Super Jet Porting or High compression & girdled head. Where should I start?

[Quinc]

ADA head is not just about raising your compression. Different dome shape and squish band angle and tighter squish size all work to incease power over a stock or stock milled head.

Porting for freestyle will not lower compression, that is with race porting and raised exhaust ports. You are on the right track though. Pick a good builder and follow his recommendations.

Also raising compression will lower engine life somewhat as will widened exhaust ports lower ring life somewhat. However, the way you care for your motor is also very important. We have customers on their 4th year with fully ported motors with high compression, but this isnt advisable. Best to teardown and inspect every season or 2 depending on hours and type of use.

How many hours used, how motor is dried out between uses, how much water is injested during use especially saltwater, heat/overheat developed during use, etc. all affect reliability.

If you want ultimate reliability, then remove bpipe and install stock pipe, cdi and jetting.

If you are building a ski for freestyle, then understand you are will be making tradeoffs for power gains. That said, you can still have a reliable freestyle motor, just understand that it will be higher reving, higher compression, higher performance motor that must regularly drink water that gets run hard so preventative maintenance becomes more important to longevity.

When you get a chance can you give us a break down on what you recommend for maintenance between rides, and what too check for every season or 2 during a tear down?

 

[Roseand]

ADA head is not just about raising your compression. Different dome shape and squish band angle and tighter squish size all work to incease power over a stock or stock milled head.

Porting for freestyle will not lower compression, that is with race porting and raised exhaust ports. You are on the right track though. Pick a good builder and follow his recommendations.

Also raising compression will lower engine life somewhat as will widened exhaust ports lower ring life somewhat. However, the way you care for your motor is also very important. We have customers on their 4th year with fully ported motors with high compression, but this isnt advisable. Best to teardown and inspect every season or 2 depending on hours and type of use.

How many hours used, how motor is dried out between uses, how much water is injested during use especially saltwater, heat/overheat developed during use, etc. all affect reliability.

If you want ultimate reliability, then remove bpipe and install stock pipe, cdi and jetting.

If you are building a ski for freestyle, then understand you are will be making tradeoffs for power gains. That said, you can still have a reliable freestyle motor, just understand that it will be higher reving, higher compression, higher performance motor that must regularly drink water that gets run hard so preventative maintenance becomes more important to longevity.

Excellent info! I love this site for that reason. Interesting to hear that the ADA head is engineered for more than just higher comp & a girdle kit.

I'm putting on a lot of hours, freshwater use, and will be running dual cooling to make sure my engine is heated properly. Still need to figure out the best way to run dual cooling too..

I would like to hear what you recommend for preventative maintenance too.

Another thing about bumping up compression, say I'm tuned correctly or a little rich to be on the safe side. If I bump up compression to say around 185, is my biggest concern going to be detonation @ WOT? And can't that be solved by adding 1 gallon of av gas or so to every 4 gallons of the supposedly 93 octane that gas stations offer? I'd be maintaining stock timing for now.

Chris, compared to switching over to a 9/15 hooker over stock, how much of a difference would bumping comp from 150-185 make?

I'd love to hear what some other builders have to say about this too. This is awesome insight

 

[High Speed Industries]

I had my stock head milled for 185psi and it made a huge difference. When a stock head is milled by somebody that knows what they are doing they generally change the dome and squish at the same time. All of that gives you a very similar setup to the ADA head without the bling factor. You can still run a girdle kit, but I really don't think it's necessary. I thrash my engine without a girdle kit and I've never had any issues and I really don't see how I would have any issues. If I was at like 210psi I would consider a girdle kit, but for pump gas I would think you're fine.
Porting can also wake up your engine, but this generally works best with more compression.

Here is what I would do if I was on a college budget

Have stock head milled by a good engine builder (the builder will determine the cc, squish, and dome shape that is needed)

Use OEM Yamaha base gasket, head gasket, and crank seals (oem is the best quality)

Have fun (that should be the most important part)

The only question I have for you is the amount of hours that you are putting on your ski. I know you said 100 a season and I'm not trying to call BS but that sounds pretty high. Last year I did 78 days of riding and I only managed to put 65 hours on my ski. If all you have is a B pipe with high compression I bet you will get 300-350 hours out of it. I would think that would last for you college years. Just my .02.

Just think about it, you are already past the hard part. You own a yamaha, most people do all of this crap to a kawasaki and then they switch to yamaha.

 

[Roseand]

I had my stock head milled for 185psi and it made a huge difference. When a stock head is milled by somebody that knows what they are doing they generally change the dome and squish at the same time. All of that gives you a very similar setup to the ADA head without the bling factor. You can still run a girdle kit, but I really don't think it's necessary. I thrash my engine without a girdle kit and I've never had any issues and I really don't see how I would have any issues. If I was at like 210psi I would consider a girdle kit, but for pump gas I would think you're fine.
Porting can also wake up your engine, but this generally works best with more compression.

Here is what I would do if I was on a college budget

Have stock head milled by a good engine builder (the builder will determine the cc, squish, and dome shape that is needed)

Use OEM Yamaha base gasket, head gasket, and crank seals (oem is the best quality)

Have fun (that should be the most important part)

The only question I have for you is the amount of hours that you are putting on your ski. I know you said 100 a season and I'm not trying to call BS but that sounds pretty high. Last year I did 78 days of riding and I only managed to put 65 hours on my ski. If all you have is a B pipe with high compression I bet you will get 300-350 hours out of it. I would think that would last for you college years. Just my .02.

Just think about it, you are already past the hard part. You own a yamaha, most people do all of this crap to a kawasaki and then they switch to yamaha.

