S3 Race 250 Port Matched Cylinder and Head

[Jakobi]

Really REALLY interested to here how this turns out as I also would like to go down for 250 for harescrambles. Wife wont green light a new bike for at least a couple more seasons.

I've just about put 100hrs on my 250 top end now Ernie. I couldn't be happier. Prior to the 250 top end I was running a 300 set up for top end power. Largish squish, moderate compression, ports timed for top. This was with 1.3mm of gaskets and the S3 300 black insert.

From my experience I would say the bike has given up very little off idle torque. It'll still tractor down and pull a gear heigh. Maybe not as well as the 300 did, but enough to keep the bike moving in the right direction. The 250 has a bit more hit and feels more aggressive to ride.. or should I say I feel that I can ride the 250 more aggressively and it rewards you for doing so. The 300 was agro when riden that way but it was always too much to hold onto. Added to that the 300 comes into comparable power around 1000rpm sooner so with the power curve sitting lower in the rpm it was tugging at the arms more often than not. I like that the 250 has the soft bottom end that you can ride all day without issue, and any time you need the power just turn the throttle and you'll have as much if not more than the 300 up top. I'd have to go back to a 300 to evaluate again, but for now I'm sticking with the 250 Look forward to hearing Trevs reviews in a couple weeks!

 

[nambo-trev]

Well I finally have gotten the 250 top end in and it turned out to be a little more of a pain than anticipated. The 300 cylinder came off looking great! No wear signs on the walls at all but were we encountered problems was the retrofit of the PV into the new 250 cylinder. I cleaned it up really good(I thought) but after install there was some binding every 6 or 7 twists of the shaft so teared it all back down and dug away at the carbon again on the assembly until she was near spotless then re installed and was operating very smoothly. I used a .5mm base gasket and the red(high compression) insert. Everything went back together smoothly but forgot new crush washers for the head and thought I could get away with the old ones cleaned up and I was wrong! Put new washers on head and all is good with no leaks. I changed my jetting to 172 main with Jd red needle middle clip and a 38 pilot(for the rest of winter then 35) she started second kick and sounds good. Haven't had time for a ride yet but should be on it within the next week. Ill post back my thoughts of the first ride then!

 

[Jakobi]

Ready, steady....

 

[nambo-trev]

So I've had the 250 out about 3 times so far and put about 12 hours on it. I had to adjusted the pilot slightly richer to a 40 and will leave it there since my smart carb will be here soon. I also changed the rear sprocket to a 50t on the back as I felt from my initial impressions that I was lacking a tiny yet subtle low low end threw tight single track. I feel fast on the bike, I don't know why because to me the bike doesn't feel heavier but perhaps the throttle and bottom end lacking a bit might inspire confidence because of less thought put on control. I took my 200 cam out from my g2 throttle system and went with the 100 and find it quite good but might prefer one step quicker cam in delivering the power. The biggest improvement I can see by far for me is the hill climbing. It almost seems as though everything is in slow motion when I'm climbing now. I can focus on things I previously wasn't focused on like terrain I'm about to hit ie. step ups and big rocks etc. I can only relate this to the fact that I'm not focused on taming the bike on wild technical hill climb, instead I just let it scream and clutch away and it seems like the power gets delivered in a much more manageable way. Top end feel is very similar and don't feel my buddies on there 300's pull on me in the straights. I am very pleased with the down sizing and the control it has offered me and am now excited to see what a 200 would feel like! I'm going to the track tomorrow(first ride on rubber this year) and am going with a buddy with a new 200 so it'll be a very interesting day!

 

[Jakobi]

So I've had the 250 out about 3 times so far and put about 12 hours on it. I had to adjusted the pilot slightly richer to a 40 and will leave it there since my smart carb will be here soon. I also changed the rear sprocket to a 50t on the back as I felt from my initial impressions that I was lacking a tiny yet subtle low low end threw tight single track. I feel fast on the bike, I don't know why because to me the bike doesn't feel heavier but perhaps the throttle and bottom end lacking a bit might inspire confidence because of less thought put on control. I took my 200 cam out from my g2 throttle system and went with the 100 and find it quite good but might prefer one step quicker cam in delivering the power. The biggest improvement I can see by far for me is the hill climbing. It almost seems as though everything is in slow motion when I'm climbing now. I can focus on things I previously wasn't focused on like terrain I'm about to hit ie. step ups and big rocks etc. I can only relate this to the fact that I'm not focused on taming the bike on wild technical hill climb, instead I just let it scream and clutch away and it seems like the power gets delivered in a much more manageable way. Top end feel is very similar and don't feel my buddies on there 300's pull on me in the straights. I am very pleased with the down sizing and the control it has offered me and am now excited to see what a 200 would feel like! I'm going to the track tomorrow(first ride on rubber this year) and am going with a buddy with a new 200 so it'll be a very interesting day!

Falls very much in line with what I found Trev. I still haven't had the chance to try a 200 but I bet it would be a blast. Might lack the top end more than we're willing to give up though. Did you notice any reduction in vibrations?

 

[john r b]

s3race cylinder

Carefull Jake,
The 200 is a ripper for sure!!!!

 

[nambo-trev]

Yup I actually did notice quite a big difference in vibration!

 

[nambo-trev]

Carefull Jake,
The 200 is a ripper for sure!!!!

I'm friggin stoked to try this 200! Sounds crazy cause I love this new 250 but after all the 200 talk I want to know what all the hype is about

 

[GMP]

I was always in the 250 camp. Managing extra power is just wasted energy, not to mention the added vibes. I have a 300 top end I was going to try but I'm selling it instead, ridden the 300 s enough to know the 250 is better for me.

