I got an (essentially free) shady F2 motor to replace the definitely bad one in a wrecked F2 that I've rebuilt. However, when I went for a pre-start oil change, out came a very thin layer of clear coolant/water that had settled to the bottom.

In response to this, I freaked and took off the water pump and the coolant/oil heat exchanger on the front of the engine. I disassembled the exchanger and replaced the o-rings that seal the inner oil radiator to the oil/coolant housing, because they looked disgusting. I cleaned their mating surfaces very well.

I have determined that there is no way coolant could get through the water pump into the motor, because the weep holes were clean, and frankly the seals feel fantastically snug and happy in the first place.

This leaves me with heat exchanger oil seal woes (which I have addressed) or the obvious slew of other terrifying deep-engine things that would require me to take the motor BACK OUT and do naughty things to it and spend more money.

What I need to know to proceed intelligently is this:

1.) Are the stock bores sleeved cast iron, or ceramic plated bores? I view a single casting w/plated bores as a solid arrangement, but pressed-in sleeves as a possible oil/coolant transfer mode.
2.) Besides a cracked head/head gasket leak, where else can this exchange take place? I need to know whether to cut my losses or not here.

 

I don't think a sleeved motor would ever leak anything between the case and the sleeve, especially if it's the original sleeves.

Having said that, I believe that the F2 motor is a plated cylinder cast into the block (no sleeves)

I think you should replace the water pump as a unit to rule that out, they are fairly cheap and are a maintenance item anyway.

You were on the ball replacing the o-rings on the oil cooler, that is a likely cause of oil or coolant contamination.

The only other - and most common - cause of coolant in the oil is a head gasket... Don't be scared off by this, if you have the motor out of the frame already the hard part is done.

Changing a head gasket is quite simple if you have a clean area to work and if you stay organized.

 

That makes me feel better about the o-ring job. I ran it up to temp after I fixed it (while I listened to a horrifying valvetrain noise...) and then let it set for a bit. I raised the front of the bike with the garage rafters to pool any coolant toward the rear of the oil pan, let it sit some more, drained off a bit of the oil, and didn't see any coolant. Oil didn't look like a milkshake or anything either.

I'm going to do a compression test to determine the state of the head gasket. I just have to find a gauge that fits that tiny plug thread. I know it's not a tell-all, especially with coolant/oil exchange as the problem, but I'm going to give it a shot. As the cost of my build goes right now, a $60 hit for a gasket is a serious impact on the cost of the build, but of course what must be done must be done...

I'm more than confident with a complete overhaul of the motor if necessary, but that's going to add up fast I'd imagine. Rod bearings, crank bearings, gaskets, oil seals, rings, one-time-use-nuts, other crap I find and break while I'm in there.... I've been leaning toward it more and more after seeing my sump screen, though. It wasn't that bad, but it left me a bit on edge...

Thanks for the help. I'll keep my problems/solutions posted.

 

Don't bother rebuilding it, these engines are bomb proof... Just get the small things sorted out and you'll be golden.

I pulled mine all apart just to realize I didn't need to AT ALL, it was new inside... I just got carried away.

Have you ruled out the CCT for the valvetrain racket you heard?

 

I have an APE manual CCT on the way. Should be able to make another attempt Wednesday evening when it arrives. My purchase decision is based on fairly sound logic...
1.) I will end up getting this F2 running somehow.
2.) That said, regardless of what motor I end up with, I will want an APE manual tensioner on it anyway.
3.) So... I just bought it, even if the rattle I'm hearing in this engine isn't entirely caused by the cam chain. It's partly a diagnostic procedure for my current motor, and a good mod for any future engine I may get if that's necessary.

The clatter does come from the right side of the motor, but it's louder than I imagined given the descriptions on here. It's like there's a miniature freight train in my engine attempting to escape via my pulser cover.


PS I just found your build thread, and careful examination yielded the answer to my internal engine construction questions. I had a gander into the nether regions when I had my oil pan off, but it's informative to see it apart. Hopefully it makes it feel worth your time that many people reference your build thread when they need to know something for diagnosis purposes.

 

The CCT rattle can be quite loud, especially if it has been doing it for a long time.

Glad my thread is useful to you, I still have that engine in pieces - I bought an F3 motor to throw in the bike - so if you have any questions let me know, I can go look at the parts.

 

Haha. I just took an f3 motor out of my bike. It came with one in it, and I wanted a nice all-stock f2 so I found an f2 parts bike that served more purposes than just the motor for me (new dash housing, nicer tank, micron full exhaust... etc.) and put that motor in my good titled frame. The only thing that confused me was that I thought the transmission was busted up/had no neutral until I discovered that the f2 shift fork guide drum is machined backwards compared to the f3 one, and all became well. One must invert the shifter link to achieve proper functionality... Plus, I don't have random wires going to nothing at all anymore, which feels better.

I guess my preception of the noise I was to expect was a bit off. I imagined a consistent hissing or constant light grinding, but some are describing it as a clacking, or sounding like a diesel engine which is precisely what mine does. I happen to drive a diesel car, and the noise it makes is very similar to the bike at idle.

 

Should have stuck with my initial opinion... Problem lies much deeper. Believe I have head/valve issues. The APE CCT made no difference in the noise at all. Motor comes apart this Sunday.

 

Knocking? Check bottom end bearings

 

It doesn't sound like a rod knock of any sort or any type of oil film bearing noise. It's some extreme valve clicking, almost as if a valve were sticking down and getting hammered back up or something horrible. It's definitely coming from upstairs. When I take the pulser plug off while it's running, I can hear it quite clearly in there, and it appears to be emitted from the center of the head. Looking on the bright side, I might get to drive somewhere fun for another motor or engine head. Something in there is quite busted.

What's interesting is that it doesn't hamper performance. It's super snappy just like I expected, idles smoothly, and responds to choke predictably just as any bike ought to.