HuaSheng 142F vs Honda GXH50 vs Dax XC50s

[Quenton Guenther]

Remove the filter in the air breather and see if it helps. I have seen some of them restricted due to over filling the crankcase and causing the oil to feedback into the air breather.

When we were testing the HS 142 motor on the DYNO it easily gained 1 MPH wth the air breather element removed.

I don't suggest you remove it forever, just to see if it is causing issues.

Have fun,

 

[Scootmeister]

Hey Quenton, somehow I missed your July 7 post. Must admit I suffer from being an old Go Kart racer where we focused on everything BUT the exhaust. For my 2-strokers I have been using 1" thick walled conduit because it is available, it's cheap, and it is easy to weld. Both bikes run great but I'm going to be experiementing with some expansion chambers for some boost. I like the old vintage ones that came on the 2-stroke bikes you raced ( I rode Bultacos, Matese, Bridgestone, and Suzuki 2-smokers), the newer ones look like an alien's intestines!!! My HuaSheng is on the bench at the moment. I've been fabricating lighting coils to charge a battery and run lights. I'll either install it on my Schwinn Spoiler or an old Huffy Triton that's in storage. At that point based on your suggestions I'll probably install a 7/8" straight pipe and go from there. I'm thinking about playing with a CVT to see if I can make it work with some top end. Thanks for your input.

 

[Quenton Guenther]

Hi Scootmeister,

In the day, I raced many 2-strokes including Bultacos, Ossa, Yamaha [twin flat tracker], Kawaski, AJS [ 2-stroke], and even Carabela [2 stroke] from Mexico, and they all had tuned expansion chambers. All the 4-strokes I raced also had tuned exhaust [Triumph, Ducati, HD, BSA, Norton, etc].

I wouldn't spend too much time adapting a CVT to the HS motor as they eat a lot of power. When starting with 2 HP you won't have much to give up for the CVT needs.

If you want the maximum setup for your motor, make a header pipe 28.5" long and weld a reversed cone to the end. Cone need to be 14" long and the exit must be 5/8". The cone needs to be 11" before it tapers down.

Although it is very possible to increase the RPMs on these motors [Honda GXH50, HS 142], if run at higher RPMs too long it will drop the rod from the crankshaft.

We found it more important to increase the torque than the RPMs, and the correct exhaust will do just that. A correctly tuned system will advance the torque curve between 500 and 700 RPMs and increase it slightly.

Have fun,

 

[Scootmeister]

Quenton, I'm trying to picture the exhaust. I understand that the overall length is 28.5", the reversed cone is 14" long and the exit is 5/8", but I don't understand where the 11" dimension comes in. You aren't saying the front of the reversed cone is 11" in diameter are you? Thanks for the clarification.

 

[Quenton Guenther]

The distance from the front of the cone to where it reverses is 11", and the rear of the cone is 3".


I will attach a picture of my 1999 Whizzer's version of the reversed cone [68 MPH @ Portland, IN 2005] so you can get an idea of how to contruct one for the 49 CC motor.

Have fun,

 

[Scootmeister]

Got it, Quenton. Thanks. BTW, when is the Plainfield meet each year?

 

[Quenton Guenther]

Plainfield ??????????

Not aware of any event in Plainfield.

Have fun,

 

[Scootmeister]

sorry, I meant Portland.

 

[Quenton Guenther]

Just returned from the Portland show a few weeks ago. Is planned for July 5th week in 2013.

My 1951 Schwinn S4 Whizzers won 1st place best restored motorbike senior class this year

Have fun,

 

[chrisnbush]

Scootmeister -

Thanks for the help.

I got a compression tester from Harbor Freight, nice kit as it has the 10mm fitting (1.00 mm thread, fine) that you need for the Hua sheng / Titan / Super Titan to fit the spark plug threads.

Ran the motor for 5 min, then checked compression - about 40 psi. Then adjusted the valves AGAIN using a trick I came up with to be more certain on TOC - simply a 10mm bolt that I advance until I can stop the movement of the piston, then I back it off, get the TOC stroke, then advance it again - to just stop the piston. Now I adjusted the valves to .004, forgot what DAX said to do in terms of thousandths - "thickness of a piece of paper" doesnt' work for me (what kind of paper ?). Anyway the TOC bolt gives me some confidence.

Ran the motor for 5 min again, now my compression is 50 psi (pic attached). How does that compare with your younger Super Titan - have you measured it ?

Thinking maybe that what was happening with me was that the input valve, being loose, was not opening for enough time to let all the air/gas in - so my "compression" was lower, not having enough of anything to compress.

Anyway, it is better now at 50 psi - more power - but still not up to what it was when I got the motor. Again I have 6700 miles on the motor, so I would be interested in what the compression is on a new one.

By the way, I attached some pictures of the 142F valve springs, compared to the Super titan springs (I have an old blown 142F on the shelf). Look identical, you can see the bolt I am using to estimate TOC in the lower part on the pic of the Super Titan.

So, it must me higher compression on the super titan ? Again, I don't see any doming on the piston thru the plug hole, but it might be more subtle than this. Maybe I will check the flywheel at some point, I can do it on my 142F.

Regards

Chris