General Lee minibike.

#61
I wouldn't think even if the cast aluminum was thick enough it would be safe to bolt a steel hub to it without worry the cast aluminum fracturing from the bolt holes. but I have machine Tecumseh cast aluminum flywheel before and was very impressed how solid and dense without any voids after machine the starter teeth off.
Li'l Popeye do you have the ability to harden the stock cams? if so you could also run set of stamp 1.3 rockers. that would help the performance by using a stock cam. also might be able to get away with not harding the cam by a couple different ways. I know from the pass some guys ran stock cams in there builds with 18 pound springs and didn't have a problem with eating up the lobes,but anything more you could chewy up the lobes. cams are not harden very well from the factory. 18 pounds could still work with 1.3 rockers if there is no coil bind and set at the correct spring height. engine should pull good up to 5000+ and at that rpm your not going to float the valves and it wouldn't hurt to run a good zinc oil. make a good little hot rod engine with just stock parts and couple mods.
An adjustable hub in these flywheels is not going to happen. They are not thick enough.
Hardening stock cams; there might be companies that are able to do so, but I'm not going that route (for now). Like you mentioned; "make a good little hot rod engine with just stock parts and couple mods."
There are no roller lifters available for these engines? I can't seem to find any. There are roller rockers, but no roller lifters.
"and set at the correct spring height": What's the correct spring height?

How I look at it:
The engine is designed and manufactured for stationary purpose at max 3600rpm, with a small diameter stock carb. a highly reliable powerplant.
I don't need +8000 rpm's. So 18Lbs springs will do the job.
I replaced the stock rod with a billet one and the heavy steel flywheel with aluminium, as an insurance and the aluminium flywheel also helps throttle response.

Right now:
I will take the 14cc cylinderhead and mill some material away around the valves, as to me that looks obstructive for proper flow. I know chamber volume will increase, but according my quick calculations it will stay below 15cc (my calculations are not always good, so I will measure the chamber volume when I'm done milling).
I will replace the dished piston with an aftermarket flat top piston, which is 20 grams lighter. This will help against vibrations.
I will replace the stock, thick GX160 headgasket with a thin GX200 headgasket.
Compression ratio will be 10,7:1 (if chamber volume will reach 15cc).
 
#62
Today I have done some work to the 14cc cylinderhead.
First I had to replace the exhaust valveguide, which had come up a bit. When I wanted to push it back in place, it broke.


It is a very tight fit, that's why I heated the cylinderhead. This works great and fast. Because the cylinderhead is made of aluminium the heat is transferred quick and good through the entire head. When it was heated, I used the shop press to push the new steel valveguide in.


Creating some room for flow.
I also did some slight porting inside the intake and exhaust ports.

I also checked valve springs and their loads. I have checked the stock gx160 springs, GX140 springs and 18Lbs springs.
The GX160 springs are the weakest with 5 kg. The GX140 springs look the same as the 18 Lbs springs I bought and when measured, they have the same spring load (8 kg). With the GX140 or 18lbs springs installed and a fully opened valve there's just 1mm more travel possible, before coilbind. Installed spring height is 21,6mm.
I might need a more accurate scale for these measurements. Or don't measure at all, like most people do...
 

delray

Well-Known Member
#63
you got to quit giving us everything in mm. that's all greek to us usa guys....LOL thank god for google. 1mm only puts you about -.040 spring coil gap when open. little on the tight side. when you say load what kind of load are you putting it on(stock cam?). opening the chamber around the valves is going to kill your cc's you had. creating more of a open area around the valves will help flow. but with a stock life cam ?
you can mill a safe .050 off the head and not worry about changing the push rods. .050 will bring the compression back up little. are you using the honda 18 springs?
 
#64
you got to quit giving us everything in mm. that's all greek to us usa guys....LOL thank god for google. 1mm only puts you about -.040 spring coil gap when open. little on the tight side. when you say load what kind of load are you putting it on(stock cam?). opening the chamber around the valves is going to kill your cc's you had. creating more of a open area around the valves will help flow. but with a stock life cam ?
you can mill a safe .050 off the head and not worry about changing the push rods. .050 will bring the compression back up little. are you using the honda 18 springs?
The metric system is as greek to you as the inch system is to me. I can try to keep in mind that USA has not evolved to metric, yet. LOL
0,040" is about correct. It's not much, but it is what it is. This is the measurement when you replace stock gx160 springs with 18lbs springs (at full stock lift). The stock springs do not coil bind that fast.
As I said in a previous post, creating a slightly open area takes makes the chamber bigger, but not that much. It will be over-compensated with the use of a thin gx200 headgasket. No milling off the head needed. Also the flat top piston will help.
I have installed the GX140 springs as they measured the same as the 18lbs'.
 
