Topic: cb350f plugs fouling

[ripamarcone]

Hi. just chasing some possible cause for my plugs fouling.
some info firstly.. originally had head gasket leak. while having head off had the rings replaced. found the head to have slight warping so it was machined to rectify the problem. on bike returning back to me i found that plugs 2 and 3 were fouling. carbs had been rebuilt and taken off and put back together when found that there was no problem with them.. thought it might have been an electrical issue,(plugs 2& 3 running from same coil) possibly coils or even just some tear in the loom somewhere. Have had all wiring replaced, coils replaced, regulator /rectifier replaced etc. Hondaman ignition in place. ( also checked original coils and they were fine)
on picking up the bike from the electrician i noticed a huge amount of smoke blowing out the rear end and the breather. got home and checked to find oil was extremely low. topped up the oil seemed to stop the  smoking... but still not explaining why so low on oil. plugs 2 & 3 still fouling. did notice today that on riding home that the bike was blowing smoke on hard acceleration and the bike was probably fouling up again..
my thoughts are that the rings are shot... would i be on the right track or is it possible that something else could be causing this issue

any thoughts would be appreciated

[calj737]

Could be rings, could be valve seals. Have you done a compression check or a leak down test? You don't indicate how it's running (bogging, stumbling, flat spots) so there's not much info to go on there.

It does sound like you've thrown money at problems without diagnosing the actual problem. Why were the rings replaced when head was off? Were the bores honed afterward? Did the pistons need actual replacement? Lots of info missing, lots of work done.

Does the exhaust blow smoke constantly, only when hot, or only under acceleration? A shot of the plugs? Are only 2/3 fouled and is it dry or wet fouling?

[ripamarcone]

No compression check or leak down done as yet, was all done originally and all was good.about 600 km ago
Under acceleration the bike runs really well, for a 350. If im coasting and go to open the throttle there is a slight bogging, also on down gearing the throttle bogs through all the gears.
i replaced the wiring etc  due to this being an everyday rider.. the wiring when i got it was burning when you went to start and I got it together to a point where i could ride it , but not being sure what the previous owner did, it was easier to replace than to try to repair. rings replaced more for a freshen up than anything else and yes bores were honed.
Smoke blows only under acceleration and the bogging occurs more and worse when the engine is hot. I have an oily residue on the end of the pipes. the plugs seem to be slightly oily but not as bad as I have seen in the past on other bikes. Only plug 2 & 3 are fouling. 1 and 4 are looking good

[calj737]

If it were me, I'd run a compression test and then follow that with a leak down test. I suspect a valve train issue from your description unless the rings were damaged upon install.

Oily residue in my opinion rules out electrical and indicates seals or rings

[ripamarcone]

thanks....i assumed it was... just needed another opinion