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Discussion Starter · #21 ·
really, thanks so much, i love you guys too-

anyway, i got down to the head, but won't be able to compress the spring until tomorrow. and since i'm right there, does anyone have a line on some new rings to fit the OEM pistons?

what i've seen so far: (jb, my camera is at the garden right now)

there doesn't look to have been any contact between the valve and the head.

the intake valve in question looks to have a face that's seating a little closer to the head than the "good" valve face. which i'm thinking doesn't differentiate anything...tuliping face or recessed seat or i suppose even a bent valve if it's not the same all around?

the other odd looking thing is that the spring seat looks like there could be a problem or just some rough machine work...thin little bits of metal where the spring seats are sort of rolling away from the spring...kinda like what you see on the underside when you drill thin sheet metal or aluminum too fast with a bit that's too big. there's some evidence of this at the base of the other springs, but it's more pronounced on the problem valve. but if the spring were digging into the head, i'd be gaining clearance instead of loosing, right?

the cylinders look pretty good, no ridges, no scoring but i'm burning oil on the right side which makes me think i should slap new rings in while im there?

anyway, chris i'll try to bring a sorted bike to summit.

night guys, and thanks again-
tt



Edited by - ttilghman on May 29 2007 11:16:11 PM
 

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TT,
The spring seats wouldn't effect valve clearance...they'd just make the spring a bit weaker. And yeah, the machining in that area is usually kind of sloppy. You know there typically should be an actual "spring seat" in there...a steel washer that fits between the bottom of the spring and the aluminum of the head.

But anyway...spring problems wouldn't cause your symptoms. Picture the valve as a string (that doesn't stretch) with a knot on one end passing through a hole that is too small for the knot. The knot represents the valve head...the hole represents the seat. The only way for the string (valve stem) to move farther through the hole is if the hole gets larger...or the knot gets smaller.

If the bad valve head is recessed into the head noticably more than the "good" valve...then you have probably located your problem...now you just have to find out what cause the problem. There can be small differences....say one seat was cut a bit deeper than the other to take out some imperfections, but usually that difference can be adjusted for at the tappet. A continually changing clearance points to the valve sinking farther and farther into the head.

Which as Chris pointed out...could still be a bent valve pounding itself back into square with the seat...or pounding a dent into the seat. Won't be able to tell much until you get it apart. But don't fret...probably not a hard fix if you have the spares.

You'd be amazed just how much power is to be gained by properly setup valves and seats. When I rebuilt the head on Mary's bike it was literally twice as hard to turn over the rear wheel by hand due to the decrease in leak down. On an FCB bike, a real nice proper valve job can give you a big edge over the competition. It's a very often ignored aspect of engine building. I'd say the average honda twin loses more compression past the valves than past the rings. For about $300 and a little practice you can be cutting your own primo valve seats and lapping them for about zero leakage. Not to mention proper valve to seat contact helps keep the valves cool by transfering heat to the seat like they should.

I'm no expert at it, I often don't get the width of the contact area set properly (too wide and it doesn't seal well enough, too narrow and it doesn't transfer enough heat) but I get them close. And I can suck on the ports and then seal them with my tongue and the vacume will hold the valve closed. Of course that requires a nice stem to guide fit...and I have a nice set of reamers for that, and I make up my own guides from Ampco45 blanks.

You'd be surprised how much of this you can do with fairly inexpensive tools and some patience.

Too bad we don't all live a few miles from each other and have some giant ass warehouse rented with all our bikes and tools there. We could build some serious machines with all the various expertise in different areas among this crowd.
JohnnyB
 

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Tim
Also check your valve guide shape to make sure it's not slightly oval and valve to guide fit. Take a really close look where the head meets the valve stem. Someone borrowed my 350 for a quick blast once and didn't know the shift pattern. Over-rev led to slight bend but must have weakned the weld and the head dropped off soon after at Frontierland.
You have to be careful comparing something with a tulip when talking to a gardener- of course they will assume it to be growing :)

Evil- Still have that head in the pre-crashed spares box. Pretty odd loking.

The really weak valve spring idea was shown to me a while ago. Can't check for some things like clay can but with a degree wheel mounted you can see clearance at any position of lift lift.
bfd
 

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what size rings? i probably have a spare almost comlpete set of 040's. you might need to order one compression ring. if chris doesnt care if i give them away. i kinda left him all my spares. and i know there was an almost complete new set. tim, you should drop chris a note, or give him a call. hell have 2 350gp bikes at summit. so no guarentee....

jc

jc

"tex, if your bikes a cheater, its not a very good one"
 

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Discussion Starter · #25 ·
bfd-

thanks i'll keep an eye on the guides.

joe-

stock pistons, but thanks. and i want to do every thing i can before i look for a loaner...i want to kick your fancy new bike's ass with my POS clapper.

