What to upgrade 1st?

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Capnspaldin

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May 15, 2019
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When I built my bike I took advice I learned from this forum and I broke my engine in slowly and I ran it thick @ 20:1 for about 4 - 5 GL of gas until it really opened up. I was told I would know when it happened and it was clear...now I run it @ about 36:1 I found that it runs best at that mix. And it runs great I ride comfortable around 35-40 mph. Wide open I've had it to 47......But I wanna start upgrading to stage 2 so where should I start at? Or not start? Any info welcome. Thank you.
 

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Jul 28, 2019
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not enough oil! try running it at 25:1 max if you wqnt youe engine to last. personally i run 27:1. this is my priority list for what I'm going to upgrade:
1. 36t hub mounted sprocket (the spoke mounted one has a habit of destroying your wheel causing it to buckle.)
2. gas cap that needs key to open
3. banana pipe
4. performance carb
5. high compression head
6. nice looking grips and clutch handle.
7. upgraded fuel tank
8. reed valve and piston or the new bt100/any other better motors
 

Capnspaldin

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May 15, 2019
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not enough oil! try running it at 25:1 max if you wqnt youe engine to last. personally i run 27:1. this is my priority list for what I'm going to upgrade:
1. 36t hub mounted sprocket (the spoke mounted one has a habit of destroying your wheel causing it to buckle.)
2. gas cap that needs key to open
3. banana pipe
4. performance carb
5. high compression head
6. nice looking grips and clutch handle.
7. upgraded fuel tank
8. reed valve and piston or the new bt100/any other better motors
Thank you for the list I pretty much planned on doing all those things except the locking cap....good idea
I thought once your engine has been broken in that I was sposed to find the mix it runs best....it's what I was told at the start but makes sense maybe I'll gradually go thicker.
Is that the order you would upgrade in?
 

indian22

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Dec 31, 2014
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I have always broken in with heavy mix fuel & back off the oil after the engine starts to run "free" exact ratio of mix depends on the type/brand of oil synthetic, straight mineral etc. I run Lucas semi synthetic & ash free oil at 30:1 ratio after break in for example, but with another synthetic this would vary. I've been riding 2 strokes for more than 50 years & each one talked to me. For example if an engine 4 strokes a little that indicates it's getting lubed, but if it 4 strokes through a good bit of the power band it's mix is too thick and I thin down a bit, trial and error, not too much at a time.

The thinner the fuel mix the better it runs, but the sooner it blows...so it's about getting a balance between running good and being lubed & cooled adequately. These little motors are air cooled externally but fuel cooled internally, not just lubricated & fed but cooled by the fuel mix. So remember to keep fuel flowing constantly and don't idle the engine keep blipping the throttle at stops and never coast a long downhill run with a dead throttle trying to engine brake like one would ride a 4 stroke. It's a whole different riding technique and if you ignore this your motor won't last long no matter the fuel mix.

Wide open throttle for extended runs will kill these motors quickly as will increasing the compression too much, a little increase in pressure is ok, but the true value of the aluminum heads is in engine cooling & I run them on all my bikes for that one reason along with a copper head gasket. Getting rid of the kit sprocket rag joint and buying a hub clamp, three bolt sprocket adaptor is where I'd spend my money first and the aluminum head second.

Have fun!

Rick C.
 

indian22

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Rick and I run the same oil, I run 32/1. I have not had a failure due to oil in 8 years.
Yes Greg ditto on your experience. The 2012 motor in my hybrid had over 700 hrs. on it two years ago when I took the run hour "clock" off it. No failures along the way, but many mods. Yet I'd say most on the forum have bought into the "Chinese junk myth" repeated by those who actively do everything they can, unknowingly or not, to destroy their engine. WOT with their hair on fire & too busy to actually learn about and maintain these inexpensive motors.

I like and build 4 strokes as well....seems the Predator etc. motors are ok, though also inexpensive Asian products, the big difference is that most of us know more about & how to take care of & use 4 stroke powered equipment.

Rick C.
 

Capnspaldin

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I don't agree with the Chinese junk bandwagon either, it's all in how you treat them for the most part....the only time I went WOT was to get a top speed. Most of the time I just cruise....
I definitely learned alot I'm so glad I posted this.
I can't thank you enough for taking the time to explain some things. RIDE ON FELLA's.
 
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Jul 28, 2019
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Thank you for the list I pretty much planned on doing all those things except the locking cap....good idea
I thought once your engine has been broken in that I was sposed to find the mix it runs best....it's what I was told at the start but makes sense maybe I'll gradually go thicker.
Is that the order you would upgrade in?
I did the locking cap because theres this one kid who likes to sniff my fuel. I also don't trust anyone with my bike as they might slip their dick or something more harmful into my fuel.
 

