I just rebuilt the motor on my 01 660. Second gear broke in the tranny so since I had it apart I put a 12:1 piston, stage 2 hot cam, 04 tranny (the whole thing). Piece of the tranny hit the rod so I put a HOT crank and rod in it. Vitos degree key, aftermarket head pipe, all new gaskets and seals.

The problem is that it will not wind up at all. It sounds fine at idle, then if you barley crack the throttle it starts missing bad. I thought it sounded like a tight valve so I loosened them all up a couple thousandths. Still did it the same. Put a different plug in it to make sure it wasn't fouled, but it was the same. Thought maybe it was way lean becasue the head pipe started glowing when it was idling. Turned the idle screws out to 8 turns from 3 (22.5 pilot), and moved the clip to the 5th notch (was 4th stock, needle I think) from the top down. Still is the same. The last time I had it running for just a few minuets it pushed some anti freeze into the overflow tank.

Also when I put the timing chain back on the dots were not exatly lined up it was slightly clockwise, I figured it was from the degree key. I moved the chain a tooth and it was worse so I put it back to what I thought it should be. Are these lined up perfect with a standard key?

I think the head gasket is leaking but I guess I want another opinion before I tear it apart again. Also I was thinking maybe it could be something with the decompression pin. When I loosened the valves a little, I cranked it over with the plug out on the exhaust valve and I could see the extra bump on the exhaust valve and it went back down. Looked like I think it should.

I didn't put any sealer on the head gasket, maybe that was a bad choice?

If this is what it is what is the best brand of head gasket and sealer?

I have not leaked it down yet, waiting for it to cool. Not sure I have the right adapter for the plug anyway, but if I do I will do that. That may tell me more.

Anyone had a similiar problem?

 

Ya know what...Id help ya out but ya know more than me. Never been past the valves.
good luck...

 

I don't have one of these things but I will give it a shot based of the symptoms.
From the symptoms it sounds way retarded. Can/could you have put the key in wrong? I know on my V you can.

#2 could be lean. They both cause heat to build up quick.

You might also check the oil and see if there is any coolant in it. Sounds more like a timing issue though. It could be a million other things also.

 

If you change to a #25 or 27.5 pilot, your head pipes will stop glowing at idle.

If the auto decompression pin was in wrong, you would hear a loud tapping sound.

I doubt if the problem is the valves or timing. The symptoms wouldn't be that extreme.

Could the problem be the reverse limiter or the parking break limiter? Check the sensor connectios and clean them. Can you get any RPMS at all?

Don't use any head gasket sealer. It's not needed. Did you use a stock or aftermarket head gasket? Where is it leaking?

What main jets are you running? Is your lid off? Is your head ported?

You should try a few more things before tearing it down. I usually notice the head gasket spueing some drips on the out side after a build. I used a cheap (Tusk) after market head gasket once and it blew right away. If you used Cometic or Yamaha, then you are proabably OK. If it is really blown, then it will fill your coolant reservoir to the top and bubble when you reve the motor. It will also make your oil reservior over flow.

 

The main jets are 150, 152.5, which may be lean yet but I figured I could run it in the shop with those. The lid is off, I tried choking it some to see if it would get any better and it didn't. The head is ported a little, all I did was clean the intake boots up, thinned the divider for the paired valves at the very begining of it, and smoothed a couple casting marks up. I didn't really remove any material.

The gasket set was a K&S. The motor has run about 15 min. now and it filled the overflow resivoir up all the way. I wasn't sure if it maybe had an air pocket in it and that boiled a little of the coolant?

The degree key can be put in wrong but it actually had directions that I followed. Put it in the way it said. It was getting late when I put the key in so I could have done it wrong.

The oil resivoir has not overflowed though.

The rpm is about the same as the reverse limiter, maybe a little less, but this one does not have that. It'll go faster in revese than it will in first gear. I should say, if it has one it does not work. If I was guessing I would say it runs to about 2000 rpm at the very most.

Still need to do the leakage test.

 

Sounds like your main jets are right with the lid on. With the lid off, I would start at 170/175 with the needle in the middle position. #25 pilots. This probably isn't your problem though.

Check the sensor connection behind the front sproket. Mine had the same symptoms you described and the problem was this connection.

If you can get it to rev up, look for bubbles in the coolant res. That's a sure sign of a blown head gasket. It happend to my and I had to tear it back down. It sucks. It is suspicious that it is full. 12:1 does not show mercy to head gaskets.

 

you blew a head gasket. when you rev up the motor and it starts popping, does your reverse light flicker on and off? on the left hand of your bars (clutch side). their is a wire connected to teh clutch(its actually the parking brake rev limiter) chase this wire down behind the left head light, (its a two prong connector) unplug it. its your motor make any loud unusual noises? i would change the jets and fatten it up.

 

I checked the two wires by the front sprocket and they both seem ok. The reverse light comes on with the lower one, which that also works fine when I put it in reverse. The upper one was not that dirty but I cleaned it up any way.

The reverse light does not flicker at all. I have not heard any unusual noises out of the motor, just misses.

I'll check the parking brake wires.

I don't have the right adapter for my leakage tester so I can't do that. The oil in the tank looks normal after it sat for a while, but the radiator is low on coolant again.

 

When the head gasket blows, it pressurizes the radiator. This forces coolant into the reservior and puts air into the radiator. It don't sound good for your head gasket. But, you should still be able to get above 2000 RPMs.

 

It can be a real b!tch to get the timing just right with a degree key. When I put mine in I set the mechicanal timing with the flywheel off, meaning I put the cam in and the chain on and lined all the dots up according to the book then I adjusted the valves at the same time. Then I put the flywheel on and buttoned everything up. Not sure if thats part of your problem but the dots should be aligned perfectly. If your running a 12:1 then I would suggest the cometic head gasket with the fire ring, it works very well but you have to special order it, take about a week to get made. I always use a very thin( very, very, very, very thin layer of ultra copper rtv on both side of the head gasket) if I am not replacing it all together. I have taked the head off after running it for a short time after a new rebuild with problems. Just boil the gasket in water for about 15 min then put the thin layer of rtv and it will work fine( thats with a cometic, and stock yamaha), of course if you have alot of time on the motor just replace the gasket.

But back to your problem, double check the timing, pull the head to check the gasket just to be safe.