Potential Group Purchase - Wiseco GS650 741cc pistons

[5hrine]

Chuck, reading your info again and if i have understood correctly, it seems as if i should go for one at 0.8mm and the other at 0.9mm, as then I can either run the block as it is, or run with a zero decked block.

[Chuck78]

Decision needed here - John says it's $5 extra to have the bushed style stud holes to rivet the gasket together, or else we will have external tabs protruding out from the head/block where the gasket is riveted together externally.

I think I'd prefer the bushed hole style where there are no external protrusions, but he did not answer my question as to whether or not they could do the 4 inner holes in a 60% bushes method as the OEM 4 center studs are done. I will check back with him on that. He didn't confirm the estimate, but his original estimate was 5-24 gaskets approximately $80 each, externally riveted. So this would likely be $85 each with the bushed holes self-riveting the layers of gasket together, or $80 with external tabs and rivets.

Your thoughts???

Hi Chuck,

Sorry for the delay in getting back to you.

To bush those bolt holes like that would add $5 to each gasket.

If you place an order for 20 I would be happy to send you one with external rivets first for your approval before mfg and sending the remaining units. If the only function is to hold the gasket together I don't think there would be any difference.

Regards,

John

[Chuck78]

Chuck, reading your info again and if i have understood correctly, it seems as if i should go for one at 0.8mm and the other at 0.9mm, as then I can either run the block as it is, or run with a zero decked block.

Running the block almost zero decked (piston down in hole .003" with base gasket torqued) with a .8mm gasket would be the minimum clearance one would need. This gives you a .033" squish band (TDC piston to head clearance) as Old Colt the veteran race engine builder is shooting for.

In my hot rof car days, I was under the working impression from other veteran builders that you wanted to shoot for .039"-.045" squish band. This is on a water cooled V8 engine. I was going to shoot for that myself.

Another note - if you are planning to optimize your quench distance down to .030" or .040", you will be moving the cams closer to the crank, which is going to alter your cam timing quite a lot, and may require slotting the cam sprockets to dial them back in where you want it. This requires a runout type micrometer pointer gauge and magnetic base (I hit one at garbkr Freight tgat works well enough), a TDC piston stop device, & a cam degree wheel.

Running a very lightly skimmed / milled block and head and a 1.0mm or 1.1mm gasket will keep timing fairly close to where it was when the bike left the factory. This is another grey area, as factory timing tolerances varied quite a lot - 1 area where Suzuki skimp ed on assembly tolerances.

It is best to at least check the cam timing lobe centerlines regardless. 110 Int / 110 exhaust or so is better for lots of high end power. 104 intake / 106 exh builds lots of mud range street torque. Big lift cams can't advance the timing as much due to piston to valve clearance issues.

Any alteration of the cam timing requires checking piston to valve clearances, as the pistons and valves chase each other closely thoughout parts of the crankshaft rotation. You don't want them too close or else a missed shift at redline could start to float the valves and you might have some harsh contact there and bend a valve.

So what I am saying here is that if you zero deck and run a .9mm gasket, or run close to a zero deck and a .8mm gasket, you are definitely going to want to check the cam timing or at least piston to valve clearance (you can see thus through the spark plug hoke but pro builders do a clay mockup on the piston and assemble the engine and rotate, then pull back apart).

So if you are considering the thinner gasket and a zero deck, you definitely need to be aware that you should be checking your cam timing and piston to valve clearance.

If you run a lightly resurfaced head and block or stock, a 1mm gasket, your timing will be closer to factory soec, but again, the timing could be several degrees off at factory built conditions even, so it's best to get a degree wheel, runout gauge micrometer, & a TDC piston stop and read the Web Cams article on cam degreeing. Time consuming but not too difficult. A custom pointer on the runout gauge may need to be fabricated to clear the cam lobe to get on the bucket properly if you want to get the most accurate valve lift measurements.

Also just wanted to make sure you all realized the .8mm gasket may compress down to just a touch over .7mm, and about .76mm is around .030" which Old Colt was shooting for in total quench height, so he'd need to have his piston down in the hole at TDC about .04mm or approximately .003", which is just short of a zero deck.


Please make sure you are all aware of this info before we commit to ordering your thickness requested.


As to the bushed holes vs external riveted tabs, if there is any question of the 4 inner stud holes being able to be only half bushed (half of the circle riveted back on itself, not the half closest to the cylinder bores), then maybe we should lean towards the external rivet method and save $5/each

[Chuck78]

John is asking me now if we want to do an embossed MLS gasket, or if we just want a standard flat gasket as the OEM Suzuki MLS gaskets are. Does anyone have any feedback? The flat gasket would be cheaper. The embossed gasket I am assuming would be better, but he says he would need to make one prototype to send it to me first for approval. I know there is at least one member waiting for a head gasket very eagerly as they are rebuilding their bike right now. The standard style like Suzuki uses is the more affordably priced option. Can anyone give me a vote either way?

