Alternator has now been fitted and tightened, another day another tool made! With that done, I temporarily fitted the standard 0.6mm base gaskets, barrels and pistons to check the deck height/squish clearance. As standard, I had the horizontal piston 0.80mm below head gasket surface, and the vertical 1.03mm below head gasket deck. Am I correct in that the newer-type multi-layer head gaskets have a compressed thickness of 0.6mm? If so, to get to 1.00mm squish clearance, I can remove the horizontal base gasket completely, and run an 0.2mm base gasket on the vertical to get the pistons 0.4mm lower than the decks at TDC. Ring gaps checked in the bores, all within the "as new" spec from the service manual. Clutch plates and springs fitted, which is as far as I can go without a base gasket for the horiz' cylinder. Once I get a gasket I'll then be able to put the heads on, and the rest of the cover plates. Last bits to do will be cam timing and then wrestle the lump back in. We're getting there. If anyone's interested I'll keep updating, otherwise I might just update if it all works!
Forget the deck height for now and.. Torque it all down with your new multi layer head gaskets* with some soft solder on the piston crowns at 12,3,6 and 9 O'clock and measure the thickness of the squashed solder/squish clearance, then adjust the base gaskets/barrels to give you a clearance of 0.8mm. You might need to machine the base of the barrels. Anything 1mm or over and the squish isn't doing it's job, anything under 0.8mm and you run the risk of the pistons hitting the heads at high revs. * The gaskets are OK to refit as long as you have NOT run the motor/put them through a heat cycle.. Steve R
Thanks Steve, is it OK to run without base gaskets, just Threebond between cases and barrels, if that gives the correct clearance? The old head gaskets (which were MLS type too) are still here, is it best to use the new ones or the old ones?
You can run the motor without base gaskets shims, just use a good quality RTV like Threebond 1215. Use the new gaskets so that you get the exact measurement that you would get when you fit them finally. Steve R
Probably the best option. When I was building mine, base gaskets (shims) of anything other than 1mm or (IIRC) 0.4mm were not so easy to source with the 'standard' new gaskets being 1mm. Ideally I needed 0.8mm gaskets to get it spot on so had the barrel bases skimmed by 0.2mm so that I could use the, 'off-the-shelf' 1mm gaskets. Also, may not be applicable to the OP? due to only removing a small amount from the cylinder height, but as I also had 1mm skimmed from the heads (for more compression) I needed to fit larger tensioner pulleys to get the belt tension back and this also meant having to alter the cam timing.
In the end I decided not to remove any material from the cylinder heads. I am however going to be installing the adjustable pulleys from a later bike, to get the cam timing where I want it.
Base gaskets/shims (in whatever thickness you order) are available from Cometic Gaskets in the USA, they don't cost to much and arrive in under 2 weeks. I've quite a large selection here (collected over the last almost 30 years) that I juggle to get the correct squish clearances. Steve R
If you remove differing amounts from the heads you will be altering the combustion chamber capacities. To get the correct squish clearance you need to shim up or shave the bottom of the barrels, this way should keep the correct comb' chamber capacities. If you want to be totally anal/build a blueprinted motor or a race motor you should also CC the comb' chambers. Steve R
Agree, Steve. My comment regarding removing material from the heads was more in reference to your post #11 on page 1 of this thread, talking about removing 0.6mm from the heads to increase compression. I wonder if these heads have already had some material removed, the inlet valves are proud of the gasket surface. Edit for added picture
Managed to get some time this evening to check squish clearance on the vertical cylinder. I assembled the cylinder with no base gasket, the new head gasket and torqued the bolts with grease per the spec. I made a star shape of solder to make sure I could get it all out again without searching for smaller pieces. and after a revolution of the crank, this:- I had calculated from the deck height measurements that I would need an 0.2mm base gasket to get to 1.00mm squish. The solder measurements with no base gasket were 0.79mm & 0.90mm (average 0.85), so the measurements match up quite closely. Will check the horizontal tomorrow, hopefully.
Got round to the horizontal cylinder tonight. Started by making the same type of solder shape, and fitted the head. Felt a bit strange as it was being tightened up, so took it apart:- Whoops, the solder must have slipped. Ah well, no damage done, try again. Second time lucky, resulting in 0.80 and 0.90mm thickness, so again an average of 0.85mm. I think there was a small amount of paint causing a stand-off for the deck height measurements previously, which was cleaned off tonight. So the choice now is whether to try to obtain some thin base gaskets - 0.2mm parts seem to be available from stein-dinse.biz for very little money, 0.1s may be harder to achieve. The standard parts are 0.62mm.
Been making progress with the rebuild. Today I got the combustion chambers, piston crown valve cutouts measured for volume, and the compression ratio calculated. I think the heads may have been shaved before, as the compression ratio calculates as 11.9:1. It probably also explains why the inlet valve seats are so close to the head gasket surface. With that measured, got everything cleaned, rings put back on pistons, pistons in barrels, and heads back on! Waiting for opening rockers to come back before I can do opening clearances, and cam timing! Getting closer.
I noticed that you had the same colour paint on both sides which looks good. Is it me or as standard, is the clutch side a differnet colour more of a mid grey not a silver. I think yours looks good but I dont really want to get my RH case cover off to match it.
As far as I could see on this ST4S-02 all the cases were the same colour. Looking at the parts manuals online at Stein-Dinse.biz, it looks like the RH crankcase cover & clutch basket cover were anthracite on bikes earlier than 2002, then they changed to all the same colour (silver).
I've just used Halfords Silver Wheel and Trim paint, it seems to be a reasonable match, but what was on there was very oil stained, and there was a lot of it missing.
Does anyone have a spare opening rocker of which they could provide some rough measurements and a couple of photos? I'm looking to make a 3D model of one, but all my rockers are away being refurbished. Some decent square-on pictures would do it, I can measure from known dimensions (pivot shaft bore ID). Thanks for any help in advance.
I've got a few here, I could post you one but it will be slightly worn on the follower face, but usable for someone who's desperate. All of the good/perfect ones I've got have been refaced/reclaimed by Newman Cams with new Stellite hard faces brazed onto the working surfaces. Steve R
