2 stroke / 4 stroke experiment

BarryT said:

I slowly turn the idle adjustment screw out and I can get it to idle around 1000 RPM for a second or two and then it dies.

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Normal idle speed for a GXH50/HS is ~1800-2000RPM. These aren't large engines with a lot of torque.

Your legs have more torque than the engines do.

BarryT said:

For those of you who have tried to mount an HS-142/shift kit combo on a GT-2 frame, you are aware of the clearance issues with the air filter, etc.

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It is a very tight fit but doable with the stock carb on it.





The first thing have to do on most 142F/4G/JS builds is cut the choke lever off at the base, then cut off the rest of the shaft from the lever and then drill, screw and glue the lever back onto the carb at a 90 so you can get to it.

I then cut off the muffler clamp part of the bottom mount plate and welded it to the top plate, ground off the nut on the top plate that held the 2 plates together and then re-drilled new engine mount holes to put the silver valve cover almost dead center under the top bar all the forward as it could go.

Then you have to pull the 4G 10T sprocket off, grind the bushing spacer down, then put the sprocket back on reversed to line up with the JS left sprocket which only gets 1 thin black washer. Last but not least cut all your mounting muffler clamp U-bolts down to the nuts.

The HS carb has an air/fuel idle mix screw to adjust for your altitude, here in Phoenix ~2 1/2 turns out will let you get the idle to ~1800 RPM and not die.

That doesn't answer your 'how to use an NT carb on the thing' question, it simply points out you don't need to.

On a side note...
If I build another 4-stroke on a GT frame I'll use the 2-stroke frame, it has more of a beach cruiser curved front tube than this V frame that should let the engine go much farther forward just above the pedal sprockets with the mount pedestal out of the way and solve many of these issues.

BarryT said:

Looking for one of you REALLY smart guys out there for an answer or lead:
For those of you who have tried to mount an HS-142/shift kit combo on a GT-2 frame, you are aware of the clearance issues with the air filter, etc.

To solve this, I made a 90 degree intake manifold out of an electrical conduit coupling and attached a stock NTTC 2 stroke carb. Clearance problem solved! BUT, it lights right off and winds up the 3000 to 4000 RPM. I slowly turn the idle adjustment screw out and I can get it to idle around 1000 RPM for a second or two and then it dies.

So, whaddaya think? Re-jet? Larger and smaller jet? Will the jet from the HS-142 carb fit in the NTTC carb? Any other ideas?

Thanks in advance!
Barry

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I've used those carbs on several 49cc 4-strokes with great success! The stock jetting is almost perfect for that enine.

I would guess that you have a air leak.

I agree. Sounds like an air leak.
Many conduit connections are NOT airtight. Maybe some sealer around the couplers?