whats ahead?

Discussion in '2-Stroke Engines' started by happyjourney, Nov 28, 2011.

  1. happyjourney

    happyjourney Member

    I was reading a pre build checklist at either this or the other forum and it had that you should sand approximately 1mm off the head to increase compression i beleive. I am not acquainted with motors at all much before taking up this project of my first build and made the mistake of asking which was the head, the top part that the spark plug extends through or the lower jug which holds the piston. I was chided quickly with a statement of something to the effect of "if i told you to touch your head would you have to ask where it was" that post was then followed up with some over my head jargon but i never got an explanation. viewing my troubles i didn't have the courage to ask again and still i need to know which part to sand. do i sand the top portion of the cylinder with the head studs extending through it or the cap as i've said with the spark plug extending through it. also i've seen pictures in my browsing of people who had bored out or shaved off more clearance area inside of the cap that the spark plug extends through. what would be the benefit of that? perhaps the shaving off of metal from one side or the other of the head peices would extend the spark plug further towards the gases and oxygened area that would need exploding? is that the reason it creates more compression? I would think that making the inside areas bigger and inlet and outlet areas bigger would give more power not smaller which is effectively what i'm doing when i shave off metal from one side or the other (of the top or bottom). i don't want to get into a whole big chemistry lesson if i don't have to but i would like an idea of what is occuring.:idea:
     

  2. oldnube

    oldnube Member

    i am new also, but the head is the part with the spark plug. You want to mill (sand with very find paper) only the areas where the gasgetsets take a sharpie and lightly mark that area then follow the directions given. When the marks are gone your surface is "true". This makes for a better seal and improves compression.
     
  3. happyjourney

    happyjourney Member

    a sharpie huh. sounds like a good tip. i'm not with my engine right now but i'm going to check it out again when i get home. i'm going to have to buy some finer sandpaper.
     
  4. motorpsycho

    motorpsycho Active Member

    no, no, no...back up!
    ok first off, the head is what's bolted to the top of the cylinder. (where the spark plug is).
    you have to remove the head (4 nuts) from the cylinder.
    There will be a thin metal gasket between the head and the cylinder which you should replace once you pull the head off of the cylinder.
    flip the head over and look at the area where the gasket sits. you can set the gasket back on the head with the head upside down to see the exact contact area.
    THIS is the area on the head that will need to be sanded or milled.
    you have to do it on a perfectly flat peice of glass to get the surface true.
    tape a peice of 220 grit sandpaper to the glass and then sand the head (mounting surface) in a figure 8 pattern. you don't want to remove too much material because if you remove too much, the spark plug could end up hitting the top of the piston. If you remove too much you could end up with so much compression that the clutch won't be able to grab enough to turn the engine over. If you remove too little, you won't get any results and you end up having to do it again.
    you want to remove like 1-2 mm at the most i think (i have never done it myself, but i know how to do it).
    there are 2 reasons for doing this.
    #1, it trues up the mounting surface of the head where it seals to the cylinder, BUT if the cylinder is not true, this won't make much difference.
    #2, removing material from the head mounting surface will lower the combustion chamber in the head (where the spark plug electrode is) closer to the piston. It's not the fact that the spark plug is closer to the fuel/air mix that gives you more power. It's the fact that removing material from the head mounting surface will create less volume in the combustion chamber which will raise the compression. Lowering the combustion chamber closer to the piston creates higher compression. more compression = more power. think of filling a gallon jug with paper towels. Now try putting that same amount of paper towels in a 3/4 gallon jug, it won't fit easily but if you force it all in, it will fit and be more compacted together. this is the same idea, you are reducing the volume in cylinder / combustion chamber, but you are putting the same amount of fuel/air into it as before.
    BUT too much compression will require running higher octane fuel, and it will make the engine a lot harder to start and it will run hotter.
    if you are unsure about any of this, maybe you should just leave it alone.
    You have to know what you're doing and you have to know when to stop removing material. You also have to be careful when you re-install the nuts that hold the head on because they can strip out real easily, you have to get the head torque right (I have no idea what it is on one of these engines). sometimes you can break a head stud when trying to torque the head nuts, which would require removing all 4 studs and replacing them with stronger ones.
    there's more to it than just sanding the mounting surface of the head.
    I'm no expert on this by any means, but i have been around engines all my life (40 years) i've built engines for drag cars, motorcycles and all kinds of high performace stuff.
     
    Last edited: Nov 28, 2011
  5. happyjourney

    happyjourney Member

    i'm not with my engine right now but my gasket as i remember seemed to be a thick peice of wax paper not a metal one. i plan on replacing that one with a metal one from sick bike parts and i plan on upgrading the studs coming out of the head and the intake and exhaust. i believe i can handle smoothing out the bottom of the spark plug holding cap which is called the head i suppose. does the sharpie trick sound like a sufficient depth to you? i want to do this right. I've spent alot of money on accessorizing parts mostly and am in love with the project i'm building and I'm hoping to keep this thing runnin.
     
