Topic: I could use some help, the other problem

[wookie]

Hey Guys, first post hoping you can help.  Here is some background.
I have spent the last two years building a cafe out of a 73 cb750.  My teething process has been long and painful thus far.  I am not new to restorations (cars and bikes) and for the most part consider myself amply qualified to wrench.  I will do everything except tear into an engine.   That being said i have reached a level of frustration here and am close to putting the bike away for awhile.

Here is what i have done to the bike:
836 with dynoman cam
29mm cr smoothebores
Dyna ignition and coils
New wiring harness
everything is new or rebuilt.




When i first got it together it started to smoke almost right away and was pissing oil out of #2.  Tore it down and found the head gasket went.  My mech wouldn't warranty it and i ate it.  Rebuilt it and put a mild cam on the second go around.

Managed to get 66 miles on it but was having charging issues which made it difficult to set up properly.  So i replaced the reg/rec with a solid state unit and replaced the stator and field coil with a couple that were closer to factory spec resistance.

Yesterday, after swapping the stator, washing the bike and letting it sit for a couple hours i was ready to go for a test ride.  It fired right away and ran for two minutes before sputtering, a couple backfires and stalling.  Haven't been able to fire it again.  It's not even trying to fire.

I have checked spark on all four, ample
Fuel in the tank, the filter and bowls.
No obstructions between the pods and carbs
Turns over freely but i get nothing.

Help, I'm all ears.....

Jame

[vern401]

I would pull off a couple of the pods and spray some carb cleaner or WD 40 in them to see if it starts using an outside fuel sorce

[wookie]

Vern401,
 just tried some wd, nothing.

Has anyone ever encountered a cam chain skipping?  I also tried the range of retarding and advancing the ignition but nothing either.

[KRONUS0100]

good use of newer model fuel tank.  running points or electronic ignition?  if you have spark......you also need fuel and air.  did you check spark thru the plugs...or just the screwdriver in the boot?  I have had a couple of plugs themselves fail. Check em with an ohmmeter just like everything else....low resistance good....hi resistance is bad.  Does the choke work..possible too much fuel and it flooded.

[vern401]

OK check the compression.
pull off your timming cover and the valve adjustment covers for CYL #1
Bring the #1 cylendar to top dead center. the 1-4 mark on the timming should be clost to the timming mark "F" The rocker arms should have some free play in them.

[wookie]

So i stripped the tank off, checked compression, checked all leads, cleaned the plugs and tweaked the timing a bit.   It's alive!

 I don't think it was one thing, but quite possibly a combination.  The plugs were likely the greatest cause being wet.  Never thought.....

thanks guys,

JJ

[Duke McDukiedook]

Did you power wash it?

[wookie]

No no, just a little water from the hose and a wash mitt.

Plugs wet from fuel, not water

[Stev-o]

I never use a hose on my bike, water can be a bad thing.

Great lookin' bike, glad you got it running.

[wookie]

So now that it's running again, back to the original problem i'm dealing with.

I have a non charging bike.
Wiring harness is new and everything else works.
I have replaced the reg/rec with a solid state unit from rmstator
Battery is new and it holds a charge from a trickle charger
I replaced the stator (soldered the connections) and field coil, used but within factory spec.

I am running out of things to replace here.

Has anyone had to replace the rotor? Can it be tested? 

Even though the stator and field coil have the right resistance, it puts out nowhere near the amount of voltage required.

ideas?

[Duke McDukiedook]

Are you sure that battery is OK?

[wookie]

I am not 100%, but my thought is if it takes a charge from a trickle charger and reaches 13.25v  then why wouldn't it take a charge from the alternator?  The batt is three months old and it was activated when purchased

[vames]

There are a lot of posts that go into trouble shooting charging, but a few things come to mind:

Do you have a multi-meter?

Are you checking whether it's charging at 3K+ RPM? Charging on a lot of these bikes won't kick in till they're reved a bit.

It's pretty easy to isolate what's wrong with a multi meter and an hour to spare -- do a search or check your manual and find out how. Just replacing parts without testing them could turn out costly for you and may not fix the problem.

[andy750]

I just went through the same non-charging issue as well and have new harness, new reg, new recitifier and had replaced the battery....it was showing 13.8 at 3000 rpm with a  multi-meter but...would not hold charge after riding...so replaced it and test rode it Sunday with a 120 mile ride and no problems...I had also tested the alternator by removing the white connector plug and testing the resistance across the connections and they were all good. Worth trying but most likely its your battery...

Good looking bike and I like your tank! How did you get it to fit?
cheers
Andy

[wookie]

Thanks for the compliment Andy,  At last someone who shares my pain.  I have a multimeter and have done a multitude of tests, hence the part replacing.  I could throw down for a new batt but i'd like to be sure it's nfg.  More testing i guess.

As for the tank,



It involved a lot of cutting, grinding, brazing, welding, filling, sanding and painting.  I do like it tho, it really matched the cowl.

I cut most of the factory mounting points off except for the front frame mounts.  I then brazed some threaded pieces that aligned with the airbox mounting tabs.  I had to ease some of the pinch welds to clear the carbs too.

[wookie]

Fixed!!!

This way too long saga is over.  Turns out the white wire from the stator had corroded inside the plug.   
Simple as that, cut the plug off and temp crimped some spade ends. 

Thanks for all the input

JJ