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Sudden hard start and hesitation? Burnt valve?

1780 Views 43 Replies 7 Participants Last post by  SoakedKarma
Bought the bike with left (drivers side) cylinder disconnected from head, no air filter. Started up and ran great, drove it 32 miles home (I know that's not good).

Replaced exhaust collar, gasket, and air filter runs great.

Replaced starter clutch (Chinese junk), ran like garbage, put old starter clutch back in (but with new Chinese internals), runs great, but now occasionally makes a "barking" or "honking goose" noise on start up.

Right side exhaust came loose while riding, drive it about 10 miles home. Looked like some oil was bubbling and boiling out of the valve cover gasket. Fixed exhaust, went to bed.

Today: Put some "engine restorer" in the oil, starts rough and stalls when given gas. Rev it to get it moving in first, runs okayish. Still runs rough.

What happened? It used to run 100% flawlessly!

Burnt valves from loose exhaust?
Engine restorer messed something up?
Something went wrong with starter clutch installation?

Help me out fellas

EDIT: Just went for 30 min ride. Seemed better. Still a little hesitating and sounded like backfiring? Liveable, but could be better
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If it contains the same friction modifiers that some automotive oils have, I doubt the fiber plates can be saved if the clutch has begun to slip in higher gears.
If the plates got soaked with friction modifiers, the clutch will slip in less than 1,000 miles. That middle metal piece looks familiar, but can't recall where it goes, or if it even belongs on a CMX. Maybe a PO's kids dropped that junk in there?
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I just use 10W/40, but I really think that actual motorcycle oil may perform slightly better.
In the only comparison test I'm aware of, motorcycle specific oils didn't perform as well as automotive oils. More money, less performance, but big bucks for the seller. :eek::dunno:
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But I thought I got into this whole mess because regular oil has friction modifiers?
All XXW-30 automotive oils in North America contain friction modifiers. As mentioned above, currently, 10W-40 and 15W-40 automotive oils do not. All motorcycle specific oils are safe in wet clutches and do not contain friction modifiers, but they typically cost 3-4X as much as the 40 weight oils.
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The STP is the first 10W-40 I'm aware of that contains friction modifiers. Castrol 10W-40 and Shell Rotella 15W-40 are the oils most forum members use. Those oils have been widely used for years with no problems.

Emil, if I mix up a batch of my custom motorcycle oil, and bring it to the Ohio rally, would you be interested in buying some? I'll sell it for 3/4 of whatever you are paying for motorcycle specific oil. Disregard that it is in sealed Rotella jugs. Just let me know how much you want so I can plan ahead. I can probably cover the fuel costs for my trip with the proceeds. :D
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Castrol 10W-40 and Shell Rotella 15W-40 are the oils most forum members use. Those oils have been widely used for years with no problems.
Forum member Buickguy put over 100,000 miles on his '87 CMX250 using Castrol, and never had an engine issue, including the clutch.
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