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Discussion Starter · #1 ·
Hey folks. I had a weird experience this morning that I thought I'd ask about. I rolled the CM450 out of the garage as usual, pulled the choke out, and started it. It started up fine, and seemed to be running normally (with the choke out, around 2800 RPM). I then went to grab my helmet and jacket, put them on, and got back just as the engine died. I confirmed the fuel petcock was on (I've been down that road enough times to check it first), and started the bike... which came up at about 1100 RPM, and then slowed down until it died again. For the third try, I unset the choke, and used the throttle to keep the RPMs going. It ran fine for a few minutes, so I set off to work.

It continued to have problems roughly until the end of my street (maybe a couple hundred feet), and then picked up and ran fine. The only other potentially related problem I'm having is a slight stutter between about 2800 and 3200 RPM: above or below that range it's entirely fine. I'm guessing that's a partially clogged jet in the carb, but I don't know for sure.

Anyone have a guess what was going on this morning? I'll be riding home in a couple hours, so I'll have more information then.
 

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If you leave the choke completely closed, as the engine warms up the mixture will be too rich and it will slowly flood and die. You've effectively loaded the cylinders up with more fuel than the air coming in can burn. It sounds like you ran it until it burned that excess fuel out which cleared that problem up. Some of that excess fuel may have leaked past the rings and diluted the oil. You may want to change it.
 

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Discussion Starter · #3 ·
I wouldn't have thought it would go that fast, since it was probably running on the order of 2-3 minutes. I suppose it's been hot out, so it's possible. I'll check the oil, see if there's any gas smell.

Thanks!
 

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Discussion Starter · #4 ·
JT, good call. It's faint, but there's a definite gas smell to the oil. How much of a risk is it likely to be to the engine to leave it as is for a while? I changed the oil a couple of weeks ago, and was planning to do it again at 100 miles or so, since it sat for a long time and I have no idea how much crud built up. Having to do it this early will be annoying, but oh well.
 

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Any gas in the oil is a likely path to a trashed engine. Oil is cheap. Parts are not,
 

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Discussion Starter · #6 ·
I figured that was going to be the answer, but you can't blame me for hoping!

I'm going to be out of town for a few days, so I'll do the oil change this weekend.
 

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I start mine with choke full, then cut it to half or less while donning helmet, etc.
 

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Discussion Starter · #8 ·
That's what I mostly did with the Rebel. Unfortunately, the CM450C choke cable has been replaced with one that only has stops at "off" and "on". It's on my list of things to replace, but it's pretty low on the list. I'll get around to it eventually, and for now I'll just be a lot more careful getting it running in the morning.
 

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Discussion Starter · #9 ·
To finish this thread off: I changed the oil and filter over the weekend, and I'm glad I did. The oil (put in about 70 miles earlier) was much darker than I expected, and the magnetic drain plug had picked up a lot of crud. The gas smell was almost undetectable, but better safe than sorry.
 
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