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Discussion Starter #1
I've repeatedly read online that you can't mill the head 'cause of the gear-driven cams. But the idler to the gears is IN the head, so milling the head a teensie bit isn't any big deal. Don't know whether there's sufficient metal there to make much difference, but is sure looks like one option for a small reduction of squish.
 

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tls and r have chain driven cams..unless I am reading this wrong...
 

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Discussion Starter #3
Chain from crank to the idler, gears from idler to cams.

But for some stupid reason for all these years I thought the idler was in the cylinder, which would not have been a very good idea...but it's not, so I can mill the heads a bit, which should be easier than milling the cylinder base.
 

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The cam drive system won't be a problem, but you will retard valve timing by shortening the distance between the cam chain sprockets. The gear drive portion won't be affected either way. I'm sure Art will know for sure:thumbup

I don't see how it really matters what you mill, although a cylinder would be easier I would think. You don't have to worry about re-shaping the combustion chamber and its pretty reasy to chock one up in a laythe and turn it down on one end (disclamer: I've never tried it with a TL cylinder - this is just in general for single cylinder castings......).

have fun
 

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The hard part about milling the head would be if the machinist didn't notice that the top parting surface isn't parallel to the cylinder-side parting surface. Depending on the milling operation he uses and how he sets up his datum, that could make an expensive paperweight. A little bit wouldn't hurt a street motor, but you're also reducing chamber size and creating a shrouded band around the top of the piston. Rule of thumb is remove enough material at the deck to remove any corrosion pitting and give the gasket a good surface to mate to.
 

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You can mill as much as you like off a head and it wont help with squish :coocoo

The only way to play with squish is to get the piston closer to the top of the cylinder. The easiest way is to drop the cylinder down into the crankcase by altering the thickness or removing the base gasket. (If you need more, then removing material from the base of the cylinder. I don't know if you can do it to the TL, but taking material from the top of the cylinder works too - not all engines have removeable cylinders like the typical bike engine.)
 

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Milling the head does not move the piston any closer to the head. So no squish clearence change. It does make the combustion chamber smaller and rise the compression ratio up. It does put slack in the cam chain. You can mill a head down until you get to the intake valve seat or the head gets too thin, which ever comes first.
 

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Discussion Starter #9
Good point! So within limits I can have some independent control of compression and squish. I just sold N2hweelies' old '97 heads and just stripped down some other late-model heads. I just now realized the squish area of the head is flat with the sealing surface to the cylinder. On my old Honda 750 SOHC it wasn't. These do have some radial side play in the guides, but I didn't put a dial indicator on to try to measure how much. I was thinking of porting them a little bit around the guides, but can't do much to the roof 'cause the wall to the corner of the valve spring base is already pretty thin. Sure would be handy to have the right kind of calipers to measure that wall as I go... And I need to leave enough meat to hold the guide of course. If I'm going to get those Ferrea intake valves I guess I should put them in first and then measure the play in the guides?

I notice my cam caps have "7" painted on them on one head, and "8" painted on the ones for the other head, so I'm being careful not to mix them up. But is there any matching marking on the head? I ask because the seller removed the cams before selling the heads, and it might be nice to confirm he put the right caps with the right head. Not much wear at the cam journals.

I might just have the PAIR holes welded up. Should be pretty cheap.

So what is the finish on the cylinders and heads? Is that just how the castings come out, or is it painted or anodized and dyed or something?
 

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Discussion Starter #10
...altering the thickness or removing the base gasket...
Art suggested some stock-bore gaskets from the Yosh race kit were thinner..are they still available? Thru what, Suzuki or Yosh? Anybody got a part number? Who makes custom thinner gaskets?

If I remove the cylinder base gasket completely, can it be sealed with some sealant or is it better to have it o-ringed, grooved for a soft metal o-ring or something? Seems to me that would cost more than just milling it.

I'm going to do both, take a little off the head and a little off the cylinder base.

It would be nice if I can still get acceptable compression for aftermarket cams with the cheap flat-top Wiseco pistons.
 

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The Suck, Squeeze, Bang, Blow Moderator,
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I always machine the barrels, more reliable than reduced thickness/no gaskets.

On my 1040cc engine the squish started at 1.05mm with the +2mm JE Pistons, stock TLS/TLR's are usually about 1.4mm

1.0mm Squish is safe for stock rods and generally no less than 0.9mm for aftermarket rods.

I'm running Arrow rods and reduced the base flange of the barrel by 0.15mm to get from 1.05 to 0.9mm Squish

In the last picture you can see the squashed lead used for measuring the clearances.







 

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Hey Fiche-man, nice work! Learned how to mount up a barrel with a mandrel on the face plate, from your pics, many thanks. That lathe looks older than both of us, dont make them like that anymore :). The auto blokes were always asking for solder from me....
 

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Discussion Starter #13
Ahh, that's a handy-looking chunk of aluminum to center it.

BTW how did you manage to clean the outside of those cylinders so nicely? Just boil it in a solvent tank for a few days? Oven-cleaner? I sold N2's '97 heads, now I've got 3 pairs of late-model heads, one pair is very clean and nearly new, the other 2 I can't get clean unless I wire-brush them shiny. One head looks like oil and fuel dripped onto it and cooked there for many years.

One pair also has a strong distinctive odor of castor bean oil. Brins lots of memories, but a strong odor for working inside the house.
 

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You can seal the cylinder base with the same sealant you use to seal your cases up with.

I milled my heads 0.50mm and used Suzuki bond to seal my cylinders (no gaskets). Stock head gaskets with all three layers. This results in a piston to head clearance of 1.02-1.03mm range. My timing gear on the cam side is about 1/2 tooth off.

This half tooth timing error causes a lot of thinking when you go to reassemble your engine. You have to determine which side your error goes on, is it advanced or retarded? I had to spin the engine over a few times and look things over. In theory, you could advance your timing or retard it depending on which way you install the idler gear.

I have a feeling my bikes problems around 3500-4500 are caused by the timing error from changing the effective length of the cam chains. Something I should probably look into, but it's a pain to drop an engine when you don't have a garage.
 

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The Suck, Squeeze, Bang, Blow Moderator,
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BTW how did you manage to clean the outside of those cylinders so nicely?
They had just come back from the platers after been bored +2mm and re nikosil'd

Chemical bath I guess :)
 

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Hey fiche-man, did you ever get your plating issue resolved on your overbore cylinders? Did the company re-plate them? Did they give you any reason why the plating came off?
 

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The Suck, Squeeze, Bang, Blow Moderator,
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They said very little, just re-did them both and sent back within 2 days, says it all really :devious

Unfortunately it cost me another set of rings/gaskets/oil pump and the hassle of a full engine rebuild.

I managed to clean up the scored piston which saved me £300.

The valve seats were quite badly pitted aswell and really should have been recut but instead I just relapped the valves in until sealed so the 3 angles aren't as good as they were but that will wait until the next rebuild.

The temperature rose to about 105 Deg and the fan cut in when I was out testing on the roads and got stuck at a level crossing waiting for a train. They say boiling the water can cause nikosil to flake, but I doubt it was that hot and how many stock TL barrels have had the plating come off when riding through towns etc ?
 
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