Do I need to get a valves ajusted on my bike?

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Frank_Fullman

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2 years a go I did a engine rebuild on my 2015 Honda cb300f, do you guys know if when you get a engine rebuild done they put new valves to? I’m trying to figure out if I need to get my valves inspected because I’m at 27000 km but I only got my rebuild at 19000 km.
 
"Rebuild"??

Why was it rebuilt?

Was that the crankshaft-replacement recall? If it was, that "rebuild" would have only involved precisely what Honda told them to do, and not one turn of a wrench more. Certainly it would not have included replacing valves ... not even checking them.

If the "rebuild" was something other than the crankshaft-replacement recall which was specific to a certain range of bikes with that 300cc single cylinder engine, then you tell us what the scope of that rebuild was, because at least you have a fighting chance of accessing paperwork showing what was done. The rest of us, have no idea.
 
I did the recall I’m convinst that’s why I ended up need to do a rebuild. Basicly my bike was consuming more oil then normal end I ended up with low oil in the engine and my piston got burnt. So I ended up geting a engine rebuild
 
Would you not have a detailed invoice or service report from the dealer outlining what was done on the bike at 19k km 2 years ago? I don't think fixing a "burnt piston" means the valves were changed, but if they were, you'd see them on the invoice.

Your manual says the service interval for valve clearance inspection is 26,000 km, so if they have never been touched then they are due now.
 
Compression test, is fast and easy with nothing except a sparkplug needing to be removed.
if there is a problem with either the piston and rings or valves it will very likely show on the compression test as a reduced pressure.
(record the compression test results in your owner manual for future reference)

When somebody says they inspected the valves, it will likely refer to the valve clearance tolerance, which imho is virtually impossible to check the valve clearance, without actually adjusting them on a Honda motor fitted with screw type adjusters.
Reasoning: the valve clearance is expressed as a plus or minus ~1 thou tolerance & nobody can fit the correct sized feeler gauge into a space that is under spec. You have to adjust the valve clearance to know it is within +_ spec and a simple visual inspection isn't going to do that.

Sooner or later it will need the valve clearances set. If it becomes hard to start that is one possible indication and the compression test is another.
 
Trials said:
Compression test, is fast and easy with nothing except a sparkplug needing to be removed.
if there is a problem with either the piston and rings or valves it will very likely show on the compression test as a reduced pressure.
(record the compression test results in your owner manual for future reference)

When somebody says they inspected the valves, it will likely refer to the valve clearance tolerance, which imho is virtually impossible to check the valve clearance, without actually adjusting them on a Honda motor fitted with screw type adjusters.
Reasoning: the valve clearance is expressed as a plus or minus ~1 thou tolerance & nobody can fit the correct sized feeler gauge into a space that is under spec. You have to adjust the valve clearance to know it is within +_ spec and a simple visual inspection isn't going to do that.

Sooner or later it will need the valve clearances set. If it becomes hard to start that is one possible indication and the compression test is another.
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CB300 has shim type valve adjustment. Best take it to a shop if you aren't fairly mechanically inclined.
 
TK4 said:
CB300 has shim type valve adjustment. Best take it to a shop if you aren't fairly mechanically inclined.
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Yep, that complicates a bush fix. To start with you need a selection of appropriate valve shims.

... he could still do a compression test if he can get access to a tester, that is a no brainer test.

Nobody is born mechanically inclined, mechanics is a developed skill ;) you are either inclined to try and learn, or not.
 
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Compression test will only reveal a tight valve after it's too late. Checking is not a hard job, adjusting is quite a bit more because the camshafts have to come out.
 
Also, doing a compression test on that bike requires gaining access to the top of the engine, at which point you might as well just take the valve cover off (easy) and do it right. Biggest part of the job is getting to the top of the engine.
 
Brian P said:
Compression test will only reveal a tight valve after it's too late. Checking is not a hard job, adjusting is quite a bit more because the camshafts have to come out.
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+1

By the time you seeing reduced compression you'd have a burnt valve and this guy has already had a damaged piston due to low oil levels in his engine.

