S3 Race 250 Port Matched Cylinder and Head
- Thread starter Jakobi
- Start date
Jakobi
Super Moderator
Haven't you heard? She maybe did..
Jakobi
Super Moderator
The test ride..
First I'm out and riding and the bike sounds like its going to blow up! The worst imaginable sound on decel from revs you have ever heard. Clutch in or out. I won't say what I thought initially. Traced it to the bash plate vibing. Took the whole lot off and set off to the start of some nice tight single.. Here's how it went..
http://youtu.be/R8U-Hz9HyEY
..More to come! Haha! LOVE IT! The bike feels really very much like my 300 did. Smooth and silky off the bottom but not as strong as the 300 obviously. The mid is much much much better. No more horrible vibration that makes you feel like your teeth are going to chatter out. The explosive hit is the same as well with very similar power when hammering WOT. The bike feels nice and nimble but the geometry of the raised bars, the effect of the damper, and having not set up the TTX forks yet had the front end push a couple times in turns. I also have a small shudder when braking but only at very very slow speeds. Hard braking from speed is fine. I think it might be the bushes. The Sachs forks have always had some play in the lower legs from day one. No oil leaking from them, and yet to bottom them on stock clicker settings. I should probably check the sag on the rear end before I get too carried away too.. Its all smiles over this side!
Doing it right.. http://youtu.be/M_7otgJBzB8
First I'm out and riding and the bike sounds like its going to blow up! The worst imaginable sound on decel from revs you have ever heard. Clutch in or out. I won't say what I thought initially. Traced it to the bash plate vibing. Took the whole lot off and set off to the start of some nice tight single.. Here's how it went..
http://youtu.be/R8U-Hz9HyEY
..More to come! Haha! LOVE IT! The bike feels really very much like my 300 did. Smooth and silky off the bottom but not as strong as the 300 obviously. The mid is much much much better. No more horrible vibration that makes you feel like your teeth are going to chatter out. The explosive hit is the same as well with very similar power when hammering WOT. The bike feels nice and nimble but the geometry of the raised bars, the effect of the damper, and having not set up the TTX forks yet had the front end push a couple times in turns. I also have a small shudder when braking but only at very very slow speeds. Hard braking from speed is fine. I think it might be the bushes. The Sachs forks have always had some play in the lower legs from day one. No oil leaking from them, and yet to bottom them on stock clicker settings. I should probably check the sag on the rear end before I get too carried away too.. Its all smiles over this side!
Doing it right.. http://youtu.be/M_7otgJBzB8
Last edited:
Jakobi
Super Moderator
I'm always fogged. I think there are some scratches to the outside of the housing which doesn't help. I usually seal the housing with some of those absorbant pads inside and only quickly open it to drop the unit in when I'm about to use it. Yesterday I hadn't done this though, and it was drizzly so high humidity.
Jakobi
Super Moderator
Another one.. Different camera, different mount, travelling in a different direction. Sorry for all the noise. Need to get this Drift set up with some foam over the mic. Happy little 250!! 
I need to buy that Dave bloke a beer!
http://youtu.be/Fj_ZE0nxsLw
I need to buy that Dave bloke a beer!http://youtu.be/Fj_ZE0nxsLw
Jakobi
Super Moderator
A little humour
I was in the shed admiring the girl again.. as we all do when I noticed what appeared to be a small pool of coolant around one of the head bolts. Strange I thought as I had continually monitored for coolant leaks while breaking the engine in and had most definately not lost any coolant. Maybe the head was hot enough to evaporate it off while running under pressure? Maybe the warm up and cool down expansion process has slacked them off (I had to do the second retorque of the head bolts yet). Wiped the little puddle off and called it done for a day to follow up later on.
Follow up came and I look from the other side. WTF! A small puddle surrounding another bolt on the other side of the head that wasn't there before. The bike hasn't been started nor has the coolant system been pressurised. I had intended to remove the tank to retorque the head bolts again. It really blows that you need to drain the coolant and remove the water line housing to nip the front 2 bolts up! But back on topic. I remove the tank and what do I see sitting at the front of the head but a little brown frog! FROG PISS on my head! No leaks at all, and definately not again after giving all the bolts a small nip up.
