[MechaTomato]

Hey everyone, I'm a complete noob when it comes to bikes, but I've recieved a 1974 cb450 that I'm trying to get running again.

The first thing I did was check the engine oil, because I don't want to be kicking on the bike testing compression without oil.

However I don't know how to read the dipstick, here's a pic of it after I wiped it off, stuck it back in (without screwing back in) and pulling back out.



It seems that there's only a bit of oil on the very bottom part.

I just want to make sure that I did it right, even though I followed the manual's instructions.

And if it is too low, what should I do? Drain the oil and replace it (if so, what oil should I buy?), or should I just add oil to it?

The manual also says to only drain the oil when the engine is warm, but that wont be happening. Bike doesn't run.

Lastly (sorry for so many questions) will having no oil vs having oil affect a cold compression test?

 

[80cb400t]

Just drain the oil and replace it unless you know it's less than a year old, cb450s do not like dirty old oil. Any old Honda with a centrifugal oil pump will punish you for not changing the oil often enough. The way the cb450 oil passages are makes it extra important to have good clean oil (and even then let it idle for a minute without revving after starting). Don't worry about draining hot, the oil will drain slower and possibly less completely when cold but that's not too big of a problem. Once you get it running it might be a good idea to change it after a couple hundred miles because of the contamination that builds up over time in a sitting engine

Someone else will tell you the type of oil they run in their cb450. I'm pretty sure the oil is supposed to be between the two notches on the dipstick and you want it as close to the top as possible but wait for someone else to confirm. You checked with the bike upright(not on kickstand)? I would add oil if I saw that level when checking hot.

Amount of oil shouldn't have much impact on a compression test (unless you spin it too long with no oil in it and you'd damage things other than compression), the only way oil can change compression is if you put a couple drops into the spark plug holes to check your rings are okay.

More important is that the throttle is wide open and to know that stone cold compression will be lower than hot.

 

[ancientdad]

^^^+1 on changing the oil. The upper of the two marks on the stick is the full mark, you should keep it there. The 450 engine is happy even if it's a little overfull, as long as it doesn't exceed the top of the flattened area on the stick. as above, check it on the centerstand (bike level) and set the dipstick in the opening, don't screw it in. The engine is small enough that cold or hot won't make much difference, the oil returns to the bottom end pretty quickly. 80cb400t is absolutely correct when he says to warm the 450 up at a low rev for at least a minute - I'd give it 2 minutes to be safe - to get oil flow to the top end. The DOHC 450 does not puddle oil under the cam and followers (equivalent to rocker arms) and relies on oil flow up the 2 right hand studs in the engine to fill the camshafts and cam bearing caps and then oil gets to the followers out of orifices in the cam lobes to keep them lubed, so there are a lot of parts to get full oil flow to before putting the engine under any load or you can do some serious damage to the lobes and followers if you treat it like a car and fire it up and go.