CBR started for first time, now won't run!!! Help
 

Hey guys, new to this bike and forum. Bought it for cheap, not running. Would turn over and occasionally backfire but wouldn't start. Replaced plugs and gas today and got it to start with the choke all the way up. Bike sounded strong through its revs, but wanted to die off choke. It was smoking out of the exhaust pretty heavily (not sure if it was just burning off crap from not running for a while?) and also off the header because someone spilled oil on the pipes, so it was kinda hard to tell what the smoke was from out of the exhaust.

Anyway, I backed it out of my garage and cut it off to make sure I wasn't dumping oil out of some gasket (it wasn't), then it would start and idle pretty rough and die if i gave it any throttle. It wouldn't start at all off choke. Died a few more times trying to give it some throttle, then it wouldn't start at all with or without choke... and thats where I am now. It will crank, but won't fire up. I don't know what to do at this point.

I'd love to hear some ideas from you guys! I really don't wanna have to take it to a shop since I'm fairly mechanically inclined. I'm just not sure what my next step is...

I really don't know much about the bikes history other than the former owner claiming he had the carbs rebuilt recently (not sure if I should trust that or not). Couldn't get a straight answer about when it last ran really, maybe a year according to the guy. So the carb rebuild might have been a while ago. I was just glad it fired up for me tonight, since I wasn't even sure the motor would even run at all. The battery seems good too btw. It'll crank for a while without sounding like it's struggling.

Whats my next step with these symptoms?!

Gasoline gets "gummed up" when it sits idle for a while, and can begin to block fuel circuits in your carbs - running some SeaFoam in a tank of gas or 2 will help the issue, but the best next step for you, would be to pull and THOROUGHLY clean the carbs - there's lots of info out there on cleaning the carbs - if you've never done it, get a manual, and search for the info on the forum.

About the smoke - if it's blue smoke, that's engine oil...no bueno! :icon_sad:

+1, clean those carbs. then adjust and sync them properly. also look for any vacuum leaks between the carbs and engine.

pull the spark plugs and see how they look. whatever its burning to cause the smoke will show on the plugs.

Ok, I'm glad you guys think it's carb related. I just wasn't sure since it started up and ran fine and smooth for about a minute then started running really poorly. Though it sounded fine when it first started, I'm still kinda worried the motor might be messed in some way. But I will check some more things when I get home. Unfortunately my compression tester fittings don't fit this bike! So I haven't had a chance to do that.

The old plugs were black, solid black. After it ran for a minute with the new plugs in, I pulled #1 and couldn't see anything that helped me much. Maybe I'll post a picture later and see if I can get other opinions on that. I'm not great at spark plug analysis especially when it was only running for a few minutes.. The plug didn't look oily or wet to me.

One of my concerns is that it's a head gasket, and as the engine heated up and the pressure built in the coolant system, it started to pour more into the cylinders. It was hard to tell if the smoke smelled sweet since the oil was burning off the exhaust manifold right below me.

Thanks for the help!

Runnin' if for a bit, and then "reading" the plugs is definitely a good indicator of what's going on - you can find lots of online resources to help you do that.
A compression test is definitely a must do - let us know how it goes, once you get the appropriate fittings.

Alright... so I got home and checked over everything I did yesterday and realized the vacuum line on the petcock had come off when reseating the tank. Rookie mistake, I know. I got her to fire up (not smoking that I could see) and made a trip half way up my driveway and she died. Roll back down, pull the plugs and the tip of #1 is covered in oil. Haven't pulled the rest, but I'm guessing I've got some work ahead of me. Now here's the million dollar question. Do I fix this motor or replace it? Funds are limited, but so are my rebuild skills. Ugh.