Custom/Hybrid Poor man's big bore

Norass411

Norass411

Hoarder
Location
NC
In my pursuit of low budget brap, I've done a good deal of horse trading and wound up with a super fresh 64x. The goal is a hard hitting low-end ski primarily for boat chasing and some surf. As far as performance add-ons, I've got a Riva girdled head, B-Pipe and a lightened 61x flywheel from speedysprocket. Also picked up porting templates for when I get up the nerve to start grinding. My biggest undetermined factor as of yet is how to address the issue of port timing. My options as I see them are deck the 64x cylinder or punch out one of the spare 61x cylinders I've got laying around.

If I go 61x, I shouldn't have to cut my domes but I will be left with a cylinder that is already on its final bore.

With the 64x, more initial machining will need to be done, but I'll have plenty of sleeve left to step up bore over as the need arises.

Any input on which route I should take would be greatly appreciated. Also trying to determine the best (charging) electronics to manage it all if you've got any input. Thanks y'all!
 
Roseand

Roseand

The Weaponizer
Site Supporter
Location
Wisconsin
@Nuklear6 can mod a 760 cylinder to perform very well for a reasonable price. Corrected port timing and a ported top end will definitely be a good budget setup. New domes won't be too expensive either.
Stick with an enhancer. Epics are real spotty. Rumor has it that JSTL is coming out with a programmable charging ignition though...

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Norass411

Norass411

Hoarder
Location
NC
His stuff looks really sweet but I'm cheaper than that. Hell, I only paid $100 for my ski and trailer! Got some of Yamanub's templates. I have a lathe for my domes and, if I go decked 64x, I'll hopefully be using a friend's mill. Trying to keep it as 'in-house' as possible since time is money.

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Norass411

Norass411

Hoarder
Location
NC
Yeah man. Prop is TBD but it will be stock pump w/ a stubby cone and a 62T trim nozzle (likely bored).

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yamanube

yamanube

This Is The Way
Staff member
Location
Mandalor
Personally, if you are trying to keep it super cheap, I would do some porting yourself, bump the compression up as high as you can for the fuel you can afford and advance your ignition a bit.
 
Norass411

Norass411

Hoarder
Location
NC
yamanube said:
Personally, if you are trying to keep it super cheap, I would do some porting yourself, bump the compression up as high as you can for the fuel you can afford and advance your ignition a bit.
Click to expand...
That's why I jumped on your last sale! Haha. I'm not averse to high dollar gas (smells delicious when mixed w/ klotz) and it will probably be necessary w/ porting on 38cc domes...

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Norass411

Norass411

Hoarder
Location
NC
Roseand said:
I'm with yamanube. What cases and carbs are you running?

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Click to expand...
Building from a complete 64x so no case work needed (unless I port/epoxy them) and I'll have dual 44s

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Roseand

Roseand

The Weaponizer
Site Supporter
Location
Wisconsin
Norass411 said:
That's why I jumped on your last sale! Haha. I'm not averse to high dollar gas (smells delicious when mixed w/ klotz) and it will probably be necessary w/ porting on 38cc domes...

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Click to expand...
The amount extra you're gonna spend on race gas could go into a professionally ported cylinder. Which then, in the future, you can throw in a stroker crank kit from HPE ;)

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yamanube

yamanube

This Is The Way
Staff member
Location
Mandalor
If it's going into a superjet, I honestly don't think getting the little extra low end hit is worth the money. It's not a flatwater freestyle ski, it's a rec ski and the extra mid and top that the higher porting gets you will make for a more fun all around ski.
 
Sasquachcrap

Sasquachcrap

Location
North Carolina
I have been down this road and can tell you exactly what you need to do to have the Motor that you want to have. Put your cases in the oven for 20 minutes at 450°. When the cylinder slides down away from the sleeves take them out with a pair of gloved hands. Take the cylinders. To a local machine shop(that you trust) have them cut .060 off the bottom. Call up chuck (nuckler6) and send him your domes. Tell him what you did. Porting will help. But don't raise the exhaust ports any. You may have to grind the corners of the sleeves off where they fit down in the cases some times they interfere. I was running 200 psi and 93 gas. I would limit my long wide open runs to less then 10 to 20seconds. Go with a larger domes if you want less compression. The next thing I would do is buy total loss. When I changed over from stock I saw such a difference and you can find the old single channel 4270 brains cheap and in my opinion they are better then the digital for longevity. I can ride several days on a small battery. I'm sure you could go longer on a good big Superjet battery.

Edit: I just saw where you have access to a mill and lathe. Cutting the domes will have to be trial and error. You want .055-.060 squish. I would use soft solder to measure it. I would cut the cylinders and then take maybe .015 off the domes. Assemble it and check squish. Disassemble and recut until you sneak up on your desired number.

What is your compression with your domes now?
 
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Norass411

Norass411

Hoarder
Location
NC
This was the plan exactly. So glad to hear that it worked out for you!

Since I'm going to drop the sleeves to to the milling, is it any easier to port them while they're out and then go match up the casting once they're back in?

Edit: Yeah, gonna be winging it on the domes. I had seen that method discussed on the X before. I'm not sure what it would be because I've never installed it on a motor but it's got 38cc domes. Is there any concern over too little squish so long as the compression is within the desired range?
 
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badvinny

badvinny

Location
Saskatoon,SK
Norass411 said:
This was the plan exactly. So glad to hear that it worked out for you!

Since I'm going to drop the sleeves to to the milling, is it any easier to port them while they're out and then go match up the casting once they're back in?

Edit: Yeah, gonna be winging it on the domes. I had seen that method discussed on the X before. I'm not sure what it would be because I've never installed it on a motor but it's got 38cc domes. Is there any concern over too little squish so long as the compression is within the desired range?
Click to expand...
No less than. 040" squish is required.
 
Norass411

Norass411

Hoarder
Location
NC
Sorry, I just realized that I worded that backwards. Is there a problem with too much* squish. I was thinking less as in less 'squishing' action not less distance from piston to dome.

Basically, if I'm sitting at 200psi, can I go up to .080" to give me some more volume and lower the compression?

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Blue

Blue

Judging your cheapness
Location
St Cloud Florida
You dont want a lot of squish clearance. If compressions to high go to a bigger domes.

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Norass411

Norass411

Hoarder
Location
NC
Roger. That's what I figured. Riva domes are like friggin hens' teeth so I may have to bite the bullet and buy an ADA if my comp is too high.

Thanks to everybody for all the info!

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