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Old 11-16-2011, 06:33 AM   #1966
oldskool640
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Wow Laramie, really like the headwork. Can't tell from the photo if its a hi-flow head or not. I'm assuming we're looking at the exhaust tracts. Would the exposed sharp valve guide ends be prone to burning over an extended period?

I have a related question for the brains trust. My '99 640 is due for a top end refresh (35k km's) and I intend on doing some performance mods along the way. A rallye cam is going in and I am wondering what can be done to the low-flow asthmatic head. Is a port/ polish and flow the head all that can be done, or is there some other tricks?

Thanks for your replies.
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Old 11-16-2011, 06:44 AM   #1967
Lortdadu
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Are you also planning on putting other performance modifications to your LC4? (Big bore kit, camshaft, etc.) Looks sweet! I hope it performs like you have planned!
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Old 11-16-2011, 12:50 PM   #1968
makazica
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Quote:
Originally Posted by laramie LC4 View Post
finally got a sneak peak at some parts of my new engine rebuild.

ported and polished head...



and my new/old - 43mm Gen 1 FCR....



hopefully one of these days i'll have the rest of the engine to boot....

laramie
'Bout time........

M.
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Old 11-16-2011, 01:00 PM   #1969
juames
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Quote:
Originally Posted by laramie LC4 View Post

and my new/old - 43mm Gen 1 FCR....
FCR? Anything tricky when installing one? I have a line on one for my '02 640 Adv.
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Old 11-16-2011, 01:19 PM   #1970
joe cool
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Quote:
Originally Posted by dirty_sanchez View Post
Bill-

The automobile industry stopped using cut gaskets like the ones used to help seal the valve inspection covers on the LC4 Mill back in the '70s. And there's a reason for it.....cut gaskets are prone to taking on a compression set which results in leaks.

I try not to use cut gaskets on anything that uses a spark plug in our house and use instead...you might guess, one of which ever Gasket Eliminator product I have closest. 518, 515, or even 510 all would be entirely suitable.

Acetoxy cure RTV's like ALL red high temp RTV's don't play well with non-polar fluids such as oils and fuels. The hydrocarbons absorb into and are attracted to the silicone molecules, then sometimes slowly and sometimes rather quickly the RTV breaks down and a leak is born. This is what you experienced. Then there's the small bit of squeezeout that will become dislodged and might come to rest at an oil pump intake location.

Plus RTV's we all use are cured by moisture. As soon as a thick or thin bead of RTV or any other solvent based gasketing product is applied it immediately begins to cure and skin over. If you fiddle around once you draw out a bead of RTV, by the time you mate the surfaces it's already skinned over to the point the exposed product has cured to the point it won't wet out the mating surface which is needed for a satisfactory seal.

Gasket Eliminators have no open time to worry about like you do with the gasketing products mentioned above. You could apply the material, go to lunch, take a week vacation, then return and mate your parts. It doesn't begin to cure until you remove air from the equation...mate your parts and tighten things up.

A little 6ml tube (think small like a tube of Chapstik) of 518 is an ideal thing to have in a tool bag.

The use of Gasket Eliminator does not change the torque specs.

On the inspection covers I dab a thinnish visable film on the top of the head, place the covers in place, then with a bit of blue threadlocker on the hex head bolts thread them in. Once finer tight, I'll go back around and snug everything up, then wipe off any squeezeout to keep the dust from finding a place to call home. Because we're not using an elastic/mildly compressible gasket, arriving at "tight" feels different. I suspect you work on your own bike so you should know how tight...tight is. I've never torqued these buggers with a real live clicker torque wrench.

A head or base gasket can be removed and reused by dressing both sides of the gasket with a thin film.

Careful work with a razor blade will allow you to remove the head or base gasket. Tedius, but I've done it with no real issues.

Once everything is buttoned up, no need to re-torque simply because you upset the seal. Same goes for nuts and bolts with a threadlocker.

My LC4 does not have any sort of oil leak.

Dirty

Dirty, this my 3rd time fixing an oil leak from the rocker shaft o-ring.
took your advice and picked up some 518 hoping this is the last time for awhile.
thanks in advance
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Old 11-16-2011, 02:21 PM   #1971
rxcrider
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Quote:
Originally Posted by oldskool640 View Post
Wow Laramie, really like the headwork. Can't tell from the photo if its a hi-flow head or not. I'm assuming we're looking at the exhaust tracts. Would the exposed sharp valve guide ends be prone to burning over an extended period?
Looks like intake to me based on spark plug angle. I think 2002 was still the low flow. I thought 2003 625SXC started the high flow era. Laramie will know for sure.
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Old 11-16-2011, 03:13 PM   #1972
laramie LC4
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Quote:
Originally Posted by oldskool640 View Post
Wow Laramie, really like the headwork. Can't tell from the photo if its a hi-flow head or not. I'm assuming we're looking at the exhaust tracts. Would the exposed sharp valve guide ends be prone to burning over an extended period?
no it used to be a low-flow but now has the same 32mm exhaust valvesd as the high-flow head.

Quote:
Originally Posted by oldskool640 View Post
I have a related question for the brains trust. My '99 640 is due for a top end refresh (35k km's) and I intend on doing some performance mods along the way. A rallye cam is going in and I am wondering what can be done to the low-flow asthmatic head. Is a port/ polish and flow the head all that can be done, or is there some other tricks?