#65
The metric system is as greek to you as the inch system is to me. I can try to keep in mind that USA has not evolved to metric, yet. LOL
.
I've known several American machinists who use the metric system. Our engineers at NASA have used it for years as well. Even some of our automotive industries use it. Of course I am certain those engineers have nothing on the very talented Dutch rocket builders. I'm sure when the EU went to the moon and walked around, those were metric space suits. And no doubt that one car produced over there is chocked full of metric measurements.

We also know how to use a cam card and a degree wheel, and I know I was using valve spring compression scales before you were born. But hey, if access to a large machine shop is all that separates us, (and a few million gadgets that you didn't invent but we did) there is hope for you yet. Who knows, it could be a Dutch company who someday installs a GPS unit in space for the rest of the world to use for free.
 
#67
Here in the Netherlands we only make (metric) wooden shoes and cheese...:cool:
Exactly. And here in America, we walk around with cowboy hats, and say "Pilgrim" and "Make my day" a lot. My own ethnocentrism never had the chance to fully develop, since I spent most of my life "over seas." Metrics are simple, and despite being in high school during the 1970's attempt at Government-mandated conversion, it just never took hold- Until I lived over seas, and part of getting a drivers license was being able to compute MPH to KPH back and forth in my head. After that, (a .6 and a 1.6 solution by the way) a base ten system was far simpler than fractions. Or, we can discuss octals and how they make a checking account ledger coded for wives, or other broad brush stroke painting.
 
#68
Well, this made my day;
The low oilsensor and governor have been taken out the engineblock. The governor top hole is plugged with a cut-off piece of the governor shaft. The low oil sensor hole is plugged with a piece of 0.472441" (12mm) metal shaft.
The cylinder is de-glazed and new stock size piston rings will fit within specs given by Honda.


Checking bearing clearance with use of a conversion chart for inch/pounds to N/m to set my torque wrench (my torque wrench is scaled foot/pounds and Nm).
It's an old Honda crankshaft, but it was just within specs given by ARC. Checked it with plastigage, too; Good to go.
The ARC rod is truly a great American made part.


Pictured above you can see the blocked governor hole.
This time I installed FAG 6205 C3 as crankshaft bearings. They were $5,95/each (€5,27/each). These are also sold as "racing" bearings for $12,99/each.
Also new sealings have been installed.
New flat top piston, with piston rings. 20 grams less reciprocating mass and a higher compression ratio.
 
#69
I've known several American machinists who use the metric system. Our engineers at NASA have used it for years as well. Even some of our automotive industries use it. Of course I am certain those engineers have nothing on the very talented Dutch rocket builders. I'm sure when the EU went to the moon and walked around, those were metric space suits. And no doubt that one car produced over there is chocked full of metric measurements.

We also know how to use a cam card and a degree wheel, and I know I was using valve spring compression scales before you were born. But hey, if access to a large machine shop is all that separates us, (and a few million gadgets that you didn't invent but we did) there is hope for you yet. Who knows, it could be a Dutch company who someday installs a GPS unit in space for the rest of the world to use for free.
The large machine shop is because, untill several years ago, I was a tractorpuller. We (together with the team) ran a modified tractor with 3 Allison V-1710 engines. Yes, it's American made and nothing is metric to them. It's quality is superb. Alu/magnesium engine components, everything very lightweight.
Here are some of our links if someone is interested:
Our website: http://www.teampopeye.nl/
Our video's: https://www.youtube.com/user/3Popeye/videos
 
#71
The large machine shop is because, untill several years ago, I was a tractorpuller. We (together with the team) ran a modified tractor with 3 Allison V-1710 engines.
We utilized Allison gas turbine engines.

Outstanding! I saw some earlier races that must have featured your machine with the three engines. Later model in 2012 sports two? Great videos, great machine! Thanks for sharing this!


 
#74
We utilized Allison gas turbine engines.