  6. oldnube

    oldnube Member

    Thank you Motorpsycho for clearifying and expanding what I was wanting to say. There are 3 prebuild checklist for 2 strokers check out "What Every NOOB needs to read" by AL FISHERMAN and his pic thread on takeing them apart (both are "stickie". I know the sharpie tip will get the surfaces true I dont know if it is too much or too little. Maybe someone will help us both out on this.
     
  7. happyjourney

    happyjourney Member

    the gasket was metal not paper. thanks oldnube for giving me the ideas on the prebuild checklist i'm going over many of those lists and trying to prepare the engine properly.
     
  8. Big Red

    Big Red Active Member

    The Head

    Another little thing to think about. If you don't apply pressure evenly across the head while sanding you could make the head sit unevenly on the cylinder. I've found when trying to hand sand and keep it as true as possible, you will need to rotate the peice you are sanding in your hand. Sand in a figure 8 as suggested back and forth eight or ten times, then rotate the peice in your hand 1/4 turn, Repeat. turn 1/4 turn in same direction as last, Repeat. While holding something like that I've found that you will always apply more pressure with the palm of your hand than your fingers. Rotating the peice helps solve some of, (not all) of this problem.
    I discovered this problem while taking down the back side of a rear engine mount to fit a tight mount situation. First time it did not fit flat between the engine and frame. I was much more carefull the next time, and rotated it as I sanded it down. It came out a LOT closer. Heads are a lot more critical than an engine mount and need to be done as carefully as possible.
    Big Red.
     
  9. Big Red

    Big Red Active Member

    Head Gasket

    Hey happy, I've also read on this site, (somewhere) that you can get a thinner head gasket that results in the same as milling the head. A thinner gasket will lower the head closer to the cylinder and will also result in higher compression. Wish I could remember where I saw it. Perhaps someone else will remember.
    Big Red.
     
  10. happyjourney

    happyjourney Member

    i do remember seeing a post somewhere about a thinner gasket as well. I remember also when looking at the inside of the head cap that on the gasket fitting area on the inside of that area where the gasket would go there was an elevated ring i thought. more details later when i go look again this evening.
     
  11. Big Red

    Big Red Active Member

    Head

    Hey happy, Just looked myself and your right. There is a raised ring on the head. Looks like it would make better sense to mill the top of the cylinder instead. But still, I think the better option is the thinner head gasket.
    Big Red.
     
  12. happyjourney

    happyjourney Member

    i will look at milling the top of the cylinder. the sick bike parts gasket says that its thinner. i haven't looked anywhere else yet. i might be putting the whole project on hold if i can control myself so i can save up to get my motorcycle shipped down here from va. i'd hate to get done with this project and have something malfunction. right now my bicycle is my only transportation and i have to ride normally 20+ miles everyday. more later...
     
  13. Big Red

    Big Red Active Member

    Transportation.

    Hey happy, Most of us are into M.B's as a hobby or just plain fun. Some use them for everyday tranportation. If you need it everyday I say, If it ain't broke, Don't fix it. A thinner gasket will do the trick in your case just fine. Their are also things you can do to increase power without doing anything to drastic to your engine. A better carb will increase throttle response and a GOOD exaust should get you another 1/2 HP or so. You should also look at cleaning up porting. there are a couple of really good posts on that subject on this site. Just try to K.I.S.S. I've found the more you "improve" something the more their is to go wrong. If an "improved" part fubar's then you might not have another one just laying around for a quick fix. I keep an old engine or two around just for all those little parts I might need. A good used part is better than no part. Just try to keep it as simple as possible, It will make for an easier fix when the occasion arises.
    Big Red.
     
  14. happyjourney

    happyjourney Member

    no doubt. i hear you about that kis thing but i have been in the process of building this bike with whatever moneys i can spare (wage slave) for many months. I had to take the bus for a week while i waited for the bicycle shop to build the bike from parts after i had it taken apart to spray paint the frame. I already ordered a longer muffler and a dellorto carb with some jets. I've been lurking around these forums for a long time now and i've learned alot. it ain't broke but it isn't even together yet. The motorcycle i plan on making my daily driver. then i can focus on putting this thing together further. it's a shame that i'm almost on the road with this thing when i decide to get my motorcycle shipped though. I have been collecting parts and planning for a while now and expect to get turn signals and brake lights as well as headlights fixed up to it and have an industrial laundry basket hooked to the back rack. this will be the bike i go get my grocerys on as i know from experience its hard to fetch even a jug of orange juice on a motorcycle if you haven't got a pack or saddlebag. I already have a big wald 157 basket fixed to the front and i spent a hundred sixty some just buying another one and hinges basket liners and hardware along with it to hopefully fix it up to be a lockbox of sorts so i can keep my laptop locked up in it while i go for a jog along the beach in the morning. I've already got the rear hub on it and my axle is full. the bike itself is a seven speed beach cruiser and already it weighs a ton though. especially with my laptop and toys in the basket up front along with a jug of water or some food and a towel or whatever. i can't wait til i get it all hooked up and done and i can afford a camera to show you guys. I've been searching through the forums looking to put lights on my bicycle and noone seems to finish and fully explain putting a full working lighting system in place. alot of threads to nowhere and empty promises. i'd love to babble more but i'm off to make the money to allow me to do all this junk. toodaloo
     
