Honda-SOHC
SOHC.co.uk Forums => CB500/550 => Topic started by: bigmockuk on December 12, 2017, 08:22:50 PM
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I must be doing something wrong here,dont think so but must be.Allways had 2/3 silencers running cold or misfiring ( they run somtimes) and blaming 40yrs old boyer ignition module so,bought points back plate+new points/condensers and set left set of points to 14 thou when fully open,then set right points the same,turned back plate and using bulb/wires got it to light as 1/4 marks aligned.did same with 2/3 points back plate til marks aligned.bike reluctantly starts but no power and stutters,totally flat sound! and cuts out but would continue to tick over roughif restarted,real rough,no 3 misfiring badly.got freezing cold and tired so ended up moving back plate anti-clockwise fully and engine shot into life so moved no 2/3 back plate and amazing difference but tickover rough.only thing is,timing is well out but it runs with purpose? question is tho....why wont it run after static timing was spot on? static shows completely different from what the strobe says.any ideas as im getting exhausted with this cheers.p.s. i run pods with original pd46a jets and plugs/manifolds are badly sooted black but dry, thanks
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the fact 2-3 run iffy could be ignition,
they use same coil,points etc,
check plug caps,is the resistor ok ?
are you using resisitor plugs,a no no with resistor caps,
a long shot,but when you assembled the ignition cam,did you assemble it 180 out ??
I personally would put the Boyer back on and check coils,leads and caps
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The easiest check first. All CB500/550s are prone to misfires due to (intermittent) arcing between HTleads or caps to the head (= GND). This is best observed at idle in the dark.
Then I'd check the resistance of the plugcaps #2 and #3 and if their connection to the wires is still good. What plugs do you run, with or without "R"?
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The points should start to open at the 1,4 F mark. So if you you have supply from battery through bulb and then through the wire to points, it should be on until it gets to the F mark at which point it should go out.
The points are switching the earth to coils, all the time the points are closed it will be making the circuit live to store energy in the coil, when the earth is removed ( by points opening) it fires the HT voltage to the plugs.
Looks abit backwards at initial viewing, but it works that way.
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If you're running stock jets with PD carbs and pods, it will be running very weak, the PD carbs run lean anyway, and with pods, well! More likely to be a coil on it's way out, or a dirty/loose connection in the wiring to the coils. Check and clean ALL joins in the wiring from the points to the coils, especially the connectors that join the points wires to the main loom, near the back brake light switch, they get incredibly dirty/corroded there. Did you clean the faces of the points to remove any protective oil/grease put on at manufacture before fitting? What pipes are you running? Almost certain this will be an electrical issue though.
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wow thanks for the quick relies guys! right first off,i fitted new ngk cr8es plugs,got new 5ohm caps and cheap 5 ohm coils from ebay,2/3 still acted the same so disconected wires at boyer module and ran original wires up to the coils and fitted a plate with new points/condensers from ebay.i thought if i went back to conventional ignition and it worked this would prove the boyer faulty."john" you mention the ignition cam being 180 out? are you refering to the lobed cam on the advance unit? that could be poss i guess? "deltarider the lugs are "r" i wouldnt have thought that would really have any effect? K2-K6 you say light should be on mine is off then go off? mine is off and comes on when points open,strange."hairygit i know what you mean by running weak but mine is exact opposite tottallysooted up like pure black but im thinking maybe a malfunction in ignition could cause this?.im running 4-4 original pipes and have cleaned faces of the points.if i connect strobe to no1 the light dont flash but will if connected to no 4.it will flash if connected to no2 but not no3 this cant be right surely it should flas with all 4?
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just a thought,is it possible the auto advance unit i bought is from another model? maybe cb500 or that
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Has your bike ever run correctly with the Boyer ignition on it?
I chased a fault for a long time, caused by the Boyer 6v micro coils having been wired in parallel instead of series. This was causing poor starting, erratic tick over and poor performance. Your Boyer system might’ve used the original 12v coils so it might not be this.
Also, my Boyer, didn’t use the advance/ retard weights on the a/r unit, just relied on going to full advance, electronically at 4,500 rpm. Have you refitted the weights to the a/r unit now you’ve gone back to conventional points?
I agree with the others that if the fault is on a pair of cylinders, it’s likely to be electrical. Good luck.
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If you describe how you've connected the light we can see what is supposed to be happening with it.
Which terminals do you connect to? And do you disconnect the lead to coils to setup?
They'll run with whichever advance unit, you can sort it out if wrong after getting it firing reliably.
If the cam is assembled 180 degrees out it'll not usually run until you connect the points to the wrong coil (so reversing the error) or swing the points plate so far it comes in range to make it go.
Another post on here recently showing how to check the above, I'll try and find it.
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just a thought,is it possible the auto advance unit i bought is from another model? maybe cb500 or that
If you had the same poor running fault with the Boyer as you do now, then it’s possible it’s not the points.
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"Jon" yes i had the bike running real good then had battery prob so jumped the bike off the car (switched off) and thought i must have fried something basically so bought new coils and same intermittent fault was there so thought it could be boyer so trying to go with points set up to see if it runs or how it runs.the boyer does not have weights either just centre cam and an annoying plate with 180 magnets that are not aligned to anything so have to guess thru trial/error as to when their lined up."K2-K6" i earthed one lead to engine casing and other to blue or yellow wire on the points with ignition on.there was no real difference from new coils to old coils so might be better with original coils which were not as flimsy.with boyer and using strobe light its impossible to line up the "F" mark it line up with full advance marks,should this be right
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Apologies, I do it with coil leads disconnected, so you should get light on to fire when connected in your way.