I think I found what the 250 likes for low end grunt, and that's a larger ID silencer core. Ever since I put that Canon on the bike pulls hard off the bottom and rips through the range. I know a local shop used to do the same to GG200s a few years back. I can't wait for the SmartCarb to see what that adds.


Sent from my iPad using Tapatalk HD

 

[Jakobi]

Carefull Jake,
The 200 is a ripper for sure!!!!

I have tried buying a 2012 and 2013. None delivered to Australia. That ship has sailed. The coins saved actually went towards the suspension setup, tooling, 250 build, and just maintaining the current bike. After owning the 250 and being as stoked as I am I think its the bike for me. The 200 would be grouse for the single track, but I think the 250 gives the best of both worlds (he says without trying a 200). Hahha!

Yup I actually did notice quite a big difference in vibration!

Me too! I think the step down from the 300 really felt like I didn't really give anything up. It was all a postive change.

I was always in the 250 camp. Managing extra power is just wasted energy, not to mention the added vibes. I have a 300 top end I was going to try but I'm selling it instead, ridden the 300 s enough to know the 250 is better for me.

I think I found what the 250 likes for low end grunt, and that's a larger ID silencer core. Ever since I put that Canon on the bike pulls hard off the bottom and rips through the range. I know a local shop used to do the same to GG200s a few years back. I can't wait for the SmartCarb to see what that adds.


Sent from my iPad using Tapatalk HD

I think you're the one who got me interested in the downsize originally Glenn. I'm yet to see you post anything I haven't agreed with or isn't true. What other silencers have a large ID?? I might bolt one up if its a big win as really I don't see me selling this bike any time soon.

 

[GMP]

For a '10, I'd just pick up anything used and mod it as an experiment. Just a slightly larger core tube. I'll measure it tomorrow. I'd like to see if someone else thinks it makes a difference.


Sent from my iPad using Tapatalk HD

 

[Neil E.]

It might be the core diameter, but I'll bet it has more to do with the Stealth insides. I just repacked mine and it's best to drill out the rivets. There is a second section of packing (~1.75" long) at the arrestor section that stays in place if you only disassemble the Stealth by using the front end screws.

The exhaust does a complete reversal after passing over the Krizman bullet. It moves out to the outside of the end cap and has to reverse direction to come back forward to get into the smaller exit tube welded to the end cap hole. The tubes overlap by at least an inch.

I think the lack of this reversal is what makes the big difference in using a different muffler.

 

[GMP]

I see, never had mine apart. Also explains why its an oil tanker. All I can say for sure is its definately not the best choice. I have an '07 250 with a Messico silencer, otherwise set up the same as the '12. It was always the low/mid champ until the Cannon went on the '12.

Seeing that I'd mod it for sure if a replacement was not in the plan.

 

[Neil E.]

As to the best mod, I'd say that simply cutting out (or radically shortening) the smaller exit tube would be all that's necesssary to let the Stealth flow well. The long front perforated tube is about 1.125" diameter and the orifices through the bullet are reasonable. With this mod the end cap would "catch" the gas flow off the bullet.

Rear view of bullet:

 

[Jakobi]

The TC2 has the same looking turbine thing when you look down the guts of it. I haven't had it apart so can't comment on the rest.

 

[GMP]

That's a Krizman type spark arrestor. Many mufflers use it. That in itself is not a bad thing, TC2s work fine, as did the KTM OEM silencers that used these for years. Only bad thing is that the fine oil mist in the exhaust is stopped by the bullet to an extent, and builds up in the end cap and packing.


Sent from my iPad using Tapatalk HD

 

[kiwia]

Congratulations Jakobi, it is one of the best post I have ever seen.
Regarding S3 I have put on my 300 2010. I have put the red insert and my problem is that I can not get a good engine idle. I have proof many settings but no way. I have 3 cilinder gasket.
I want to proof 3 cilinder gasket and black insert S3 is any damage for the engine? Maybe too much, what do you suggest?

 

[Jakobi]

Congratulations Jakobi, it is one of the best post I have ever seen.
Regarding S3 I have put on my 300 2010. I have put the red insert and my problem is that I can not get a good engine idle. I have proof many settings but no way. I have 3 cilinder gasket.
I want to proof 3 cilinder gasket and black insert S3 is any damage for the engine? Maybe too much, what do you suggest?

Have you measured your squish height with the red insert? If you're not sure how see below.
http://www.gasgasrider.org/html/measuring_squish.html

Also could you confirm, are you running as a 300cc or 250cc? Which model carb? AS1 or AS2? Even with a largish squish you should have no issues setting up the idle and its probably more a jetting issue than an engine issue.

Trev, Lectron man? What jetting specs did you end up with on the PWK?

 

[kiwia]

My 300 2010 use a ASII. I am going to check the squish, but you say that even a large one does not do any problem.
I am running now with 48/178 NECJ on 2?. What do you think? It will be too much if I try black insert S3?

 

[Jakobi]

Which country? Temps? Altitude? Initially I'm thinking thats a big pilot, and probably a size or two larger on the main than I'd suggest (comparing to my own experiences though).

Engine wise, measure the squish with the red insert, and then measure it again with the black. They are both the same volume and its just the height that varies. I ran the black insert with my stock engine and a base gasket stack of 1.3mm which gave me around 1.8/1.9mm squish height (from memory) and 13.something:1 CR. Bike ran well.