Topic: simple diagnosis?

[HonderCB]

Should start off by saying im a relative newb as far as motorcycle mechanics...

On my way home from a vintage bike night tonight, had put approximately 65 miles on the bike there and back (almost home) when all of a sudden it starts sputtering and popping.

My first thought is fuel is low, so i reach down and flip it to reserve on the fly.  Doesnt fix it.  I keep it pegged cause it acts like it will die if i dont.  I limp in to town and as i come down off the throttle taking a turn and it seems to come back to life, until i get the rpms up then its back to sputtering.  I try slowing back down and it doesnt help, its sputtering all across the full rpm range.  I get all the way through town popping and sputtering and as i slow down pulling up to my friends garage it dies and wont start.

Spark?  I pull out plug number 1, it looks ok.  I put it back in the cap and hold it to the block as i hit the starter.  I have spark.  I put it back in, and for sihts and gigs i hit the starter... it fires up.  It seems fine idling there, so i take it around the block, but it does the same thing again after i get down the street.  I limp it back, dies in the driveway, wont start again.

Bad fuel?  I pull the tank off and drain the gas out, walk a block to the gas station and buy some fresh fuel (not the same gas station i had bought previous fuel from).  Pour it in, hit the button, starts up, but doesnt sound right, i dont even get out of the driveway this time.

Only thing i guess it could be now is fuel delivery in the carbs.  i got tired of messing with it for the night and got a ride home.  I'll go back tomorrow with a fresh mind.  I guess i'll start by pulling the bowls off the carbs and cleaning the jets, anything after that and i will be lost.

Anybody else have any ideas or similar experiences to share so i know anything else i might check?  I really was having a pretty good night until this, bike was running great and saw a lot of neat bikes.  Oh the joys of riding a 35 yr old bike lol.

Thanks in advance for any input

[scottly]

How much gas did you drain out? How much did you put back in? Did you switch from reserve back to the on position? Please post pictures of all 4 spark-plugs before tearing into your carbs.

[HonderCB]

couple gallons, couple gallons, yes, and i will definately look at them all before i do anything else

[scottly]

Stock ignition?

[HonderCB]

yes, as far as i know

[scottly]

And the electric starter works fine all the time?

[HonderCB]

it seems to, i kinda wore the battery down though while attempting to start it to the point it wouldnt crank.  5 mins on the battery tender and it had enough juice to crank though, it will be on the tender all night.  I always start with the electric started and havent had a prob in the year i have owned the bike

[scottly]

Post a pic of the plugs, and we'll go from there. Your problem sounds like it's a bit intermittent, which makes me suspect ignition?

[HonderCB]

i wondered about that too.  the fact that it started back up after cooling down and nothing else changing made me suspicous of the electronics, but the way it ran had me thinking fuel.  The more i think about it, ignition makes more sense.  I'm glad i came on here instead of messing with it tonight.  Hopefully i have some time to mess with it tomorrow, definately some time this week though.  Thanks for the help scottly.  Have a good evening.

[CB750F2]

I have had similar trouble. I was able to trace the trouble to the "new" Daichi points that I had recently fitted. There was a loose rivit on one set which caused a high resistance and so acted like a very dirty set of points. The result was I was intermittently running on two cylinders. I suggest that you check your points for this condition. Disconnect the blue and yellow wires from the points and check the resistance across the points when they are closed. You should measure close to zero ohms. You will need a digital multimeter to do this. Pat

[dave500]

if you think it has stock ignition as far as you kinow and youve had this bike for a year i think its about time you removed the points cover and find out?

[phil71]

undervolt from weak charging can cause this too.. sitting will help the battery recover a little, but before long, you'll be back in the same boat.

[HonderCB]

if you think it has stock ignition as far as you kinow and youve had this bike for a year i think its about time you removed the points cover and find out?

