How many cc's to upgrade?

Discussion in 'Rack Mounted Engines' started by rkbonds, Dec 10, 2008.

  1. rkbonds

    rkbonds Member

    My question is this I'm currently running a 24cc engine I have a 31cc engine I could use but, would it really be worth all the trouble of making new mounts drive assembly and everything. Or what would be the the minimum amount of cc's to provoke an upgrade. I know I want to be able to tell the difference I'm just not sure 6cc's is enough to validate all the trouble. :thinking: :-/
     

  2. srdavo

    srdavo Active Member

    IMHO....
    run what ya got.......
    ....................when it quits,,,,,,,
    ........................................build ya another!!
     
  3. 5-7HEAVEN

    5-7HEAVEN Guest

    Use two!

    Leave the existing engine as is, and install the bigger engine up on the other wheel.:grin5:
     
  4. Mountainman

    Mountainman Active Member

    yes -- you may feel 6cc more -- a very LITTLE

    but -- a better outcome would be

    putting the other engine on another bike

    two to ride that THING
     
  5. rkbonds

    rkbonds Member

    On my bike I only have room for one engine (have a child seat on the back) but, my thoughts were leave things as they are unless I find an engine with a minimum of atleast 10cc or more than what I have now. Then keep the smaller engine for a back up in case something happens to the new one.
     
  6. Mountainman

    Mountainman Active Member

    quality engines - no need for back up

    that seems to be a good thought RK

    at least 10cc for a true chance of power

    still thinking about my next upgrade - power wise
    at least 10cc would be a minium

    wouldn't wish to kept my current engine as a back up though
    because - if I bought another quality engine such as this one already owned
    should be no reason for a back up for a very long time
    the quality engines should give years of trouble free performance
    thus I would just add the new engine to another bike - have two

    maybe take along a friend as we ride those things
     
  7. rkbonds

    rkbonds Member

    Ok now I know exactly when to upgrade. Wait until your oldest son tears up his 50cc pocket bike (not his fault, front end problems) then take the back half and make a push trailer out of it. It becomes a win situtation for me because he no longer wants it anyway (he wants something bigger :thinking:).
     
  8. rkbonds

    rkbonds Member

    This may be the easiest build ever. (I hope) I removed the front wheel which was the problem on the pocket bike and believe it or not the trailer hitch on my bike is the same width as the front wheel on the scooter :grin5: This means 1 grade 8 bolt and rewire the kill switch and run a throttle cable and she's done! Sounds easy I just hope it works out that easy when I put it all together hopefully this weekend :cool2: I'll post pics as soon as I'm done. I may also look into regearing it for a better (slower) speed for those cumbersome hills.
     
  9. Mountainman

    Mountainman Active Member

    are pocket bikes legal back there ?

    I guess that if caught -- not much harm done ?

    have fun as you ride that thing -- should be pretty FAST
     
  10. rkbonds

    rkbonds Member

    Here in Huntsville, Alabama everything with a motor has to be registered and insured so I'm just building for fun. If I get caught I'll just take it all off. So far when I have run into the cops they just kept right on going.
     
  11. duivendyk

    duivendyk Guest

    Power output is roughly proportional to displacement,so going from 24 to 31 cc, an increase of 7cc, would represent close a 30%!! increase in torque (and power),assuming they are the same type engines,that is both 2 strokes or 4 strokes.Not to be sneezed at if you have little power to begin with.If the 31 cc engine is a 2 stroke and the original one a 4 stroke the increase could be even higher.If you crave more getup&go ,I'd say: go for it,assuming that making the change is relatively painless.
     
    Last edited by a moderator: Dec 13, 2008
  12. fetor56

    fetor56 Guest

    If u think your getting a better engine then upgrade....after the work is done you'll probably be glad.
     
  13. Happy Valley

    Happy Valley Active Member

    In my recent experience, meh, not much difference in 7cc's. I swapped a 33cc 4 stoke with a 40cc 2 stroke a number of times this past summer, same bikes, same drive systems.
    The smaller 4 stoke still had more torque and the larger 2 stoke, as expected, had a bit more top speed.
     
  14. duivendyk

    duivendyk Guest

    The reality is that engines cannot be compared based strictly on displacement,there are a host of factors that enter into it.For instance the R466 2 stroke with around 50cc can put out around 4 HP (at high rpm) due to superior engine breathing.But to take advantage of this superior high speed performance, the gearing would have to be lower since the low/mid speed torque is not much higher than less highly tuned engines (and may actually lower).The only valid comparison is to look at the HP/rpm chart or max power/rpm info.This is usually not easy to come by.The best thing that can be said is that based simply on displacement 2 strokes can only be compared to other 2 strokes,and the same applies to 4 stroke engines.2 strokes tend to be more peaky,so in the abscense of a multispeed transmission a lower output 4 stroke may well be easier to live with in terms of overall performance.If you are dealing with the same type of engine from he same manufacturer you are an safer ground.It's pretty much guaranteed that the larger engine will outperform the smaller one.
     
  15. rkbonds

    rkbonds Member

    Initial set-up

    Ok, I got around to getting everything hooked up today still have to do a little more work on it but, this gave me a good idea of what to expect. Here's some pics of what I have going now, it's not exactly how it's going to end up but it'll give you a pretty good idea of where I'm heading. No garage and rain made for a short day of playing with my bike. :grin5:
     

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  16. rkbonds

    rkbonds Member

    I'm liking this new set up a lot! I lowered the triple tree to give it a more level push and that made a huge difference. If I want I can ride without having to pedal at all. I haven't checked top speed yet I've kept it between 10 -15 max during testing and that's not even half throttle. I'm also going to completely box the trailer in with milk crates to hide what's underneath but, also for use when I go to the store. I'll get some more pics up as soon as it decides to quit raining.
     
  17. rkbonds

    rkbonds Member

    Ok, today I went for a 8 mile ride in 22 degree weather the bike did really well. I need to do some work on my throttle it's not opening completely (easy fix). Other than that I'm very pleased with the new set up. The only other problem I have is it tends to want to bounce, hop, etc... if you don't baby the throttle. Thought about adding some weight or maybe try some kind of spring tensioner? And see if that helps.
     
  18. 5-7HEAVEN

    5-7HEAVEN Guest

    Dang, rk, looks like you're towing a pocketbike!

    Law man might think it looks unsafe traveling at speed. You mentioned dropping the front fork. If you drop the fork all the way down, remove the seat and all the panels it would look better.

    JMO :cool:
     
  19. rkbonds

    rkbonds Member

    I plan on doing just that then I'm going to add milk crates to each side to concel and haul stuff in. I'll try and post more updated picks today if I get the chance.
     
  20. rkbonds

    rkbonds Member

    I've done some more mods and have been able to solve the bouncing problem I was having during take off by using a spring as a tensioner and 7lb worth of weight. This has been the best mod I've done to the bike yet. I am very pleased with how this has turned out. I still have more cosmetic work to do but that's about it.
     
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