-tt



Edited by - ttilghman on May 30 2007 12:11:47 PM
 

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" want to kick your fancy new bike's ass with my POS clapper"

damn timmy - that's way to easy.

Sotomoto

"Dude just connect the dots on the track and you'll be ok"

Edited by - alskee750 on May 30 2007 7:35:48 PM
 

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Discussion Starter · #27 ·
guys-

springs are out. valve seat is just a floatin' around in there loose as can be. also the valve face is pretty wobbly warped. on the other side, the "good" intake valve just slipped right out of the guide once the keepers were off and i've been buring oil on that side....any chance that's where i was oiling instead of blaming the rings?

i just picked up a head from a CL350, it's the same head as the CB right, just a different cam? i guess i can compare valves as easy as anyone elese?

thanks again to all you guys, i'm sure i'll have more questions as i start to get things back together. i'll check the valves/springs/seats on the new head and lap them all in. what elese.

oh, and on the cam, the intake lobes show a bit of pitting and some discolorization at the tips. am i wearing through the heat treatment, nothing looks too bad to put back in but i don't really know anything?

thanks again-
tt
 

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hey floaty mc valveypuss.... stock cams are the pitts... they get pits in em. make sure the overall shape is smooth also check out the rocker faces too. put that other head on and jump some curbing dude.

watch out for those hillbillies and their moonshine.. I heard jc runs the shine instead of c12....



latered
 

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HAH!! ! !! !

I told you it was the seat floating!! Didn't I! ! ! !

Usually pretty rare to have a problem with an intake seat. Evil, your bike was running a sloper 175 head....exhaust valve seats will drop out of them if they get too hot...usually because of poor contact with the head pipe or lack of a "finned" clamp of some sort. Very important to keep the exhaust port area as cool as possible as it draws the heat out of the exhaust valve seat.
 

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Discussion Starter · #30 ·
monkey-

thanks for givin' me back my mojo. let's go later the lwsv grid next week.

EVIL, you win the prize. and i'm simply overjoyed i found this before it lit the fuse. i think i'll start drinkin'.

lonejaquar, i'm lookin' for you and that TEX boy.

3widemonday-
tt
 

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"Usually pretty rare" doesn't mean impossible.

Evil...even a broken clock is right twice a day.


TT, if you dropped an intake seat like that....unless the head was total crap when you installed it...then you need some attention somewhere. Seats usually losen up because the head gets too hot, similar to the same process of heating a head to install them.

If you run a fairing, or have anything that's obstructing air flow to the head try to change it. Also...run a synthetic oil if you aren't already. Open up your valve clearance to .004" to make sure that valve is seating nicely and combustion gasses aren't sneaking by heating up the seat.

Valves will often slip right out of the guide after some use. Slide the valve down about 1/2" off the seat...try to move it back and forth...any noticable movement and the guide is probably shot.

Typically smoke on accleration is rings, smoke on deccerlation is guides/valve seals.

Eventually you gotta start getting out the mic's and checking clearances and specs on the parts you use. Sorting through used spares you can often find some nice stuff if you check them carefully.

JohnnyB
 

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TT
You're right, the top end on all the 350's are the same except for the cams. SL's usually have lot's of decent spares (except cams) because they were too big and stupid for woods riding.
bfd
 

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cool, good find. see you at summit with tex, on the inside at t-1!!

free beer for any wanker who beats tex.



jc

"tex, if your bikes a cheater, its not a very good one"

Edited by - joe c on May 31 2007 08:39:47 AM
 

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Discussion Starter · #34 ·
guys-

thank you all for the help. the bike is better than it's ever been. starts super easy, holds an idle, is crisp on the throttle though the whole rev range, and launched like it never has on a practice start. for those of you who've never seen the back of my bike, it has a solid gray bumpstop and i'll be wearing Rev-It leathers with a white helmet.

T1 bitches-
tt
 

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You go man go. I know you will not read this until you are back from summit and NH...so, take a picture of those trophies and post them. This seals it, I am going to spend July/August taking apart the spare engine and making sure all is well internally. I already found that the cam chain tensioner wheel looks like a sprocket with all the flippin' chips in it.

Pete

Yeller'
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Ask not what the wanker can do for you, but what you can do for your wanker!
 

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oh...and tim forgot to tell you guys that No225 now has float bowls from the wankermobile No223. So if he wins, I get a .25 point of it! lol.

Yeller'
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Ask not what the wanker can do for you, but what you can do for your wanker!
 
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