Checking valve clearances is simple, but gaining access is time consuming. If you actually have to change a shim you going to need a shim kit and the skill/experience to pull cams, change shims and then reassemble properly to ensure timing not screwed up.

Based on how the OP describes his issue I'm assuming he has minimal mechanical experience and he should just take the bike to a qualified shop to get this work done.
 
Have 2 Honda singles here that needed only a valve adjustment very recently after they became impossible to start,
compression test is what led me to suspect the valve clearance adjustment, they are not burnt.
Welcome to test ride if you like, if you are into riding something that has no seat (y)

Adjusters are indeed screw type, very little disassembly is required with that type, only removal of the valve adjuster covers. ymmv.
Same as my Honda generator that needed a valve clearance adjustment last year.

Twin cams with shims are easier in some respects to service and harder in others,
the biggest obstical being you need parts instead of a wrench to do the job.

We can assume the original lack of oil problem is history, seeing as he put miles on the bike after that service.
+ don't imply a compression test is a waste of time to a noobie, that would be doing them a great disfavour.
 
Over time valve's pounding action gradually drives the valve seat back into the head and can shorten the valve stem by a few thousandths of an inch. For proper operation there is a gap (clearance) between the valve and the rocker or camshaft, this needs to be 'in spec' for performance and wear reasons - operating outside the spec accelerates wear and can impact performance.

If the the rebuild was on your own motor AND they did not overhaul the cylinder head you should have clearances checked now, you cannot tell if the dealer did this when reassembling the motor.

If the engine was swapped out for a factory rebuild, you would get a motor that was in spec, basically as new so the valve check would be needed once the new motor hits the inspection mileage.
 
Brian P said:
Also, doing a compression test on that bike requires gaining access to the top of the engine, at which point you might as well just take the valve cover off (easy) and do it right. Biggest part of the job is getting to the top of the engine.
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Compression tester bungs into the spark plug hole.

... and no Mike, the clearance is to deal with expansion from heat. That's why it is so much greater on the exhaust valves then on the intake valves.
 
Trials said:
Compression tester bungs into the spark plug hole.

... and no Mike, the clearance is to deal with expansion from heat. That's why it is so much greater on the exhaust valves then on the intake valves.
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I think we are both right. I'm speaking about wear -- how valve clearance get out of spec, you're talking why they need to be in spec. Running out of spec will interfere with valve cooling -- they expand more and wear faster, even burn.
 
boyoboy said:
Yup, a valve clearance check and adjustment should be carried out on your bike.

The 2015 CBR 300 had a major problem that req'd a recall to fix the crankshaft.
The problem is a lot of metal shavings were typical - and the shavings went anywhere the oil went. Honda only repaired the crank on recall, not the whole engine. Sorry to be the bearer of bad news, but the 2015 cbr300 (engine) is a lemon. Later years were OK.

I would look for a used 2016 or later cbr 300 engine from a wrecked bike if my 2015 needed a rebuild. Heads up for any 2015 owner.
On a cbr300 forum there was talk of a class action lawsuit but I don't know if that was ever carried forward.
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Best Honda engine ever, roller rockers, roller bearing shaft, auto decompressor on the cam that is about the size of your fingernail,
great performance, easy to work on, no silly anti-vibration stuff, PGM-Fi fuel injected, no batteries required. (y)
:cool: ease of starting is in part because the valve springs and cam action help spin over the motor ;)

rollerrockers-1.jpg
 
His: ... is indeed far more complex to service.
honda-cbr300r-review-specs-cbr-engine-motorcycle-sport-bike-cbr300-cbr250-3_mini.jpg
 
Trials said:
Compression tester bungs into the spark plug hole.
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Yes ... and getting to that spark plug hole involves removing all the same stuff around it on the bike that you have to remove in order to get the valve cover off. THAT is the time consuming bit.

Single cylinder engines are not immune to being a pain in the tail. The KTM 390 series is way worse than the Honda is.
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