HuaSheng 142F vs Honda GXH50 vs Dax XC50s

[Quenton Guenther]

Seems a little low. Did you have the throttle wide open during the test?

Hopefully I can test a new motor within the next few days and post the results.

Have fun,

 

[BigBlue]

As Quenton stated, make sure the throttle open all the way when checking compression. Also, make sure you pull the starter rope several times and record the changes in compression. One pull ain't going to do the job. Make sure you push the reset button in between pulls and recordings to release all the compression.

Here's a note from the Harbor Freight Compression Test Kit manual on how to check the health of your engine:

"NOTE: Good engine cylinder compression will be indicated with a high initial reading, and a progressive build-up to the final maximum reading. Poor engine cylinder compression will be indicated with a low initial reading, and a much slower build-up to the final maximum reading."

Good Luck,

Chris
AKA: BigBlue

 

[chrisnbush]

Checked it again at WOT, as many times as I pull it (releasing compression in the guage between pulls) I get 50 psi. It is pretty steady at that number, maybe ranging from 48 to 52 psi.

One thing I do notice, if I don't release the guage between pulls, it climbs up maybe to 90 psi after a couple of pulls. Kind of wonder why it does that, thinking it might be an artefact of how the guage works ?

Anyway, I am getting 50 psi. If that is low compared to a new engine it makes sense to me, as I am no longer getting that stiff stroke when I pull the cord, the one that shakes the bike a little. I am thinking the rings / cylinder might have worn. I now have 6810 logged miles, pretty good for a air cooled tiny 4 stroke motor. I put 30+ miles a day on the thing, have done this maybe 1/2 of all work days in the last year and a half +. And this isn't on the flat, there are some pretty good hills hear in new hampshire.

Also remember that this motor has been pushed somehow to make it a "super" 142F, I am wondering now if it be higher compression than the standard 142F - I don't see any difference in the valve springs between the stock 142F and the "super" titan. So maybe it has taken its toll.... Out of the box, this motor was at LEAST 15% stronger than the stock titan.

Will be interesting to know the compression on a new motor.

Regards

 

[Scootmeister]

I agree with Quenton, 40-50 psi sounds low even for 50cc engine. I'm thinking either worn rings and/or valves that aren't seating properly due to pitting or carbon build up. Did you check the valves to make sure they aren't burned? If any of these things exist and the rings are good, a little lapping could bring the compression back to stock (assuming head gasket is not leaking.)

 

[MotorBicycleRacing]

I agree with Quenton, 40-50 psi sounds low even for 50cc engine. I'm thinking either worn rings and/or valves that aren't seating properly due to pitting or carbon build up. Did you check the valves to make sure they aren't burned? If any of these things exist and the rings are good, a little lapping could bring the compression back to stock (assuming head gasket is not leaking.)

Honda GXH 50 and it's Chinese clones have a one piece head so there is no head gasket to leak.

 

[Quenton Guenther]

New motor checks 50 pounds with a single pull, and up to 90 after several pulls. I would guess once it breaks in the compression should settle in at approx. 100 pounds.

The Honda motor would check higher as the compression ratio is slightly higher.

Hope this helps!

Have fun,

 

[chrisnbush]

So mine gives me 50 on the first pull, and doesn't climb up (I am releasing compression after each pull). Thanks everyone for the help.

By the way, I completely dissembled my older 142-F, in order to get some practice in case I decide to do some valve lapping - cylinder honing on my Super Titan. Someone asked about the flywheel key, mine appears to be steel, not aluminum, and is not deformed. Just to finish the post thread. Of course who knows, with all the clone chinese companies that make the same product, if other motors don't have soft keys in them.

Kind of a weird question, but has anyone ever tried supplying pure oxygen mix to the carb with these motors ? I have done a lot of research on mechanics of doing this. Nitrous provides oxygen to combustion, but why nitrous ? Why not O2 ? I can get a 22CF oxygen welding tank, and a flow regulator to provide lets say 10% enrichment. There are charts on the web that allow you to determine what the total gas volume through put is on these motors - running this thru I come up with 6 CF per minute at WOT for the 142-F (49cc). SO a 22CF tank (which is like 15 lbs, 6" diameter 1' high or so) would supply 4 minutes of pure oxygen under WOT. It costs 20 to refill one of these tanks at the welders. SO, lets say you want to make an "O2 burst" system, kind of like nitrous. You might make it to give 10-30% enrichment with O2, which brings you to 12 - 36 minutes, not necessarily WOT all the time you need it, so at half WOT maybe 24 to 72 minutes. Thats a lot of "bursts" to help you up hills. But the cost has to stay lower than 20mpg in my jeep, figured on a per gallon basis...

