rings or bearings or ???

The bike was suddenly rather difficult to get started, and was very
loud and rough when it did start - to the point that even holding the
throttle full open, it was spluttering a lot and barely running. Since
it has mostly had only very short runs around town in the last 6
months, I thought it was just the plugs and got a new set to put in.
However, the two that I have pulled so far were both very liberally
coated in oil.

So...combining difficulty starting and running with an increase in
noise, what would be the likely causes of the problem? Would it just
be rings, or am I looking at something more serious and PITA, such as
bearings etc? I'm not expecting anyone to provide a complete and
detailed diagnosis, but some info/advice that could help point me in
the direction in which a solution is most likely to be found.

TIA

Damien
GPX250 -> CBR600 -> F650/R1200GS (when the $$$ are there!)

 

What bike?

Boxer

 

'95 CBR600FS

Damien
GPX250 -> CBR600 -> F650/R1200GS (when the $$$ are there!)

 

SOunds like it needs a good thrash and then a compression check.

 

Oily plugs usually indicates worn rings. What's your mileage on the
bike? Sounds like it's time for a top-end rebuild (piston rings,
cylinder hone, pistons OK if you're lucky, new valve stem seals,
valves re-lapped).

The bad news is that it's gonna cost ya. A CT90 is cheap to rebuild
($40 piston, $30 rings, $25 intake valve, $8 head and $3 base gasket),
but I think you'll find that a CBR600F will be significantly more than
that.

Another (unlikely) possibility is that you filled it up from the 2-
stroke lawnmower fuel can.


BTH

 

I did the valve-stem seals about 18 months ago, so they should be
fine. It's done about 3000km since then, and currently has 52,000km
total. And there's no chance of incorrect fuel, since it's only ever
been filled straight from the pump - unleaded only.

I'm cancelling the rego on Monday (runs out in July), as I simply wont
have the time to do anything at all in the next few months (5 weeks to
the wedding now!), and have nowhere that I can work on it even if I
did. I might have a crack at it during the July school holidays, if I
still have it. I'm thinking maybe just chuck it up on eBay and see
what it gets - when you factor in the cost of parts, and the time
involved, the lower sale price looks quite reasonable. What do you
think would be a reasonable starting price? Or a realistic sale price,
for that matter?

Damien
GPX250 -> CBR600 -> F650/R1200GS (when the $$$ are there!)

 

Well, that was the plan, but I couldn't get the bike running long
enough to get further than the petrol station a couple of blocks down
the road! I thought at first the plugs were just a bit caked from all
the short trips, and was going to fill up and take it out on the
highway for a bit, but that was as far as I got. I went and bought new
plugs this morning, but gave up thoughts of replacing them when I saw
the state of the old ones, and just got a trailer instead. :-(

Damien
GPX250 -> CBR600 -> F650/R1200GS (when the $$$ are there!)

 

Should have put this in the previous post...

Minx has a Hyosung GT650R, doesn't she? I was looking at the prices
and specs, and they seem like a lot of bike for the money - and at
$9000, quite affordable without putting a dent in our plans to buy a
house at the end of the year. That's probably the front-runner if I
buy another sportsbike, I still haven't ruled out maybe going for a
cruiser instead this time. The BMW will have to wait.

Damien
GPX250 -> CBR600 -> F650/R1200GS (when the $$$ are there!)

 

If you get one, just pray you never need to replace the indicator switch
on it......ask Yeebok (new entrant to this group) all about it

MrBonk
http://www.mrbonk.com
(Sorry Yeebs......I'm sure they'll get your parts sooner or
later.....maybe....)

 

Is it blowing great clouds of blue smoke? Engines usually give you lots of
warning before this sort of symptoms, rings dont just fail overnight, they
wear over time.

Al

 

Getting it running and a quick thrash will establish whether the dodgy
work you did on the guide seals is allowing oil to wick down the steams
or it's the rings /other mechanical things are bad , best you get it
running with a change of petrol in the tank to be sure its not oil
contaminates and a quick ring out then check , takes all of 20 minutes .

 

Well, I suppose I could always sacrifice the new plugs to find out, as
I wont get it running with the ones in there at the moment! I
can't say I'd really noticed anything unusual like that, but prior to
the onset of the problem I'd not really had any reason to suspect
anything might have been amiss in the first place.

The first sign was when I started it up and the engine sounded quite
rattly, which it had certainly not been doing the last time I'd ridden
it before that. Basically, it was running well until it wasn't. I
don't know if it is rings, or maybe something else (hence the subject
of this thread), only that the plugs are all I've been able to check
thus far.

Are there any other things I can/should be checking to get a more
definite diagnosis of the full range of symptoms and the most likely
problem?

Damien
GPX250 -> CBR600 -> F650/R1200GS (when the $$$ are there!)

 

You didn't fill it up with diesel did you?

 

Look at Atecs response, and you can use a compression test to look for
really obvious piston or valve problems, then a good workshop can do a
leakdown test to give you a definite answer if the compressions look OK.
Rattly bottom ends dont make spark plugs oily, if the plugs are oily, the
oil is coming from somewhere; past the valves, past the rings, a bad
breather, engine extremely overfilled with oil? Check your airbox/air
filter for signs of oil too.

Al

 

Oil levels are fine, and I will have to wait until next pay to get a
compression tester now, but I can easily check the state of the filter
whenever I get a chance to take a look.

The main issue re the rattle is that the engine wasn't rattly at all
before the problem appeared. I went to start it one morning, and it
sounded like absolute shit and was extremely reluctant to start at
all. Before that, it had been fine, no problems or obvious signs of
problems at all. Certainly, rattles on their own don't foul plugs with
oil like that, but my question is what sort of problems could I be
facing that would produce symptoms such as this?

Now that I think of it...a few months ago I had a minor tumble in the
backyard, when the front-end slipped out on some grass as I was
parking the bike behind the house. I was doing little more than
walking speed, and just went straight over, but the engine was running
for a couple of seconds until I realised what had actually happened
and hit the kill switch. Is it possible that "stuff happened"
internally as a result, and just took a little time to become
noticeable?

Damien
GPX250 -> CBR600 -> F650/R1200GS (when the $$$ are there!)

 

Could be contaminated fuel, drain tank change fuel filter etc, check air
filter is not blocked, if injected bike it could be blocked injectors
(remove and have serviced).

Boxer

 

Water in your fuel...

Ask Smee

H

 

How would water in the fuel result in oily plugs though?

Damien
GPX250 -> CBR600 -> F650/R1200GS (when the $$$ are there!)

 

Only someone that spreads disinformation can answer that...

This is the bike that has been having problems with batteries discharging
themselves?

Is the bike's voltage up for the job? Is there an connections that may be
allowing a crap spark, and poor burn? Coils OK?

H

 

Never been better since both battery and reg/rec were replaced.

Damien
GPX250 -> CBR600 -> F650/R1200GS (when the $$$ are there!)