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Iv got a 4 mil Serval on pump gas. 137lbs of compression (1100 above sea level)... motor is very fresh 24cc domes. Play ported. Puts down around 76 hp consistently on a dyno. Best legit pull was 79hp (had an 83 hp pull... cold tire slip was clear). My primary type of riding is LSOK duning. My question is... if I lower the squish and get into 110 octane game, will I lose any driveability while duning. My current squish is .055 and .057 which seems like there is plenty of room to close it up a bit. I understand that I can squeeze more hp out of the motor, but will torque equally increase? I definitely like the way it runs now, but I really can’t say no to more power if it’s available. I’m guessing 18-19cc custom cut domes will get me around 165lbs of compression. Just need some thoughts on what to expect if I make this change. Also... I’d assume jetting would remain the same, but would like confirmation. Thanks guys!

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Iv got a 4 mil Serval on pump gas. 137lbs of compression (1100 above sea level)... motor is very fresh 24cc domes. Play ported. Puts down around 76 hp consistently on a dyno. Best legit pull was 79hp (had an 83 hp pull... cold tire slip was clear). My primary type of riding is LSOK duning. My question is... if I lower the squish and get into 110 octane game, will I lose any driveability while duning. My current squish is .055 and .057 which seems like there is plenty of room to close it up a bit. I understand that I can squeeze more hp out of the motor, but will torque equally increase? I definitely like the way it runs now, but I really can’t say no to more power if it’s available. I’m guessing 18-19cc custom cut domes will get me around 165lbs of compression. Just need some thoughts on what to expect if I make this change. Also... I’d assume jetting would remain the same, but would like confirmation. Thanks guys!

I would keep it a pump gas motor for a playbike imo. My pump gas ported 4mm serval with a airbox and snipers is making 90/51. Exhaust port was not raised at all. Just reshaped Ect. What pipes ya running? Pods I’m assuming since your in the dunes? Who did the port job?

 

 

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1 minute ago, bluebanshee98 said:


I would keep it a pump gas motor for a playbike imo. Are the cylinders ported at all? My pump gas ported 4mm serval with a airbox and snipers is making 90/51. Exhaust port was not raised at all. Just reshaped Ect. What pipes ya running? Pods I’m assuming since your in the dunes?


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Yes... it’s play ported on Shearer inframe pipes. Believe me, I paid about $700 in 3 separate dyno sessions at 3 separate places and that’s all I could get out of it. I mean we went thru everything trying to increase power. I could have messed with timing a little more, but I left it at +4 for all the sessions. I wish I could say it was throwing down 90 but it just isn’t. Jetting wasn’t changed from the first session to the third, as the A/F read perfect on all 3 dynos. 

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Yes... it’s play ported on Shearer inframe pipes. Believe me, I paid about $700 in 3 separate dyno sessions at 3 separate places and that’s all I could get out of it. I mean we went thru everything trying to increase power. I could have messed with timing a little more, but I left it at +4 for all the sessions. I wish I could say it was throwing down 90 but it just isn’t. Jetting wasn’t changed from the first session to the third, as the A/F read perfect on all 3 dynos. 

Timing is good @+4 for pump gas. Who ported it?


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I was told it could use a richer needle. I’m running an EEL 5th clip PWK 35s. I just don’t think jumping to the next richer needle would spike my numbers that much. Basically, that’s why I’m considering a dome change. With my squish clearances being a little on the high side, I just see some room to tighten it up a bit. But if you guys think it will affect my dunability, then it’s not really worth it.

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1 minute ago, bluebanshee98 said:


Timing is good @+4 for pump gas. Who ported it?


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A site sponsor. I’d rather not say, because I don’t want the dyno numbers to deflect any business from them. I was curious if the 24cc domes they sent were meant to be “safe” since they weren’t building the motor, just porting.

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A site sponsor. I’d rather not say, because I don’t want the dyno numbers to deflect any business from them. I was curious if the 24cc domes they sent were meant to be “safe” since they weren’t building the motor, just porting.

Gotcha and definitely respect that answer. Cam @ redline did my motor. I would give him a call and see what he can do for ya


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Timing on a low port engine like your serval ain’t gonna make a difference. +4 is where you should keep it.

you need to ask yourself if you really want to go to race gas?  You’ll see a difference no doubt but if it was me I would look into reporting or dropping a bigger crank in and having your ports adjusted to the larger crank.

ive got two sets of domes for you if your looking. Ones 21cc with light use the others 18cc brand new in package

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9 hours ago, BlackandYellowBanshee said:

I understand that I can squeeze more hp out of the motor, but will torque equally increase? 

Learn the formula for horsepower.

HP = Torque (lb-ft) * RPM / 5252.

 

So, only way to increase HP is to either get more revs, or increase torque. You measure torque and RPM, you always calculate HP.

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39 minutes ago, ClaudeMachining said:

Look like a "clean" ported engine to me.

 

Envoyé de mon SM-G935W8 en utilisant Tapatalk

 

 

 

 

Yea.... Iv definitely wondered if that were the case. I do recall looking at the porting and not seeing anything aggressive. I’m not an expert so I assume it’s correct. Basically I trust that you pay “x” you get “x” I mean the numbers do line up with a “clean” port though.

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I guess I could pull the intake boots at some point and take some pictures. I’d assume you guys know what you are looking at. It’ll be awhile to get to. Iv got a new baby so it’s hard to spend any length of time in the garage without getting squawked at. Between the new LT setup and rear end, Iv been using the “be up in a minute” line a little too much lately.

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