Cheap Friction Drive.

Have been riding the GX50 FD a bunch. Nearly 200mi in short runs to town. Its a great engine. Lots of power for what it is.

I once ran out of fuel forgetting to check the tank because they burn so little and I rode a bit too long I guess.. I added a 2L CG tank tee'd into the primer return line. The stock tank is 1.2L and I figure 1.5 in the CG tank do to the angle, for a total of 2.7L. Using Hondas fuel burn rates thats 130mi.

The CG tank will gravity feed automatically as the fuel is drawn from the Honda tank. It cant over feed due to vent lock by the vent in the cap on the Honda. Just have to remember to shut of the CG tank if I ever remove the Hondas cap.
 

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Heres the finished conversion. Works well. Top speed around 27 in flat, no wind conditions. Not bad for a 31cc.
was easy to do, and can be converted back just as easily.
This is a great idea. The 5:1 gearbox is totally reliable and cheap, and to combine it with a chain drive on the left side of the
bike is wonderful. I did the same thing but drove the rear wheel from the right side. Your concept is simplier than mine.
 
Have been riding the GX50 FD a bunch. Nearly 200mi in short runs to town. Its a great engine. Lots of power for what it is.

I once ran out of fuel forgetting to check the tank because they burn so little and I rode a bit too long I guess.. I added a 2L CG tank tee'd into the primer return line. The stock tank is 1.2L and I figure 1.5 in the CG tank do to the angle, for a total of 2.7L. Using Hondas fuel burn rates thats 130mi.

The CG tank will gravity feed automatically as the fuel is drawn from the Honda tank. It cant over feed due to vent lock by the vent in the cap on the Honda. Just have to remember to shut of the CG tank if I ever remove the Hondas cap.
BRILLIANT! I think that brass T is where it's tied into the return line, not clear in the pics. The brass T barbs, 1 looks 5/16ths the other 3/16ths. How did you get 1 hose to fit both with no clamps? Is the hose that flexible? What brand hose is that? You hit a home run there Bubba!
 
This is a great idea. The 5:1 gearbox is totally reliable and cheap, and to combine it with a chain drive on the left side of the
bike is wonderful. I did the same thing but drove the rear wheel from the right side. Your concept is simplier than mine.
Thanks!
It works well. I got the ratio a bit high with a 40t sprocket the first time. A 44 is much better.
 
BRILLIANT! I think that brass T is where it's tied into the return line, not clear in the pics. The brass T barbs, 1 looks 5/16ths the other 3/16ths. How did you get 1 hose to fit both with no clamps? Is the hose that flexible? What brand hose is that? You hit a home run there Bubba!
Thanks!
The barbs are actually 1/8. I also cut the first barbs off to shorten the tee so as to fit in the confined space. The tee is in the return side. The hose is type Im not familiar with. Its pretty hard and required boiling in water to get it over the tee.
The hardness worked out at the tank end as its inside of a sleeve of larger fuel line to adapt it to the tanks outlet and with stands clamping.

Initially, to fill the lower tank, the cap is opened just enough to vent. It fills the tank totally, the tank remains completely full as it fills by displacement. To run it out, just shut off the upper tanks valve.

The fuel line is MaxFlo, its pricy.
 
Heres the finished build. Had mags in the attic so found a home for them. Running. 203mm line pull hydraulic. Kinda
overkill on this bike but had the stuff sitting around.

My experience with the clone engine has been perfect. No issues in 400+ miles. Good power, and a smooth runner. Would recommend it. Good deal at $155 shipped.
 

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So far so good on both clone engines. I really like the 31cc, its a bit quieter than the 50 but not as powerful.
I bought a low time oem Honda Gx31 to put on the shelf as back up.
I made an oak roller for the 50cc. Its 1.30. Folks dont believe what a good roller oak makes. Have run them for years. They are smooth and quiet, and last a long time even when run on dirt.

This one is laminated from 5 pieces then pinned to the lock collars which lock it to the shaft.
Question to you folks running these style engines. How does the engine intake cooling air? The fan is on the clutch side, and I assume pulls air thru the clutch area? It blows air out the vents on the recoil side (crossflow). Shouldnt there
be vents like the housing in the pic? Bolted to a gearbox or a friction drive it looks like the air flow would be greatly reduced.
 
So far so good on both clone engines. I really like the 31cc, its a bit quieter than the 50 but not as powerful.
I bought a low time oem Honda Gx31 to put on the shelf as back up.
I made an oak roller for the 50cc. Its 1.30. Folks dont believe what a good roller oak makes. Have run them for years. They are smooth and quiet, and last a long time even when run on dirt.

This one is laminated from 5 pieces then pinned to the lock collars which lock it to the shaft.

Question to you folks running these style engines. How does the engine intake cooling air? The fan is on the clutch side, and I assume pulls air thru the clutch area? It blows air out the vents on the recoil side (crossflow). Shouldnt there
be vents like the housing in the pic? Bolted to a gearbox or a friction drive it looks like the air flow would be greatly reduced.
I would not have believed that oak would make a good roller. Gonna try that today
 
About oak rollers. As I have said, I have been running them for years with excellent results. This was however
on direct drive, larger slower turning rollers, generally under 4000 rpm.
On the faster rollers like the smaller engines turn, the roller gripped well enough, but wear was more accelerated. Especially considering top roller speeds in the 7500 range.

The roller I used in this thread worked well but noticeable wear began to show around 250 mi. This may have been influenced by the fact I ride a lot of sand roads. So I went back to metal.
For a slower turning roller they last a long time.
Heres a pic of a 2.5 hp build running a 2.1” roller at 4000 max, cruise generally 3200. It has several thousand miles on it.
If you are going to run a larger slower roller (which is best) oak is hard to beat. Not so great on fast rollers.
 

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