Feedback - Advice - Predator

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Bunkster

Member
#1
#1
All:

in addition to my Warrior build my son has a Warrior with a new style Hemi Predator engine.Need feedback on plan.

He opened up the case this weekend so its time to update the guts. He currently has: TAV - 2, Hot Rod mini bike exhaust, ARC air filter and ARC 615 carb.

Ive ordered a stock length billet rod, Billet flywheel with 8 degree timing, 22lbs springs and a ARC Mod 2 cam Will remove the governor and will check to see if a thinner head gasket will work.

Any advice or additional stuff I should consider? Doing want to go 800 MPH but hoping this will add a little more power but be reliable and safe.

Thanks in advance for any feedback.
 
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Moto Walt

Member
#3
#3
You won't have any clearance issues with the 10thou gasket. When you get tired of the baby carb and upgrade it will wake up to a whole new tone.
 
B

Bunkster

Member
#4
#4
Moto Walt said:
You won't have any clearance issues with the 10thou gasket. When you get tired of the baby carb and upgrade it will wake up to a whole new tone.
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Any advice on a carb that would work better with what I have planned? I do have a 390 carb in my parts pile.

Since the engine is torn down I'd gladly consider a better carb if it would help performance. I do want to stay with gasoline.
 
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Moto Walt

Member
#6
#6
Bunkster said:
Any advice on a carb that would work better with what I have planned? I do have a 390 carb in my parts pile.

Since the engine is torn down I'd gladly consider a better carb if it would help performance. I do want to stay with gasoline.
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I LOVE 390 carbs and style all over mikunis. Some people have issues with the 390 on gasoline but not me or any of my friends. We have them babies worked out. IF you aren't one to tune a lot on something or understand how a carb works you might want to go with the mikuni as its a little more user friendly.
 
B

Bunkster

Member
#7
#7
Another quick question on the Mikuni carb. Do you still need to use the gaskets between the head and the adaptor and between the adptor and the carb itself? Also do the come preset from the factory or should I expect to make major adjustments.
 
T

tlizard2

Member
#8
#8
On a genuine Mikuni 22mm try a 125 or 130main jet to start, along with a 15 to 17.5 pilot. Out of the box they come way to lean. Carb has an o ring on the flange so no gasket needed but between the engine and intake you need a plain ole paper gasket, nothing special.
 
S

San Diego

Member
#9
#9
You'll only need a gasket between the head & the intake adaptor.

I'm running exactly the same setup on an old-style (CA) Predator, bought this Stage 3 Kit from NR which has most everything you have:

Hop Up Kit- 212 Predators, Stage 3, Old Style (non-Hemi)

I opted for the 22mm Mikuni. It has worked very well.

They also have a Hemi version of the Kit:

Hop Up Kit- 212 Predators, Stage 3, New Style (Hemi)

You may want to consider the .020" longer rod.

This setup has worked well for me on my Taco Flat Track Racer & has been stone reliable. I also am running a torque converter:



I just had my head ported and 3-angle valve job done. Looking forward to see how that will increase the power.
 
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danford1

danford1

#13
#13
San Diego, What cam did you go with?

Moto Walt, my advice is to get a genuine Comet brand belt. The cheap China belts just don't hold up at all.
As for size you need to accurately measure the center to center distance of your crank and shaft your driven clutch is on. Then see if you have a 6" or 7" driven clutch. Next go to a Comet belt chart and see what belt number you need. Start searching all over the net until you find a good price, most likely eBay... You can use this chart to find your belt number.
https://www.gokartsupply.com/beltchart.htm
Danford1
 
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B

Bunkster

Member
#14
#14
Thanks for the feedback. Ill try the gasket. I installed the billet std length rod, billet flywheel. molly push rods, 22 lbs springs and Mikuni 22 carb and had trouble getting her started. Good spark so I replaced the Mikuni with an old card and got it started but probably need to adjust the old carb since it didn't want to idle. I'm assuming since it started that I have good compression but will double check that and the valve lash tonight along with the valve train. The flywheel came with advanced timing so I used the keyway and not a timing gun. How likely is it that timing is off? I have a timing gun but wondering how I spin the engine enough to check timing. Can a drill connected to a nut on the flywheel do the job?
 
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Moto Walt

Member
#15
#15
danford1 said:
San Diego, What cam did you go with?

Moto Walt, my advice is to get a genuine Comet brand belt. The cheap China belts just don't hold up at all.
As for size you need to accurately measure the center to center distance of your crank and shaft your driven clutch is on. Then see if you have a 6" or 7" driven clutch. Next go to a Comet belt chart and see what belt number you need. Start searching all over the net until you find a good price, most likely eBay... You can use this chart to find your belt number.
https://www.gokartsupply.com/beltchart.htm
Danford1
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Thanks guy!
 
M

moetrout

Active Member
#17
#17
San Diego said:
@ danford1: The MOD 2. In hindsight, I may have gone with something else.
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What other cam would you consider? I have a CS cam in my motor and was thinking about going to a MOD2. The CS cam is rated at 7000 rpm. The MOD2 I looked up said 7000+. Not sure how much distinction there is between the 2.
 
B

Bunkster

Member
#18
#18
So I got the Hemi started which of course leads to more questions. 1) The engine now seems louder. Would the cam and heavier springs cause that? 2) The throttle cable that came with the kit has a very short run of bare cable to hook to the throttle handle hosuing. Do I need to use a different housing.

Once I get everything back on Ill give an update but thanks to everyone for the help so far.
 
TheDullCarbide

TheDullCarbide

Active Member
#20
#20
I like the bored out carbs. I've never seen too many problems with the moderate bore SA carbs, but Mikunis, many good stories, many bad stories. They're seeming to be hit and miss from my perspective.

What rpm are you aiming for on that TAV2? If you keep the 3400-ish rpm setup, that MOD2 cam will be useless. The MOD2 likes 4500rpm and above. You can either lighten the driver weights or get heavier garters. Or if you plan on the stock garters, the CL1 old style cam would suit you better.

edit: Dang, forgot to read the second page before posting. The CS/CM is a good grind, but it's not a stock lift like the MOD2 or CL1. A little more attention to the valve train geometry is needed with the CS/CM. Also, if you can, I'd go with the 7" driven pulley especially if you DON'T have the TAV2 mounting plate. If you do, that's okay, but you'll have to deal with non-ideal belt lengths.

Afterthought: Why TF doesn't Comet make the right size belt for a 7" TAV2? Would it be that hard?
 
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