best stock combination brainstorm, specific class rules posted in this thread:

#1
hey guys, I have a question for our forum journeymen:) I'm struggling to figure out the best head and carburetor to use. I'll post the specific class rules, pretty much stock clone leaving a lot of stuff optional.

Stock carburetor only:
Choke must be installed and working.
Choke bore .810" no-go.
Venture .615" no-go.
Rear carburetor bore .751" no-go.
No Fuel Injection.
No pressurized systems.
No fuel pumps.
Jetting is allowed, including adjustable jets.
No aftermarket carburetor or intake may be used.
Aftermarket air filter is allowed.

I was wondering if this carburetor would fit this bill:
https://www.OldMiniBikes.com/Pro-_615-Blueprinted-Carburetor.html?category_id=1623

and for the head I was here's the rules on the engine:

All engines shall remain stock with the following exceptions:
Piston must be dished.
Advancement of timing is allowed.
Camshaft CL-1 by DynoCam (Keep Spec card for Tech).
Intake duration at .050 lift 218.4 degrees and at .200 lift 85.6 degrees. Peak lift .223".
Exhaust duration at .050 lift 221.4 degrees and at .200 lift 96.9 degrees. Peak lift .230".
Flywheel:
Should be SFI certified fixed timing steel or aluminum flywheel. SFI certified flywheel will be mandatory for 2016.
Stock rockers with maximum lift measured at valve of .245".
Valve spring maximum wire diameter .698"
Valve spring pressure of 10.8 lbs maximum at .850".

does a gx 140 or 160 head suit these rules? Or basically my question is, which clone head has the most compression and the biggest valves/intake/exhaust ports?
 
#2
You don't need bigger valves with that carb restriction. I see no mention of a head CC check in there. So I suppose you could get away with a 14cc head or a milled stock. But just because the rules don't mention it doesn't mean it is allowed.
 
#3
Is this for a kart or minibike ? If it's for a kart engine the you should go to bobs 4 cycle . Those guys know rules for karting much better than most on here .
 
#4
I bet you are going to need to run the stock head. The 14cc head looks stock when it's on there. Not sure if they'll pull it and check it. You could also have yours milled from 18 to 14. Again, it probably isn't allowed. I also don't think that you'll be able to run that carb.
 
#5
Heres what we run in the CL class:
Stock Block...with the oil return hole between the push rod holes opened up to 1/4" inch
Max stroke crankshaft from B&M karting
Stock rod sized for .003 clearance on crank fit
CL-2 cam from Dyno cams
Stock dished piston
TG-1 head (best flow) usally found on Ebay
Trick 10.8 springs from B&M Karting
Holy Moses carb from Dover Power ( comes with 39 & 40 jet )
ARC billet flywheel at least a 2014 model with 34 degrees of timing built in
Coil gap at .040 to .050
Combustion chamber at 26.5 to 27 cc's (usally have to flatmill the head .020 to .030 )
AR3910X spark plug ( Autolite)
Just something to think about. Hope this helps.
 
#8
If you are allowed use the RTC6 or RTC8 head... Has big intake and exhaust runners, and comes stock with 27/25 valves...
Mill it to get your compression up...and a light P&P it will make a good head...
For carbs get a Dover HM carb... Or talk to youngengines on this site he Builds some kick a$$ carbs...
What about fuel? Alky will give a extra hp!
 
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