Weird idea I know, and thanks for your patience. I am kind of in it from the ultimate cheap transport / green angle. So I try to figure out things like "what would it cost to make 02 in your home" - they have medical O2 generators, I am thinking they can't cost very much in Watts if it costs a couple of dollars to charge up your prius (!). SO I guess the question is, has anyone ever heard about someone trying to enhance the power of these motors with 02 ? Wondering if this would cut down on pollution also, less nitrogen going in to make NOx.

Way off topic I know.

 

[The_Aleman]

Pure oxygen? No, your engine would turn into a grenade! Nitrous oxide functions as it does because it's easier to store and the nitrogen in the mix has a cooling effect.

All nitrous oxide does is allow you to run more fuel. Pure oxygen would make your engine dangerously lean immediately and if you're lucky, it won't throw shrapnel everywhere.

You may find this article interesting. http://auto.howstuffworks.com/oxygen-engine.htm

 

[Quenton Guenther]

Just want to take a few minuites and try to discourage everyone from modifiying the HS or Honda motors. Both motors will destruct if run above redline [7800 RPMs] for any extended period of time. Both motors will explode [rod will leave crankshaft] because they are tuned in such a way as to "not know when to quit". Several companies found this out when they offered kits with ratios above 20 to 1 and of course many owners tried to reach 35 MPH and found the motor turning over 9,000 RPMs [can you say "BOOM"].

Most motors are modified to add additional RPM and move the torque curve to a higher level, sadly the HS and Honda motors don't work long at elevated RPMs. As an example, most Whizzer motors max at about 6,000 RPMs, however my record setting motors will exceed 8,000 RPMs and survive.

Best to increase HP and torque rather than increase RPMS levels. Becuase of the motor design, it is difficult to bore, increase compression, increase valve size, or increase the compression ratio [head is part of block].

If you want additonal performance from the HS or Honda motor, look into tuned exhaust systems, or better power transfer from the motor to the rear wheel. Both of these concepts will add addition HP and use the torque more wisely. Always remember a lot of power can be wasted in the drive system [gears, chains, grease, bearings, design, etc].

Here is a perfect example of advanced power transfer..........We recently upgraded the Q-Matic with a special balanced secondary drive pulley and EVERYONE reports increased low end torque, increased hill climbing ability, more top end, and a much smoother system. The change was from the original aluminum 5" pulley to a steel balanced 4.95" pulley. If the motor flywheel weight is increased [weed eater clutch on a tapered shaft] the motor will rev much slower, use direct power to spin the clutch at motor speed and transfer less power to the rear wheel. The Q-Matic doesn't have the clutch on the flywheel and only spins the rear monted clutch at approx 1/3 motor speed, which uses far less power. The Q-Matic stores secondary "flywheel" action without taxing the motor as much as other systems.

It is possible to reach almost 50 MPH with the HS 142 motor, Q-Matic drive, 24" wheels, tuned exhaust, 165 pound rider, light bicycle, no wind. The bike will easily average 40 MPH which is too fast for an average bicycle.

Have fun,

 

[MotorBicycleRacing]

.
It is possible to reach almost 50 MPH with the HS 142 motor, Q-Matic drive, 24" wheels, tuned exhaust, 165 pound rider, light bicycle, no wind. The bike will easily average 40 MPH which is too fast for an average bicycle.

Have fun,

That's a big claim with no proof....
Does almost 50 mph mean 49 mph? 48mph? .....

Was that downhill?

Last time I saw you making a 50 mph speed claim on the Q Matic
you were using a Whizzer speedometer that was set for 26" wheels
on a 24" wheel bike which inflates the speed.

What sprockets are being used for your almost 50 mph speed claim?
10 tooth to 56 tooth rear?
2" to 5" Q Matic pulleys?

Do you have a GPS or a trust worthy means of determining speed?

1) At what rpm are you going "almost 50mph?"

1) At what rpm are you averaging 40 mph?