Thanks for smart-a$$ comment, but it isnt needed here, try another thread, maybe someone else will like being treated like an idiot while trying to get help and learn something, i dont.  I know what kind of ignition my bike has, i just dont know if the points are stock or aftermarket, now for those who are actually trying to help, heres whats happened so far....

First i drained and flushed the tank.  There was some debris/ rust flakes in there, but the filter was clean.  The flakes most likely came from the underside of the gas cap, as the tank has been sealed with caswell kit.  (putting cleaning underside of lid on my to do list.) 

I pulled the plugs, i didnt get a pic, but they looked like the bike was running a bit rich, but they werent too bad, cleaned them and put them back... didnt help

Pulled off points cover and checked gaps, they were off, but not much.  reset them to .014 plus or minus a thousandth... didnt help

Re-timed ignition using timing strobe... didnt help

Replaced both coils with spares... didnt help

Replaced all 4 spark plugs... didnt help

Pulled the carbs (twice actually).  Jets were dirty, and turns out were oversized (110 instead of 105).  Must be because PO had pods on when i bought the bike, but i switched to stock box.  This also explains why the bike was running rich i suppose.  Cleaned the carbs, put in 105 mains, set screws to 1.75 turns out per the manual as a starting point.  Cant get the things tuned because the bike still wont idle steady or long enough.

Bike is still running rough and fluctuating RPMS at idle, but it does start and run now, so i guess i am getting somewhere cause it would hardly do that before, it just doesnt want to run well.  plus i am getting pretty good at pulling and re-installing my carbs (push-pull cables are a pain to get on) quickly.

The only thing i am still weary about is the points.  How much spark am i supposed to be seeing between the contack points when they are open?  1-4 is sparking quite a bit, whereas 2-3 is sparking hardly at all.  I still have spark at the plugs, but it seems wrong for them to not be sparking equally.  Do i need to replace and start again from there?

Total cost so far... $11 bux for 4 D8EA plugs, and a crap load of frustration burning my hands tring to adjust the carbs... seriously... who put the adjusters on the bottom?!  Not to mention the PO had a serious over-tightening problem, thank god for impact drivers.

[HonderCB]

oh yea, all the things i did werent necessarily in that order, thats just the order i remembered them in lol.

[NewOldSchool]

Sparking between the points?

I'm willing to bet everything that you sir have a bad condenser or two.

Had the exact same symptoms and replaced my condensers and BOOM perfect. Replace/adjust the points as well while you're at it.

[HonderCB]

yea, i knew one or the other had to be wrong, i just didnt know which was correct, i will replace the condenser on the sparking set of points tomorrow and see what happens, i have a garage full of parts bikes to rob from at my father-in-law's guess i picked a good wife, her dad likes the same kind of bikes i do

[CB750F2]

Yes check your conensors and spark plug caps and do the check that I suggested in my first post. The spark plug caps should have either a 5k or 10k ohm resistor in them. Remove them and check with a multimeter on the ohms scale, While you have the caps off check the ends of the ignition wires for corrosion. You may need to trim back the cables to get rid of the corrosion. You may need the help of a friend if you don't have a multimeter or don't know how to use one. Pat

[NewOldSchool]

yea, i knew one or the other had to be wrong, i just didnt know which was correct, i will replace the condenser on the sparking set of points tomorrow and see what happens, i have a garage full of parts bikes to rob from at my father-in-law's guess i picked a good wife, her dad likes the same kind of bikes i do

Awesome!

Good luck brotha, report back, I'm curious.

[scottly]

What do the new plugs look like?

[HonderCB]

still clean, havent run the engine enough yet to get any sort of color on them, i just put them in today.  They did help the bike run better though, but i wasnt able to run it much.