Tyler6357

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Mar 15, 2012
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Santa Barbara, CA
Great Upgrades to get:

---> Expansion pipe-- You will get much more range on the throttle and better low end. This is one of the best performance upgrades you can do from stock. Just make sure you get a good one and not a crappy one. bigger is usually better. Read the threads on this forum to get a good idea what a good one is.

----> Rear Sprocket Adapter-- This can save you many a headache, broken spokes, and walking it home. Get rid of the stock rag joint connection and drive the hub instead of the spokes with a sprocket adapter for the rear sprocket. Just make sure you get the right size that fits your rear hub and one that won't slip. There are some crappy ones out there.

----> Port Engine-- Get out a dremel tool and port the intake, transfer, and exhaust ports. Just make sure you do it correctly, there is a right way and a wrong way, a bad port job can cost you a new $20 cylinder. If you don't know how to do this find out before attempting it.

----> High Compression Head-- Get a new high compression head with large fins. This upgrade will make your engine run much cooler and dissipate heat better. It will also provide a superior head gasket seal. You can expect to extend the life of your engine with one.

----> Reed Valve This is a major performance upgrade that will give you much more power along the entire throttle range. Make sure you have flawless brakes that can handle the extra power, also, expect a drop of about 30% plus in MPGs. This is usually accompanied with an upgraded carb as well. This is mostly a racing upgrade and it would probably better to do other upgrades first.

----> A Double Leg Kickstand-- This will make it much easier to park and work on your bike without it tipping over.

----> A shock Absorber Front Fork-- It's good when you hit an unexpected pot hole going 35 mph. If you get one, try to get one that is compatible with a disc brake so you can upgrade your front brake to disc if you want to.

----> You can get different sized rear sprockets. The stock rear sprocket is 44 tooth, a smaller tooth like a 36 tooth will give you more top end but less hill climbing ability.

---->High Performance Super Charge CDI-- I don't know if these work better than stock ones or not, never tried one.

----> Bottle Boost-- I once tried one of these, noticed no difference at all. I don't recommend it.

----> Duel Brake Lever-- Make it easy by hooking the front and back brakes onto one lever, just make sure you set the brakes to the correct tension.

There are tons more upgrades that you can get to fit your needs. These include, headlights, tail lights and brake lights for night driving, a good horn, fatter tires (the fatter they are the better it will be for traction and leaning into turns), mag rims, fenders, extended range gas tanks, kick ass road tires, speedometers, jack shaft kits so you can use bicycle gears for the engine drive. And tons more upgrades that I can't think of right now.
 

Tyler6357

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Mar 15, 2012
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Santa Barbara, CA
I don't agree with the Chinese junk bandwagon either, it's all in how you treat them for the most part....the only time I went WOT was to get a top speed. Most of the time I just cruise....
I definitely learned alot I'm so glad I posted this.
I can't thank you enough for taking the time to explain some things. RIDE ON FELLA's.
I agree for the most part, although sometimes the Chinese factories make parts so far out of spec that they are all but useless. But for the most part you are right about the China girl engines, treat them right and they will 'love you long time'.
 
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indian22

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Dec 31, 2014
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Good stuff guys. Tyler that's an excellent parts break down & comments well thought out and Greg I'm certain that expansion pipe has been a good one for you and many others...I call it the "Miami" style.

There are lots of Chinese manufacturers of these engines and the lack of quality control is a problem with some, unfortunately, is true. Even the best of these engines have some areas of concern that I always address. I tear down each motor and inspect and correct, when necessary, any problems I find...which is seldom. I then modify the jug, port work, depending on whether it's to be piston port or reed valve design, upgrade wrist pin bearing and reassemble the motor using grade 8 fasteners, especially the head bolts. Allen heads replace slots & Phillips fasteners externally, also grade 8, as well. Head is tossed and mild high compression head and copper gasket added. NKG iridium plug and plug wire replaces the no name & I add a high quality 2 stroke CDI as well on the highly modified versions I build, but I can't see any real value for on mildly tuned motors. I've had great fortune with the Dellorto carb on stock through high tuned street bikes, for those running motors in the 6 to 10 hp range a switch to larger Mikuni for racing is a good thought.

So know that my comments on Chinese junk is tempered by my attention to detail that might be overlooked or ignored at the factory, but the original design, 1947 Russian engine, was and is in it's many copied versions a very solid motor, to build on.

In all fairness the company supplying the Harbor Freight version of the Predator motors is doing a superb job of quality control with it's motors and the return/exchange warranty policy has been outstanding at Harbor Freight, unlike that of many Chinese distributors of the China Girl 2 stroke.

I may try the U.S.A. made billet aluminum cases in a future build. If these continue to be produced.

Rick C.
 

indian22

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Dec 31, 2014
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Greg where do you feel the expansion pipe you run "hit" and how wide is the power band? Is there any benefit at the top end or does it actually help at all on the top?