I was in the shed admiring the girl again.. as we all do when I noticed what appeared to be a small pool of coolant around one of the head bolts. Strange I thought as I had continually monitored for coolant leaks while breaking the engine in and had most definately not lost any coolant. Maybe the head was hot enough to evaporate it off while running under pressure? Maybe the warm up and cool down expansion process has slacked them off (I had to do the second retorque of the head bolts yet). Wiped the little puddle off and called it done for a day to follow up later on.
Follow up came and I look from the other side. WTF! A small puddle surrounding another bolt on the other side of the head that wasn't there before. The bike hasn't been started nor has the coolant system been pressurised. I had intended to remove the tank to retorque the head bolts again. It really blows that you need to drain the coolant and remove the water line housing to nip the front 2 bolts up! But back on topic. I remove the tank and what do I see sitting at the front of the head but a little brown frog! FROG PISS on my head! No leaks at all, and definately not again after giving all the bolts a small nip up.
Gasgasogeros
New member
new model frogas
Jakobi
Super Moderator
Put some more time on the bike today to evaluate the jetting and get a feel for the 250. I'm really really enjoying the stability that the head mods have made. The engine now gives fanastic feedback and each change is more definite in how it reacts, but also less extreme.
At the end of the day N3CJ #3 is perfect power. Half a clip richer and you get the burbles. Half a clip leaner and the power flattens out a touch on the bottom half of the needle (off the pipe). Feels like it takes a little more to put it on the pipe too, and then the bike hits hard. Thats how I had my 300 set up but it required a full clip leaner to do it, and going back the other way the bike would burble with only a half a clip. Its much more stable now and made the process a real walk in the park. I hope the fuel economy still comes in around where it was. I'd like to be able to get around 100km from the tank.
At the end of the day N3CJ #3 is perfect power. Half a clip richer and you get the burbles. Half a clip leaner and the power flattens out a touch on the bottom half of the needle (off the pipe). Feels like it takes a little more to put it on the pipe too, and then the bike hits hard. Thats how I had my 300 set up but it required a full clip leaner to do it, and going back the other way the bike would burble with only a half a clip. Its much more stable now and made the process a real walk in the park. I hope the fuel economy still comes in around where it was. I'd like to be able to get around 100km from the tank.
andoman
New member
I'm curious about the economy, too.
I would think that a 250 should get better economy than a 300. However, a 250 has to be pushed harder to go as fast. But if you are on the pipe more, the economy should be better since that's where a 2-stroke is most efficient. But if you average a gear lower on the 250, then your drive is less efficient...
Like I said, "curious."
Which reminds me: did you keep the same final gearing?
I would think that a 250 should get better economy than a 300. However, a 250 has to be pushed harder to go as fast. But if you are on the pipe more, the economy should be better since that's where a 2-stroke is most efficient. But if you average a gear lower on the 250, then your drive is less efficient...
Like I said, "curious."
Which reminds me: did you keep the same final gearing?
Jakobi
Super Moderator
I have no intention of changing the gearing for the riding I do. The bike will still lug down to second gear and pull tight single trail uphill switchbacks. I can chugg around at walking pace in second. Open the throttle and take off cleanly. I currently have 13-50 though so I am a bit shorter than stock.
The jetting definately feels and sounds a bit richer than I was running on the 300, which is what you would expect going a clip position richer. I had run both clips back to back on the 250 and there is a definite mid range boost in position 3. Half a clip leaner the bike runs super crisp and clean, but just doesn't seem to have the same punch off the bottom end. Its weaker and smoother on the bottom and much more pipe orientated. It turns into your typical 2T screamer. This is how I ran the 300 and the extra bottom end of the 300 compensated. The end result they both feel very similar.
The pros are that the 250 has much less noticable vibration and definately revs up quicker. The handing is much improved, but a lot of that could be attributed to the TTX forks.
