Modified Chinese motors?

GoldenMotor.com

JoelC707

New Member
Jan 21, 2009
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Tucson, AZ
I'm not sure if this would be the right place for it but it looks like a good spot. If not please move it where it needs to be.

I'm sure all this info is out there scattered around but I was curious if we could get it all in one place. What are your biggest complaints about the Chinese two stroke motors? If you could change ANYTHING on the motor what would it be? How much extra might you be willing to pay for those changes?

One thing I've been kicking around is taking the motors I have (Star Fire Gen II's, Gen II-A's and GT4's) and reboxing them and sorta rebadging them as a "modified" motor kit. The biggest thing I had in mind to replace were the bolts. I know everyone (including myself) says the Grubee motors have Japanese fasteners that are better than the Chinese parts but lets face it, they still aren't a match for a good old American bolt, even a low grade one. I know there are kits out there for this purpose but would you consider buying a kit that has the same modification already done?

The other thing that needs to be fixed is the muffler. I'm not sure about others but the screw that holds on the end cap of my mufflers flat out SUCKS. The hole it screws into doesn't give it much bite to begin with and ultimately loosens itself to the point the screw no longer holds. what we have been doing it taking a short stud (about the length of the exhaust stud on the enging), and welding it in place then you can put a nut on the outside with a lock washer, nylock or double nutted if you want.

So what else would you like to see changed for the better? I would of course continue to offer both the original, unmodified kit for those that prefer to do the work themselves or just don't care. But I suspect most would welcome an "upgraded" kit even if it costs a little more. What are your thoughts?

Joel
 

oylavabeer

New Member
Jan 9, 2009
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Perth Australia
I enjoy the challenges that come with these motors, but not all are like me so I think there is a market out there. I was thinking of similar maybee a performance pack with better leed, spark plug, ported intake and exhaust etc
 

oylavabeer

New Member
Jan 9, 2009
214
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Perth Australia
There are many many things that can be done to these motors, just sudjesting a few, depends on what the customer wants to pay as to how far modify and how much you charge. you could offer 2 levels of mods ie. performance and premium one with less mods than the outher
 

commander

New Member
Mar 19, 2009
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penn state
Yea Red , that's exactly what I was referring to , But he was looking for additional mods he could add to his motors and sell them complete. Rather than going to a whole bunch of sites to get parts
 

JoelC707

New Member
Jan 21, 2009
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Tucson, AZ
Alright so far we have:

Better ignition and spark plug
Ported intake and exhaust
Upgraded clutch arm
And vibration free

Lets start from the top. The first thing I want to point out is the spark plug. While I personally have never had much experience wit these motors yet, my uncle has and I'm using his knowledge to guide me. One of the first things he told me was that pretty much any plug you get from the store is not going to work as well as the factory plug, they just foul out too quickly. Now I don't know if he took the plug to AutoZone and had them try and match it to a Champion or NGK or if he just went to Home Depot and get a weed eater plug for it.

On to the better ignition. Before we got the inventory we have now, my uncle found a good replacement for the plug wire. As I'm sure everyone knows the wire just screws on. He got a coil wire from a 60's Chevy at AutoZone, cut it to length and screwed it on. Now the plug does need the cap on it for this new wire to work but it has worked just fine for quite some time now. The insulation is a little thicker and was harder to screw in but it went it. Is this what you are talking about for a better plug wire?

Ported intake and exhaust. That would certainly fall into the "performance" category. It's not out of the question but would likely be a custom build. Something we would have done when we get an order for it. If we get a lot of orders I'm sure we could stock a small number of them.

Vibration free. Are you talking about the vibration the motor translates into the frame? If so we are working on that. We have a friend at Boeing that has sent us some demo products to try out. We like them and we're going to get some of our existing customers to try them and let us know what they think. If they like them we'll become dealers and start selling them or add them to the kit. He has among other things, a Dynamat type material you put inside the three covers. It is supposed to reduce noise and heat expenditure. He also has a solid rubber mounting bracket setup that on my uncles bike took out at least 80% of the vibration from the motor.

Now one thing I didn't see mentioned and forgot to mention myself is a better front mount, a universal mount. We've come up with a front mount that is more or less universal and even made it adjustable so you can adjust the pitch of the motor side to side. About the only frame it won't fit on is the ones with an elongated tube that looks more like a rectangle than an oval or round. The rear mount almost always fits without problem in our experience but we have come up with a couple ideas for that too but I don't know how needed they will be. Now all we need to do is find a way to get it mass produced, so far we've just been making our own and it's time consuming and expensive.

I tend to agree with the idea of multiple upgraded kits. One would be a standard "premium" kit with just some basic upgrades like the bolts, exhaust, and the universal front mount we've come up with. The "performance" kit would build on the premium one and would add the vibration free mounts, cover insulation and some other things. The performance one would most likely be the one people would request the ported intake and exhaust or other modifications.
 

captainrichhill

New Member
May 31, 2008
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Knowing what I know now about how much fine tuning (upgrading) of the parts I would be doing, I would buy the "upgraded kit" and maybe the "performance kit". I'm a little more cautious about the performance kit because I think these enginges don't have the quality control to be tapping every last HP out of them without sacrificing longevity. IMHO.
 

