Topic: Oil coming from overflow tube on oil tank

[EvanB]

I just got a 75 Cb750. The previous owner said it has an oil leak so I was trying to figure out where it was coming from. I filled the oil tank up to the level and started the bike. Oil starts to pour out of the overflow tube for the oil tank and when I open the tank (after the bike is shut off) it is completely full of oil, more than I put in. Anyone know what my problem could be?

[KingCustomCycles.com]

It is over filled with oil.  Someone topped it off with a fair amount of oil in the engine.  Drain it down, run it for 5 minutes or so and recheck. The oil only leaves the cooler when the bike is running. (check valve)

[EvanB]

Thanks, that solved my problems with that. Now I have another problem. The bike has 60,000 miles. It has unifilters and what looks like a homemade 4-1 header and megaphone. It will only start with the choke all the way on and the throttle on, it will die if you don't keep pumping (twisting) the throttle. If you take the choke off a little bit it will also die. Could it be the pod filters? Should I just put a stock airbox back on? Thanks for your help.

[KingCustomCycles.com]

It is lean.  You can go back with the original airbox and you will not have to rejet, provided the jets in there are stock.  It sounds like you are in for a carb clean and inspection.  It is well covered with a search of the previous posts.  Not difficult, just alot of details to attend to.  Plugged jets act as you describe.

[Bob Wessner]

I just got a 75 Cb750. The previous owner said it has an oil leak so I was trying to figure out where it was coming from. I filled the oil tank up to the level and started the bike. Oil starts to pour out of the overflow tube for the oil tank and when I open the tank (after the bike is shut off) it is completely full of oil, more than I put in. Anyone know what my problem could be?

How long had the bike been sitting before you checked the oil and found it low, causing you to add some? Many of these suffer from leak-down from the tank to the sump after sitting because of a leaky check valve. Always check oil level immediately after a ride to insure you are getting an accurate read on the oil level in the tank.

[mystic_1]

It sounds like you are in for a carb clean and inspection.

+1 clean up the carbs, then re-evaluate.  Take a look at the jets to see if they're stock size or not while you're in there.  After that you can decide what route you want to take.  Lots of people find that the stock airbox performs the best for street riding, pods look great but take lots of tuning and tweaking to make them perform well, and even then you're likely to have flat spots in certain circumstances.

mystic_1

[EvanB]

Bob: I am not sure how long it had been sitting, the previous owner said it was leaking oil and the tank was empty so I added more and it poured out, after draining some off as suggested and riding it for a bit it seems fine and the oil is at the right level.

mystic: I took the carbs off to clean them but they are very clean inside. Main jets are 125. I am not sure what the pilot jets are, can you tell without taking them off? I put the carbs back on after I had noticed the previous owner had the inline fuel filter reversed to so the fuel was not going with the flow marking on the filter.

I got it running better and off the choke but it pops at low rpm and decel. At mid throttle it bogs but if I roll past that point it takes off and runs great in upper rpms. Sounds to me like a problem with the pilot jets but I don't have much experience (none) tuning carbs. I am going to order a stock airbox on ebay and see if that helps out any.