Joaquin Suave
New Member
Has anyone toyed with different carbs, porting, or pipes???
Performance Modifications to the GXH50
- Thread starter Joaquin Suave
- Start date
MotorBicycleRacing
Well-Known Member
Yes.
Don't forget the Huasheng 49.4 cc Honda clone.
One more option is a free flowing air filter with
the standard carb.
SickBikeParts.com has an air filter upgrade.
AffordableGoKarts.com has a larger carb and air filter upgrade.
Also a reground cam.
A couple of exhaust systems.
The only company claiming upgraded porting on the Huasheng
motor or Honda is Dax with his Super Titan / Huasheng.
Dax claims 1/2 hp more with the Super Titan than the regular Titan
which he claims is accomplished by better porting and higher compression.
Personally I doubt these claims and Dax has never proven that his
$40 more expensive Super Titan has any porting or compression changes
over the regular Titan.
All experts including AGK I have talked to say there is really no way
to change the porting to improve over what Honda has designed.
scotto-
Custom 4-Stroke Bike Builder
How would you raise the compression in a 4-stroke where the entire cylinder and head are cast into one as part of the crank case. Maybe Merlin the magician could do it using thicker valves or something............NOT! As BiMoPed said.....air filter, carb, cam and pipe upgrades.......same as it ever was.
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MotorBicycleRacing
Well-Known Member
You could raise the compression in these motors with a taller piston
or longer rod???
Not easy to do though and probably not worth it.
Honda GXH 50 has higher compression than what is claimed for the
Huasheng 50 clone.
I have both motors and the finish on the Honda is much nicer than the
Huasheng. Just looking under the valve cover is amazing. The Huasheng
is very crudely finished compared to the Honda but they seem to be reliable.
I will take some comparison pics one day when I ain't so over my head with this race.
scotto-
Custom 4-Stroke Bike Builder
And who makes these rods and pistons??? Nobody yet that I know of. And I'd like to see someone try to port one of these 50's seeing as how the head is one with the cylinder (and half of the crankcase). Unless they've got skilled mice machinists
The_Aleman
Active Member
The motor is already ported fairly well. I'd like to see if there's any difference in piston heights between the GXH50, HS, and the Super Titan. Otherwise the only way to account for compression differences are rod length and whether or not the crankshaft is offset-ground.
Elmo
New Member
With a higher compression piston. We used to call them popups in the old days.How would you raise the compression in a 4-stroke where the entire cylinder and head are cast into one as part of the crank case. Maybe Merlin the magician could do it using thicker valves or something............NOT! As BiMoPed said.....air filter, carb, cam and pipe upgrades.......same as it ever was.
Joaquin Suave
New Member
Thanks guys!
Out of curiousity, does anyone know of a <50 cc 4-cycle that has a counterweighted crankshaft? I'm interested in finding a motor that does not need a flywheel (yes, I would be running electronic ignition).
Out of curiousity, does anyone know of a <50 cc 4-cycle that has a counterweighted crankshaft? I'm interested in finding a motor that does not need a flywheel (yes, I would be running electronic ignition).
scotto-
Custom 4-Stroke Bike Builder
Flat top pistons rule....who's making high comp piston's for these little 50's? Wiseco pistons perhaps....I don't think so. If someone was making them, I'm sure AGK would be selling them.
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karma1968
New Member
i had good results by adding two washers under the valve springs. the timing gear survived after a full summer of riding non stop so i can say it safe to try.
works great on the Honda clone.
The_Aleman
Active Member
hey karma1968, all that's going to do is slightly raise the RPM that the valves will start floating. It's not going to raise compression. It's not going to fix the simple oil system that can't supply enough oil at high revs for extended periods. It's not going to prevent the conrod from getting thrown. There's a few guys here who practically bronzed their conrods from revving too high for too long.
i had good results by adding two washers under the valve springs. the timing gear survived after a full summer of riding non stop so i can say it safe to try.
works great on the Honda clone.
How do washers under valve springs raise compression?
andrewflores17
New Member
i just took a drill to the plastic sheild on my airfilter box helped a little and its free
MotorBicycleRacing
Well-Known Member
If you really increased the airflow you will need to rejet your carb.
here is a great tutorial.
AGK - High-flow Air Filter Modificationon 49cc Engine - Affordable Go Karts
scotto-
Custom 4-Stroke Bike Builder
They don't raise compression, they just raise the spring tension on the valves......it's not the same thing.
andrewflores17
New Member
realy cool link wish i could remember which sprocket works best for what but gearing is definatly gona make or break what your looking at 
The_Aleman
Active Member
No one has posted any info here on piston heights, conrod bearing center distance, combustion chamber area, or any other info that would be helpful to ascertain the compression differences. Further, we would also need cam lift + duration info and valve size, as well as rocker ratio. All these things can solve this mystery.
It's too bad B-E didn't delve into this back when they sold GXH50s and the HS142F side by side.
It's too bad B-E didn't delve into this back when they sold GXH50s and the HS142F side by side.
Found some info on this that might shed some light:
Huasheng 142f: Bore: 41.8 Stroke:35.8---Actual Displacement: 49.1
Honda GXH 50 : Bore: 41.8 Stroke:36-----Actual Displacement: 49.4
Since the honda has a slightly longer stroke (by .2mm) it has a displacement advantage. This could be why they make a little bit more power. Also, if the motor castings are the same (and sleeve height/combustion chamber), this would account for the increase in compression.
Huasheng 142f: Bore: 41.8 Stroke:35.8---Actual Displacement: 49.1
Honda GXH 50 : Bore: 41.8 Stroke:36-----Actual Displacement: 49.4
Since the honda has a slightly longer stroke (by .2mm) it has a displacement advantage. This could be why they make a little bit more power. Also, if the motor castings are the same (and sleeve height/combustion chamber), this would account for the increase in compression.
scotto-
Custom 4-Stroke Bike Builder
Therefore if the tolerances between the Honda and the Huasheng concerning the crankshaft, con-rod and wrist-pin are compatable, you could use the Honda's rod in the Huasheng for slightly more compression.
Now what about the the Honda?
There really isn't much to work with using this engine design (whole jug cast in one piece) and it's given displacement. Larger valves, port work, and anything else substancial would require a full machine shop and the knowledge and skill to pull it off.
If you want more power.....get a larger engine.