Schwinn Alloy Seven 4 Stroke with pics


Irish John

Hi guys,
Today I started assembling my HuangSheng 4-stroke with Grubee gearbox.
I'm using marine lithium grease in the gearbox cos it's a great grease and sticks like glue and the instructions recommend lithium grease (see attached pic). I'll see how it goes and if I have any noise or am dissatisfied I'll use a wet gearbox & clutch as per all the info on the gearbox thread. I've replaced all the studs and bolts that hold the motor to the tray and the tray to the bike with good hard steel ones. I made the studs for the rear attachment longer but they are still a bit short. I am having trouble getting the motorbike type exhaust to fit around the tray and might have to do a bit of bend & twist. The downpipe will need to be fixed to the downtube and the silencer will need to be fixed to the rear chain stay. I'll fabricate stainless steel straps but finding room on the chainstay without affecting the chain tensioner will be a problem. I'm using the bike that I have just put the 70cc HT into which is a pity because it was such fun to ride and wasn't even run in. I've kept the HT tank because it has a special paint job to match the metallic blue of the frame. It looks prettier than the tank that came with the kit. More of a tear drop shape. I'll eventually paint the other tank and see how it looks. To line the chain up really true I had to move the motor over to the drive side as far as it would go. If it could have gone another 5mm I would have moved it further over but it's pretty good now, I think there will be more stress on the bolts holding the tray to the frame on the drive side because the engine is so far over and although it looks OK the weight is pretty left sided.
I'll try using the twin cable brake lever because the twist clutch I normally use on the HTs isn't any good with this motor because I'd have to hold it wound back all the time to drive the engine. I'll probably eventually have to try the reverse lever method described by HoughMade on another thread. Thanks guys for your advice - it is really helping me.
Should be riding it by Thursday morning or poss wed afternoon. I wish there was some way of taking electrical power off the motor to run a really bright headlight. The HT's had the white wire for taking power off but I never got round to using it. I'm not sure how to install the kill switch but I guess I'll find out. Here are the pics. I am glad that it is finally happening after all this time.


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Active Member
Local time
7:04 AM
Mar 19, 2008
South Mississippi
Me too, honestly... Large Filipino told me that when I asked where the toggle switched needed to be located.

The toggled killswitch is the last thing on my mind right now, so if you find out where to put it... let me know.


Active Member
Local time
5:04 AM
Jan 11, 2008
Gilbert, Arizona, USA
I'm afraid that sounds like Greek to me.

Which part is greek? - Toggle switch, Magneto, or coil?

A toggle switch is just a switch with two positions - on, or off. A light switch in your house is a form of toggle switch. The picture below is a toggle switch. This one is a single pole single throw switch, meaning that the switch has two positions, and a single contact. Normally, the ON state would be where the switch conducts electricity, and the off state would be where it doesn't conduct electricity. For reasons we'll get into later, for a bike motor, you may want to reverse this (On = not conducting, Off = Conducting)

Next - the magneto. A magneto is just a coil of wire, wrapped around a laminated iron or steel core. (the laminated core acts to focus a magnetic field.) In small engines, the magneto is placed near the flywheel. The flywheel has a powerful permanent magnet contained within it. As the motor turns, the flywheel is spinning, which makes the magnet, and the resulting invisible magnetic field, move around the drive shaft also. As this moving magnetic field sweeps past the coil of wire in the magneto, it induces an electrical current within the coil. This is the electrical current which will cause the spark in the spark plug.

But, the voltage of this pulse isn't large enough to cause a spark to jump across the spark plug, directly. It is fed through a step-up transformer, known as the coil. The coil steps up the voltage to a much higher level - to several thousand volts (or more.) The amount of power must remain the same, so while the voltage is stepped up, the current is stepped down, by the same amount ratio.

So, what large is saying is this. You need to interrupt the current between the magneto (which generates an electrical pulse) and the coil, (which increases the voltage of the pulse so it will work to create a spark)

Now, you could run a wire from the magneto to the switch, and from the switch back to the coil. When the switch conducts electricity, the electrical pulses are routed to the coil, and the motor can run. OR, you can wire the switch so that the pulses are run through the switch to ground (the metal frame of the bike.) This approach, since only a single wire is needed between the motor and the switch, is how this circuit is normally wired. In this case, when the switch conducts electricity, the pulses are routed directly to ground, and this bypasses the coil. Thus, no sparks can be generated by the coil. When the switch doesn't conduct electricity, the coil pulses aren't shorted out - they can cause the coil to generate the sparks. So, the switch is wired "backwards" from how you would normally think.

Now, as far as location. A kill-switch is used to kill the engine; to stop it from running, immediately. So, it should be located where you can reach it in an emergency. Normally, this is on the handlebars, right in front of you.


