2000 Cr 80

[showtime586]

I picked up this bike for my son to ride on. He outgrew his 60.
Anyhow, this bike makes an aweful sound from around the exhaust manifold. When the bike is revved, you can see the motor separate from the pipe. The spring is tight, and I have used the Hi-Temp orange sealant, but it still separates. Honda used some type of little metal sleeve to seal instead of the standard "O" ring, but it doesn't seal. There is a distinct (very annoying) rattling sound when he rides it.
Also, (As if that was not enough) there is some "growling" and vibration coming from inside the head. It may be normal piston noise, but it is louder than my 2002 RM 250, and the RM has no vibration. The bike was completely rebuilt before we got it, but something does not sound right.
If anyone has any ideas, it would be greatly appreciated. I have ZERO experience with Hondas, so I am in the dark as to what is normal for these bikes. Thanks.:)

 

[DRZ_Dad]

I would guess excessive clearance between the piston and cylinder, those symtoms sound exactly like what my sons was doing, except the piston skirt would break after 2-4 hours ride time

I sent the cylinder and head to Eric Gorr and got the big bore kit.

 

[showtime586]

Thanks for the reply.
This motor was completely rebuilt right before we bought it.The previous rider had it lock up on him and decided to move to a 125. The rebuilt bill was around 1300 dollars and just about everything was replaced. I guess I need to pull the top end to take a look. I sure don't like the fact that I see the motor move upon acceleration, but the motor does not have a top motor mount bracket to hold it on place either. Just no Honda experience to go on...............:)Thanks again.

 

[Bodge]

It dosnt have the top too motor mounts? Are there holes for them or no? How is the power output?

 

[DRZ_Dad]

There are no top motor mounts on a 00 CR80 just the two on the lower down tube, and at the swing arm...

My guess on the earlier post maybe totally off, And if you trust the person you bought the bike from I prolly am off, for 1,300 bucks something seems a little strange to me.................

 

[showtime586]

When I bought the bike, the dad gave me the invoice on the repairs. It was quite extensive. The boy basically rode it when he was actually "borderline" to big for it, and it had seen several hard rides.
The sound literally drives me bonkers when my son rides it. The rattle and growl makes the bike sound like it is getting ready to grenade. Should there be ANY movement visible in the motor upon acceleration?

 

[DRZ_Dad]

I have never paid attention to my son's as far as motor movement, but I cannot see where any visible movement should happen,

Sounds to me there may be a gap in between the motor and swingarm, like maybe the washers/shims were leftout. or maybe the frame below the motor is cracked.

 

[showtime586]

To satisfy my own curiosity, I took the exhaust system off and started the motor briefly. Even though it was very loud, most of the noise seemed to be gone with the pipe removed.I did feel some vibration coming from the head, so
I went ahead and took the top end off just to be on the safe side. The cylinder is not scored in any way. The piston has some carbon build up on it, but not what I would call excessive. The ring looked okay as well. The only thing I am unsure about is there is a bit of play in the rod itself. I have a service manual, so I need to check and see what the tolerance is. I'll post back with some more info. Thanks again for the help.

 

[DRZ_Dad]

Well, I can tell you on my sons the plating looked good to me, but I am by no means a real mechanic, but after the piston skirt broke for the second time, I sent the cylinder and head to E.G. he said the plating was gone, way too much play between the cylinder and piston, Now this may not have anything to do with yours, but that was our expierance. If you have vertical play in the rod that aint good.

 

[showtime586]

Hey DRZ,
I have a little bit of wiggle at the small end of the connecting rod. According to the repair invoice May of 2002, this motor has a new crank and bearings. The side to side movement, between the crank and the crank weight, is well within tolerance, but I am a little curious about the wiggling of the rod at the small end.

 

[Rcannon]

Did you replace the exhaust gasket on the bike? There is a flat gasket for the manifold (tin colored) and there is a black gasket that slides inside the pipe. We have had several of each go bad on the 2002 CR 80 I have been working on.

If the pipe gasket was bad, I would imagine the pipe would move a great deal.

 

[showtime586]

The tin gasket was there, and I replaced the metal sleeve a week ago, but that did not stop the noise.
The piston and ring look fine. I still cannot fathom that this 80 would have more cylinder chatter than my RM 250.

 

[showtime586]

Installed a new top end kit. Most of the vibration and extraneous noise went away. The old piston and ring looked fine, but I replaced them anyway. What I think I hear now is a whine from the main bearings. I have had them go bad before, so I am familiar with the sound.
This bike had over a grand spent on a rebuild right before we bought it. The repair invoice shows a new crank and bearing. We have not rode this bike enough to need new crank bearings, but I guess it is what it is. :ugg:

 

[Bodge]

Go back to the shop where the work was done. The crank bearings wining? Id grip the flywheel and see if it has any play.

 

[showtime586]

The kid who had the bike raced it for a short time after the rebuild. We bought it when he moved to a 125. He rode the bike until he was too big for it, and he rode it hard. The shop knows him and in all likelyhood wil associate any mechanical problems with his racing endeavors. If the whining is not bearings, but just normal 2 stroke engine noise, I guess I just have a very annoying cr 80. My son does not race much anymore, he just playrides, so we can probably get by with it until I tear it down this winter.