I wouldn't be to quick to tear that engine down. It may not even be broken in yet. If you do tear it down, I would recommend that you try to match up some OEM Honda stem seals. I would bet they are better than the Chinese copies. All other parts, I would go with Raceway. As you can see, John is on top of these quads and has already chimed in above to let you know that Raceway has the parts. There service is unmatched!

Shawn

B.T.W. I have mine running again. It is purring like a kitten. I installed the new head, used assy. lube on the new cam assy and adjusted the valve to .003". I started it up and let it run for about 8 minutes at a high idle to break in the new cam. I adjusted the valves again and changed the oil. My kids went for a ride and it sounds great. Seems to be running the best it ever has. Much crisper response and a smoother idle.

 

Hey, I want to thank everyone in this thread. My son also has the 90 with about 15 hours on it. Same symptom. Quad just stopped, about an acre away from the garage..... Needless to say we pushed it back and I first thought it was a gas issue.

I won't go into the troubleshooting, but the flow followed exactly what was stated previously. I put a call into John at Raceway (where I puchased the bike) and he gave me a short email on adjusting the valves.

Now I'm pretty mechanically inclined but I've never attempted to do this before. So I'll let you know how it works out tonight.

But thanks again for a great detailed writeup on the symptoms and fixes. I was out of ideas and was getting a little upset until a google search hit this thread.

 

Ok,

I've now confirmed that I have a broken rocker arm. I've spoken to John and he has a replacement head coming for me. I have a few questions before this thing arrives. I've spent a few hours on "how things work.com" learning about the workings of a 4 stroke. Like I said before, I'm pretty mechanically inclined but I've never attempted this.

1. I've taken the bolts off the head (carb, exhaust...) and the only thing left that I believe is holding the head to the lower block is the timing chain. On the sproket for the timing chain there are 3 bolts. These have to be removed I assume to get the head off. Is it as simple as that? Then put the other head back on then place these three bolts back into the new head for the timing chain? Hoping that the lower part of the chain doesn't come off of that sproket.

2. I don't think the engine has to be pulled from the chasis. At least it doesn't look like it. Right?

3. I have fresh Amsoil, I assume when u do something like this it's a good idea to replace the oil as the new head will have fine pieces of metal that may shear off after the first run.

4. The valves should already be adjusted and there is no need to adjust the valves or lub them right?

5. I shouldn't have to use any gasket goo, just make sure the two pieces of metal are clean of debris before placing the seal on.

Is that it? Anything I missed or helpful hints will be greatly appreciated.

Thank you,

Scott[img]i/expressions/face-icon-small-confused.gif[/img]

 

If you give me a call tomorrow I would be happy to go over all of this with you! You are pretty much on point!

 

you'll have to make sure you keep it in time.. Look at the stator cover, it's the cover on the side of the motor same side as the sprockets. You'll see a small chrome screw about the size of a nickel. Take that screw out and you should see a few marks on the stator. Make sure the piston in at dead top center, and the marks should be visable thru that hole. Then with that mark visable look at the cam sprocket there should be a mark at the 12 oclock position. When both marks are lined up, grab the rocker arms and they should have play to them.. Now take the bolts off the cam sprocket. I always tie the chain up so it won't fall into the motor...

later,
Chad

 

Accessing the engine in this frame is more work that the top-end rebuild. About the seals: this motor appears to be a variant of the CT70 engine. Are these the valve guide seals you are recommending?

As for the rest of it; I am going to give it a bit more time to see if the light smoking is related to the piston rings bedding in since I have a 125cc pit bike that is behaving in a similar way without the deceleration smoke.

 

ok, so after a 4 hour experience this is what I've learned:

Symptom:
Falcon 90 won't start (read reefskinner's symptom, same issue)

1. Called Raceway and spoke with John and explained my symptom. No problems, after learning what was wrong I had a replacement head shipped to me.

2. Week later I receive the new head and I begin to research (www.howstuffworks.com, excellent resource). I'm pretty good mechanically but have never tried this before.

3. You can not remove the head from the 90 without swinging the engine. I of course found this out after 30 minutes of studying how I could. So I removed the four bolts and the one rear bolt that ties the engine to the frame. I cut the electric wire strap and got enough play in the wires to swing the enigine enough to remove the head.

4. The timing chain was a bit tricky. Thanks to the earlier post of securing the sprocket before removing the head. I did not want the chain coming off the lower sprocket in the block.

5. After securing the chain, the head comes off pretty easy. You have the 4 top bolts and the side screw securing the head. Plus you have to remove the carb and exhaust. Pretty easy.

6. Put new gasket on and made sure the washer for the oil outlet is set and put the new head on. The cam was in the same position as the original cam, so timing was not an issue. There is also a mark on the cam sprocket which denotes TDC. So that made it a bit easier too. I am/was a noob, so TDC means Top Dead Center. Your rocker arms should play a little since both valves are closed at this setting. I read other posts about TDC and didn't have a clue, hope that helps.

7. Getting the timing sprocket on the new cam shaft was probably the most difficult/PITA. Not sure if there is a trick or not, but I used a flat head and was able to move the sprocket onto the cam shaft by gently wedging the flat head on the sprocket and moving it towards the front of the bike. There are 3 screws that secure the sprocket to the cam shaft and while putting preasure on the screw driver I was able to finger tight the screws onto the sprocket. Hard to explain, but if you see it for yourself you'll understand what I'm talking about.

8. Secured the engine back to the frame. Put the four bolts on the bottom in frist, that will line up the rear bolt.

9. Reconnected carb and exhaust.

10. With valve covers off I disco the plug and I hit the starter. I adjusted the valves so that the rocker arms were nearly touching the cam shaft. I read somewhere there is suppose to be a .003 space there. You can't get a spacer in that little of area so I used my best judgement. .003 is pretty thin so there is like a paper thin gap between rocker and cam shaft. I hat the starter and watched the valves operate. Pretty cool.

11. Put the plug in and hit the starter and boom.... One nice firing 4 stroke engine once again.


So everyone is happy once again...until......

Not more than 5 hours running time I started to hear a rattler. I checked all my work and I found a new issue. The exhaust pipe is cracked right where the smaller pipe goes into the muffler. It's cracked all the way around and essentially is useless. Pretty loud from the engine and the rattles.

So, John any chance I can get a new tail pipe assembly? This will obviously be much easier installation, but until I can get one I asked the boys to not ride it. Pretty darn loud and I don't want to cause any friction with the neighbors.

Long post, but it was a long job.

 

Haven't been on here in a while, been busy. My kids 90 seems to be okay for now. They haven't ridden it much, so time will tell.
Injuhneer,
Yes, I would try to match them up with Honda CT parts. I am pretty certain they will interchange with one another.
bowhun2r,
Glad you got it running again. Bummer on the exhaust pipe.

 

Give us a call we will take care of it!

 

Hollar at me if you still need a pipe I have my boys I pulled off maybe as 1/2 hour ride time on it, our 1st pipe crack just like yours. I put a after market on after getting the replacement pipe under warranty.