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Discussion Starter #1
Guys,

I have a really nice 1980 Z50 that I fitted with A China 107cc top end off a china four wheeler. I got the 107cc for a good deal so I figured I would give it a try. I have a aftermarket pipe and a 20mm carb with the angled manifold. It does run a lot better then the old 50 top end but nothing like I thought it would. I was wondering if a cam change would help out. I just ordered a 16 tooth front sprocket to help it out some since the 107cc top end has some more torque. I was wondering if you guys have any recommendations or am I just wasting my money on this topend.



Thanks in advance

CC
 

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Discussion Starter #4
Where can I purchase that from? I am almost sorry already that I did not just buy the 140cc Lifan kit on ebay for $399.
 

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Discussion Starter #6
Guys,

I am relatively new to all of this stuff. Yes, stock Z50 crank but the engine is off of a later model 50 with electronic ignition. It runs good, but I thought it would have more power then it does. My buddy bought a Lifan 140cc kit that came with everything on ebay for $399 shipped and put it on his bike and it is a rocket, mine is a turd compared to his.



Where do I get TB Piston?

What is FPM?



CC
 

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FirePowerMinis.com or pm Firepower354



Terry chime in pls...doesn't a China 107 have a longer stroke than a stock 50...am I missing something
 

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Discussion Starter #8
Is this combo worth spending more money on or should I just buy another engine. I really like the way it starts easy and idles really good. My buddy's Lifan is a little hard to start sometimes. I also like that I do not need the clutch on mine. His is cool with the 4 speed though.



Here is the kit my buddy bought- http://cgi.ebay.com/ebaymotors/LIFAN-140CC-ENGINE-MOTOR-HONDA-CRF-XR50-CRF50-Combo-Kit-_W0QQcmdZViewItemQQhashZitem19bf169f47QQitemZ110580113223QQptZMotorcyclesQ5fPartsQ5fAccessories



CC
 

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eBay listing specs math-out to 125cc, the 1-down 3-up trans is iffy, and the clutch on the crank holds back attempts at making power. you can get a good 140 from a PM vendor (;)) for less.
 

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true, granted it i ahve a death wish, the eBay 125cc lifan kits make okay power. how ever if it isn't enough you are limited in power. I think Terry is refering to the crank mounted clutches witch from what i read around here is a draw back. Terry that Z155 satisfies, I feel like Burt Monroe when I nail it on the streets.
 

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So... i still dont get how he put a 107 top end on a 12V Z50R bottom end?? The rod length/stroke is all wrong. The cylinder is waaay too beefy to slide in the cases. The studs would have to be swapped over for the 69mm tall cylinder. The longer cam chain would have to be swapped too. Stud spacing is the same at least?



Are you sure it was a 107?



My suggestion would be to throw a 49.5mm crank in it with a high compression 52.4mm piston, that way it has more than 5:1 compression??
 

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Carlo C. said:
Guys,

I have a really nice 1980 Z50 that I fitted with A China 107cc top end off a china four wheeler. I got the 107cc for a good deal so I figured I would give it a try. I have a aftermarket pipe and a 20mm carb with the angled manifold. It does run a lot better then the old 50 top end but nothing like I thought it would. I was wondering if a cam change would help out. I just ordered a 16 tooth front sprocket to help it out some since the 107cc top end has some more torque. I was wondering if you guys have any recommendations or am I just wasting my money on this topend.



Thanks in advance

CC


If I'm reading this right, this is a 69mm tall cylinder swapped in place of a 63mm tall cylinder, but still running the short stroke crank and the rod sized for the 63mm tall cylinder. Thus leaving the piston a ways down into the hole at top dead center, and probably resulting in a compression ratio of about 5:1 or something. It's interesting to hear that it is in fact more powerful than a stock 50 despite this.



If you ever needed to build a mini that could run on very low octane fuel...
 

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I was trying to visualize what would happen with a tall 107cc cylinder and a rod + stroke sized for the shorter cylinder, and it occurred to me those old two-cylinder John Deeres (many of which could burn kerosene or other lower-grade petroleums) had the pistons so far down into the jugs at TDC that the spark plugs actually screw into the tops of the cylinders. Not the head, which itself is flat underside, like a diesel head. I believe my model B's compression ratio is something like 4.75:1 and it's like that.



Carlo C., I know I kind of went off on a tangent...I'm not being a smartass here or trying to derail your thread. I'm honestly interested to learn that this combination works at all. If I've got this figured right, you'd have needed the China 110's crank, which has a 49.5mm stroke, and its longer connecting rod sized to work with the taller cylinder, to be ideal. Apparently you did swap the longer cylinder studs and camchain...? I was asking about very similar things to this a year or so ago, when I was thinking about doing this to my Z. I ended up deciding I didn't want to have to switch to the later ignition type.
 

