton.com/forum/index.php?topic=41296.msg452041#msg452041

Now the bike in question will not fire. I removed the plugs and cleaned them off, replaced them and no go. I installed 2 new plugs and still no fire.
Any ideas?

Many thanks in advance
 
Is your battery charged now?
Is the kill switch in the run position?
Do you actually have a spark....remove a plug, connect it to the spark plug wire, crank the engine. Spark?
If no spark, check for 12V to coil. thenlook to the points.
If a spark, check timing anyway.
If all good, the fuel will have to be looked at...

Carbs have fuel in bowl? Petcock turned on?

That should get you started......

Don't laugh at the kill switch and petcock...Even though I have been riding since 1972, I get tripped up now again by that....
 
Is your battery charged now? - yes
Is the kill switch in the run position? yes
Do you actually have a spark....remove a plug, connect it to the spark plug wire, crank the engine. Spark? - no
If no spark, check for 12V to coil. thenlook to the points. - no clue what that means
If a spark, check timing anyway. no clue


need to get a beer.
 
No spark...

I realize the CB400 has CDi ignition, not points.

There is a checkup for the CDi box, but you will need to search for it...I am still old school points.

Check fuses though before going further...
 
OMG I am an idiot... I was not grounding the plug. so yes I have spark!!


Is your battery charged now? Yes
Is the kill switch in the run position? Yes
Do you actually have a spark....remove a plug, connect it to the spark plug wire, crank the engine. Spark? Yes
If all good, the fuel will have to be looked at... added 5L of fuel
Carbs have fuel in bowl? not sure
Petcock turned on? Yes

Is it possible that the "Run" position of the switch is not activating? I could have messed something up when install the bars. Is there any way to check?
 
I have FSM for the 350 and 360, but not the 400. the 400 ignition is a slightly different animal. The point system's kill switch controls 12V to the coils/points. I believe the kill switch on the CDI just grounds the circuit on the cdi side. But don't take my word, get a schematic.

Maybe someone with the same system can chime in here...
 
81 CB/CM400 is electronic ign with no mechanical advance so points check doesn't apply
It's also a self generating system so you can bump start bike with a dead battery (just as well, they removed the kickstart in 80 ;D )
 
Factory manual. Best money you don't have to spend. http://www.mediafire.com/?cnkmdznfjgz

If you are getting a solid spark when the bike cranks, the run switch is in the correct position. That means there are two possible issues remaining; fuel and air. Are the carbs covered is a way that would prevent air from getting in? Do the bowls have fuel in them? You can easily check by cracking open the set screw on the bottom of the bowls (left side if I remember). If you have both fuel and air, try shooting a little starting fluid into the carbs to see if it fires.
 
Factory manual. Best money you don't have to spend. http://www.mediafire.com/?cnkmdznfjgz Thanks for this!!!

If you are getting a solid spark when the bike cranks, the run switch is in the correct position. That means there are two possible issues remaining; fuel and air. Are the carbs covered is a way that would prevent air from getting in? Do the bowls have fuel in them? You can easily check by cracking open the set screw on the bottom of the bowls (left side if I remember). If you have both fuel and air, try shooting a little starting fluid into the carbs to see if it fires. I will check this out tonight after work and let you know how it works out. Thanks for all the knowledge
 
I checked my air intake tonight and found this mess. While cleaning it out the filter crumbled, so a new filter is next. ugh
I cleaned it up and took a vacuum to it, bolted it back down with out the foam filter and still no go.
It seems so close to want to start but just cant.
I have to say I know enough to say that at this moment I dont know about checking the bowls.

Question...should the bike turn over while the kill switch is off?
 

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With the kill switch set to off, the engine will turn over, but there won't be any spark so it won't start up.

Check the bowls by opening the set screws on both bowls with a long flat blade screwdriver. Put a beer can cut in half under them to keep gas off the motor/floor. If gas starts flowing out, you at least have gas in the carbs; if it doesn't you don't have gas.
BowlSetScrews.jpg
 
right on... thought it was much more difficult. Depending on the weather for tomorrow will depend on me trying this. thanks man
 
Well it finally stopped raining here so I had a look at the bowls, (Thanks for the instructional pic, that was perfect) and I had fuel in both. On the weekend I picked up a throttle tube since I broke the current one I have and installed that. With that all tightened down I turned the engine over and it almost started!!!! I pulled the choke and hit it again and what do ya know it roared to life!!!!!!

Thanks so much for all the advice. We are supposed to have good weather the Thanksgiving this weekend (Canadian version) so I will post some photos and probably be back with some wiring advice. Cheers !!!!
 
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