HuaSheng 142F vs Honda GXH50 vs Dax XC50s

[BigBlue]

Scoot,

I don't know if this helps, but AGK does sells high performance cams for the HS and Honda and they appear to be made of different materials and the Honda has compression release. According to AGK, both have the same stock lift.

http://www.affordablegokarts.com/mm5/merchant.mvc?Screen=CTGY&Category_Code=MTRBK49

Happy Holidays,

Chris
AKA: BigBlue

 

[Scootmeister]

Hi BigBlue. Good to hear from you and your tip is very helpful. I contacted AGK to find out when they expect to get the HS cams in. It looks like item 1610, the cam for the HS, is ground steel, but item 1608 for the Honda looks like plastic. They recommend synthetic oil for both to minimize wear. They also recommend a bigger carb and open exhaust allow the engine to breathe better and rev quicker. I'm thinking Quenton will chime in and warn against "self destruction".

 

[Old Bob]

A "regrind" on a stock cam is not worth it. It also messes up the rocker arm geometry.They would have to offer a longer pushrod to use it. But if there is enough travel in the lash adjuster you might get away with it.

I would use caution and keep rpm below 7500.Having an engine blow up between your legs could change your social life.

 

[darwin]

Also changes the suction equation with the carb needing to provide adequate gas and air volume.

 

[GreenMantis]

The longer rod will change the torque. When I raced British singles and twins the short rod motors had less bottom end torque and a higher top end. We always used the long rod motors on "short tracks" and the short rod motors on the 1/2 mile and mile tracks.

The HS 53 CC motors use a longer rod and have more bottom end than the 49 CC versions.

Not sure if the Honda camshaft will fit, but would be worth the effort to find out as it would surely last longer.

Have fun,

I just replaced the cam in my 53cc 144f engine with an original Honda GXH50 part, reground by AGK. It's got a neat centrifugal compression release that makes a wierd noise, but seems to make the engine easier to start. But it fits, drop in. There is a round metal washer looking thing on there with the original camshaft, I disregarded that. I believe that it is only there to "dummy" the original cam's centrifugal adavance device, as the Huasheng cam is hollowed out inside identically to the original Honda cam (molded directly from it, I think), that is that it has the space there for the device, but no device, and therefore needs that washer looking thing on there to fit correctly.

I noticed in the pix of the disassembly posted that on theirs, the camshaft came off with the case cover, mine didn't do that. When mine came apart, the camshaft, as well as the steel pin it centers on, stayed in the block part of the case, the outside cover part of the case came off without taking anything with it. This is how it is supposed to, the pins for the cam, and the cantelevers stay in the case. There are timing marks on the cam, and the crankshaft, those just point directly inwards, and line up with each other, to line up TDC on the engine, all done inside the case, then the cover goes back on.

I fitted mine up with a 15mm rotary valve diaphram WYK clone, and it loves it.

 

[Scootmeister]

I just replaced the cam in my 53cc 144f engine with an original Honda GXH50 part, reground by AGK. It's got a neat centrifugal compression release that makes a wierd noise, but seems to make the engine easier to start. But it fits, drop in. There is a round metal washer looking thing on there with the original camshaft, I disregarded that. I believe that it is only there to "dummy" the original cam's centrifugal adavance device, as the Huasheng cam is hollowed out inside identically to the original Honda cam (molded directly from it, I think), that is that it has the space there for the device, but no device, and therefore needs that washer looking thing on there to fit correctly.

I noticed in the pix of the disassembly posted that on theirs, the camshaft came off with the case cover, mine didn't do that. When mine came apart, the camshaft, as well as the steel pin it centers on, stayed in the block part of the case, the outside cover part of the case came off without taking anything with it. This is how it is supposed to, the pins for the cam, and the cantelevers stay in the case. There are timing marks on the cam, and the crankshaft, those just point directly inwards, and line up with each other, to line up TDC on the engine, all done inside the case, then the cover goes back on.

I fitted mine up with a 15mm rotary valve diaphram WYK clone, and it loves it.

Hey Mantis: Did the new cam make a difference in the performance of your HS, or was it the new carb that kicked it up a notch?

 

[GreenMantis]

The carb made a bigger difference. The cam does have more torque in the midrange, but 7000rpm is what it is, so it's not "faster" in that sense. But it does make it sound stronger, for lack of a better word for it. It sounds different than it did, I like it. However, the pipe I used is only 3/4" id, while they say to use 7/8". That might put a limit on how much difference the cam can make. I also think that the 15mm carb I have on is too big, although it does work great. The stock carb has a .416" bore, and the overbored ones they have are .475", or thereabouts. The 15mm comes to .59", that seems like overkill to me. I have a 12mm rotary valve carb, and that comes to .472", which seems more appropriate, but I haven't been able to get that one to work correctly. I have to be carefull how I roll the gas on with the 15mm, not that I mind that, but I'm thinking that the smaller one would be better, if I can make it work. In any case, it loves the diaphram carb, it was well worth changing. I don't know exactly how this carb manages to stay primed without the crankcase pulse, but it does, even when the gas tank is nearly empty.

 

[Scootmeister]

Hey Mantis, I'm with you on the diaphram carbs. I've been a fan since running them on gokarts powered by West Bend and Mac engines. You can adjust them to suit any riding condition and they seem to have fewer problems than float types if you keep them clean. BTW, they stayed primed from your engine suction on the intake stroke. It doesn't take much vacuum to depress the little spring on the diaphram to let gas through. As far as the pipe goes, Quenton had some good suggestions earlier in this thread based on his trial and error with HS engines. Apparently the diameter of the head pipe and the shape of the silencer makes a big difference in torque.

 

[GreenMantis]

Asside from that metering diaphram, these carbs also have another pump diaphram, which makes up a cavity between 2 one way valves that is pumped by a pulse signal from the crankcase. The pulse is routed through a small port underneath the intake port. This is an internal fuel pump, which appearantly isnt needed, since they work without it being connected. The metering diaphram with the spring valve serves as the float in these.

 

[Scootmeister]

On some applications the primer circuit is connected via a bypass gas line to a primer bulb and you simply depress the bulb a couple of times to inject gas directly into the carb for cold starting. I've had these on snow plows, hedge trimmers, and line trimmers with diaphram carbs. It works well until the rubber in the bulb hardens and cracks. The first sign of this problem is when you think your tank is half full and it turns up empty! I'm rebuilding a vintage Sachs motorbike that has a Bing carb on it. It's an interesting slide carb without a needle. Oops, I think I just highjacked my own thread.