Recent content by bob58o

Well I also found this thread at Bob's.... Jody from ARC says the Gen 3's have the larger valves.... Perhaps there are a few different styles with the 5.0mm stems???? https://karting.4cycle.com/showthread.php?76115-What-gen-is-my-predator-engine "The easiest way to tell the difference in a...

I keep seeing OldMiniBikes stuff saying the Gen 3 Non-Hemi's with the 5.0mm stems have 25mm/24mm valves. Is this correct? I was under the impression that the new non-hemi's came with the larger (27/25mm) valves...

Awesome thread. Glad I didn't see any threads like this when I was looking to modify an OHH50 I had. I wasn't sure which parts might fit, so I got as far as the plastic cam and then gave the engine away. A thread like this probably would have had me spending a bunch of money. LOL

Hemi Predator 212 TAV-2 6" Driven 8T Front Sprocket 54T Rear Sprocket (6.075 :1 Final Drive Ratio) 13.5" Tires just under 50mph at 7500 RPM Black Mamba Jr Cam gx390 Carb 32 BTDC ignition timing 11:1 CR 7500 RPM all day. No issues revving. Stock Driven Spring (middle preload hole) Stock Drive...

As I said, this isn't really a "drag" bike, but I like toying around with stuff like this. I'll swap out the TC sprocket for a smaller one when I don't feel like 50 mph at 6000 rpm is appropriate for the style of riding I'll be doing. I built the engine with a NR cam described as "serious...

54:10 with 6" pulley is 4.86 :1 in highest "gear" 54:10 with 7" pulley is 6.05 :1 in highest "gear" So yes the 7" pulley will rev faster and get to top speed quicker 7500 RPM is 46 mph. With the 6" pulley 6000 PRM is 46 mph 7500 RPM is 57mph. I think you want the fastest speed at the end of...

Anybody try tuning the 30 series Driven Pulley for drag racing a minibike? Either switching from the middle preset hole, or swapping to the stiffer "Yellow" Spring? I'm putting a built Predator on an El Lobo minibike with a 30 series TC. Going to try the 6" Pulley first and see how it...

Calculation for Pipe Diameter.... Pipe Cross Sectional Area = (Displacement x RPM) / 88,200 1" Pipe with 0.065 wall thickness has ID of 0.87" CSA of that pipe is 3.14 x r^2 r= 0.87"/2 r =0.435" CSA= 3.14 x 0.435" x 0.435" CSA = 0.59 sq inches Displacement of 212cc = 12.94 cubic inches CSA =...

I told you it was going to wheelie. LOL What did you end up using to raise the engine? I'm thinking about a 2" x 5" x 7" piece of Aluminium. It's like $30 shipped. It is what I used on my last minibike. I'm also considering the 7" pulley. Does the pulley need clearance or just the...

Its going to wheelie! LOL 30 series TAV-2 with 6" Driven pulley have 0.90:1 overdrive. 54:10 w/ over drive is 4.86:1 13" Tires should have a circumfrence of ~3.4 ft. 5000 RPM = 40 mph. I'm putting a Hemi on a 6" El Lobo (54T sprocket) with a 30 series TAV-2 as well. Just finished the engine...

OK, I got the +0.020 ConRod, SS valves, 26lb springs, Black Mamba Jr Cam, stock rockers, stock pushrods, and ported the intake a little bit. I have been running the stage 1 exhaust pipe without the included screw on muffler. After installing the new Rod, I was 0.003" in the hole. I got the...

The build may have gotten a bit more complex. I decided I want to learn how to port and polish. I bought a HF air die grinder w/3" extension ($18 w/o coupon). I have started reading up on it. This link was helpful. Do-It-Yourself Small-Block Cylinder Head Porting - Tech Article - Chevy High...

Hey Bob, sounds like a great lil engine build that you're doing...and ole is giving you some great info. My stock engine that I built was a hemi head (60363) and the piston was .020 in the hole , so I bought the ARC billet rod that was .020 longer which gave me nothing down in the hole and no...

Well I guess I'll try to keep my questions in a single thread... What do you guys think about using a gx390 carb on the Hemi with these Mods? Is there a different option I should be looking at?

I've been reading through this. It is an awesome thread, very close to what I'm doing, and put together beautifully. It is the reason I joined the forum