Little XR no go
Steve in CO
I have an '84 XR80 that I bought for my son last fall. It looked good when I
bought it, but the closer I look, the more it appears to have been abused in
a past life. (The word "thrashed" comes to mind) But despite it's hard life,
it has run like clockwork since we bought it. It always started first or
second kick and would just purr merrily along no matter what.
The other day, I took it out of the garage and went for a spin to the end of
the driveway and back, and on the return trip, it suddenly lost power and
stalled. After several kicks, it started and idled rough for a few seconds,
then stalled as soon as I tried to give it any gas. Several more tries got
it to idle a few more seconds and gave a couple backfires, but now it won't
even try to start. I've kicked it till I was blue in the face, choke on,
choke off, throttle on, throttle off, all the obvious stuff over a period of
about a week. No sign of life.
I checked the carb, everything seems to be working and clean.
The tank is draining fine (it poured all over the garage floor when I forgot
to reconnect the fuel line to the carb).
It appears gas is getting to the cylinder because the plug looks wet when I
pull it after kicking for a while.
There is a pretty healthy looking spark when I do a spark check. Certainly
enough to at least get some sort of action.
I checked the points, looks like they are opening and closing like they
should. The gap was a little tight, so I opened that a hair. Nothing.
The exhaust is clear. (Won't start even with the pipe off)
The intake is clear. (Won't start even with the boot disconnected)
The intake valve clearance was a bit tight (ie: none), so I backed off that
a little. Still no joy. Exhaust clearance was about right.
Compression has always seemed a little low (I imagine it could use a ring
and/or valve job with as much time as it appears to have) but there are no
visible signs of a leak at any of the cylinder/head gaskets. Besides, I
wouldn't think that low compression would cause a sudden failure like it
did.
So now I'm out of ideas.
The only other thing I can think of is to pull the head and see if maybe
that tight intake clearance caused some valve damage. I really don't want to
get that deep if I don't have to though. I was hoping to at least get a
couple seasons out of this thing before it died completely.
Any suggestions?
Thanks in advance.
---Steve in CO
'86 TT-350
jesse jarzabski
something a little newer.how much did you buy it for because there is an
1990 xr100 in my ads for 800.i imagine you spent somewhere around there
for the 80.so i recommend spending a few more bucks for somethin a
little newer,bigger and faster.
OrAnGePoWeRbAnD
Uwe Hale
> Compression has always seemed a little low (I imagine it could use a ring
> and/or valve job with as much time as it appears to have) but there are no
> visible signs of a leak at any of the cylinder/head gaskets. Besides, I
> wouldn't think that low compression would cause a sudden failure like it
> did.
>
> So now I'm out of ideas.
>
If the ring is sticking or broke it could.
Have you tried a new spark plug anyways?
Do a dry and wet compression check to test the rings. You can't warm it up
since it doesn't run but at least make sure you hold the throttle all the way
open. Above 150 is in great shape. Below 120 you need to do a
top end on it. Being a 15 year old XR80 it's probably time.
Uwe Hale - 89 YZ250WR, 99 GasGas EC200
http://www.rrdr.org
http://www.smackovermotorsports.com
Ray
streched that it chews up the sprockets and then starts jumping teeth and
then piston and valve shall meet. BUT, when the valve{s} get bent the
external indication is a whole lot of valve clearance and you CLAIM :-) to
not be suffering from this.
So, have you tried a NEW plug??? As a note to anyone trouble shooting a
non-running motorcycle: PUT IN A NEW PLUG, if it still won't crank then PUT
IN ANOTHER NEW PLUG! After that then start checking other possible problems.
If the spark is blue then every thing is good. If the spark is yellowish
then the condenser is bad.
Ck the compression as suggested before.
Plan B, take it to a well respected independent repair shop { like ME,
except the drive to GA is boring } and spend some money { probably less than
$100 if the problem is not internal } and get it fixed. It amazes me the
number of people who would never consider plan B. In front of my shop I have
a sign that reads: WANTED: DEAD DIRT BIKES. People will bring in some bike
that someone gave them, or they got it cheap or they have had it for a long
time , and sell it to me not running for very little money. They will say "
It can't be fixed". In many cases I can make it run with very little effort.
Moral: find a mechanic you trust and spend some money with him when you have
a problem. In the long run you will save time and aggravation.
Ray
...
Steve in CO
> little newer,bigger and faster.
Newer yes, if I could find one. In the three months I was looking for this
one, I never saw a single XR80 listed in the papers. They are hard to come
by.
Bigger and faster, no. My son is only 9 and he's barely able to manage the
thing. A 100 would be out of the question till he does some growing and gets
more comfortable with operating the controls.
