Exhaust Chirping and Misfire

Sounds to me that the chirping has disappeared because you re-adjusted the 2 carb idle screws putting side pressure on the slides in their lowest setting/ seating area. I'll bet they are worn out.

Torontonian said:

Sounds to me that the chirping has disappeared because you re-adjusted the 2 carb idle screws putting side pressure on the slides in their lowest setting/ seating area. I'll bet they are worn out.

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Slides are newly installed anodized types as for Wassell and Premier Amals. But I guess the bores could be worn.
Chirping gone after swapping to fresh plugs as well as resetting idle and air screws. May be I had one side way out of adjustment when I was previously unable to dial it out.

Well then simply remove the air filter and rubbers and reach in with your finger(s) and try to wiggle the slides. Wiggly would mean worn bodies.

Would guess bores are worn ...

Replaced the petrol cap secondary seal today original was not in spec:



Used bit of 3/8" diameter fuel line hose which fit the cap center riser about the same looseness as original. Cut it to 13-14 mm which is a few mm longer than original. Tapped a 10-32 thread into body of rivet still swaged into the riser hole and fit a screw with a bit of loctite blue for security

After fitting back to tank, latch seems more positive with out much ability to press cap down further than latching point unlike before. Gave the nearly full tank a slosh side to side few times. No evidence of gas reaching a dry rag wrapped around cap area.

Road testing to come.

40+ yr old rubbers will do that...

Test ride today. Fuel leak completely resolved. So nice to be able to fill that new tank!
Now the misfire has gotten significantly worse today. Very notable by 4k esp when pulling up hill. Thought maybe fuel starve from taps or filters but opening both taps made no difference. Got some resistor plugs coming so will see if that helps. Had tried a compression check but the forty plus year old gauge I recently bought of craigslist had a failed seal so couldn't get a reliable measure.
Is it a good idea to try one of those spark checkers with variable gap to see how strong the spark is?

Worse going uphill... Had that happen once and it turned out to be a clogged air filter. Ham-can paper filter was saturated with oil from overfilling.

I would run a compression check or better yet, a leakdown test to see what's happening at the cylinder-to-head joint if it's still weeping oil.

I’m in the dark as to why R-plugs might/could help eliminate the chirping , thanks for any info !

Craig said:

I’m in the dark as to why R-plugs might/could help eliminate the chirping , thanks for any info !

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Not trying to solve chirping anymore....seems to have been cured after more thorough tweaking of carbs. I found I could cause it to chirp one side or the other by going too rich on air screws.

Have heard the electromagnetic interference from "noisey" high voltage spark systems can induce current in electronic iginitions giving erratic firing triggers. I'm running the Vape-Wassell EI which is supposedly the same as Boyer MKIII (which I believe is ok without resistor plugs or leads or caps). It's normally the digital EI's that are concerned with excessive noise. But will try these NGK resistor plugs to see.
I did the tug on the stator plate trigger leads going in to the timing case while at idle but could not detect and effect on rpm. Need to take tank off and go through all the connections again.

maylar said:

Worse going uphill... Had that happen once and it turned out to be a clogged air filter. Ham-can paper filter was saturated with oil from overfilling.

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Interesting. I'm running a K&N filter at the moment. I will check if it's plugged a bit too much....yes my head front is still seeping and that oil ultimately migrates back and flies aft ending up on the side covers, fuel/oil lines and air filter plate and likely into filter somewhat. And I'm not immune to slightly overfillng my oil tank....

Tornado said:

Interesting. I'm running a K&N filter at the moment. I will check if it's plugged a bit too much....yes my head front is still seeping and that oil ultimately migrates back and flies aft ending up on the side covers, fuel/oil lines and air filter plate and likely into filter somewhat. And I'm not immune to slightly overfillng my oil tank....

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Conventional wisdom is that a K&N flows more air than stock replacements, but usually in modern bikes, those are oiled-foam.

Spent the day working on the bike. Had tank off to access the EI ground point near coil mount. Gave the metal under the terminals a good scrub with steel brush and added a direct line from that point to the headsteady ground point, in an effort to ensure EI is getting a good ground. Re-fettled the carb slides to get them sync'd as best I could (chopstick method). Had the splitter off and discovered the grip side cable ferrule was jammed into the plastic housing very tightly....I could not pull it free of the plastic will a very strong pull. Should this just be freely sitting in the opening? Maybe somethings the wrong size and it's slid in further than supposed? I managed to get it out but only after dremel cutting the plastic casing around the ferrule area to allow it to open up a bit. The Ferrule was jammed deep into the opening, past the inside shoulder (if that makes sense?). "Repaired" the plastic cut with epoxy and re-drilled to accept ferrule. Will need to order a fresh one I guess.

New NGK 5K Ohm plugs fitted. My EI instructions do recommend 5k Ohm HT resistance but also no resistance should be OK. Checked all EI connections...all good and snug. At idle, wiggled the EI stator wires a fair bit and no idle affects.
Went on a short test ride. Had a few points of misfiring up at 4k+ rpms. Maybe less than last ride but need a proper long up mountain run to confirm and it was hitting rush hour so couldn't make that trip today.

Coulpe of things still need to do. Compression check (need a new gauge), voltage check when revs get high. I'm worried my Zener ain't cutting the mustard and letting volts go above 15.5....the EI instructions state operational range is 9-16 Volts....maybe that triggers misfires? I did put my DigiVOM across the battery terminals and rev'd it up and saw 15-15.5 at higher rpms.

15 volts will cook your battery.

Yup , my battery used to boil if I didn't have headlight on , this was maybe 25 yrs ago , then primary ate itself and replaced stator,rotor , inside cover etc. , at the time installed a mitymax RR and removed the dual zener setup , all good , until original Boyer failed , then went with podtronics RR and Boyer mk4 since then all good , easy start ,steady idle , good performance and nice looking plugs too

Might have finally solved misfire. A test ride yesterday showed it coming hard around 4k rpm. But only when engine loaded while going uphill etc. Could not reproduce it at standstill in neutral revd past 5k.

Did some thread search and found one stating 4k misfire solved after noting fuel leakage at one carb bowl gasket during tickle. he solved by tightening a loose bowl screw. I checked my gaskets and could not rule out a leak and one screw was a bit loose. Decided to go all in and pull carbs and manifolds to redo flange flatting. I never did the manifolds so seemed prudent. When reassembling I discovered one main jet had come loose and was maybe half its full thread length, (maybe 1/4"?) backed out. This must be the cause!

Test riding now.

Thanks for the follow up

So in the limted riding I could get done in rush hour city traffic with the added benefit of a logging trucker protest convoy crawling through the city, I can report bike is much more responsive to thrttole input and absolutely no hint of a cuff/cough/misfire at 4k+ higher...mainly in first and second gear of course. Need to get out onto the highway and up a local montain tomorrow to really ring its neck a bit, but I'm happier than I've been since this thread started some months ago.

I think you the guy who questioned mikuni reliability not long ago .... ah-hum .... glad you got it sorted for now !