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mexicanyella said:
those old two-cylinder John Deeres (many of which could burn kerosene or other lower-grade petroleums) had the pistons so far down into the jugs at TDC that the spark plugs actually screw into the tops of the cylinders. Not the head, which itself is flat underside, like a diesel head. I believe my model B's compression ratio is something like 4.75:1 and it's like that.


They are still a bear to turn over by hand with that compression haha. I have a 1941 JD H in the barn...



The original poster needs to shed some light on his setup!?
 

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Discussion Starter #17
Guys,

I am not sure what you guys are referring too with the Front clutch or rear side clutch, but the engine that was sent to my buddy has the lever for the clutch on top of the engine. It is different from the picture that I posted, but it is a 1 down 3 up tranny. Here is what his looks like with the clutch lever on top of the engine- http://cgi.ebay.com/ebaymotors/LIFAN-140CC-OIL-COOLED-ENGINE-MOTOR-XR-CRF-50-125-4-UP-_W0QQcmdZViewItemQQhashZitem53db7766faQQitemZ360164321018QQptZMotorcyclesQ5fPartsQ5fAccessories

http://img.auctiva.com/imgdata/4/7/8/9/5/1/webimg/196693223_o.jpg





I would like to know if the Paranha engine is a better engine and can you get one with all the stuff that my buddy got for the same price shipped from another vendor?





mexicanyella said:
I was trying to visualize what would happen with a tall 107cc cylinder and a rod + stroke sized for the shorter cylinder, and it occurred to me those old two-cylinder John Deeres (many of which could burn kerosene or other lower-grade petroleums) had the pistons so far down into the jugs at TDC that the spark plugs actually screw into the tops of the cylinders. Not the head, which itself is flat underside, like a diesel head. I believe my model B's compression ratio is something like 4.75:1 and it's like that.



Carlo C., I know I kind of went off on a tangent...I'm not being a smartass here or trying to derail your thread. I'm honestly interested to learn that this combination works at all. If I've got this figured right, you'd have needed the China 110's crank, which has a 49.5mm stroke, and its longer connecting rod sized to work with the taller cylinder, to be ideal. Apparently you did swap the longer cylinder studs and camchain...? I was asking about very similar things to this a year or so ago, when I was thinking about doing this to my Z. I ended up deciding I didn't want to have to switch to the later ignition type.


I have to be honest I did not check the piston at TDC and it could be in the whole deep. Maybe that is why it was not as big of an improvement as I thought it would be. I removed all the parts from a basically new china engine off of a 4 wheeler that was a automatic. I used the timing chain and the studs and had the cases opened up for the cylinder to fit. I had no idea that the china engine was a different stroke.



T Bolt USA said:
Front clutch and 1DN / 3UP is less than ideal for a number of reasons.

Rear clutch and 4up has proven to be a better system over the years.
I am not sure what he has for a clutch as the lever is on top of the engine, but I do know he has 1 down three up. His bike runs really good and he has been 55mph and he is 195lbs.



firepower354 said:
eBay listing specs math-out to 125cc, the 1-down 3-up trans is iffy, and the clutch on the crank holds back attempts at making power. you can get a good 140 from a PM vendor (;)) for less.
Thanks man I am considering a Paranha engine from T-Bolt and fixing this engine since I have so much time invested already. If I don't fix it know I will feel like it whipped me.



thorwarrior915 said:
So... i still dont get how he put a 107 top end on a 12V Z50R bottom end?? The rod length/stroke is all wrong. The cylinder is waaay too beefy to slide in the cases. The studs would have to be swapped over for the 69mm tall cylinder. The longer cam chain would have to be swapped too. Stud spacing is the same at least?



Are you sure it was a 107?



My suggestion would be to throw a 49.5mm crank in it with a high compression 52.4mm piston, that way it has more than 5:1 compression??
I used the studs, timing chain and bored the cases. I still have the bottom end from the four wheeler will the crank out of that engine work in my Z50 cases?
 

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"I am not sure what he has for a clutch as the lever is on top of the engine, but I do know he has 1 down three up. His bike runs really good and he has been 55mph and he is 195lbs."



One look at the ebay sale and its a front clutch motor, but a picture of the actual engine would help



If you only did the 54mm big bore to your engine and still have the stock crank its 95cc
 

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I know a normal 49.5mm crank will swap into honda cases, but i'm not sure if the atv crank will swap out or not... its possible that the clutch side of the crank is a little different? Actually, if its electric start, the ignition side of the crank could possibly be different too. You would have to pull it and take some measurements.



You might as well continue building this honda/china hybrid with the amount of work you have in it?
 
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