Outstanding! I saw some earlier races that must have featured your machine with the three engines. Later model in 2012 sports two? Great videos, great machine! Thanks for sharing this!


The tractor was able to run with 2 or 3 engines. We ran with 2 engines in the 3,5 ton class and were able to place the third engine for the heavier class (4,5 ton).
The Dutch association decided (years ago) to lower the weight in the heavier class, that's why we only could start in the lighter class with just 2 engines.

In this video (should start from 5:30 min) is shown how we replaced the transmission and added the third engine. Almost in realtime.
 

delray

Well-Known Member
#77
The metric system is as greek to you as the inch system is to me. I can try to keep in mind that USA has not evolved to metric, yet. LOL
0,040" is about correct. It's not much, but it is what it is. This is the measurement when you replace stock gx160 springs with 18lbs springs (at full stock lift). The stock springs do not coil bind that fast.
As I said in a previous post, creating a slightly open area takes makes the chamber bigger, but not that much. It will be over-compensated with the use of a thin gx200 headgasket. No milling off the head needed. Also the flat top piston will help.
I have installed the GX140 springs as they measured the same as the 18lbs'.
ok, it just looks like your taking a lot of material off around the seats. whats the difference in the off set for the new piston. .020 higher? and the head gasket I am assuming your going with a steel gasket that is only .010 thick.
 
#78
It's not a lot material I took away, I think it is approx 1cc. Piston measures the same with a caliper, I still need to check deckheight. The new headgasket is the thin metal version.
 
#79
The engine is running by now. Here's what has been done:

I did a cc check of the cylinderhead. It now has a 14,5CC chamber. And it also had a leaking exhaust valve, which is lapped and not leaking, by now.


I milled this part down, as this little notch wasn't flat with the surface where the torque converter bolts to. It was about 0.015 that I milled of. It is not much, but it makes the torque converter backing plate twist a bit. While the side cover was off, this was easy to do and I hate to use the grinder.


Valve cover is painted. At this stage; with just the crank in the GX160 engine, I mounted the new alu flywheel (31110-Z1V-810) and spun it with a drill and checked timing with a timing light. It came out as 20 degrees BTDC (out of the box, on a Honda GX160 crankshaft). After grinding the stock key, it is now set at 29 degrees BTDC.
I also checked crankshaft endplay at this stage, while there's no connecting rod installed it would be easy to take the crank out, if needed. It has 0.004" endplay, which is fine by me (I couldn't find any numbers what it should be, but the endplay "feels" good. The engine that will be replaced has approx 3 times more endplay and that does not feel good.
While the new bearings seemed to be very loose out of the box, they don't show any play once they're installed with crank in position. They do spin good. Untill now; good bearings.


Installed stock, genuine, camshaft. Rod and piston, too.
While checking deck height (0.01" at the side of the piston), it turns out that the flat top piston isn't flat. I can't feel it and it can't be seen by eye, but the dial indicator tells me that in the center of the piston it is dished 0.007".
It's not much, but I used this number in the compression ratio calculations: 10,6:1


This part of the crankshaft was rusty and I had to sand it to make the new flywheel fit as it was not seating well on the rust.
To prevent corrosion, I painted this part of the crankshaft. Some paint will be removed in the process of lapping flywheel to crank.


Swapping engines. In the back is the new assembled engine. On the minibike is the engine with the ARC 6602 ultra lightweight flywheel.
The new engine got a yellow, solid core, spark plug wire and another sparkplug boot. 0,0 Ohm resistance from coil to sparkplug.
Blower housing with recoil starter, intake, exhaust and breather tube will be used with the new engine.
Why do I swap the engine? The engine that will be replaced has some crankshaft play issues. At TDC and BDC there's a point where the crankshaft turns to "freely" to the touch. I also want to check how the ARC rod with bearings have hold up in this engine untill now.
If I swap it, I am still able to ride the minibike.


The engines have been swapped and disassembly of taken-off engine has started.

The minibike with the new engine runs ok and needs some tuning. Untill now it seems to be jetted to high.
The new alu flywheel (1500gr) is twice as heavy as the ARC 6602 flywheel (700-800gr). This is noticable with throttle responce. It is a bit sluggish. But compared to a stock steel flywheel, the new alu flywheel is a lot more fun to drive.
 

Top