    Last edited: Nov 30, 2011
  15. Big Red

    Big Red Active Member

    Camera

    happy, Walmart has a digital camera for $20.00. They had a slot for a $10.00 one but they were out of stock so I got the one for 20.
    Their are only two way's to set up lights on a bike. Real cheap or very expensive. Of course the white wire wont work or at least work very well. I've seen some that use an add on coil to produce a new 6v source to run the lights. Of course THEN ya gotta buy the wiring harness, the batteries, a battery box, the voltage regulator, ect,ect,ect. That all can run into real money real quick. I've found that the best "cheap" way to light your bike is with a good bright LED headlight that you can use regular batteries in. Also, I'll include a picture so you can see how I put tail lights, turn signals and brake lights on my recumbent. It's the cheapest way I could find and not have it look homemade. It has a horn button but it blows as a horn for a motorized so you'll have to come up with a way to do a good horn. Other than that, it has worked well for me for over a year. It's the tail light assembly on the fender with the control box on the handlebars. Came from e-bay.
    Big Red.
     

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  16. motorpsycho

    motorpsycho Active Member

    wait a minute....
    you had to have a bike shop re-assemble your bike?
    you couldn't do it yourself?
    if you can't build a regular bicycle, how do you plan to maintain a bike with an engine on it?
    there's a lot of maintanance involved, including re-packing wheel bearings, and adjusting them along with brake adjustments, engine tuning, chain alignment, chain tension adjustments, etc.
    If you can't build a bicycle, you won't be able to maintain a bike with an engine on it.
    50% of having a reliable, long running motorized bike depends on maintanance.

    so you plan on keeping your laptop on the basket on your bike while you go for a swim?
    hmmm, i think that it would be MORE of a reason for someone to steal your bike.
    If one person sees you put the laptop in there, your bike will become even more of a target for theives. Locks and chains only stop the "honest" theives.
    If a real theif wants it, nothing will stop him from taking it.
    good luck.
     
    Last edited: Dec 1, 2011
  17. happyjourney

    happyjourney Member

    I did have to have them take apart certain parts on my bike that i didn't have the tools to do besides not being acquainted with the process. Mainly the headset that i got replaced they have a special tool that was really expensive. i could have gotten a hammer and some blunt metal instrument but that might not have worked out well. i also wasn't acquainted with putting a new bracket in. i had ordered a pedal and crankset that was a three piece and i had a one piece in their originally so i had to get and adapter put in. i am also not familiar with wiring up brakes and i had a unusual setup. I'm familiar with using tools as i was a carpenter before and i did have to modify my sprocket adapter to fit my sprocket and hubs alignment. I'm learning as i go along. If i knew everything about how to do this then i don't think i'd be on here asking questions. as far as somebody breaking into my box to get my laptop or steal my bike it's never gonna be impossible for the most determined person but i can only make it more difficult as a discouragement. on a side note, i won't be going swimming in the ocean here. its a little bit scary as far as germs and things for me. i said jogging.
     
  18. happyjourney

    happyjourney Member

    i was thinking of going with the 12volt magneto and the 12v charger from wonderful creation and having a 12v motorcycle battery along with a system emulating the wiring on a motorcycle. I don't know anything about voltage regulation but fuses are in the wiring chain of motorcycles. I understand it takes money, as all things do.
     
  19. motorpsycho

    motorpsycho Active Member

    ok, ok, i appologize.
    I kind of sounded like a jerk when i went back and re-read what i wrote.
    That wasn't my intention.
    I understand that not everyone knows all there is to know about bikes, and you have to learn how to do things sometimes.
    the good thing is that you're learning as you go and try8ing to figure out how to do it right...no fault in doing that.
    I just get so used to being able to do everything myself, it's hard for me to comprehend how someone has to have someone else do the work for them or they can't figure it out on their own.
    I'm one of those people who has grown up in the shadow of a mechanic (my dad). I'm one of those guys that learns by doing and it's very easy for me to figure things out just by taking them apart. I guess it all comes naturally to me because i grew up around a person who can literally fix everything. It's hard to explain, but i think you know what i mean.
     
  20. happyjourney

    happyjourney Member

    No problem. I never had any of that unfortunately. I won't want to start in on my own sob story so i can have a pity party though. My project isn't as specialized as your recumbent so i don't feel very daunted.
     
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