[dave500]

Thanks for smart-a$$ comment, but it isnt needed here, try another thread, maybe someone else will like being treated like an idiot while trying to get help and learn something, i dont.  I know what kind of ignition my bike has, i just dont know if the points are stock or aftermarket, now for those who are actually trying to help, heres whats happened so far....

no sweat,at least we know it has points now,heaps of these bikes have had conversions of some sort over the years and will need different types of advice depending on what type or brand it has,like itll have different ohm coils and the way its wired etc,i wasnt being smart HonderCB.

[Retro Rocket]

Thanks for smart-a$$ comment, but it isnt needed here, try another thread, maybe someone else will like being treated like an idiot while trying to get help and learn something, i dont.  I know what kind of ignition my bike has, i just dont know if the points are stock or aftermarket, now for those who are actually trying to help, heres whats happened so far....

What an ass of an answer from someone that was asking for help...  The answer was common sense, maybe you should look at that as well...

[HonderCB]

haha RR, if your not here to help then you have no business.  kindly stay away.

As for dave, i'm sorry.  the way your post was worded it seemed like a smart aleck comment.  i appologize and hopefully no hard feelings.

[dave500]

no sweat.

[HonderCB]

just got back from workin on the bike at my in-laws.

when i got there my father-in-law had swapped out the points for a set off a donor bike, and it was running better, but still not good... still rough.  I noticed it was still sparking pretty good on the 1-4 points, so i pulled the condenser off and swapped it for another and viola!  the bike ran smoothly.  I got the strobe out and re-checked the timing... still good.  I did some tuning of the carbs, ran the bike a bit, pulled the plugs and they looked nice and light greyish-tan.  Plug 1 had just a tad oil on it, the valves probably need adjusted... but as i mentioned previously, the PO had a SERIOUS over-tightning problem and i cant get all of the tappet covers off.  guess i will have to try a chisel and hammer, otherwise cut them out, but its good enough to last the rest of this season, i'm just happy it runs now.  I'm planning to pull the head this winter anyway.

Final verdict... mostly the condenser, but i think there was a big chain reaction of little things, because everything i cleaned/adjusted/replaced helped the bike to run just a little better every time.  Thanks all for the help.

[lucky]

if you think it has stock ignition as far as you kinow and youve had this bike for a year i think its about time you removed the points cover and find out?

Thanks for smart-a$$ comment, but it isnt needed here, try another thread, maybe someone else will like being treated like an idiot while trying to get help and learn something, i dont.  I know what kind of ignition my bike has, i just dont know if the points are stock or aftermarket, now for those who are actually trying to help, heres whats happened so far....

First i drained and flushed the tank.  There was some debris/ rust flakes in there, but the filter was clean.  The flakes most likely came from the underside of the gas cap, as the tank has been sealed with caswell kit.  (putting cleaning underside of lid on my to do list.) 

I pulled the plugs, i didnt get a pic, but they looked like the bike was running a bit rich, but they werent too bad, cleaned them and put them back... didnt help

Pulled off points cover and checked gaps, they were off, but not much.  reset them to .014 plus or minus a thousandth... didnt help

Re-timed ignition using timing strobe... didnt help

Replaced both coils with spares... didnt help

Replaced all 4 spark plugs... didnt help

Pulled the carbs (twice actually).  Jets were dirty, and turns out were oversized (110 instead of 105).  Must be because PO had pods on when i bought the bike, but i switched to stock box.  This also explains why the bike was running rich i suppose.  Cleaned the carbs, put in 105 mains, set screws to 1.75 turns out per the manual as a starting point.  Cant get the things tuned because the bike still wont idle steady or long enough.

Bike is still running rough and fluctuating RPMS at idle, but it does start and run now, so i guess i am getting somewhere cause it would hardly do that before, it just doesnt want to run well.  plus i am getting pretty good at pulling and re-installing my carbs (push-pull cables are a pain to get on) quickly.

The only thing i am still weary about is the points.  How much spark am i supposed to be seeing between the contack points when they are open?  1-4 is sparking quite a bit, whereas 2-3 is sparking hardly at all.  I still have spark at the plugs, but it seems wrong for them to not be sparking equally.  Do i need to replace and start again from there?