Thanks for your replies.
port and polish, if your putting in a rally cam you will need to replace the stock valve springs for the '03 and newer rally springs.

Quote:
Originally Posted by Lortdadu View Post
Are you also planning on putting other performance modifications to your LC4? (Big bore kit, camshaft, etc.) Looks sweet! I hope it performs like you have planned!
balanced and lightened crank, balanced counter-balancer, post-polished head, new valves, monster cam, and the fcr-43. if it preforms as advertised, it should have over 70 HP to the rear wheel with close to 55 lbs. of torque.

laramie
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Old 11-16-2011, 03:18 PM   #1973
laramie LC4
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Quote:
Originally Posted by makazica View Post
'Bout time........
M.
no shit. im not exactly happy right now. this has taken a lot longer than expected. in his defense though, this is the first time he has built an LC4 and there has been a learning curve. hopefully we are past that now...

Quote:
Originally Posted by juames View Post
FCR? Anything tricky when installing one? I have a line on one for my '02 640 Adv.
nope, pretty easy and straight forward. do yourself a favor and order the intake boot from a 625. it makes life a lot easier.

Quote:
Originally Posted by rxcrider View Post
Looks like intake to me based on spark plug angle. I think 2002 was still the low flow. I thought 2003 625SXC started the high flow era. Laramie will know for sure.
'03 was the first year for the high flow head. the only real diff is the exhaust valves were 32mm instead of the 30mm.

laramie
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laramie LC4 screwed with this post 11-17-2011 at 04:20 AM
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Old 11-16-2011, 03:38 PM   #1974
BRYANDENNY71
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Got a little bored at work.

New vs. Old Devol stamped guard.

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Old 11-16-2011, 05:18 PM   #1975
dirty_sanchez
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Quote:
Originally Posted by joe cool View Post
Dirty, this my 3rd time fixing an oil leak from the rocker shaft o-ring.
took your advice and picked up some 518 hoping this is the last time for awhile.
thanks in advance
On Clean parts did you draw a bead around the O-Ring Sealing area and then insert the shaft?

The OD of the Shaft and ID of the rocker arm shaft might have too large of a gap for the 518 to cure through. I suspect it very well might be. A suitable RTV would be a better thing to use given the gap we're dealing with.

The last time I had my tank off I noticed some slightly oily dust on the end of the intake rocker shaft area. I wiped it off real good and drew a bead of 598 Black RTV (an oxime cure/sensor-safe RTV) around the end of each shaft. Now I have two little black circles on the end of the rocker arm shafts- They'll never leak again. Motor oil won't break down this type of RTV.

I'm not saying to ditch the 518, but I don't think it's the right product for that particular application. 518 would be a fine choice for Sealing the valve inspection covers, all case assy. gasketing apps., fitting the water pump into the head, sealing the jug to the case or the head to the jug.

Read up on oxime cure vs. acetoxy cure RTV's in the Loctite thread and post up any threadlocking, thread sealing, gasketing, or bonding questions in that thread so the guys who might not keep up with this thread since they don't ride an LC4 can feed their brain as well.

The Official Loctite Thread:

http://advrider.com/forums/showthread.php?t=265016

Dirty
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dirty_sanchez screwed with this post 11-16-2011 at 05:32 PM
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Old 11-16-2011, 05:30 PM   #1976
dirty_sanchez
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Quote:
Originally Posted by laramie LC4 View Post
.......balanced and lightened crank, balanced counter-balancer, post-polished head, new valves, monster cam, and the fcr-43. if it preforms as advertised, it should have over 70 HP to the rear wheel with close to 55 lbs. of torque.

laramie
On behalf of the collective, we will find out where you live and OLS (Occupy Larmie's Street) if you don't give us the full scoop on this engine once you get it back, installed and jetted.

Who's with me!

Dirty
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Old 11-16-2011, 10:23 PM   #1977
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i'll go...


Mine's so stock!!!
b
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Old 11-16-2011, 11:50 PM   #1978
Sumi
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laramie, I have a 2005 bike with the TPS circuit. My dealer offered me a 41mm FCR off from an EXC for a reasonable price.. My only problem is that this FCR doesn't have a TPS sensor.. Do I have to mod the carb, or just go without the TPS - leaving it unconnected? Or should I look for a carb with a TPS sensor on it?
Thanks
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Old 11-17-2011, 04:11 AM   #1979
laramie LC4
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Quote:
Originally Posted by Sumi View Post
laramie, I have a 2005 bike with the TPS circuit. My dealer offered me a 41mm FCR off from an EXC for a reasonable price.. My only problem is that this FCR doesn't have a TPS sensor.. Do I have to mod the carb, or just go without the TPS - leaving it unconnected? Or should I look for a carb with a TPS sensor on it?
Thanks
no, you don't need the tps. i don't run it with mine but my bike did not come OEM with a sensor. i doubt that it would make any diff for you to just leave yours disconnected.

laramie
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Old 11-17-2011, 04:17 AM   #1980
laramie LC4
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Quote:
Originally Posted by dirty_sanchez View Post
On behalf of the collective, we will find out where you live and OLS (Occupy Larmie's Street) if you don't give us the full scoop on this engine once you get it back, installed and jetted.

Who's with me!

Dirty
don't worry. im gonna share everything about the engine, once i do get it back. one of the plans was for him to document the build so that i could share it with the LC4 asylum and drum him up some more business.

laramie
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