As for fuel economy time will tell. I used to push the 300 every chance I got and always got pretty decent fuel range. Granted a tad leaner on the needle, the squish height was 0.8mm larger. I'll definately be setting the 300 up with a single base gasket next time around which will put me at 1.15mm squish with the high comp insert. I'll need to crunch some numbers to see how the CR will turn out and if I need Dave to take some out of the bowl for me.
The jetting definately feels and sounds a bit richer than I was running on the 300, which is what you would expect going a clip position richer. I had run both clips back to back on the 250 and there is a definite mid range boost in position 3. Half a clip leaner the bike runs super crisp and clean, but just doesn't seem to have the same punch off the bottom end. Its weaker and smoother on the bottom and much more pipe orientated. It turns into your typical 2T screamer. This is how I ran the 300 and the extra bottom end of the 300 compensated. The end result they both feel very similar.
The pros are that the 250 has much less noticable vibration and definately revs up quicker. The handing is much improved, but a lot of that could be attributed to the TTX forks.
As for fuel economy time will tell. I used to push the 300 every chance I got and always got pretty decent fuel range. Granted a tad leaner on the needle, the squish height was 0.8mm larger. I'll definately be setting the 300 up with a single base gasket next time around which will put me at 1.15mm squish with the high comp insert. I'll need to crunch some numbers to see how the CR will turn out and if I need Dave to take some out of the bowl for me.
Jakobi
Super Moderator
Back to 42 N3EJ#2 178. The bike definately loses some bottom end torque going a half a clip leaner but it just feels so much crisper and reactive. Definately runs better for the type of riding I do.
In other news I was checking the bike over tonight as I'm taking it on an adventure to break in some new trail and noticed someone has done the sly on my ignition switch. It was sitting in rain mode. No idea how it got like this or how long its been like this, but I was wondering why it wasn't hitting as hard as I'd expected. Update tomorrow. Might take some video too.
In other news I was checking the bike over tonight as I'm taking it on an adventure to break in some new trail and noticed someone has done the sly on my ignition switch. It was sitting in rain mode. No idea how it got like this or how long its been like this, but I was wondering why it wasn't hitting as hard as I'd expected. Update tomorrow. Might take some video too.
Jakobi
Super Moderator
Special package arrived from Dave earlier this week. 3 x PV spacers each 8mm thick. Anyone experimented with different PV volumes to determine where the sweet area is? From what I have read the spacers add torque to the bottom end, but also make it less snappy. I might start with 1 spacer and see if I can notice any difference. Has anyone noted any jetting changes required when adding volume too?
Jakobi
Super Moderator
Also a little update from the previous post re jetting the 250. Have moved back to 45 N3CJ#3 178 until the N3CW arrives which I hope to be able to run with a 40 pilot in clip 3.
Custom sticker kit is on the way from ride PG which I may or may not install. I might save it until the old stickers are shagged out.
Ohlins TTX setup in the front is running well with the .46 springs, however after initial break in around 10hrs I plan to change the oil out and make any adjustments to oil level based on how they handle a decent ride. Will drop some fresh seals and bushings in at that time too. TTX shock is going in tomorrow morning with a 5.4 rate spring.
Custom sticker kit is on the way from ride PG which I may or may not install. I might save it until the old stickers are shagged out.
Ohlins TTX setup in the front is running well with the .46 springs, however after initial break in around 10hrs I plan to change the oil out and make any adjustments to oil level based on how they handle a decent ride. Will drop some fresh seals and bushings in at that time too. TTX shock is going in tomorrow morning with a 5.4 rate spring.
Jakobi
Super Moderator
http://www.gasgasrider.org/forum/showthread.php?p=89141#post89141
Update posted in ride&pics section.
Update posted in ride&pics section.
djroggen
New member
It really blows that you need to drain the coolant and remove the water line housing to nip the front 2 bolts up!
You should not need to drain the whole system, if you just take the bolts out of the rad hose connection and pop it loose there is enough suction in the system to keep the antifreeze in.
My Star Head leaked with the bolts they gave me too, the bolts look sweet, but I had to replace them. I used the factory head bolts so I could actually tighten them, and added some antiseize while I was at it. They didn't have much room but once you get them tightened down they fit perfectly.