Total cost so far... $11 bux for 4 D8EA plugs, and a crap load of frustration burning my hands tring to adjust the carbs... seriously... who put the adjusters on the bottom?!  Not to mention the PO had a serious over-tightening problem, thank god for impact drivers.

I do not feel like that comment was a smart ass comment. He stated the facts.
He is asking you a question.

QUOTE: "as far as you kinow and youve had this bike for a year i think its about time you removed the points cover and find out?"

I believe the comment was honest and that you do need to find out some of the info on the bike since you are asking forum members for their opinion.

Some mechanics would not be that nice. They would just say, "When you find out what you have, then comeback and we can help you.?


About the points....
Quote:

"The only thing i am still weary about is the points.  How much spark am i supposed to be seeing between the contack points when they are open?  1-4 is sparking quite a bit, whereas 2-3 is sparking hardly at all.  I still have spark at the plugs, but it seems wrong for them to not be sparking equally.  Do i need to replace and start again from there??

What matters with the points is that they are not burned with a mound on one contact face and a hole on the other contact face. The gap must be correct and they must start to open at the correct time. They must have the minimum amount of dwell.
They are not like spark plugs.
The job of the points is NOT to produce spark. The function of the points is to open and release the field of energy to the spark plugs at the right time.

[HonderCB]

this misunderstanding is over lucky, thanks for your concern, though.

[lucky]

this misunderstanding is over lucky, thanks for your concern, though.

Yes... on the internet misunderstandings can occur.
A therapist told me one time that if a person does not want to hear a complaint,
that they have no courage and you do not want to hang out with them.

[HonderCB]

your therapist sounds smart.

[Retro Rocket]

haha RR, if your not here to help then you have no business.  kindly stay away.

I was helping my mate Dave, who just happens to be one of the more knowledgeable guys around here ....  Public forum dude..

[HonderCB]

haha RR, if your not here to help then you have no business.  kindly stay away.

I was helping my mate Dave, who just happens to be one of the more knowledgeable guys around here ....  Public forum dude..

Your right, he is, as are you.  However, Dave didnt need your help.  We had a misunderstanding, i appologized for it, its over, we are fine now.  Thats how mature adults handle things when they have problems.

[HonderCB]

What matters with the points is that they are not burned with a mound on one contact face and a hole on the other contact face. The gap must be correct and they must start to open at the correct time. They must have the minimum amount of dwell.
They are not like spark plugs.
The job of the points is NOT to produce spark. The function of the points is to open and release the field of energy to the spark plugs at the right time.

Thanks Lucky, this is a great description.

[Retro Rocket]

[/quote]

  Thats how mature adults handle things when they have problems.
[/quote]

Good to see it sorted, that approach above would have helped at the start = no sh1t fight....

[USCG_C130]

Honder-

i just went through this exact same issue and was curious about the big sparks between my points, one set has alot of spark and the other didnt.  this confirmed what i was looking for. but i, like you, did everything before i looked at the condensers, so i replaced one which i found bad and still the same issue, after 2 days of trouble shooting turns out they both were bad and now tomorrow i will be buying another and hoping to get it back on the road and entered in a small local bike show on the 2nd.
 
but i did fuel and timing and all new plugs plus several other things before i replaced my condensers and what a PINA it has been, but thatnks for this write up it gave me a little insight, i wont be making this mistake again ill be sure to have an extra set of condensers laying around.

[HonderCB]

Glad my pain was able to help you out!

Rather than keeping around extra condensers I ended up swapping out the points system for a DynaS electronic ignition the following winter.  It works great, was simple to install, and I don't have to worry about about it.  Lack of quality OEM points parts was a contributing factor as well.  Seems like every set I found were the cheap Chinese ones that were notorious for having problems, so I spent $110-ish dollars on Ebay to buy the DynaS and haven't looked back.