running like crap - 2000-3000 RPM - a bit stumped and not sure where to go

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Schwany , while you running a different set up than I , and it did take a couple whiles for me to get there , you have described pretty much what I have experienced these last several years .... I’m running a Boyer mk4 , 34VM Mikuni with a pod , Denso plugs , almost exact way I would give my results if someone asked , the idle and pottering through town no fun anyway .....
 
RoadScholar said:
Joe, any updates? A lot of good ideas; any progress?

Best.
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agree, lots of good ideas. went through most suggestions, nothing yet. either i'm overlooking something, or something else is at play. as were speaking, the postman dropped off the mosfet R/R from Greg Marsh. i've been busy on the Spitfire project, and haven't spent much time on the norton. - hopefully tonight, i can get back on the commando. my friend called, said the plater called and his parts are ready, so tomorrow, were heading south to pick up both our batches of parts, so most of the day will be shot. there's only so many things that can go wrong here - it's probably looking me in the face, and i'm just not seeing it. bike week starts friday - hope it's back on the road soon. was looking to hook up with a few of you folks at nortonar, but it's cancelled this year. maybe next year.
 
You'll catch the gremlin Joe. The bike is too fine to just sit there.
 
Hi Joe, sorry if this has been previously covered in earlier posts.
Have you run The engine in your problem Rev range and held your hand over the exhausts to see if the problem is both or just a single cylinder?
I‘m asking because I had a similar problem that had me going in circles like a headless chicken. In the end I had to start at the beginning again and eliminate the possibilities one by one. My impression is that you have not eliminated the carbs as the problem.
Have you fitted new Amal premiers recently.
My bike was also running very rough in the 2-3000 range after fitting new Amal’s. I refitted my old carbs and the problem went away. I sent the new carbs back to Amal and one of them had a leaking blanking plug.

This was causing extra air to be sucked in, causing the backfires, popping etc.
Obviously, this may not be your issue but I wish someone had suggested it to me before I had changed my Boyer, coils and loads of wiring. Having fitted new carbs I just did not think they could be the problem.
Anyway, good luck and I look forward to hearing how you get on.
 
SteveC said:
Obviously, this may not be your issue but I wish someone had suggested it to me before I had changed my Boyer, coils and loads of wiring. Having fitted new carbs I just did not think they could be the problem.
Anyway, good luck and I look forward to hearing how you get on.
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Without having a very expensive differential pulse counter to test the ignition on marginal dirty fouled plugs vs screaming hot clean plugs, IMO this will be an endless mission of fools. The best clean plugs and skilled seat of the pants operator is possibly the only option to finally decide if ignition or carbs. The second option is as suggested, NEW carbs.
I'm out of here!
 
SteveC said:
Hi Joe, sorry if this has been previously covered in earlier posts.
Have you run The engine in your problem Rev range and held your hand over the exhausts to see if the problem is both or just a single cylinder?
I‘m asking because I had a similar problem that had me going in circles like a headless chicken. In the end I had to start at the beginning again and eliminate the possibilities one by one. My impression is that you have not eliminated the carbs as the problem.
Have you fitted new Amal premiers recently.
My bike was also running very rough in the 2-3000 range after fitting new Amal’s. I refitted my old carbs and the problem went away. I sent the new carbs back to Amal and one of them had a leaking blanking plug.

This was causing extra air to be sucked in, causing the backfires, popping etc.
Obviously, this may not be your issue but I wish someone had suggested it to me before I had changed my Boyer, coils and loads of wiring. Having fitted new carbs I just did not think they could be the problem.
Anyway, good luck and I look forward to hearing how you get on.
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not counting out the carbs 100%. carbs are (upgraded) originals. been experiencing this problem for several months and it's getting "progressively" worse - hot, cold, first start - problem is 100% of the time. picking up chrome parts today - TOMORROW WILL BE A NORTON DAY.
 
joe czech said:
not counting out the carbs 100%. carbs are (upgraded) originals. been experiencing this problem for several months and it's getting "progressively" worse - hot, cold, first start - problem is 100% of the time. picking up chrome parts today - TOMORROW WILL BE A NORTON DAY.
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Two different experience with leaking blanking plugs. Years ago A customers 850 was missing the aluminum blanking plug in the mouth of the carb that blanks off the idle fuel passage , It was only here for a tune up, but as I was reworking the carbs I saw the plug was missing.

More recently this year I finally got around to finishing up a Basket case Combat, when I was flushing the pilot circuit one of the plugs in the carb mouth was squirting fluid by it, It was in the hole firmly, as I had to drill it out , but leaking. I had not run the bike much, as I had just rebuilt it,, but when I went over the carbs, I found it. Pilot/ idle jets and passages are hard to clean out and they can re plug easily even after you clean them so they flow, The Combat's problem was always there from new and it must have caused a lot of rough running that no one ever solved. But I done it and it idles great and runs strong. Easy as pie, if you use your eyes and you get lucky sometimes.
 
well, just spent hours going through the entire electrical system. installed a fresh set of plugs, checked both coils, both HT leads, every stinkin' electrical connection - "bumper to bumper." installed the new tri-spark MOSFET r/r assembly. NOTHING' - STILL RUNNING LIKE CRAP! i've got a new tri-spark ignition system that i bought for my BSA project - might swap it out to see if there's an issue with the e-ignition unit itself. i'm also going to dump the gas - been buying non-ethanol from one certain place. it's a long shot, but may try fresh gas from a different source. if all that fails, it's got to be in the carbs. got a couple rebuild kits in my parts stash - might as well go for a fresh rebuild.
 