The long straight style I'm using with a kit muffler added to the chopped off stinger; which gives about the same total length as the pipe with just the stinger, benefits mid range to high rpm, comes on at 6,000 and rages on with the reed valve motor, but with the piston port motors it's torquey lower with not much going on by 7,000 rpm. It definitely doesn't run any faster with the piston ports, but more fun getting there.

Rick C.
 

Greg58

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May 1, 2011
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Rick mid range was the biggest gain, I would say the power band hits at around 4500-5000, I gained about 4mph at the top of the hill on our road which is a steady climb from the driveway for about 800 feet. I’m almost tempted to drop a few teeth on the rear sprocket and gain more on top end. I’ve dealt more with 48cc engines than the 66cc, they perform better at higher rpm, the 24” with a kit 44 tooth will do 33 but is screaming.
 
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indian22

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Dec 31, 2014
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Oklahoma
Rick mid range was the biggest gain, I would say the power band hits at around 4500-5000, I gained about 4mph at the top of the hill on our road which is a steady climb from the driveway for about 800 feet. I’m almost tempted to drop a few teeth on the rear sprocket and gain more on top end. I’ve dealt more with 48cc engines than the 66cc, they perform better at higher rpm, the 24” with a kit 44 tooth will do 33 but is screaming.
Good info Greg the direct add on motorized bike expansion chambers I've tried seemed to mostly center on mid range pipe hits & daily riding consists mostly in that band width. Small motor cycle pipes designed for racing & then modified for motorized bikes give the biggest bump in power, but vary in where on the bandwidth that power id most noticeable...still science mixed with Voodoo & luck!

Rick C.
 

Capnspaldin

New Member
May 15, 2019
15
6
3
46
Great Upgrades to get:

---> Expansion pipe-- You will get much more range on the throttle and better low end. This is one of the best performance upgrades you can do from stock. Just make sure you get a good one and not a crappy one. bigger is usually better. Read the threads on this forum to get a good idea what a good one is.

----> Rear Sprocket Adapter-- This can save you many a headache, broken spokes, and walking it home. Get rid of the stock rag joint connection and drive the hub instead of the spokes with a sprocket adapter for the rear sprocket. Just make sure you get the right size that fits your rear hub and one that won't slip. There are some crappy ones out there.

----> Port Engine-- Get out a dremel tool and port the intake, transfer, and exhaust ports. Just make sure you do it correctly, there is a right way and a wrong way, a bad port job can cost you a new $20 cylinder. If you don't know how to do this find out before attempting it.

----> High Compression Head-- Get a new high compression head with large fins. This upgrade will make your engine run much cooler and dissipate heat better. It will also provide a superior head gasket seal. You can expect to extend the life of your engine with one.

----> Reed Valve This is a major performance upgrade that will give you much more power along the entire throttle range. Make sure you have flawless brakes that can handle the extra power, also, expect a drop of about 30% plus in MPGs. This is usually accompanied with an upgraded carb as well. This is mostly a racing upgrade and it would probably better to do other upgrades first.

----> A Double Leg Kickstand-- This will make it much easier to park and work on your bike without it tipping over.

----> A shock Absorber Front Fork-- It's good when you hit an unexpected pot hole going 35 mph. If you get one, try to get one that is compatible with a disc brake so you can upgrade your front brake to disc if you want to.

----> You can get different sized rear sprockets. The stock rear sprocket is 44 tooth, a smaller tooth like a 36 tooth will give you more top end but less hill climbing ability.

---->High Performance Super Charge CDI-- I don't know if these work better than stock ones or not, never tried one.

----> Bottle Boost-- I once tried one of these, noticed no difference at all. I don't recommend it.

----> Duel Brake Lever-- Make it easy by hooking the front and back brakes onto one lever, just make sure you set the brakes to the correct tension.

There are tons more upgrades that you can get to fit your needs. These include, headlights, tail lights and brake lights for night driving, a good horn, fatter tires (the fatter they are the better it will be for traction and leaning into turns), mag rims, fenders, extended range gas tanks, kick ass road tires, speedometers, jack shaft kits so you can use bicycle gears for the engine drive. And tons more upgrades that I can't think of right now.
 

Capnspaldin

New Member
May 15, 2019
15
6
3
46
Wow, thanks everyone for all the info....I had planned on many of these upgrades but now I have a great idea of where to start...thanks for the links also. I'm hoping to do alot of work on her this winter and have the best running bike around come spring... actually speaking of customer service on the china girls when I received my kit it came w/o a chain tensioner....no big deal I thought they just rip one out of another kit and replace my missing part.....they sent me an entire brand new kit no shipping cost and told me keep them both....that is standing by your product my friends and your company....I am very impressed....so I'm ready to do a new install... something quick and easy any bike suggestions?
 
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