Hi it's my first bike and 1st thread here, and i've been going through it for the past 9 months restoring it to a daily rider after it sat for 3 years. at this point i'm pretty ok with how it rides, and while it has some inconsistencies, it's getting me to and from work every day, a short commute generally at under 50mph.
the issue i have happens above that speed-- if i get up to highway speeds for any sustained amount of time, when i come back to idle at a light or whatever, the bike has started smoking from the tailpipe. i've researched other threads about smoke, and this isn't condensation, and it's not black smoke that would suggest running rich. it's not excessive, but i notice it, since the bike doesn't smoke at all under moderate use at lower speeds. i'm guessing from what i've read that it's oil smoke (mostly white, but it's more on the gray side than black, maybe bluish, and smells like a lawnmower.) because it happens after the bike warms up i'm thinking it's a piston ring issue, moreso than valve guides. it doesn't smoke at start, even if i leave it on the side stand. if anyone can confirm that i'm probably looking at a piston ring problem, that would be great. it seems intermittent-- sometimes it's barely noticeable, other times it acts up more, but the common factor seems to be really getting the bike warmed up at higher speed.
in addition, i sometimes experience a power loss after i run the bike above 50mph in 5th gear for anything other than a very brief amount of time-- e.g. if i get on the highway and get up to 70, i sometimes experience what almost feels like a sagging/stuttering, like if i were running into a heavy intermittent headwind; a couple times this has happened, when i pull off at an exit, i need to give increasing throttle to keep the bike from stalling, and downshifting to a stop causes the bike to die. i think that this has been a fuel/petcock/carburetion issue, but wanted to know if that symptom could be connected to the smoke issue.
over the weekend i rode it 40 miles at highway speeds round trip, and monitored the smoke and power situation. it only takes a little bit, 5-10 minutes, of running in 5th gear at rpms higher than 4k, to bring out the tailpipe smoke. the annoying thing is that up until that first time i come to idle, the bike feels fantastic-- pulls strong through the gears, has plenty to give in 5th, and will keep accelerating above 80mph with no complaints. but if i sustain it like that for just a few minutes, it starts to feel boggy or lugged at times, and when i stop, the smoke is noticeable. today i took it out on the road just long enough to get the smoke started, and returned home at lower speeds for 10 miles. by the time i got home the smoke was still there, but pretty negligible.
if i do have a piston ring problem, is there anything i can do to help this, short of rebuilding the top end? how can i tell if the bike is safe to ride for the time being?
also, could my fuel economy and power issues be related to the smoking problem? or do they suggest issues with carb settings, jetting, petcock crud, or etc?
thanks for any help, and thanks for this great site. it's been a huge help in getting the bike running.
here is everything i know about the bike and what i've done to it so far:
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mostly stock engine aside from the 4-1 exhaust installed by PO. has baffle, he thinks MAC, i don't know.
stock airbox with foam air filter
carbs are 022a
i've thoroughly cleaned carbs and that includes emulsion tubes, replacing jets with same sizes as were installed (38 pilot jets and 100 mains), float bowls, vents, and everything i could reach. used carb cleaner, compressed air, and verified all holes, vents, and passages were clear with compressed air, small guitar string, and holding all jets, tubes, air screws, etc to a light (i.e. i checked by both sight and feel that passages were clear and clean.)
needle clip in position #3 (middle.) initially was in #4 (2 from the bottom) and i was rapidly carbon fouling spark plugs, so i moved the clips to 3 to try to lean out-- someone suggested i might have this backwards? i'm assuming the closer the clip is to the bottom of the needle, the higher it will raise when throttle is opened, and the more fuel will flow as a result.
set floats to 22mm using float gauge.
again, 38 slow/pilot jets and 100 mains in the carbs now
new battery, cleaned all electrical terminals, and bike charges correctly and holds charge
PO installed Dyna S ignition
set ignition timing both statically and double checked with timing light
adjusted valves at first to manual specs, then went back and loosened tolerance to .003 and .004 per hondaman specs
changed oil and filter (20-50 motorcycle oil)
synced carbs with morgan carb tune after other adjustments (again, done this a couple times, after tweaks and things.) vacuum is around 22, all 4.
checked compression with harbor freight compression tester. a little on the low side (about 115) but consistent between all 4 cylinders.
checked for good spark and replaced 4x spark plugs with NGKD7, gapped per manual
adjusted drive chain tension
adjusted cam chain tension
spark plugs look "good" but i haven't done a plug chop at the speeds that are giving me problems.
bike kick starts easily and idles at 1000rpm. it creeps up as it warms up, but then i just back the idle screw down.
i haven't replaced or oiled the air filter but had a couple biker friends look at it and was told it looks fine.
air mixture screws at 3/4 turn out currently. the bike actually runs fine with the screws completely closed. at stock 1.5 turns out, the throttle is sluggish and sags when blipped/snapped.
bike is either very high or very low miles: has been continuously registered in oregon since at least the late 70s, and odometer reads 05051. So either it was a barely ridden summer toy, or it's got 100k+ on it. doesn't seem excessively worn, or abused, but i don't know much else about it.
