Jetting the Flat FCR carb PART DEUX. DISASTER STRIKES!!!!!

While making the carb jetting tutorial featured at this link horrible disaster struck.

While removing the top plate of my carb, i dropped one of the allen head screws. In an effort to push forward, I decided to find it later during re-assembly, and continue taking pics for the jetting tutorial.

After i was done with the pics, i i looked around the nooks and crannines of the bike...not finding it. I humped the bike off the stand, and rolled it forward to get it out of the work area...so i could look around the garage floor. Unknowingly, the bike was in gear...i pushed forward, hearing the engine turn over, then lock..my rear tire skidded to a stop...

and it dawned on me.

I KNOW WHERE I DROPPED THE SCREW!!! :p

I immediately roll the bike back, unhook my subframe, and using a magnet retriever, fish my screw from the intake port of the engine, middle valve. DAMMIT DAMMIT DAMMIT!!! the threads of the screw are buggered up BAD...meaning it got pinched in the valve, and did God knows how much damage.

Fast forward 12 hours to friend and fellow dental student, and TT member Just034's garage. He has never taken off a head, but he HAS done a valve job before, so that means that his expertise far outweighs mine.

we drain all the fluids and start dissasembling.... find TDC and we mark our chain.

http://www.planetblade.com/arins/bike/disaster/a.jpg

Hey, my spark plug looks pretty good at least!

http://www.planetblade.com/arins/bike/disaster/b.jpg

we get the head off and my worst fears are realized. The valve seat is dinged up...and so is the top of the piston head.

http://www.planetblade.com/arins/bike/disaster/c.jpg

http://www.planetblade.com/arins/bike/disaster/d.jpg

http://www.planetblade.com/arins/bike/disaster/e.jpg

the valve wont hold acetone that is poured in the intake side...it doesnt seal.

We make a valve compressing tool from a deep socket with a window cut out, and a large C clamp. This allows us to remove the valve retaining wedges, and remove the valve.

http://www.planetblade.com/arins/bike/disaster/l.jpg

This valve is bent badly.

http://www.planetblade.com/arins/bike/disaster/g.jpg

And the valve seating surface is buggered up good, notice the galling right at the seating surface.

http://www.planetblade.com/arins/bike/disaster/f.jpg

http://www.planetblade.com/arins/bike/disaster/h.jpg

SO, its off to yamaha store to get new valve, and autoparts store to get valve grinding compound. Mind you, this is further than either of us has ever been into an engine. Im scared, Just034 is excited (he's crazy).

Seating the new valve in the head doesnt pass the acetone test either, it leaks, the seating surface of the head needs to be refinished. We use a cordless drill, with a piece of vent tubing chucked into it...we seat the valve, slide the tubing over the valve stem, so we can spin the valve against the seating surface of the head...we add grinding compound, and spin it...applying moderate force to the spinning valve.

After that, we finish up with some red rouge, mixed with grease, to put a nice finish on the seating surfaces. and i dremmel out the big gouges in the aluminum head. not so shabby anymore eh?

http://www.planetblade.com/arins/bike/disaster/i.jpg

We reseat the piston, and it passes the acetone test...it seals. thank God.:applause:

http://www.planetblade.com/arins/bike/disaster/j.jpg

I grind the burrs off of the piston head. and we reshim my valves the poor-man's way....with a diamond hone and a digital caliper...shaving the shims down until they are within the specs i need.

http://www.planetblade.com/arins/bike/disaster/m.jpg

We button up the engine, i take the bike back home and finish assembly, and it fires right up, exactly 24 hours from the time i lost the screw... and whats even better, my new jetting feels good too!

:ride:

thanks for watching.

Excellent repair...

"Im scared, Just034 is excited (he's crazy)."

of course he is excited, it is not his motor that is needing the work done.

My question is whether or not the gouges adjacent to the seating ring are going to collect carbon faster than the rest of the head. Only time will tell i guess.

good job. sounds like you pulled together well and fixed it.

Holy Shade-Tree Mechanic Batman! And I was impressed with the time you spent with the carb write-up. If it had been me, I'd still be sitting on my garage floor weeping like a little girl. This is going into my personal maintenance archive. Very nicely done!...SC

If it had been me, I'd still be sitting on my garage floor weeping like a little girl.

you have NO idea how close i was.

Good job, cooler heads prevail. I think I would have started smashing my head with a hammer!

Yeah I would have became emo. Good job keeping your head together.

My question is whether or not the gouges adjacent to the seating ring are going to collect carbon faster than the rest of the head. Only time will tell i guess.

Hopefully, it will. Now just hope the damage in the piston wasnt on the very edge and if it was, it didnt pinch the ring land hindering the rings movement. Otherwise, you will end up with a vertical score in the cylinder and maybe a broken ring which will leave a real deep score in the cylinder

We button up the engine, i take the bike back home and finish assembly, and it fires right up, exactly 24 hours from the time i lost the screw... and whats even better, my new jetting feels good too!

Good wright up...... bad luck! :p

But did u replace the screw?? !! :applause::ride:

Good wright up...... bad luck! :p

But did u replace the screw?? !! :applause::p

nope! ran the screw through the appropriate sized die, and straightened out the threads...

:ride:

Toyota tech, check this picture and YOU tell me if it is too close to the edge of the piston.

http://www.planetblade.com/arins/bike/disaster/e.jpg

Very nicely done.

Good tip about honing the shims. I never would have thought of that, and it makes perfect sence. It's not like I'm ever going to need to go up a size once my shims need to go smaller.

after re-sizing the shims, and putting it back together, we rechecked the valve clearances, and they were spot on.

Seating the new valve in the head doesnt pass the acetone test either, it leaks, the seating surface of the head needs to be refinished. We use a cordless drill, with a piece of vent tubing chucked into it...we seat the valve, slide the tubing over the valve stem, so we can spin the valve against the seating surface of the head...we add grinding compound, and spin it...applying moderate force to the spinning valve.

After that, we finish up with some red rouge, mixed with grease, to put a nice finish on the seating surfaces. and i dremmel out the big gouges in the aluminum head. not so shabby anymore eh?

I didn't realize that you could use a grinding compound to finish the seats with a coated valve. I thought that it might damage the coating used on the Ti valves.

I didn't realize that you could use a grinding compound to finish the seats with a coated valve. I thought that it might damage the coating used on the Ti valves.

Just checked the manual. I guess it doesn't matter that the valves are Ti, the valve face/seat still needs to be lapped. I should have checked before posting.

Its a good point you bring up...because i would imagine that under normal lapping conditions, you would not break through the coating...i do believe however, that i went throught the coating while doing the aggresive grinding that was necesarry to refinish the seating ring.

You may end up with that valve leaking a bit or receding into the pocket but it probably wont happen for a while. The Yamahas can use such soft valve springs that they live a little better than the Hondas, that and the cams arent as aggressive because they run three intakes instead of just two. That and the valve seats arent as hard as the Honda's either. You'll probably sell the bike running just fine before it develops a problem.

By the way, your plug looks rich to me..not horribly rich, but rich.

The nick in the piston is of no consequence. The impact came behind the ring land's inner wall. I doubt the land suffered any distortion.

ARin is my hero and should run for president.

I especially love the poor mans way of doing things. That I can relate to.

amazing story, I'm going to be super super careful now when I change my main jet this weekend.

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