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 Complete engine tear down
GIZZYRACING
Posted: Jan 11 2009, 02:11 PM


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I have decided to do a complete engine tear down and explain what each piece is and what it does. This will be very simple ,basic explanation for people that don't understand these engines. I'll get this engine ready to race .At the end I'll add some hop up information so you could build a super box or open.I'll start in about a week.


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Deriell Logan
GIZZY RACING TEAM
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GIZZYRACING
Posted: Jan 12 2009, 10:33 PM


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I'm going to explain the different types of engines that are raced on go karts. First 2-cycle engines that everyone started out with in 1957. A 2-cycle actually means that the engine runs on two cycles. To start with you are on compression at top dead center, the spark plug fires and the piston goes down, this is the first cycle. As the piston comes down you draw in fuel thru the transfer ports. It is the power stroke and the intake stroke all in one. Then as you reach bottom dead center and start back up, this is the second cycle. It is exhaust and compression cycle. Any time the piston is one third of the way down all the ports are open. The intake and exhaust are open at the same time. That's why exhaust on 2-cycles are so important, they are called expansion chambers. They are designed by size or shape to let the exhaust out but not let intake charge go all the way thru the engine. That is the 2 strokes of a 2-cycle engine.

4-cycle engines. There are only two types in go kart racing. Flathead and overhead valves. Flathead is L head, which means the valves are in the block not in the head. Overhead has valves in the head over the piston. 4-cycle start compression at top dead center then the plug fires, piston goes down and that is one stroke, the power stroke. It reaches bottom dead center and starts back up, this is the exhaust stroke. When it gets back to top dead center the intake valve opens as the piston goes down you fill the cylinder with fuel charge. That is the third stroke. The fourth stroke is coming back up building compression. The biggest difference between the two is the overhead valve has better flow and valve location. Built equally an overhead valve will beat a flathead. They are both four stroke and stroke wise they work the same.

2-cycle have fewer moving parts and they have full round crank shafts, which make balancing alot easier. That is why they will turn 15000 RPMS. 4-cycle has many more parts and has two strokes with no power. The intake and compression strokes. Which makes a 2-cylce easier to make power. Theoretically a 2-cycle will produce twice the horsepower of a 4-cycle.

The above was to explain how 2 &4 cycles work things like when the spark plug fires and when the valves open are not at top dead center they are set before TDC and BBC for the exhaust valve.

This is for beginners who do not understand the concept of these engines. And for those who are experience , tell me if I mess up anywhere. I'm getting old and can make mistakes.



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Deriell Logan
GIZZY RACING TEAM
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GIZZYRACING
Posted: Jan 24 2009, 10:26 PM


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Last Saturday we tore down the clone engine and took pictures. But later that evening we found my son in law in my garage they had his funeral yesterday . So I thought I'd get started on the tear down.
First we started with a new engine from Harbor Freight. [URL=user posted image]clone[/URL]
then we took off the air filter and muffler[URL=user posted image] clone[/URL]
took off the gas tank ,you can see the throttle linkage and governor controls
Then I took off the carburetor user posted image
user posted image
removed all linkage and the valve cover,and installed a plate I made to degree a cam with . user posted image
I also took off starter and disconnected the wires to the kill switch .user posted image
In this picture you can see I have installed piston stop and degree wheel . user posted image
I use the piston stop to find top dead center. You rotate the engine clock wise until you hit the stop then set the degree wheel 0 degrees,then rotate counter clock wise until I hit the stop then read what degree it reads [say it says 30 then you divide that by 2 you get 15 set your wheel at 15 ]Then check it and see if it's 15 both ways if not readjust until you get it rite. Then I install an indicator , put it on the valve keeper. First I check the lift This cam had 240 the most I have seen on any of our engines.Then I go through the chart and see if it will pass tech. this one didn't pass the rules I have posted on this site.None of ours will pass the Southern Kartway rules.
user posted image
Man this is hard to keep track of where I'm at going back and forth from 2 web sites trying to keep this going since I'm an amateur on computer. I'll try to post more tomorrow .


