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Discussion Starter · #1 ·
Gentlemen,

I have had this CB450 (gently used and in great cosmetic condition with 17800 miles) for 3 years now and the bike starts and runs great. This riding season, I noticed that bike is burning oil - blueish grey smoke can be seen when I start up the bike and while running too I believe. The left exhaust has a lot more smoke than the right. Last night, I replaced the old spark plugs with new spark plugs and started the bike for a few minutes and killed the engine and looked at the spark plugs. Both the plugs are little bit oily and the electrodes are almost black in color (brand new plugs and the bike started up and let it run for 5 - 7 minutes, with 30 - 40 % throttle from idle).

I have another bike - a 2012 Royal Enfield C5 which I am very comfortable working on (mainly because parts are available in plenty and I can always procure parts if I mess up anything) and have been riding this bike a lot more and have put on 2000 miles each riding season (not much by normal standards)

I love the CB450 more than the Royal Enfield C5 and hate to mess up the bike or render it unuseable by opening it up - not knowing how to address the problem unless I have a clear strategy of what to look for and how to get it fixed.

I kindly request the experts to pitch in on what I need to do (or where to start) to figure out and resolve this problem. The CB450 runs decent and I have been riding around Chester County , PA country lanes the last 3 years (though haven't put on more than 300 miles each year)

Should I start by adjusting the points, timing etc (not that there are any signs of an ill tuned engine or carbs ) on the CB450 (or atleast none that I can descern). I have been doing the oil change at the start and end of the riding season and that's about it.
 

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As above plus I'd be specific about the oil consumption. Change the oil then record how many miles it takes to get to the add mark on the dipstick.

Also consider the type of riding you do. Are you an escaping convict or grandma going to get a loaf of bread?
 

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Discussion Starter · #5 ·
As above plus I'd be specific about the oil consumption. Change the oil then record how many miles it takes to get to the add mark on the dipstick.

Also consider the type of riding you do. Are you an escaping convict or grandma going to get a loaf of bread?
Hahaha.. I usually do not punish my bikes. I always ride the posted speed (at least) and may be 15% -20% above the posted speed if the road conditions permit and there are no other vehicles on my tail. It is very common to find beautiful, single lane roads parallel to Route 23, Route 113 and Route 100 which are posted 35 mph and with no other traffic.

I believe the most I must have pushed the CB450 is up to 55mph on small stretches of Route 724. All these roads are in and around Spring City, Phoenixville, Yellow Springs, Downingtown, Kimbertom areas (just to give you a perspective).

Just drained the oil out and measured it. About 200 ml oil less since the start of the riding season i.e 380 miles since the oil change at the end of April, 2017
 

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Discussion Starter · #6 ·
My question is should I worry about addressing the root cause of the engine burning oil asap or given my riding style take it easy and just observe and watch?
 

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Less than spec could be due to where the check valve on the tester is. If it's at the end of a hose by the guage the extra volume will result in a lower reading. maybe the rings are stuck a little, or just worn. I'd ride it harder if it seems to run alright otherwise. Take it up to redline when you get the chance. Maybe put some marvel mystery oil in and try that for a bit.
 

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These engines are made to revv up to 7k rpm and more. You can actually harm it by driving on too low of an rpm for too long.
 

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Just in case anyone should ask, you can say you have a prescription from Honda Twins to do more riding. The oil consumption you report does not seem excessive but does require constant attention which can only be done from the drivers seat.

Report back when you have accumulated sufficient date.
 

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I would not accept those compression numbers as a reason to say the engine was bad. If you want to test it more do a leak down test. Typically, when a high performance engine starts to smoke on start up it is the valve guides and or valve seals. To fix this pull the engine, take the top end off and do a valve job. Since you have the head off you should have it bored too. 46 years and 17,000 miles is a lot for one of these bikes. If it was my bike, based on the smoke, I would do a top end overhaul. Winter is coming and that would be the perfect time to tear it down. All the testing in the world is not going to make it better.
 

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One other thing, how old and what weight is the oil? If you are passed the change date/ miles or the oil is too thin, it is possible oil is getting past the rings. Make sure it is freshly changed with Shell Rotella, Chevron Delo or JASO compliant oil.
 

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Discussion Starter · #13 ·
One other thing, how old and what weight is the oil? If you are passed the change date/ miles or the oil is too thin, it is possible oil is getting past the rings. Make sure it is freshly changed with Shell Rotella, Chevron Delo or JASO compliant oil.
Jim, I did the oil change at the beginning of the riding season -end of April, 2017. I used Valvoline 10w40 motorcycle oil. I believe it is JASO MA and non synthetic. I think I will begin preparing for a top end rebuild.

Have to start figuring out the best strategy to document the dismantling of the motorcycle and bag and tag the parts as they come off the bike. Any proven best practices please let me know.
 

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Final thought from me: make sure your petcock is actually turning off and gas isn't dilluting your oil. Maybe google how to free stuck rings. Sea foam? Idk give er a good run and check compression warm, I think 185psi is spec, but testers vary.
 

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Discussion Starter · #15 ·
Final thought from me: make sure your petcock is actually turning off and gas isn't dilluting your oil. Maybe google how to free stuck rings. Sea foam? Idk give er a good run and check compression warm, I think 185psi is spec, but testers vary.
I got into the habit of turning off the petcock a 1/2 mile before stopping and let the bike run dry at destination. If I decide on using sea foam, should that be mixed with gas? Thanks for your advice Lefty!

Lastly, any Honda twins members in my neck of PA - Spring City (general radius of 50 miles). I am thinking there must be someone who has prior experience with a top end rebuild.
 

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Final thought from me: make sure your petcock is actually turning off and gas isn't dilluting your oil. Maybe google how to free stuck rings. Sea foam? Idk give er a good run and check compression warm, I think 185psi is spec, but testers vary.
My final though, change the oil and run it before you tear it down.
 

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Spray some seafoam into the cylinders and let them sit for a few days to a weekend. That would free up your rings if they are stuck
 
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