If you time it as you are familiar with, then swap the two coil leads so that they go to the wrong colours, then see if it runs. This will tell you if the points cam is the wrong way round as it'll put two errors opposite to each other and cancel out. If successful you can then realign both to make it std.
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Cheers K2-K6 im on my way up to the garage the now with renewed hope,i`ll strip wires and check for breaks/corosion as hairygit was saying,realign timing,if no joy i`ll swap wires on route to the coil and see if it fires up.i also wanna remove no4 plug and use a long screwdriver to determine when piston is at tdc and check timing plate to see if they match up as they should do.i`ll check the color of the spark at each plug too.maybe even worth trying old coils too.i`ll report back later with my findings and once again thanks for all your ongoing help
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if i connect strobe to no1 the light dont flash but will if connected to no 4.it will flash if connected to no2 but not no3 this cant be right surely it should flas with all 4?
If your strobe has an inductive try flipping the pick it over as some are sensitive to polarity..
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Hi just an update,i checked the wiring and all seems ok,i checked the valve clearances and found 3 needing adjusted,no3 inlet had no clearance.instead of using a light for the timing i switched ignition on and slowly cranked until spark at the plug on no4 with plug against the head,both 1/4 2/3 were advanced by around 5 degree and no more room for adjustment so i took a dremmel buff and enlarged the the 3 slots in back plate.bike starts and runs very well except no3 which tends to now backfire as if reigniting unburned fuel in the exhaust but its ticking over and running.still to balance carbs tho so that might help and only set mixture screws at 1.5 turns out so im getting somewhere at last with the points set up! so cheers again for all your help/advice guys.i have one other niggling problem that i`ll put in a new post and see if anyone has any clues
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Did you start with adjusting the breakerpointsgap? The gap usually determines the range. If I set the gap to 0,3 mm I have less range than when set at 0,4 mm. That's why I recommend to set them at 0,4 mm. Also to be on the safe side as overtime pointsgap uses to become smaller anyway. Did you use OEM or aftermarket parts?
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Also when you move the plates the gap usually alters so it takes some fiddling to get both gap and timing correct at same time, gap should be 0.35 or 14 thou (the one that is not in cheap sets)
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"Deltarider" ye i started with points gap,i usually set it with a 14 thou sliding fit but where a 16 could not enter.1/4 points is oem it has 1/4 stamped on it but 2/3 points do not so think they could be aftermerket,i know i had to file a mm off the heel as it was way outside the gap range and opening too early. " Bryan j" i actually didnt take into account the gap might change i took it gap would stay the same.i actually bought these annoying feelers that give both imperial/metric and theres like a hundred you`ll never use lol im old school and prefer single imperial as in thou as opposed to metric.had it running today and it was acceptable apart from no3 backfire.im gonna order plugs without the "r" and see how that goes.also toying with the idea of running a second earth wire straight to engine as original runs to a bracket that mounts to the frame,the same bracket that holds the rear brake switch.peace of mind really.
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Put the Boyer back on. I had it on a previous bike and it was superb. Prob going to get it for my current bike.
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well no3 has acted the same way with new coils,caps,plugs and now points so boyer must have been ok after all? am toying with fitting the electronic ignition plate from DS,anyone tried it?
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See below my number 3 downpipe bend.
Inner pipe was collapsed with no visible indication from outside. Exhaust gas couldn’t get out. Power seriously down and number 3 spark plug constantly sooty.
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I was thinking that yesterday Jon.
Eerily similar to your own experience. That'd be quite something, odds wise, if two of the same turned up!
Worth a check with a look down the pipe to verify.
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wow who would have thought of that happening? could that be seen from the top of the pipe ? am stunned that could happen at all !
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It could be seen from the top of the pipe if you used a flashlight, but just try feeding a stiffish wire down. Couldn’t get anything passed my bend.
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pretty sure mine is clear tho as plenty of compression blowing thru but its certainly one to look out for!
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pretty sure mine is clear tho as plenty of compression blowing thru but its certainly one to look out for!
I thought that. Could feel the exhaust coming out of all four exhaust pipes. Engine ran great on idle and low revs driving through traffic. Open the throttle and it would bog down, struggling as the engine came under load. A check of the plugs would show number 3 had sooted up. Tried everything, carburation, coils, ignition, leads, caps, plugs, compression. Eventually decided to stick a boriscope down the exhaust pipes, from the engine end. Couldn’t get it more than two inches in to number 3 downpipe. Looked down it with a flashlight and saw a blockage. Still didn’t know what was causing the blockage but tried shifting it with a screwdriver and it was solid. Bought a second hand silencer from eBay, fitted it, bike performance transformed.
It’s worth a check for the half hour it would take you to get the right hand side exhausts off, check them and put them back on.
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so it can tick over with pressure still coming out but the harder the engine works the fault can show up,im gonna fit new exhausts gaskets again shortly so will certainly try passing a hose down each one for peace of mind! i take it the exhausts must be double lined and the inner liner has broken thru and warpped under heat? my no3 heats up and runs with choke on but cools down when choke is off then sits there with a slight cough/splutter.must admit tho no2 cools down a little when choke goes off but seems to run fine.1 and 4 stay warm throughout and even running.im sure i`ll get it ironed out if i treat each cylinder independently working thru ignition/fuel systems.these carbs were the worst ive ever seen due the bike being in dry storage for over 25yr,every passageway/jet was heavily blocked and took weeks to clean out,interestingly enough as i write this,the brass pipe on no 3 carb was blowing bubbles of fuel with float height at 14.5 so reset them all at 15.5 and it appeared to cure this.picture below shows pipe end filled with fuel which i understand should be an air passageway into the emulsion tube?