mikenlapaz

Got a used GoPed yesterday for the engine. It was very clean, like the piston and exhaust port were 95% carbon free. Serial # 801095 It has a Walbro WYJ 138 843 carb measuring .406" exit diameter (venturi). The carb manifold has a weird internal design with 'baffles' as the circular intake changes to rectanglar head intake. If I understand correctly, the stock carb is not suitable for RC use; have a Walbro 167-1 that could be used. On the manifold, can I just grind out the intake to .553" and cut out those 'baffles' or should they stay?
The stock muffler is straight pass-thru with a baffling material on outer surface. No Modification unless outlet pipe should be enlarged from .37" to something closer to new carb outlet size.

Briefly visited a GoPed forum, and there was mention of Zenoah g23 s made for different applications having different ign. timing. If this is correct, does anyone have any idea what the setting is for the G23LH version?

It appears that the head can be rotated 180 degrees, has posts both front and back for the coil.
If it were rotated, should the piston be rotated 180 as well (wear/seating of rings)

THE FIND
with tires, brake rotor, and engine recoil starter this thing would run as designed.
Xmas came early!

av8tor1977

My Feedback: (6)

I would think that if your carb venturi, (the smallest part), is actually .406" as you say, that should be a large enough carb and you could run it. I'm not familiar with this engine, but one thing for sure, if you rotate the cylinder you will HAVE to rotate the piston as well. The rings on the piston are pinned so as not to rotate and allow the rings to pop out into the exhaust port. If you rotate the cylinder and not the piston, the rings will be in the incorrect position. The pistons are also usually machined a little differently, with a little more clearance in the exhaust port area because of the higher heat there. You will also want to look things over carefully to see if the transfer port passages in the cylinder will line up either way with the crankcase.

Good luck,
AV8TOR

av8tor1977

My Feedback: (6)

WHOOPS...

Also look to see that there is a passage for the crankcase pulse pressure on both sides of the crankcase!! It will be a little hole, or notch, that lines up with a little hole in the cylinder that goes up to the carb mounting pad.

AV8TOR

mikenlapaz

av8tor1977
The carb manifold is shown below. Interior just seems cluttered and different. The pulse port is totally in the head. The hangup on 180 head rotatation seem to be the difference in the head's ''mating lip' and the restriction tab in the case. I do not understand transfer port design but the case part seems identical. The coil mounts are longer than the posts cast on back of head. (also one of the posts is larger bore and unthreaded)

The Zenoah website, http://www.zenoah.net/products/hobby/hob_index.html , shows a rpm/torque curves for 3 g23 models. The LH verison is the lowest rated.

Who has carb 'twister' for G23? Are they add-on to existing manifold insulator spacer or a replacement twisted spacer? Don't want to get an add-on that won't fit this model spacer.

mikenlapaz

As refernced in prior post.

ZAGNUT

My Feedback: (1)

NO,NO,NO!!

Mike, this ain't the same engine that zenoah makes for R/C...it's way down on power, about the same as the little echos and you already have some of those, no?

put that go-ped back together and you'll have a blast! the brake rotor is just steel plate and the engine doesn't need a pull starter if it has a spindle drive, you can push-start it no prob. over here i can get a nice pair of 12" pneumatic tires and wheels with ball bearings for under $40 so you should be able to find something similar too...


dave

mikenlapaz

Dave,
If I put it back together it will be short the fins down to the outer magnet surface and 4 starter lugs, as they got the cutoff wheel on the drillpress this afternoon. Yes it has the spindle drive to wheel surface. Have not pulled the fork apart, there is play, suspect the bearings are shot, bike shop may have those. I'll put it on a back burner and do some more checking for wheels and rims. Put together it may fetch enough to be worth the additional investment. Not sure I would ride it much here, too many potholes. ( A few years ago local JC's had a float in major parade depicting a VW stuck in a pothole with only half the car visiable. People laughed but government was not embarressed enough to retictify the problem)

Been trying to figure out why the low power output. I can only visualize the type/size of transfer ports; duration of time the intake and exhaust are open; and the compression (squish area at TDC) Maybe someone can enlighten us on the other factors.

av8tor1977

My Feedback: (6)

Hi Mike,

Add to what you just said; overall size of all the ports, size of carb, restriction of muffler, and ignition timing, and you basically have the whole power output scheme of two strokes. You could measure everything and then see if someone could provide you with the specs for the other G23's to find out what the differences are. Most of these things could be modified excepting the transfer ports. They are very critical in their angles, and it is not recommended to try to change them.

Good luck,
AV8TOR

Volfy

My Feedback: (23)

Mike, don't put it back together. Each version of the G23 is specifically tuned to the intended application. Engine tuning is a compromise. Study the HP and torque charts a little closer and you'll see. The LH scooter engine emphasizes low end torque, much like a pickup truck engine. Tuned to haul a 200lbs over-weight kid from a standing start means the peak HP is not gonna be very impressive. The PU aircraft engine is only expected to whip a little propeller around, so top end power is more important.

My own G23 (sold by Horizon) doesn't lik to be propped downed too much. Lugging a 18x8, it couldn't even get close to 7000rpm. Strap on a 15x8, and it spools nicely up to 9000rpm.

I suspect your LH version will do well swinging a big ol' prop. Whether that's the type of engine you're after is entirely up to you.

Volfy

My Feedback: (23)

BTW, that is a very clean motor. I love clean motors.

After you shave off the excess bracketry. This sucker will weigh less than the Horizon Hobby G23, which has that bell housing and frame for the pickup coil, assuming you upgrade to elec ign of course. You may not even need a mounting plate, if you can bolt it directly to the firewall.

mikenlapaz

Just spent a little time at a GoPed site and they market a modified woodruff key which "cures all" allowing a 10 degree advance. The keyway/stock was wide, so maybe there is some improvement with the timing even using the stock ign. (narrower key stock)

Clean up was a dry paint brush for the exterior.
If the drive spindle did not have the abrasive worn off, I would have guessed an early crash/accident. And yes, it even came with a steel mounting bracket for a template, would have to rid it of the output shaft.

hacksaw42

Did you ever get this running?

mikenlapaz

It is now reassembled with new flywheel and recoil starter. It is on the Go-Ped.