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Deriell Logan
GIZZY RACING TEAM
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Joshua Warren
Posted: Jan 25 2009, 01:24 AM


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Great First Post for the Engine Teardown!

Thanks for doing this.

Porkchop


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Joshua Warren
#75
Stock Gas Clone Jr. Racer


user posted image
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GIZZYRACING
Posted: Jan 26 2009, 11:24 PM


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http://www.slide.com/r/AybRYrI85j_ttoloNTR...l&view=original
This is a link to a slide show of pictures I took of the head. You can see the head before I took it off . you see the rockers, valve keepers ,and springs . I removed the rockers by taking off the lock nut on each stud then unscrewing the adjusters then took off the rockers and pulled out the push rods. There is a picture of them one rocker, adjuster and lock nut the other also has the push rods, in the center of this picture is the lash cap from the exhaust valve. Then I removed the head by taking out the 4 head bolts. When I got the head off I removed the valves by taking off the retainers you can hold the valves and push down on the retainers the springs are so light you'll have no problems I will check the pressure later. Push out the valves ,there you have a striped head.
You will notice the head has 2 hollow dowels for location of gasket and head. I left the push rod guide plate on .
I show the block ,one I'm checking in hole measurement . This one was .040 in the hole.
You may notice I tore it down on the kitchen table because it was below 0 outside. My wife was mad but she knows me after 48 years of marriage.
Check this out and ask anything you want to know.


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Deriell Logan
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GIZZYRACING
Posted: Feb 1 2009, 04:15 PM


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ops


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Deriell Logan
GIZZY RACING TEAM
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GIZZYRACING
Posted: Feb 1 2009, 04:17 PM


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After the head I removed the side cover.user posted imageIf your careful you can get it off without tearing the gasket ,I use my knife to pry off a stuck gasket . Tap side cover on the fill plugs , tap it out about 1/8 inch and check around the cover to get gasket that is stuck to the block loose then it will come off with the side cover.
user posted image
In this picture I show the cam located properly this is how the two dots on cam and crank should be when reinstalling the side cover.
user posted image
Taking out the cam you see the lifter is falling down.Some time they fall all the way out. This is why you have to remove the valve cover when you only take off the side cover to remove the governor and oil censor. What happens is the lifters fall down the pushrods drop out of the rocker arms. I've seen many people try to start there engine but it wouldn't run ,then they remove the valve cover and see the rockers off to the side ,all you have to do is push down on the valves and put the push rods back in the rockers. But I always readjust them anyway . user posted image


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Deriell Logan
GIZZY RACING TEAM
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GIZZYRACING
Posted: Feb 1 2009, 04:19 PM


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Here I show the lifters , how the push rod fits in the lifter, the cam you can see the spring loaded compression release,and the valves and springs .Everything in the valve train is interchangeable ,intake to exhaust except the valves and spring retainers. The exhaust retainer is counter bored for the lash cap. The lash cap is to keep the end of the valve from wearing or mushrooming .It's on the exhaust only because of the extra heat .Next I show how the compression release works first picture you see the lifter is spaced away from the cam.The next I hold the spring like it's turning some RPM'S you see the lifter is directly on the cam. user posted image
I'll post more later. user posted image


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Deriell Logan
GIZZY RACING TEAM
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GIZZYRACING
Posted: Feb 14 2009, 12:48 PM


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Actually I removed the magneto and flywheel before I removed the side cover. On the flywheel I use a strap wrench to hold the wheel while I remove the nut . I don't have a picture of this because it took both of us to get the job done. Once you get the nut loose run it out until it's flush with the end of the crank then use a large screwdriver to pry out on the flywheel while you hit the end of the crank with a hammer. It usually will come off on the first hit. Remove the flywheel and take out the key , the key on this one was tight I had to knock it out with a screwdriver and hammer.