Sounds like staving for fuel in one of your carbs, do the old way tune pull off right spark plug lead and tune left carb while running on one cylinder and if good change and do the other side, it will soon tell you if its a carb playing up or what cylinder is giving you trouble, the old ways are sometimes the best ways to finding a problem.

Ashley
 
joe czech said:
not counting out the carbs 100%. carbs are (upgraded) originals. been experiencing this problem for several months and it's getting "progressively" worse - hot, cold, first start - problem is 100% of the time. picking up chrome parts today - TOMORROW WILL BE A NORTON DAY.
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Well, how'd you do?
PM me, I forgot where you are. We're in Silver Springs this week.
 
joe czech said:
well, just spent hours going through the entire electrical system. installed a fresh set of plugs, checked both coils, both HT leads, every stinkin' electrical connection - "bumper to bumper." installed the new tri-spark MOSFET r/r assembly. NOTHING' - STILL RUNNING LIKE CRAP! i've got a new tri-spark ignition system that i bought for my BSA project - might swap it out to see if there's an issue with the e-ignition unit itself. i'm also going to dump the gas - been buying non-ethanol from one certain place. it's a long shot, but may try fresh gas from a different source. if all that fails, it's got to be in the carbs. got a couple rebuild kits in my parts stash - might as well go for a fresh rebuild.
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Your kill switch clean/intact? My gave me fits for the longest time. Just askin'.
 
Gotta admit the blanking plug issue is something I've never heard of, but that's why this forum exists! Maybe a smear of fuel tank epoxy in that area would eliminate/prevent this particular gremlin
 
You need a larger gauge shotgun! ;)

Again, an electrical problem that only manifests itself at some mid-range RPM is a very unusual occurrence. In fact, I can't think of how that could happen unless it is related to a poor connection/vibration but per your last post, you checked all the connections.

OTOH, I suppose it could be the e-ignition itself - some fault internally that is causing the problem. Not sure what sort of fault could cause that but there are various components/chips in there that could fail in some odd way that mortals do not understand and produce who-knows-what kind of symptoms! :eek: So I guess swapping the E-ignition with another one would be worth trying.

It might have been covered, if so, I apologize - does the misfire occur while in neutral at the RPM range in question or only under load (riding the bike)?
 
MexicoMike said:
Again, an electrical problem that only manifests itself at some mid-range RPM is a very unusual occurrence. In fact, I can't think of how that could happen unless it is related to a poor connection/vibration but per your last post, you checked all the connections.

OTOH, I suppose it could be the e-ignition itself - some fault internally that is causing the problem. Not sure what sort of fault could cause that but there are various components/chips in there that could fail in some odd way that mortals do not understand and produce who-knows-what kind of symptoms! :eek: So I guess swapping the E-ignition with another one would be worth trying.

It might have been covered, if so, I apologize - does the misfire occur while in neutral at the RPM range in question or only under load (riding the bike)?
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Fresh 74 850 rebuild with Tri-Spark ignition, new POD-1P-HP (Taiwan made), Tri-Spark noise suppressor, pair of OEM Lucas 6-volt coils. Bike would start and idle fine but not run properly over 1800 RPM - missing, back firing, etc. Went about crazy and finally tried a different pair of OEM Lucas coils. That problem was solved but then at about 3500 rpm it would miss badly and not go over 4000 rpm. Disconnected the PODtronics and everything was fine. Replaced the PODtronics with an old one - same model but much older, bike ran fine. Put in a Tri-Spark MOSFET and removed the noise suppressor in the process and the bike ran fine. Tried the first set of coils again and the first problem returned so put the second set in and it's running fine today.

I don't know about other e-ignitions but using a current production PODtronics POD-1P-HP with Tri-Spark does not work. I've heard but have not seen it for myself that the same is true of a current production PODtronics 3-phase regulator (POD-3P).
 
acadian said:
Gotta admit the blanking plug issue is something I've never heard of, but that's why this forum exists! Maybe a smear of fuel tank epoxy in that area would eliminate/prevent this particular gremlin
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Wonder if over use of air compressor pressure to blow out jets can lead to this issue?
 
Never heard of this being a problem with Amals. Rochester Quadrajets? Well that's a different issue. There are (as I recall) nine Q-jet casting plugs that leaked as new. JB Weld was the answer for every Q-jet rebuild..or a Holley. :)
 
Tornado said:
Wonder if over use of air compressor pressure to blow out jets can lead to this issue?
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Re using glue;
If using this method, I advise you carefully heat the plug first with a soldering iron prior to putting two pack epoxy , so it will flow into every orfice. . . .
 
What is the gasoline/ethanol rating from brand X epoxy?

"LOCTITE® 290 is a liquid medium/high-strength threadlocker designed for the locking and sealing of threaded fasteners. Because of its low viscosity and capillary action, the product wicks between engaged threads and eliminates the need for disassembly prior to application. The product cures when confined in the absence of air between close-fitting metal surfaces and prevents loosening and leakage due to shock and vibration. The product can also fill porosities in welds, castings and powdered metal parts."

90% strength gasoline
80% strength ethanol
 
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