S3 Racing Cylinder Kit and Interchangeable Head

[djroggen]

Just got done installing the S3 300 Race ported and honed cylinder, interchangeable S3 head, and S3 piston. The cylinder seems to have all the rough edges honed out. I am excited to actually put some hours on it, but living in MN is going to put a damper on that. Very impressed with the fit and finish on all 3 components. The piston from what I can tell is a Vertex, S3 branded piston.

When I get a chance to ride next I will give a whole report.

Mark @ GoFasters has the interchangeable head for a GG 250 in stock I bought his only 300 head.

He got bunch of goodies from S3 today. Some pretty trick looking wheel stickers, a kit to convert the Yamaha 250F motor to a 300, along with some other interchangeable heads for some KTM and Husaberg models.

 

[Jakobi]

Do you notice any real differences between the old cyl and the new one? IE is it just the ports cleaned up to flow better or have they been significantly changed?

Did you measure up what the squish came in at once fitted etc?

I'm about to drop my 2nd top end in my 2010 300 and will be spending some time cleaning up the casting this time round. Last time was my first top end and I was in a rush to get it back together.

 

[djroggen]

From what I can tell that the ports are much cleaner looking, no casting lips. No drastic changes to the ports, but they have all been hit with a dremel like tool. From what I hear it is done by hand, I don't know if that is a fact. I cannot imagine squish would be any different especially something that different base gasket wouldn't change. With the interchangeable head I should be able to dial in the squish I am looking for the inserts seem to be nearly identical to what RB does when they modify the head.

 

[Simmo737]

Put the black head in, the response is awesome, same fuel economy.

My bike has a broader bottom end that takes upshifting better. Jet a step richer on the main. You will love it. You may have trouble getting a reading on a new plug. Top end is still there.

Enjoy

 

[Jakobi]

Yeppers! Like Simmo I've been running the S3 head for 80hrs now with a Wossner Piston and the Black Insert. I chose the insert to bring the best squish range once setting my port timing where I wanted it. TBH I could still afford to drop another 0.3mm and may do so by leaving one gasket out of the stack when I do my next top end.

I still have all sorts of trouble getting readings on plugs with mine. The intake side always reads darker than the exhaust side. I mostly jet by feel.

Definately improved response with the S3 over the stocker (which had 2.6mm of squisho if memory serves me correct).

I'll be hooking right in with the dremel when the jug comes off and doing some hand crafting of my own. Matching ports and transfers and smoothing out the rough casting.

Me and Simmo are going to be riding home made factory bikes soon enough

 

[djroggen]

Black huh? I will have to look into that. Where did the piston rest at BDC in relation to the port? What was the squish that you were trying to attain? The more that I think about it, it would seem to me that the port was actually lower than the factory port level. I should have taken a micrometer to the cylinder before installation but I really didn't know anything specific that I was interested in seeing.

 

[Jakobi]

Black huh? I will have to look into that. Where did the piston rest at BDC in relation to the port? What was the squish that you were trying to attain? The more that I think about it, it would seem to me that the port was actually lower than the factory port level. I should have taken a micrometer to the cylinder before installation but I really didn't know anything specific that I was interested in seeing.

Oh well. If it runs well thats all that matters.

Next top end time you'll have something else to look into!

 

[PEB]

Is there a core charge for this kit? $600 with a piston and jug seems cheap.

 

[djroggen]

No core charge. It is a steal. Now everyone can afford to have both the 300 or 250 of their dreams and both at the same time.

 

[djroggen]

Got a chance to take it out for a bit of a break in. I ended up changing the base gaskets to 2 thick and 1 medium to get the piston BDC, even with the bottom of the exhaust port. Installed the Red/Middle S3 head insert. I am convinced that this cylinder along with the head setup is the ticket, I would never go back! It took less than 30 minutes to change in head insert from the shortest insert to the medium. What a sweet setup S3 did with that.

