cbr250r mc14 engine fiddling

**Speedracer** · 5th August 2006, 17:46

Changed the oil today, using an engine flush. Changed the oil to 20W-40 cheap stuff.

Anyway I then proceeded to take it for a good run. Took it off road

which was fun
I drove the bike pretty hard all day.

Anyway I noticed when coming back that it makes a really loud rattle that just becomes audible over 4000rpm. It used to make something similar over 8000rpm which I thought might be the ignition advancing or something - sounded more aggressive like a roar rather than a whirr.

I checked the oil and it's just over 1/2 way where I've always had it around.
My question is:

has my oil flush made the tappets real noisy? or is the bike fucked e.g. bearings etc. I managed to make my tappets louder than the engine on my old cb250rs once, so I could believe it, but it really is damn loud, considering that it wasn't before today. Also the top speed has noticably dropped 10kmh so it has lost power. (could be just me but it does seem slower and has trouble starting).

Its so loud I can't tell where the noise is coming from. At idle its not noticable - maybe theres a quiet noise that you'd expect from tappets but nothing else.

Also I noticed one of the pipes is cold at idle (put the revs on/ choke and it heats up) - anyone know why that might be?

I'm not going to ride it until I figure this out - don't want to make an expensive mistake and get stuck somewhere. But I will check the tappets and compression at some stage when I figure out how you get to the necessary parts.

If this bike is buggered then I guess I'm screwed once again by going for cheap bargains lol. Strange that it lasted the 1700km trip here, and then blows up on an oil change though.

Oh yeah I might have got water somewhere as I washed it after the offroad fun...?

**imdying** · 5th August 2006, 17:49

Does it run on four?

**Speedracer** · 5th August 2006, 19:23

Originally Posted by imdying

Does it run on four?

all 4 cylinders? I think so, or it would have lost a lot more than 10 ks off the top speed. But at idle perhaps not.

**Mr. Peanut** · 5th August 2006, 19:24

Considered a burnt valve? How many Km?

**Speedracer** · 5th August 2006, 19:26

update

I pulled the top off the head and there aint no tappets to adjust?! without removing all the cams etc even maybe?

Also I think it makes a difference if you put it under load - its noisier. So I'm leaning towards possible blown head gasket - running lean scenario...
the coolant water is a bit scummy - green with lots of little bits of carbon? black particles and smells of fish!

**Speedracer** · 5th August 2006, 19:28

Originally Posted by MrPeanut

Considered a burnt valve? How many Km?

if it was a burnt valve wouldn't it just run crap rather than making a loud noise? I had burnt valves on my cb250rs once and it ran as if it had no compression but wasn't noisy

It's only got 25000km on the clock dammit!