I'll respond more in depth but I'll just add something super quick.
I'm running all oem parts for this rebuild for sure. Already got oem everything!
Well I start riding in early may, and go into October easily. . I ride anywhere from 2-10 hours a weekend in the summer/spring . Rarely two, almost always way more on the weekends. And during the week I ride some too. I ride alot.. So I've gotta save money for gas too

Edit: I have time to respond now.

Getting a head milled by a reputable builder would still run you probably close to 100$. But I look at it this way, maybe it's not all that common to crack a cylinder, but after putting in 200-300$ into a top end, a girdled head would pay for itself in that instance.
How much of a difference would you say the bump up to 185 psi made? Compared to a prop, etc?
I'm almost thinking if I go the ada route, that I'd go with 37 cc domes for 170ish psi.. but I dunno. I'm waiting for someone to chime in about the risk for detonation etc.


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[Jhucke]

Zack is not going to advise running a ported cylinder without a girdled head. Do it right the first time, especially if you want the engine to last 4 years - which seems like a lot either way. If you don't want to risk detonation, run some race gas with 91 if you have it available.

 

[High Speed Industries]

I honestly couldn't compare the head mod to a prop because I've never ridden a ski with a stock prop. I would think next to a good prop a milled head is the best bang for the buck. Having the head milled is like $100. Just spend the 100 on your head and save the rest for gas and oil.
A flywheel is a good way to get more snap, but that's not what this thread is about.

 

[kevbo]

High compression mostly affects response and spool up. Low pump loading allows acceptable response with lower compression. Your 9-15 with an 85mm nozzle will spool up fairly well with a low exhaust port and 150psi. Going to 185 will make it more responsive to throttle inputs. If you were over propped there would be a much greater gain from high compression because it would be slow to get on the pipe. 185 psi is fine with pump gas as long as you are mindful of tuning the top screw and never do long full throttle runs on an empty tank. Life is easier now since we have low pitched impellers and everyone knows to use them. Before people threw lots of money at their 701s trying to overcome too much load. They should have been bending their props instead.

 

[tatronation]

This thread should have ended a long time ago. If Zack said run a girdled head first, run a girdled head first. No one wants to crack a cylinder they just rebuilt. You'll regret not getting a girdled head in the first place. In my opinion, do it right or don't do it at all.

 

[kevbo]

How did we race for so many years without girdled heads? Im sure someone will tell you exactly what you want to hear.

 

[JT_Freeride]

How did we race for so many years without girdled heads? Im sure someone will tell you exactly what you want to hear.

The girdled head is to protect your cylinder from cracking. Mainly from ingesting water which happens all the time in freestyle and surf. Now I'm not a racer but I have ridden my ski plenty of times in the bay and in very choppy water and not one time did my ski ever take on water.

 

[Roseand]

Well I'm pretty set on a girdled head now, just not set on domes yet.. Tried calling zack a few times but he didn't answer, so I wasn't able to ask him a few of the questions I needed to yet.
Considering my tank isn't running empty so I'm not sucking in air, and my timing is set to stock, and my tuning is conservative for WOT runs, is my only risk deto due to fuel quality(if the pump gas you got wasn't actually the actual octane it was rated for)?
And would I still notice a performance increase going from 150-170 PSI, or is it a no brainer to go to 35 cc domes and 185 psi?

 

[amitchell]

wet pipe 35cc
dry pipe 37cc
That should keep you on pump gas with normal mods.

 

[Big Kahuna]

Look on page 35

 

[ph1lthy11y]

I have a 97 rn with a bpipe and ada head im running 35cc domes i definitely felt more low end hit with the am head but it wasn't night and day difference like the bpipe
p.s. i ran the bpipe for two seasons before I bought ada head

 

[Roseand]

@powerhouseperformance
I'm at school so I can't answer my phone right now. I need to talk to you about sending my cyls out to be bored too. Is it possible you could chime in about this here, as it will benefit more people than just me?
Btw, I still do quite a few WOT runs every ride so I'm not sure if 185 psi is right for me.

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[Quinc]

@powerhouseperformance
I'm at school so I can't answer my phone right now. I need to talk to you about sending my cyls out to be bored too. Is it possible you could chime in about this here, as it will benefit more people than just me?
Btw, I still do quite a few WOT runs every ride so I'm not sure if 185 psi is right for me.

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I am also running 185psi when I finish my build. My plan is to mix 1 gal of 110 with 4 gal of 91.

 

[JT_Freeride]

I'm running 185 Psi with 93 pump gas. And hold WOT for a good amount of time. I would say 10-15 secs at a time.

 

[Jhucke]

@powerhouseperformance
I'm at school so I can't answer my phone right now. I need to talk to you about sending my cyls out to be bored too. Is it possible you could chime in about this here, as it will benefit more people than just me?
Btw, I still do quite a few WOT runs every ride so I'm not sure if 185 psi is right for me.

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I really doubt Zack has time to sit on the boards to talk about getting your cylinders bored. Figure out what you want, and what your budget allows for and just do it. If you need to get 100 hours a year for 4 years, I really doubt your engine will last either way, so maybe you should wait on porting.

 

[tatronation]

I really doubt Zack has time to sit on the boards to talk about getting your cylinders bored. Figure out what you want, and what your budget allows for and just do it. If you need to get 100 hours a year for 4 years, I really doubt your engine will last either way, so maybe you should wait on porting.

Exactly, I know Zack is a busy guy, so try the search function first. Google always works well for me too.

 

[Roseand]

I have searched absolutely ever thread but never found the info I needed, and I used Google too. I always search before posting.

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