Mild predator build what am I missing?

S

Streetglider

New Member
#1
#1
I have a brand new 212cc #69730 non hemi as a base for this little build

ARC standard stroke rod
ARC flywheel
Head stud kit
Side cover stud kit
Black mamba JR
1:1.3 rockers
26lb springs
Stainless stock sized valves
ARC retainer set
Mikuni 22mm with manifold GAS jetted
14cc or 18cc? higher compression head with the castings smoothed out and short radius rounded
.010 head gasket
Heavier pushrod guide plate
Cut to length chromoly push rods
4 degree timing key
OldMiniBikes minibike header
RLV mini 91 muffler
Complete gasket set

Am I missing anything I feel like I'm missing something ....
Anything obvious?
I used to race 4 stroke karts like 15 years ago mostly flatheads
And a bit of animal seat time but I forget the details with these ....


Thanks guys!!
And this is going on a doodlebug with a torque converter
To beat up on a friends crf50 he has a big bore on ...
And because I've had the sickness (minibikeitus) over the years this is my
6th minibike and the first one in 15 years so just getting my
Feet whet again :) wish I never sold the trail 50's and the rupps after high school :(
 
S

Streetglider

New Member
#5
#5
Ah cool I will grab a flat top piston for it thanks!!!

Well I say mild because stock stroke and bore and off the shelf parts haha :)
No idea on what kind of power to expect with this set up
If anyone has any ideas for a ballpark let me know :)


As for money I suppose with all the odds and ends
I am closing in on $1k
Flywheel $100
Rod $85
Head $45
Cam $75
Rockers $20
Engine itself $107
Push rods $25
Retainers$20
Head gasket $10
Gasket set $15
Breather gromet $3
Side cover studs $20
Head studs $20
Carb set up $110
Valves $30
Header came in minibike kit from OldMiniBikes $100
Now I have spare sticker parts for the next
Stock set up
I'm sure I'm forgetting something ....


Thanks guys!!
 
cdoublejj

cdoublejj

Member
#6
#6
it would be interesting to see a dished piston. one with an ever so slight/small dish and high comp head i bet it's would make for some nice torq.
 
S

Streetglider

New Member
#7
#7
I guess I never thought of that part of it we are milling the head down more anyway so we will try to take a bit off the factory piston and keep the compression ratio higher by milling the head and the .010 gasket....
 
vwfan79

vwfan79

Active Member
#8
#8
If you are milling the head then you mill the piston won't those be working against each other. What I mean is your milling the head to gain compression but if you mill the piston you gonna lose compression
 
S

Streetglider

New Member
#9
#9
I suppose that makes sense I will just order the piston today and bring it along :)
My builder told me it won't be needed as we might need to take some off the stock piston anyway to get everything to jive together as we don't know how far in the hole it is now


I will get some pics started when I get all the junk out of the boxes
And ready to tear down there is a pile of parts already sitting in the garage
The wife is getting concerned "that's a lot of parts to get a minibike going"
Haha :shrug:
 
S

Streetglider

New Member
#10
#10
I just placed an order with NRracing for the piston for $18
They are blindingly fast I had a tracking number and shipping notice within 5 min of ordering
Both times I've dealt with them they are on par with things!!!
OldMiniBikes was very fast also much faster than BMIKARTS in my experience

Thanks guys!!! :thumbsup:
 
cdoublejj

cdoublejj

Member
#11
#11
dished pistons supposedly harness/cup the explosion better, they work best wich forced induction. get the befit of the dish and benefit of the raised compression.

with naturally aspirated to keep form loosing compression or rather having lower than stock compression one would need a high C:R head to try and gain the C:R back. or say screw it and run a flat top piston or a domed piston for really high C:R.
 
S

Streetglider

New Member
#12
#12
Ok it's off to the builder he is going to set it up for 110 and dyno it we will see in a week or so !!!

I gave him the choice
Of 2 heads and 2 pistons he was going to build it to what works best
We will see what he uses :)

Next post will be dyno numbers and then I will start the doodlebug build thread :wink:
 
S

Streetglider

New Member
#13
#13
Ran into a flywheel issue the new non hemi predators will not fit the 6625 arc flywheel I have ordered the 6626 made for the hemi heads we will see when it shows up I was told by ARC that the hemi one should work

The 6625 taper and hole was way to small for the crankshaft on the new non hemi predator

:shrug:
 
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