UPDATED! New Ride - 02 CBR F4i Oil Leak
 

Hello everybody! I just purchased a new to me CBR 600F4i recently, that is very clean, rides as good as it oughta, and has had a lot of maintenance seemingly done to it - as I was told there was a full service. Valves have been seemingly adjusted (no overly loud tapping), filter and oil changed, rad fluid, brake pads, spark plugs, etc on top of new tires, chain, and sprocket. That being said, I noticed right away that there was some oil weeping down the right hand side of the bike. I've done some tearing down, and gotten all the way to the throttle bodies and it seems from the right most (cylinder 4) throttle body there is oil coming down over time. I suspected the valve cover gasket, but the oil is only around the throttle body boot where it connects with the engine block, and goes down from there.

Here's a picture of what I'm seeing:
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So, yeah. I can't wait to get to know you fine fellows and hopefully share some bits of information with others along the way - I'm just new to the realm of bike wrenching and would love some insight on what I might be looking at here, and the process behind fixing it, if anyone happens to know!

looks like it could be from an old leak at the valve cover. Did whoever adjusted the valves replace the gasket?

I would clean it all off and see if it shows signs of leaking still, unless the gasket was never replaced.... Then I would replace it and clean it.

Mechanics are not usually going to take the time to clean off more than the immediate area.

Douse an old rag in mineral spirits/paint thinner and clean it off.

Then see if it comes back. That's not a recent or big leak.

Also, that TB boot tightens around the intake port as well as the TB. Is it loose? On the intake port side? Sometimes the clamps are hard to get to, and people get lazy and don't get them tightened at all.

Hell, the boot could be cracked too...

I'm not sure what was done in regards to the valves, or gasket. Doesn't seem to be any leaks elsewhere, and I can't find any cracks in the engine casing or the likes. I'm going to do some further investigation, and then see about cleaning everything up in the event I don't find anything. Going to check the boot to see how tight it is, along with the cam chain tensioner gasket - as there's lots of oil around that, but I don't know how far oil could be sprayed out.

I did notice however that there was some oil up and around the throttle bodies. The airbox didn't have anything in it, but the little intake scoops and metal portion of the throttle body did. Almost wondering if there was too much oil put into the bike once? My FZ6 even with 20,000km on the clock had spotless valves and no oil of note around the TBs the one time I had everything off.

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Is that normal?

I just went and looked at the oil level sight glass, and it's well above the max fill line. Thinking that could be a large part of my problems...

Yeah, there's some blowback happening, you should pull the plug on both of those cylinders and look at them. Post pics.

Engine is running smooth and strong?


Unfortunately, some people think you should use the sight lines when the bike is on the side stand.....

By plug, do you mean spark plug?

I've ridden the bike back and forth, just over a block, and got it up into third gear while revving about midway, approaching 9K RPMs before shifting. It's not licensed or insured yet to allow me proper freedom in this regard, not to mention the recent snow we've had blowing in... But yes, it seems to run well. Pulls good, idles perfectly, clicks into gears like a champ and there doesn't seem to be anything out of the ordinary as far as overall operation is concerned.

I'm going to drain some of the oil tomorrow, and clean up the area on the block after I've done some further investigating - such as peeping at the cylinders and the likes. Might go ahead and buy some new throttle body boots, CCT gasket, etc as a safe guard. If I'm lucky, it'll be as simple as too much oil! There's evidence of that on each TB and butterfly, but it seems strangely focused on the right most side around the CCT and Cyl #4. I'll post back what I find!

Would recommend to drain ALL the oil, replace with something crap cheap, run it hot, drain again and add proper oil. Also seafoam or equalivent in gas, cleanup, inspection and if you don't find anything out of kilter you should be good.

Alright, I'll throw Sea Foam onto the list. What would the benefit of using a different oil be, before swapping it out? I couldn't tell you what type of oil is in there right now, so I might just use that as my test batch. It looks super clean/fresh, and I was planning on replacing it in the spring.

As Mattson stated the reason you want to run cheap oil for a short bit is there is a good chance that there is some crud inside the crankcase. You want to use the cheap oil just to act as a flushing mechanism. Like he said, get it hot, let it circulate well, then shut it down and drain it.