[Chuck78]

It looks like the embossed gasket with bushed holes will run around $85, & the flat gasket (like OEM Suzuki MLS) will run $66 or so. he is going to get back to me tomorrow or Monday on more exact pricing.
For high performance applications, it seems as if the embossing will really help seal the cylinders much better, & should give extra insurance against oil leaks on the tunnel area and oil pressure passages on the outside 4 corners. This seams to me the way to go. The metal will be pressed upward on the outer layers of the gasket to further add to the spring effect to seal the cylinder & oil passages better. OEM just used a plain flat gasket, no embossing, but that was 1982 technology.

Please give me your opinions.

Thank you,

Chuck

[Ace07]

The embossed gaskets for me.

[Chuck78]

Here's some further quench height info here for you. I was second guessing as little as .030", as when the rings and bores wear, the pistons can rock more, and you need more clearance. Also the factor of crank & rod bearing wear, as these are roller bearing cranks which seemingly last forever if oil is changed properly, but due to the labor intense process of having a crank shop press it apart and replace the very expensive bearings, our bottom ends don't get refreshed really ever unless building a race engine, so clearances may be a bit looser than fresh plain bearing crank engines.
Still, with the average Suzuki deck height having the piston down in the hole at .020" or .5mm according to some experienced opinions on this forum, even a .8mm gasket on a very lightly milled block (not zero decked) will still give you a larger quench height or quench distance.

From some hot rod v8 articles and discussions I've read over the years, they say to never run more than .060" / 1.5mm deck height + compressed gasket, & to keep it as tight as possible within reason, ideally .043-.045".

Often when dealing with engine building / machining info, if you have no air cooled motorcycle engine info to reference, a great default search is to look into air cooled VW/Porsche engine info for ckearances, machine shop experience, etc as they are basically the same setup as an air cooled motorcycle engine with an air cooled engine that has removable cyLinder jugs and pressed in cast iron cylinder sleeves. Similar boring techniques (slow and easy), similar clearances due to similar operating temperatures.

[Chuck78]

Squish band quench height info

Here's some good info from an Air Cooled VW sub-forum and the Crankshaft Coalition site. Keep in mind our rpm's are higher, so the added clearance between the disputed .035" minimal spec to .040+ would be helpful in my opinion, although our rods are designed with that rpm range in mind.
EDIT - one thought I just had is that since our pistons are generally a lot smaller diameter, perhaps we are much safer than VW/Porsche and the much bigger V8 muscle car engines, as our smaller diameter pistons won't be able to rock as much back and forth on the piston pin due to the shorter distance from the pin axis to the furthest point on the cylinder wall? I think this is a pretty good argument here. I will probably still shoot for about dead on at 1mm / .039" to account for potential wear of bearings and bores, although I wouldn't argue one bit that .035" would be the most efficient route and require less octane ratings of fuel.

A perfect deck in these air cooled VW engines is "as tight as you can run without touching". This means 1mm or more, to allow room for thermal expansion, stretch, and bearing wear etc.. that is still pushing it real close. With a tight new engine you can run less, but as it wears and develops play here and there, it's safer to start with mor deck, say 1.2mm. I generally set my high performance engines between 1.1 and 1.3mm deck.


An added bonus from running really tight deck, is reduced carbon buildup in the quench area. Less prone to detonation...

Jan


------------------------


1.1mm (.043 inches) to 1.3mm (.050 inches) is the sweet spot for our engines. Be sure and check piston to valve clearance when you run a tight deck.

.

For this discussion, we will be using the term "quench" to denote the distance between the cylinder head deck and the piston deck at TDC, as well as for the overall action/effect of the combination of squish and quench.
Quench (or squish, or "squench") is sometimes referred to as mechanical octane. It decreases the need for octane by promoting a more homogeneous air/fuel charge in the combustion chamber and it also helps promote flame travel.

What is squish?

Squish is the name given to the turbulent mixing of the air/fuel mixture caused by the close proximity of the piston to the quench pad(s) of the cylinder head. As the piston approaches top dead center (TDC), the clearance between the crown of the piston and the quench pad of the cylinder head diminishes to about 0.040" (steel rods, aluminum rods require more distance). This squeezes or "squishes" the air/fuel mixture from the area where the piston and head are closest, to the area where the combustion chamber is located. This action creates turbulence to achieve a more homogeneous mixing of the air/fuel mixture. A quench distance of ~0.040" will allow a high performance engine to run without detonation using less octane than would otherwise be needed. Of course this is providing that all the other important areas are also covered, like the static and dynamic compression ratios, correct air/fuel ratio, correct plug heat range, good ring and valve guide seal, etc.