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Deriell Logan
GIZZY RACING TEAM
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GIZZYRACING
Posted: Feb 14 2009, 03:26 PM


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flywheel
magneto
Today I can't get pictures to post so I'm using links. O.K. back to where I have the side cover off. I'll show you the hollow dowels that line up the side cover.dowels
then I took out the rod bolts. Removed the rod cap and pushed the piston out the top.
removing rod bolts
Notice the piston has an arrow this points to the push rods the slinger end of the rod cap points in the same direction. Reinstall the cap and torque to 100 in. lbs. then you can check size .
piston
assembly
I removed the pin clip with needle nose pliers and took the rings off the piston. Be careful removing the rings only spread them enough to get over the piston . Remove the pin by pushing it out with a screwdriver. After you get this assembly out you can pull out the crankshaft, then get some measurements.

rod
crank
piston
bore
This engine had .002 clearance rod to crank and .0015 on piston to bore.This is tight for racing but if it's broke in good it would be ok.
If I was building an engine with no rules I would for a box stock since they only turn in the 5000 rpm range put .004 on the piston and .002 to .0025 on the rod.If it was a modified I'd leave the piston tight but open the rod clearance to .0025. But you need file fit rings for each .This engine had .012 end gap on the top ring I would start with .002 . But running tight end gap requires a straight bore no high spots.
end gap
Since I was tearing the engine down this is when I'll remove governor and oil sensor .Take the bolts out of the oil sensor and the nut in front of the engine for the sensor wire , pull out the wire.
crank case
sensor
The first sensor I took out I used the rubber washer on the in side of the wire housing put it on a 3/8 bolt on the inside and locktighted a nut on the outside . It worked fine ,still in use, no leaks. Now I tap the hole 7/16-20 only part of the way through, about 1/2 way then install set screw with red lock tight.That way it get's real tight.
With the engine completely disassembled the easy way to remove the governor is to knock out the shaft .
shaft
Then remove the governor arm by removing the clip on top.
arm
I use a 1/4-20 tap on both holes only tap 1/2 way ,and install with red lock tight. Make sure you remove the small steel washer that is behind the governor gear .It will stick to the case you can use a magnet to get it.
I think I have explained about everything . This comes so easy for me I probably left out something you want to know . So you have to ask .
I'll give you a few tricks I use to get the most out of your box stock. Since we cant do anything to them here is a few you can. When setting the gap on your magneto I put a .015 feeler gauge between the mag. and the magnet , take the bolts out put on one drop of blue lock tight on them reinstall ,while they are loose move the mag. all the way to the left.It wont move much but this will advance your timing as much as you can.
On the carburetor ,when you get your engine remove the air cleaner . Look through it . look at the gaskets are there any mismatch , make sure nothing is blocking air flow. The better you match the gaskets with their mating surface the better air will flow. And jetting for your rules. If you can drill the pilot jet. I used .024, this works in my area . You will have to find out what works in your area. This helps on low end ,better throttle response and acceleration. Once you find out your main jet keep one jet size above and below on hand. I have had to change for weather conditions ,some times up or down.
I'll take pictures later of the carburetor and spring testing. I'm now making a head adapter for my flow bench i'll take some pictures of it too.
Setting valve lash . I use 0 lash ,get all the lift you can. You will see people using .003 to .004 they say you have to allow for expansion of heat. Try this your self Set your lash say .003 know you are wright on this measurement . Put valve cover on ,run your engine until it's hot take off valve cover and check lash . you'll see it is greater not tighter.
Setting for 0 lash is tricky when you tighten the lock nuts always changes it . If you get them tight it wont run .The springs are so light it's hard to tell , I hold the rocker arm and tighten the adjuster until the rocker has no movement then back it off until you can move the rocker then tighten the lock nut. You may have to get the feel of it but keep trying you'll get it .This way you have maximum lift.
I hope this is useful to someone ,please ask questions.


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Deriell Logan
GIZZY RACING TEAM
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