JoelC707

New Member
Jan 21, 2009
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Tucson, AZ
That's true and that's one reason why I'm a little apprehensive about porting it. Now the Gen II motors, having the steel sleeve we want to see if they can bore it out 7mm more to fit the 47mm piston from the GT4 66cc. This would give us a 70cc motor but would likely just be for personal use and special requests only (if it is even possible and holds up).
 

commander

New Member
Mar 19, 2009
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penn state
I would like the kind that run vibration free...
Not sure what ya mean by that but both my builds seem to be pretty smooth with little vibration. Just make sure you have very good mounting connections and dont use to much rubber between the mounts

@Joel , look at how there is a hole in it also for threading the cable thru and then you use a bolt and nut vs the threaded small screw on the stock actuators. I broke mine first try at tightening it (stock one)
 

outlawbiker

Member
Mar 15, 2009
282
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Chicago NW Suburbs
how bout a high compression piston like a hemi, i dont own one of these engines yet,but from the pictures Ive seen the head is concave like a dome,so why not a domed piston,or if that don't work a high top piston?? something id like to see out of one of these engines is better quality control,if there was a way for some one to go thru them before they shipped em to make sure nothing was wrong,ive seen some weird threads here about pistons installed backwards from the factory and so on...

another performance upgrade id like to see is maybe a supercharger or turbo kit.maybe a stroker kit where you bore out the cylinder and put a heavier crank in so it has more torque. maybe also a bolt on 4 speed gear box? i dont know,but hopefully there is a better way to build these engines,and it really shouldn't be called a performance upgrade when we are just fixing the problems that china/japan made when they shipped em out like that lol.
 

Pablo

Master Bike Builder & Forum Sponsor
Dec 28, 2007
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Duvall, WA PNW
www.sickbikeparts.com
One of the first things he told me was that pretty much any plug you get from the store is not going to work as well as the factory plug, they just foul out too quickly.
That is simply not true with Chinese motors. Get an NGK plug. BP5HS or BP6HS.

Most all the items you are getting at have been covered here.

Start in this forum:

Classic Instructions for Building and Repairing Motorized Bicycle Engine Kits - Bicycle Engine Kit Classic Posts at Motorized Bicycle Forum

And branch out from there.
 

DEATH4OF4

New Member
Mar 22, 2009
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Green Bay, Wisconsin (Frozen Tundra)
Clutch Lever A Must.
NGK Plug + A Quality Plug Wire (copper core)
New Hardware.
Racing Carb.
Spring Loaded Tensioner With Hard Rubber Wheel & Bearings.
Better In Line Fuel Filter.
Expansion Chamber Muffler.
Clam Shell Hub Adapter.
Customers Choice In Rear Sprocket Size.
It Would Be Considerably More For The Kit, But It Would Save Time From Having To Order All That Stuff From Different Places Like I Did.
Start With Some Of That, If You Planing On Selling Better Upgraded Kits And I'd Buy Them From You.
Hope This Helps A Bit...


Snap,crackle,pop...there I Go...
 
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2door

Moderator
Staff member
Sep 15, 2008
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Littleton, Colorado
Are you limiting your proposed upgrades to only the engine? If you really want to be of service to the buyers of these kits might I suggest you look at replacing the chintzy clutch levers (handlebar) and twist grip throttles with motorcycle grade items? There are kit suppliers out there who already offer upgrades, if the buyer is willing to pay for them. Check here: Home of the CH bicycle engine, CH80 Bicycle Engine Kits by Chris Hill, Motorized Bicycles, Bike Engine, Bike Motor, Bicycle Motor kit. You'll pay a little more but when you start adding up what you'll spend in upgrades to get the quality you want because the higher priced kits include them.
Tom
 

hiker472

Member
Nov 6, 2008
653
3
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Ontonagon County,Upper Michigan
All these suggestions for it are right on the money to me.

I'd also include an upgraded pull start. Someone has got to upgrade these things!

I've heard it said that different cdi's and magnetos also run at various amps. What about using the best of them and leave no room for lower grade material?

I also like the idea for putting out various upgrade kits. This way a person can pick and choose what they want.
 

Cabinfever1977

New Member
Mar 23, 2009
2,288
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Upstate,NY
another upgrade we need is side engine covers and smaller gas tanks,im happy with the stock parts except the carb,how about you get some of those carbs that dont need a intake pipe.
 

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Last edited:
Sep 20, 2008
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Clearwater, FL
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Pardon my ignorance but how is that an upgrade from stock? It looks to me like it is simply a billet cover and arm. Are the stockers prone to breaking? There's no description of any kind, just the two pics and a link that takes me straight to PayPal. Ahhh never mind now I remember. The actual bar inside the cover, is it rounded like a camshaft instead of flat like all the stock ones?

When I first thought of the upgraded clutch lever I was thinking of the curved arms like the Gen II's have compared to the straight ones the GT4's and almost every other brand have. I've found the curved ones to be easier to pull because you don't have to break it around a corner like a straight one does.
Good grief!!!

Jim