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Honda CR125 Power Problem, PLEASE HELP!
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Philip Harrison
Dec 31, 2000, 8:21:01 AM12/31/00
to
I bought a '98 Honda CR125 about six weeks ago from a private sale. Four
days later I was up the mountain on it when the bike simply died, all the
compression was gone. When I brought it home and got the cylinder off I
found the piston and cylinder was severely damaged. The piston ring had
caught somehow on the exhaust exit ports, taking a chunk out of the port and
bending up the top of the piston. I sent the cylinder off to Langcourt and
had it re-welded and re-chromed, I also bought a complete genuine Honda
piston kit. Put the bike back together again with little difficulty except
not knowing exactly how to set the exhaust ports. The carb and all that
wasn't touched during all this. The bike now severely lacks power,
especially at slower speeds to the point where it will cut out if it is not
revved enough. To take off the bike has to be revved very high, but it is
difficult to tell whether the power loss is bad at higher speeds, having not
had the bike that long. The bike starts OK-ish from cold with the choke on
but as soon as it is warm it is almost impossible to start without the
choke.
I have tried loads of different things that various people have suggested
with no success...
Changed the carb for a definitely working one...
Checked the reeds...
Checked spark plug...(it was wet and black)
Changed the spark plug...
Checked the spark...
Checked the crank shaft seals...
Checked the exhaust valves...(they were fully in when the bike was off)
Haven't used a tool to check the compression but it certainly feels very
strong...
days later I was up the mountain on it when the bike simply died, all the
compression was gone. When I brought it home and got the cylinder off I
found the piston and cylinder was severely damaged. The piston ring had
caught somehow on the exhaust exit ports, taking a chunk out of the port and
bending up the top of the piston. I sent the cylinder off to Langcourt and
had it re-welded and re-chromed, I also bought a complete genuine Honda
piston kit. Put the bike back together again with little difficulty except
not knowing exactly how to set the exhaust ports. The carb and all that
wasn't touched during all this. The bike now severely lacks power,
especially at slower speeds to the point where it will cut out if it is not
revved enough. To take off the bike has to be revved very high, but it is
difficult to tell whether the power loss is bad at higher speeds, having not
had the bike that long. The bike starts OK-ish from cold with the choke on
but as soon as it is warm it is almost impossible to start without the
choke.
I have tried loads of different things that various people have suggested
with no success...
Changed the carb for a definitely working one...
Checked the reeds...
Checked spark plug...(it was wet and black)
Changed the spark plug...
Checked the spark...
Checked the crank shaft seals...
Checked the exhaust valves...(they were fully in when the bike was off)
Haven't used a tool to check the compression but it certainly feels very
strong...
There are two pistons for CRs, an A and B. A pistons are supposed to go with
an A cylinder and likewise for the B, but because it was rechromed we put in
the slightly tighter piston. Hence putting an A piston into a B cylinder.
Any help would be greatly appreciated.
Thanks,
Philip.
TIMOTHY NELSON
Dec 31, 2000, 11:40:22 AM12/31/00
to
It sounds like a really bad air leak to me. I had a YZ 490 that did this
once. Probaly a crank seal and that is what wiped out your motor in the
first place. I would do a pressure test on the motor or have a mechanic at a
dealer do it( it takes a few special tools to do this, and I don't mean a
compression test)compression test checks the rings and top end, pressure
test involves only a few pounds of air and checks the motor for leaks.
once. Probaly a crank seal and that is what wiped out your motor in the
first place. I would do a pressure test on the motor or have a mechanic at a
dealer do it( it takes a few special tools to do this, and I don't mean a
compression test)compression test checks the rings and top end, pressure
test involves only a few pounds of air and checks the motor for leaks.
--
Tim
98 380 SX
01 RM250
Philip Harrison
Dec 31, 2000, 12:35:32 PM12/31/00
to
I was told by a friend who works in a Honda garage to take off the sides of
the engine and fill the crankcase with petrol(I poured the petrol in where
the reeds were) and see if any leaked out where the crankshaft seals are,
there weren't and leakages that i could see, but it was hard to see in on
one side.
TIMOTHY NELSON <nes...@prodigy.net> wrote in message
news:92nn1q$1jd4$1...@newssvr05-en0.news.prodigy.com...
the engine and fill the crankcase with petrol(I poured the petrol in where
the reeds were) and see if any leaked out where the crankshaft seals are,
there weren't and leakages that i could see, but it was hard to see in on
one side.
TIMOTHY NELSON <nes...@prodigy.net> wrote in message
news:92nn1q$1jd4$1...@newssvr05-en0.news.prodigy.com...
Tim
Dec 31, 2000, 1:00:00 PM12/31/00
to
> I was told by a friend who works in a Honda garage to take off the sides
of
> the engine and fill the crankcase with petrol(I poured the petrol in where
> the reeds were) and see if any leaked out where the crankshaft seals are,
> there weren't and leakages that i could see, but it was hard to see in on
> one side.
That may be one way of checking the seals, but you don't know about the restof
> the engine and fill the crankcase with petrol(I poured the petrol in where
> the reeds were) and see if any leaked out where the crankshaft seals are,
> there weren't and leakages that i could see, but it was hard to see in on
> one side.
of the lower end as far as it being tight(no leaks). If that piston came
apart then some debri easily could have fallen in to the lower end and
cracked the cases. Just an idea.
Roger/Debbie Bess
Dec 31, 2000, 3:38:24 PM12/31/00
to
eek, I hope you don't smoke..
JSosa
Jan 1, 2001, 11:28:25 AM1/1/01
to
I've never tried this, but I here that you can use baby powder to find air
leaks. I don't know about the oil trick unless it was really light
viscosity? I have read that CR125's are really prone to air leaks through
the flywheel side. Hope this helps.
leaks. I don't know about the oil trick unless it was really light
viscosity? I have read that CR125's are really prone to air leaks through
the flywheel side. Hope this helps.
js
"Philip Harrison" <harr...@tcd.ie> wrote in message
news:j5K36.3152$s4....@news.indigo.ie...
Philip Harrison
Jan 1, 2001, 1:51:53 PM1/1/01
to
OK, well we sorted that first problem, but the bike is now completely
flooded cause of the petrol we poured in to the crack case. We have been
push starting the bike but it will only run for a few seconds, then cut out.
Each time I have to take out the spark plug and clean and dry it as it is
always soaking wet...
flooded cause of the petrol we poured in to the crack case. We have been
push starting the bike but it will only run for a few seconds, then cut out.
Each time I have to take out the spark plug and clean and dry it as it is
always soaking wet...
JSosa
Jan 1, 2001, 5:59:55 PM1/1/01
to
You will have to dump all that oil out of the crank case. You might beable
to do it like you would if it was water flooded. Tip the bike upside down
and put the bike in 2nd or 3rd with no spark plug in. Now spin the rear
wheel until most of the oil comes out.
to do it like you would if it was water flooded. Tip the bike upside down
and put the bike in 2nd or 3rd with no spark plug in. Now spin the rear
wheel until most of the oil comes out.
js
"Philip Harrison" <harr...@tcd.ie> wrote in message
news:0j446.3371$s4....@news.indigo.ie...
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