Repowering my mini bike with a Harbor Freight motor
When I went to ride my Coleman CT200 minibike after winter storage, it did not want to run properly. It would start up and idle fine, but it would not make any power. I could not even ride it at all.
I first cleaned the spark plug. Then I replaced the spark plug.
I then assumed a fuel problem. I disassembled the carburetor and cleaned the jet. The stock Hisin carburetor has a nonremovable jet so I was limited on the cleaning I could do.
So I bought a new carburetor form Go Powersports. This had no effect. It would start but make no power.
So I pulled the valve cover and reste the valve lash. Still no change.
Next I tried a high performance carburetor from Go Power sports. No Change.
I removed the head and checked the valves. They looked like they were sealing fine and operating correctly.
I bought a new ignition coil and spark plug wire. No change.
I finally gave up and ordered a new engine from Harbor Freight. I carefully selected the part number so that I would get the non-hemi version. What I received was the Hemi.
I removed the Hisan engine by first removing the clutch and chain. I then removed the jackshaft mounting plate. I left the rear chain attached.
I hten removed the four mounting bolts holding the engine to the frame. I disconnected the kill switch wire and lifted the assembly out.
I mounted the Predator engine in the sme mounting slots. I used new bolts and nuts.
I disconnected the cover mounted kill switch and connected the wire to the mini bike handle bar switch. I connected the throttle cable to the Preadator throttle plate and loosened the swivel snut to allow the throttle to move freely and retun when released.
I then mounted the Jack Shaft plate to the engine. I adjusted the engine in the slots to tighten the rear chain.
Since the Predator has a 3/4 shaft and the Hisan has a 5/8 shaft I had to replace the clutch. I got this one from Amazon. https://amzn.to/3bFP1o8 I had to use three washers to get the spacing right to line the clutch up with the jackshaft gear.
The new engine made a huge difference in performance. The fastest I had ever gone wi the original engine was 14 mph. The bike now goes 28 easily. I have not made any modifications to the new engine and it is still running the governer.
The bike is much more powerful now. It will pull the front wheel from a start if I am not careful with the throttle.
I may swap the Hisan Gas tank on to the Predator as the fill cap is under the frame rail. But it is easy enough to refuel with a hose or funnel, so I may just leave it. The Predator engine is also quieter so I enjoy riding the bike more now.
If I had known what a difference the engine swap would make, I would have tried that first. I think I spent more on carbs and other parts than the engine cost from Harbor Freight.