I am in the market for a 100 though. I wanted to get one that my wife can
ride and that my son will be able to grow in to down the road. This will be
in addition to the 80 though, which I was hoping to pass down to my daughter
in a few more years.
Thanks for the input.
Steve in CO
Guess that's the next step. I think I have a compression gauge
somewhere...I'll have to hunt for the right fittings though since these are
a really small plug.
Thanks.
Steve in CO
> streched that it chews up the sprockets and then starts jumping teeth and
> then piston and valve shall meet. BUT, when the valve{s} get bent the
> external indication is a whole lot of valve clearance and you CLAIM :-) to
> not be suffering from this.
The timing chain and sprocket actually looks pretty good. The cam has a
mirror finish, but that's to be expected I guess.
> So, have you tried a NEW plug???
Ok, I must confess, I haven't put in a new one. I figured if it looked good
out of the cylinder, it should be at least good enough to start a fire in
the cylinder.
Wish there were someplace closer to home that carried motorcycle plugs. I
hate driving 45 minutes each way for a $2 part.
> If the spark is blue then every thing is good. If the spark is yellowish
> then the condenser is bad.
Actually looked a little whiteish to me, but reasonably fat.
> Plan B, take it to a well respected independent repair shop { like ME,
> except the drive to GA is boring } and spend some money { probably less
than
> $100 if the problem is not internal } and get it fixed.
Well, that option has been considered. There are a couple reasons I haven't
done it though.
First, I have never taken anything to a mechanic and been 100% satisfied
with the work performed. Granted, I've never taken a bike in for service, so
I can't comment on motorcycle mechanics, but in the automotive world, there
is always either something else that they screw up in the process of fixing
what I took it in for, or I take it in a half dozen times and the problem
never gets solved. No offense, I'm sure you are a very good mechanic. The
fact that you frequent RMD shows that you truly love the sport and the
machines and probably do it as much for your own personal satisfaction as
for the money. But for so many "mechanics" it's just a job. My car or bike
is just another piece of machinery to push through the door so they can
collect a paycheck.
Second, and probably most important is that I'm a "hands on" kind of person.
I like the satisfaction of being able to fix things. I know there's nothing
magical about the way an engine works. It's just a mechanical device and I'm
a reasonably intelligent person so I ought to be able to fix it. I also know
I will pay attention to the details and do it the right way because I'm the
one who'll benefit. I agree that there's nothing that can't be fixed, it's
just a matter of how much time and money it takes to fix it.
Thanks for the info though. That's a couple things to try.
Update:
Just went out and tried a compression test. I don't have the right sized
adapter for the gauge to fit the plug hole, but I was able to get somewhat
of a seal using a rubber washer and just holding it in place. I never saw
the gauge go above 10psi. Not good. From there, I pulled the carb and
noticed the sound of air rushing out of the intake manifold when turned the
flywheel. I put my hand over the intake manifold and could feel a very
strong back-pressure while turning the flywheel even when the value was
fully closed. Ah hah! If I had another hand to hold the gauge, I'll bet it
would read a lot higher than 10 psi! Sounds like a leaking valve.
So the next step is to pull the head and get a closer look. Onward ho!
Steve in CO
Steve in CO
pull the cam assembly, when I decided to check the alignment first to make
sure I knew what the end result was supposed to look like.
According to the book, the "O" mark should be at the top of the timing gear
and the gear bolts should align with the top of the cylinder head with the
flywheel at the "T" mark and the cam lobes pointing down. Someone has
scratched another mark opposite the "O", and it's the one closest to the top
when the flywheel is at the "T" mark. In addition, neither mark is at the
exact top and the gear bolts do not align regardless which way the lobes
point when the flywheel is at the "T" mark. If I move the flywheel to the
"F" mark, everything lines up fine.
Doesn't that mean it's misaligned now? Is that someone's attempt to adjust
the timing? Should I put it back that way, or follow the book? Apparently
one tooth off isn't enough to cause head/valve contact, but it kind of
scares me now.
Thanks again.
Uwe Hale
> Wish there were someplace closer to home that carried motorcycle plugs. I
> hate driving 45 minutes each way for a $2 part.
>
you should be able to find one at most any car parts store. I know pep-boys
carries bike plugs.
Ray
comes. You may find that the points cam on the flywheel has been installed
180 degrees out.
Ray
Steve in CO wrote in message ...
Tom and Michelle Harvanek
Steve in CO wrote
>According to the book, the "O" mark should be at the top of the timing gear
>and the gear bolts should align with the top of the cylinder head with the
>flywheel at the "T" mark and the cam lobes pointing down. Someone has
>scratched another mark opposite the "O", and it's the one closest to the top
>when the flywheel is at the "T" mark. In addition, neither mark is at the
>exact top and the gear bolts do not align regardless which way the lobes
>point when the flywheel is at the "T" mark. If I move the flywheel to the
>"F" mark, everything lines up fine.
