The misfire mystery continues ho hum

Well after getting a new bike(Honda Crosstourer) the silverwing has been a bit neglected, so my last post a few months ago I complained about a misfire/hesitastion at a steady motorway speed 70 ish and random backfire off throttle, I took on the suggestions put forward and have replaced these parts,
so obvious ones first
sparkplugs
airfilter
plug leads and coil
fuel regulator
vacuum pipes
After waiting a age for the fuel regulator to arrive I took the bike out straight on to the motorway for it's first run and it seemed to of  sorted itself but I went out last week week and after 30 miles of county lane riding I hit the motorway and the misfire or hesitation appeared again ,So I got a bit annoyed and wound the throttle fully open and gunned it and the bike was jerking and spluttering  though it managed 90mph.
drop below 70 the bike runs fine. starts first push of the button and is smooth as silk.

So back home and out with the muli meter and tested the rectifier and the stator and all checked out within spec so now I'm getting a bit stumped. could it be the tps sensopr or map sensor ?seems like the problem is more prevelent after the bike is warm,I don't know wether to get a set of second hand throttle bodies with injectors and see if that does it..
any ideas would be much appreciated
the bike is a 2005 A3 model

Coil/spark plug wires/spark plugs/fuel/old bike

Bad fuel. Dunno if it has been mentioned before, but you might try adding an additive to the fuel tank to deal with moisture.

https://www.silverwing600.com/t11795-techron-redex-redline-seafoam?highlight=Redline

Next bet would be to have the throttle bodies balanced.

Runs normally at lower speeds? No hesitation? Not a misfire would do it most of the time if were an ignition problem. Honda PGMFI adds a bit more fuel when cold then leans it out at normal temps. usually when they start to misfire. At 30 miles it ran fine until more load and speed? TPMS usual problems moving throttle. MAP sensor maybe but same as TPMS large throttle changes or a vacuum leak. I'd bet on fuel weak fuel pump, filter very dirty. Surge fuel pressure . Stumbles misfire. No O/2 sensor on that bike but sometimes they cause similar issues.

Thanks for the replies ,Yes the bike runs fine until holding a steady throttle at around 70mph ,so do you reckon it's more of a fuel.problem than a electrical issue ?although I haven't checked the tps sensor or maf sensor yet but it looks like you need a honda tool to do it according to the manual ,there must be a work.around some how ,just seems.strange it's in and around that speed everytime it plays up.

check spark plug caps for fit.

Not a misfire would do it most of the time if were an ignition problem. <<>> maybe maybe not, not on my S'Wing but another vehicle a loose plug wire would go to ground over 50 mph and caused a misfire, under that it ran fine. What John said is worth the try, even a cracked fitting MAY do it.

He replaced coil and plug leads already and a few other parts. I don' know if they were used or new.
Honda's going to misfire hot engine when they lean out extra fuel when cold makes it easier not to .

Mech 1 twa wrote:

He replaced coil and plug leads already and a few other parts.  I don' know if they were used or new.
Honda's going to misfire hot engine when they lean out extra fuel when cold makes it easier not to .

Hondas form of speed control Maybe? it's why I never experience it with my 05, not as efficient as the latter models?

Yes Mech 1 twa   new fuel regulator,spark plugs vacuum pipes and air filter,apart from replacment coils off another wing but tested and in good order  the misfire/stutter happens at exactly the same speed  70mph on a steady throttle after all the above replacements ,thats why i'm thinking it must be a sensor or fuel ?
looks like this isn't a common occurance, searching for misfire not much comes up

Is it the same tank of fuel? I'm sorta with Tim ... old/going bad gas. Could be old or could be a lesser quality perhaps? If it's the same tankful, run it down/out and refill with Tier 1, non-ethanol gas (if it's available near you). I'd be curious how it responds to fresh fuel.

A fuel flow test might provide some good information. I would disconnect the fuel return hose from the pressure regulator(it is the one toward the front of the bike) and attach another proper size hose long enough to reach the floor and a small container. Turn the ignition on for 10 seconds and you should collect a minimum of 4.5 imperial ounces of fuel.

Whenever I am faced with a strange or intermittent problem with an older bike I think that is a good time to disconnect all connectors that I can reasonably get to and then force some dielectric grease into the female sides. Then I connect and disconnect several times. Most connectors on the Silver Wing are under the left side cover and the top of the engine.

Yes I think that sounds like a plan, I'll do the connectors too cheers 1wingman1 for the reply

Check/Clean ground wires at frame ground in that LH cover area also. Don't use sandpaper, polish with brass brush or green Scotch Brite, clean with alcohol, personally not a fan of dielectric grease on frame grounds, but light coat is ok.

Well I have think I have found my problem , it's seems pointing to the fuel pump .... manual says minimum 0.188cm or 6.4us oz or 6.6 imp it's about half that after a couple of tries so fingers crossed this is the problem , thanks for all the advice off here , fuel pump here I come

Best of luck pulling that tank. Under the best of circumstances it’s a PITA.

There are several topics posted here regarding removing the tank. Just use the Search function to locate those discussions. On a more positive note, a member here recently posted that he was able to jam a duct tape roll under the panel (near the gas fill) which allowed him the access to remove that top tank mount nut without removing the entire front end.

Cheers for the tip cosmic jumper..being honest I'm just looking forward to having the bike back to normal so I'll be suffering with a smile