I have to say that even with it being the first day out since the first week in January, I couldn't stall the beast. I feel like it made a vast improvement off the bottom, and minor improvements up on top.

Now that the 300 can handle anything that I throw at it, hopefully I can do my part and get back into condition soon...

 

[Jakobi]

Did you measure up your squish with the red insert?

I took the time do crunch some numbers with the help of a friend. The S3 head inserts measure the same volume as the stock head. Mine measured 25.1cc but probably some small error on my part.

Based on 1.3mm base gasket stack (ports flush with piston), stock cylinder, s3 head and black insert bringing squish to 1.8mm the current trapped volume would be 23.15cc approx and therefore CR would be 13.65:1.

When I receive my 250 S3 cylinder I will use it as a guide to how I expect my hand port matched 300 cyl is to come out. I'm not sure if the 250 or not runs the same port heights as the 300 but I'll do a measure up and comparison while they're both pulled down. I am hoping to have the squish come in at 1.3mm and will probably take the time off the bike to send the head out to be corrected if required. You'd imagine S3 would have considered squish into their cylinder/piston/head combo.

 

[Simmo737]

My burrs are awaiting your findings jakobi, how cheap is that s3 kit? No wonder you went for it!

 

[Jakobi]

250 S3 Race Port Matched Cylinder, Piston, Rings, Clips, Pin, S3 Gold Head, 3 x Inserts. $834USD. Whole order including a new throttle cable and delivery cost under $850AUD. I also purchased a new little end bearing and all the gaskets locally to support the local dealers. Will be over a $100 in cardboard alone (did powervalve covers, clutch, rhs engine, water pump, flywheel, exhaust, base stacks, head o rings and exhaust o rings). Its crazy when you think about it.

Quite a lot of goodies for the coin. Its $210aud alone just for a piston kit, so to get the cylinder for an extra $400 is a real bargain.

The S3 Head will also bolt up to either 250/300 cyl with the right insert. The catch was that it was $210 for the head and 3 inserts, or $90 per insert. I'll have 2 spare inserts once mines set up if anyone else wants to buy them cheap.

 

[MrBlah]

I'm gonna have to order the 300, i've been thinking a 300 would fit my riding style better (lugger)

not sure what the final compression is on these, can these black inserts run on pump gas 92-93 octane?

 

[Jakobi]

As above CR 13.65:1 using the stock 300 cylinder and s3 head black insert with 1.3mm gaskets and 1.8mm squish. I have always run 98RON so can't comment on the 93.

It all depends on the individual cylinder and how much you need to raise it to get the ports right. The 3 inserts for the head are all the same volume. They are slighly thicker for higher comps. Essentially the same as milling the stock head without reshaping the bowl or band.

I think the S3 cylinder is the same porting as stock only that the ports are actually matched and cleaned up. No sloppy casting internally.

 

[Jakobi]

Re stock 300 - the stock engine, in this case 2.5mm squish, 11.9:1 comp, 1.3mm base gasket stack, piston level with port floors at bdc. - Taken from another thread.

My bike actually had a stock squish of 2.6mm. Same gasket stack.

 

[MrBlah]

I think 98 ron is the same as our 93 or close

I ran 13:1 on my wr without any problem on 93

 

[GMP]

Those compression ratios seem way high to me for a 2stroke. Better to use pressure as a reference. Ron at RBD told me awhile ago that 200 PSI is tops for USA pump premium gas. All heads that myself, brother, and friends have sent to him have been cut for just under this (192 - 195) and work very well.

 

[Simmo737]

I think that's non corrected cr ( uk style, advertised bore x stroke volume vs pippette taken volume at tdc to just below first thread at bottom of plug hole), not that weird jap corrected on that takes about a year to understand. That's what everyone does over here to blueprint the motors specs.

That's what you did jakobi?

 

[Simmo737]

Ps, I just bolted on the black head on my s3, never checked the squish as Scotty said it'll be ok and use 95, works perfect.