>
>Doesn't that mean it's misaligned now? Is that someone's attempt to adjust
>the timing? Should I put it back that way, or follow the book? Apparently
>one tooth off isn't enough to cause head/valve contact, but it kind of
>scares me now.
Did you take off the flywheel to see if the keyway sheared?
BTW I was surprised how finicky Michelle's xr100 was to setting up the points.
Just a thousandth or two was the difference between running well, not starting
or sputtering at high rpm.
Good Luck,
Tom
Steve in CO
No, not yet. I didn't really want to mess around down there, but I guess I'm
going to have to in order to verify this timing chain thing. It's the valve
timing that appears to be off though. That should be independent of ignition
timing AFAIK.
> BTW I was surprised how finicky Michelle's xr100 was to setting up the
points.
> Just a thousandth or two was the difference between running well, not
starting
> or sputtering at high rpm.
Yeah, I had a bike with real similar problem years ago too, so that was one
of my first thoughts. Wasn't quite as sudden on that case though.
I was out riding my old DT-250 quite a way from camp, and all the sudden it
just start couging and sputtering and running worse & worse. The only thing
that kept me moving was the fact that it was all down hill. By the time I
got to the bottom, it had gotten to the point where it wouldn't start at
all. I was only 15 and all my buddies had taken off ahead. I really didn't
know what to do, but on a whim, I decided to look at the points. It seemed
like they weren't even opening, so I took a screwdriver eyeballed what
looked like a reasonable gap. Wow! What a difference! I was so used to how
bad it had been running that the first time I hit the gas, I nearly fell off
the back!
Steve in CO
pep-boys
> carries bike plugs.
This is one of those little dinky ones. I've seen a limited selection of
some bike plugs at the auto part stores, but never these little tiny ones.
Steve in CO
out that was the culprit the whole time.
I swear I did a spark test 3 times and every time it looked fine. After I
pulled the top end apart and discovered everything pretty much looked as it
should, I put it all back together (with the cam chain at factory specs this
time) and tried to fire it up. Low and behold, it fired up on the second
kick. But then it died after about 15 seconds. Kicked it again, ran another
15, died again. Then nothing, just like before.
So I did the spark check AGAIN, and THIS time, I wasn't getting one. Popped
a different plug on (wasn't the right size, but it served the purpose) and
there was the spark. So I drove to the shop and picked up a couple new
plugs, popped one in, and sure enough, it's purring like a kitten again.
It wasn't a total loss though. Getting that cam timing back in spec seems to
have helped the performance considerably. It always felt a little mushy
before, but now it pulls much cleaner off the bottom and will rev till it
sounds like it's going to explode.
Yay!
Thanks again to all of you who gave suggestions.
DirtCrashr
>have helped the performance considerably. It always felt a little mushy
>before, but now it pulls much cleaner off the bottom and will rev till it
>sounds like it's going to explode.
>
>Yay!
>
>Thanks again to all of you who gave suggestions.
>
>---Steve in CO
Cool!
Hey, do you suppose someone might have put the timing off a little bit so's a
little one might not feel that explosive, runaway hit? At least you know how
to re-set it if you want, also saving us from a long "How Do I Slow-down My
Explosive XR80" thread ;-)
Good goin'!
DirtCrashr -'97xr400
Uwe Hale
> Ok, all you folks who suggested a new plug, please stand up and gloat. Turns
> out that was the culprit the whole time.
Living with 2 strokes teaches you that. The conditions inside the motor are
completely different than outside.
PMclain
>pep-boys
>> carries bike plugs.
>
>This is one of those little dinky ones. I've seen a limited selection of
>some bike plugs at the auto part stores, but never these little tiny ones.
>
>'86 TT-350
>
Try NAPA. My son has the same bike and we buy his plugs there for $1.59.
Paul McLain
Aurora, CO.
99 KDX200
Steve in CO
Yup, that's where I ended up finding it. They're the only place in Parker
that carries them. It was a little more than $1.59, but still cheaper than
$3.25 the dealer was going to charge me if I drove the 45 minutes away. :-)
Steve in CO
so's a
> little one might not feel that explosive, runaway hit?
No, I think they did it because they were morons. There are many signs of
someone who really didn't know what they were doing on this bike. I found
more stripped out bolts - including the plug - than I've even seen on a bike
before. A lot of missing hardware - host clamps, bolts, etc. Getting most of
it fixed little by little though.