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Discussion Starter #1
Hello all,

I have a 1982 CB450SC. I recently changed the oil on it since the previous owner probably hadn't changed in about 5 years, but I didn't change the filter. I added Castrol 10W40. Now I'm having a few issues that I wasn't having before.

When the bike idles, everything seems to be fine. I'm able to run the bike for a few minutes like normal, shifting gears down the road perfectly fine, but then all of a sudden the bike seems to have trouble getting above 4000RPM and also doesn't want to go faster than 60Km/h.

When I stop the bike, there seems to be a bit of smoke coming from somewhere and when I remove the dipstick there appears to be smoke coming from there too.

Anyone have any suggestions that may be causing this?

Cheers!

Jarrod
 

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Remove the gas cap and see if that solves it. The tank can go into vacuum if the cap bleed hole gets plugged. If that doesn't fix it then I would check the petcock filter inside the tank and also the small screw cap filter at the bottom of the petcock.
Doesn't sound like an engine issue.
 

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Discussion Starter #3
Tried removing the gas cap but unfortunately that didn't fix the issue. How do I get to the petcock filter?


New development: now the bike seems to like to stall out on me while I'm riding it.
 

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Close your petcock (it should always be closed when the bike is shut off anyway).

Disconnect the fuel line at the carburetor and place the end in a suitable container.

Open the petcock. There should be a steady stream of fuel.
 

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Discussion Starter #5
Awesome I'll give that a shot tomorrow when the rain stops.

So I should be closing the petcock every time I'm not running the bike?
 

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Yes, you should close the petcock when not riding. Otherwise you may end up with fuel in your oil.
 

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You may want to smell the dipstick for oil, it's an easy check that gives a lot of peace of mind
To get to the petcock filter you will need to empty the tank at least halfway, then tip to the opposite side of the petcock (on a towel so the paint doesn't get scratched), keeping in mind that the gas cap does not keep gas in even when shut, then undo the nut on the petcock and the filter should come out. If it doesn't it is most likely stuck in the tank and you may be able to get it out with an easy out that matches the inner diameter or a drill bit in reverse (be gentle)
 

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Discussion Starter #9
You may want to smell the dipstick for oil, it's an easy check that gives a lot of peace of mind
I haven’t had a chance to get the petcock out yet, I’ll be doing that after work this afternoon.

As for smelling the dipstick, I gave it a quick sniff this morning and it didn’t really smell of gas, but it didn’t smell like the oil from the jug. I’m assuming right now that’s just from being run a bit through the engine, or is that a horrible assumption?
 

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I think that's pretty reasonable, when it smells like gas it smells like gas. You get a whiff and pretty soon accept that you need to change the oil.
 

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Discussion Starter #11 (Edited)
I think that's pretty reasonable, when it smells like gas it smells like gas. You get a whiff and pretty soon accept that you need to change the oil.
Ok good. I just changed the oil and nothing leads me to believe something is up and I need to change it again.

I drained the tank and removed the petcock but nothing seems out of place there. It seems like the bike loses power as soon as it hits 4000RPM and then stalls. It happened once on a test drive and once while in neutral in my driveway. It's showing same signs that a car I once owned showed the problem there was water in the gas tank. I left some of the gas aside to see if maybe that was the case here but it didn't show signs of anything in the gas other than gas. Could there be an issue with the carbs? Could them maybe need a clean? Could this also be caused by me adding too much/not enough oil? I only added 2L but I'm wondering if the information I was given about oil amount may not have been correct.
 

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Discussion Starter #12 (Edited)
Update on the situation:

Bike still won't rev above 4000RPM. I've tried slowly getting up above 4000, and also gunning the engine and either way it gets to 4000 and that's the end. If I don't throttle down slowly the engine stalls on me. I've done this while in neutral on the centre stand, and while attempting to ride the bike.

I've adjusted/cleaned the spark plugs and they are firing fine.

I've also noticed that the engine seems to be at a lower pitch than it used to be. It wasn't a high pitch whine before, but it definitely seems to be a lower rumble to it.

I'm wondering if there is an issue with the carburetor? Or perhaps an issue with the amount of oil (all this started after I changed the oil)? I've also read that maybe airflow could be an issue, would a dirty air filter cause this?
 

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Did you check the dipstick level with the bike level and the dipstick just sitting on top of the threads? How long was it run after the oil change until it started doing this?
 

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Discussion Starter #14
Did you check the dipstick level with the bike level and the dipstick just sitting on top of the threads? How long was it run after the oil change until it started doing this?
I checked it with the dipstick just sitting there, not screwed in. Level was a bit high so i removed some and levelled it out.

This happened same day. First ride after changing the oil.
 

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Why don't you tell us a bit more about the bike. Are you running with stock airbox and filters or pods? What carbs? Did you rebuild or replace any carb parts at all?
I noted that you said you used Castrol 10W40 for oil. Are you sure you used the right oil? It must be rated for JASO-MA or JASO MA-2 for wet clutches.
 

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Discussion Starter #16
Why don't you tell us a bit more about the bike. Are you running with stock airbox and filters or pods? What carbs? Did you rebuild or replace any carb parts at all?
I noted that you said you used Castrol 10W40 for oil. Are you sure you used the right oil? It must be rated for JASO-MA or JASO MA-2 for wet clutches.
As far as I know everything on the bike is stock. I haven't rebuilt anything on it. The castrol says its for Motorcycle and from what I saw online this was listed as an oil for this bike. It's SAE 10w40. Could this be the entire problem? Did I ruin the bike with this?
 

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Castrol 4T 10-40W oil is fine. Even if you put auto oil in it won't ruin the engine.
You might check the timing. Pop the left cover off and fire up the engine. Timing light should hit on the F mark and when rev'd should advance to towards the 2 l l marks. Full advance hit at 4500-5350 rpm originally but you'll be later than that.
 

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Discussion Starter #18
Castrol 4T 10-40W oil is fine. Even if you put auto oil in it won't ruin the engine.
You might check the timing. Pop the left cover off and fire up the engine. Timing light should hit on the F mark and when rev'd should advance to towards the 2 l l marks. Full advance hit at 4500-5350 rpm originally but you'll be later than that.
Is there a special light I need for this? Would this be something I could borrow from a mechanic?
 

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Got the thread re-named for you. Hopefully won't confuse folks too much. In any case, pay attention to what Longdistancerider suggests. You won't find any better advice.

You need an inductive timing light. Many auto parts stores will let you borrow one.
 

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Discussion Starter #20
Got the thread re-named for you. Hopefully won't confuse folks too much. In any case, pay attention to what Longdistancerider suggests. You won't find any better advice.

You need an inductive timing light. Many auto parts stores will let you borrow one.
Thanks for your help JT!
 
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