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Irish John

KIll Switch

Thanks, That is very helpfull indeed but the Grubee / Huangsheng kit comes with a kill button on the throttle assembly and 2 wires just like in the HT kits so it is these wires I'm wondering about. The motor has an on/off switch on the front but that is not reachable when riding so I was wondering how to connect the throtle button switchh and wires toi kill the engine.


Mine did not come with the switch. What I would do, since you cannot reach it anyway, is remove that switch, connect longer wires to where the switch is connected, and use your switch of choice. On mine I replaced the cheap built in switch with a heavier duty momentary contact switch from Radio Shack.

Irish John

4 stroke up and running

Today I took the 4 stroke for its first run. Its the HuangSheng motor and I rode it for 90 minutes. I should also say that it has a 44 tooth sprocket and a dual brake lever. The engine runs very quietly and the idle is just right but the gear box makes a slight noise but less than than the HT 70cc 2stroke. Quite a bit less. I'm using lithium grease in the gearbox which I'm told is too light. I've had a look after 30 kms and it seems as good as new. The motor can't handle the steep hills with the 44 tooth sprocket but I'll push it up the two serious hills I encounter because I like the way it cruises at 40 km\hr quietly on the flat. I'll put another wheel on with a 48 tooth to see if that is better but I'll lose top speed. I suspect that its top speed under power on the flat will be 40 km\hr or 25 mph for those who aren't metric.
I'd like to thank everyone for the very useful advice I've been able to glean.
I changed the oil after 90 minutes of running because I think that's essential on a new engine and moreso on a chinese one. It looked like a good idea when I saw the oil. I recommend changing it after 1 hour next time i get a new motor. I'll use Fetor 56's magnet idea asap. And I'll change the oil very regularly. Will stay with a detergent good 10-30 oil until someone convinces me to change.
The power is disappointing and it doesn't pull away like a 70cc 2stroke but it's a much much better engine. With the 56T sprocket it came with it probably is quite nippy but the top speed might drop to 30km\hr or 18 mph which is just too slow to get me to where I need to go.
I will soon find out how it goes in comparison to a Honda GXH50 but I suspect the performance will be very similar. Anyone out there tried both motors on the same bike?
I will avoid the wet clutch idea until I learn more because there are problems recounted on these threads with the wet clutch and the noise reduction doesn't seem to be that good. The centrifugal clutch works very well but I'm learning how to engage the engager whilst running at about 15 km\hr.
It stalls engaging it uphill and I don't see a way around this problem. There is no slipping the clutch like the HT allows on a hill. As stated often by others the pulling in the clutch lever to engage the gears and having to lock it in whilst under power shows a total ignorance of human anthropomorphics by Don Grube. Unexcuseable laziness during design stage that a few more hours could have resolved before they rushed it into production. That is the politest reason I can think of for the ridiculous decision to design it that way but I'll be changing that almost immediately because it is downright dangerous and makes the bike very hard to ride with any fluency. The method shown in another thread is 100% improvement and, because of this, would probably get around any patent if it was mass produced.
I chucked out the hollow threaded brass throttle screw that takes the end of throttle cable when it reaches the carb. It was so badly made I snapped it with my fingers and replaced it with one from the many expired HT 2strokes that adorn my garden. They fit really well and are much more easy to adjust with my fingers. I've replaces all the studs that hold the aluminium part of the tray to the frame as well as all 4 engine mounting bolts and the four side bolts that hold the aluminium sliders to the steel tray. The tray design is also moronic and could be improved 100% by anyone with half a brain. Threading studs into aluminium is a ridiculous idea that might have been unavoidable on the HTs but is totally unacceptable on these heavy motors. Using 6mm dia. studs is also a total no no in design terms. It isn't even necessary from a design point of view. The side bolts on the tray are also threaded but depending how the thing sits on your frame you can replace those with longer bots and put nuts on the end. I can do that on the rear two but not the front 2 because they would hit the engine mounting bolts. The engine is positioned as far over to the left as the tray allows but it needs to move over a further 12mm for the chain to run at its best. Now that I have a mounting tray I will probably amend it to better specs and get them fabricated locally. I wouldn't need the sliders and I'd use 8mm high tensile bolts with locknuts where the studs go. There would be no need for studs. I think I could drill 8mm threads to hold the exhause as well.
So to sum up the motor is great but I might have to find another sprocket wheel to suit. The dual brake lever is set up really well and I think, contrary to my previous comments on another thread, that I might get used to it but when I employ the engager reversal idea I can install a twist clutch which I much prefer and then I can have my separate brakes back again.
I have saved a lot of heartache from the experience and the ideas of you guys on these pages and for that I am most grateful. Goodbye HTs I will not miss them. I include some pics of my finished bike. Oh yes, the full length silencer means I can't have a panier bag on the left hand side unless I have one made for me from asbestos!


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