How to arrive at the target quench figure

One way to arrive at a ~0.040" quench distance is to cut the block decks to zero piston deck height and to use a head gasket that compresses to around 0.040". This allows a quench (or squish, or "squench") measurement of 0.040".
While that is a straight forward way to go about it, there are other ways: Use a thinner head gasket and cut the deck only enough to get a flat surface with the correct finish for the head gasket to seal against. By doing it that way, more deck thickness is maintained, resulting in a potentially better head gasket seal due to the deck being thicker.

[Chuck78]

NOTE: I am editing the updated running total of what has been requested in this quoted text below:

Head Gaskets requested from the last 3 of 8 pages on this thread:
4 or 6 - Chuck78 0.8mm & 0.9mm & maybe 1.0mm
2 - Tooheys 1x 0.8mm and 1x 0.9mm. pd in Aus
2 - Ace07 1.0mm?
2 - tkent02 1x 0.8mm, 1x 0.9mm-or-1.0mm?
2 - 5hrine 0.8mm? or 0.9mm in U.K.
2 - frankenwabbit 0.8mm and 0.9mm
1 - old colt 0.8mm thickness
1 - gilldog 0.8mm in U.K.


2? - complete cafe racer
???prichmon??? I think he was needing pistons, too, so maybe not just yet on the gasket

I haven't heard much commentary, so I told John that we are ready to order the more expensive EMBOSSED gaskets in .8/.9/1.0/1.1mm thicknesses, and to put us in line for production, and that I would be collecting payments to send him the money to get started.

I also asked if he could direct ship the orders outside of the USA so that we don't have to pay shipping twice internationally, but all of the USA-bound gaskets will come to me first at least. I don't want to overwhelm him with shipping out so many different packages unless he agrees to it.

If you all could send me $85 PayPal for each gasket you are ordering, send it friends and family so that it does not charge me a fee, & please make a note of the thicknesses you want if they are different than what I have listed here or if you have narrowed down your choices. I will need additional shipping from you later, but we will figure that up when the time comes so I'm not guessing now. It was $14 to send the one gasket template overseas First Class Mail to John.
My PayPal is a yahoo dot com e mail address - chuck_lambert
Spelled out as to deter spam bots from mining my address for junk mail.

These will cost $125 each after the fact if you need another one in the future, unless you can get others together to order a total of 5 or more again. Non-embossed non-bushed (externally riveted) would be about $85 each in the future if you get a single gasket or up to 4.

[Chuck78]

I just heard back from John the owner of GasketsToGo.com, please send payments to me as directed above, PayPal friends and family payment, statw that this is for "GS740 custom head gasket order funds collection, " state quantity and thicknesses you are requesting after reviewing all if the recent posts I have made about gasket thickness vs squish band / quench distance or height.

I will request a separate shipping payment from you after we get the gaskets all manufactured. He can ship the 3 orders to the UK and Australia, the rest to me in the US to distribute.

Hi Chuck,

Great, thanks.

Just to confirm. Embossed multi-layer with the 7 holes bushed. Because those are bushed it will not need external rivets to hold it together.

When you finalize the number just let me know and I will send you a PayPal invoice.

Yes, I can ship direct to some of your customers.

Regards,

John

[frankenwabbit]

money sent!

[Ace07]

I sent you the money.

Just to make sure you know. I would like a .9mm gasket and a 1mm gasket

[Tooheys]

Chuck can I change my order to a .9mm and a 1mm please. Happy with the embossed gasket. I think I only paid $160 the other week when i sent payment. Let me know if you want the extra now or when we know what the postage will
be.

[Chuck78]

Everyone please make certain that you are sending the gasket funds collection payment to the correct address, and as a friends and family payment since I am not selling you goods, we are just pooling together for a group purchase.
Most importantly, click my profile name at the top of my posts, click on Send Email, & then copy that exact email address
The middle carachter is an UNDERSCORE not a hyphen
chuck_lambert78

It is a yahoo . com address

Sorry don't want to put it all consecutive as then the spam bots will find it and send me more junk mail!!!

I don't think I can send an invoice, as then it would charge a fee for goods and services, so I'm leaving it up to you to make certain payment address is entered correctly.

Thanks

Chuck

[Chuck78]

Who is function first motorsports??? Please include your GS username and real name when sending payment! I'm not a mind reader when email address gives no clues to which user sent me a payment!