I need your guys' 2 cents on durability/longevity issues on HT bicycle motors and...

Discussion in 'Motorized Bicycle General Discussion' started by wasabi805, Jun 27, 2010.

  1. wasabi805

    wasabi805 New Member

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    ..making them last!

    So just as I thought I was out of the woods in regards to working every technical issue on getting my second build to run, I got her going and the one of the studs used to mount the back of the motor to the seat post tube on the bike cracked in the block. After working diligently for an entire day to get her to this point and having that happen, somebody give me a "bro hug" and tell me things will be okay.

    Replacing the studs was always on the back of my mind but, just never got around to it. Boy do I regret that.

    SO......I'm planning on just getting a new base, cyclinder, and piston rings. I'm gonna port and polish it myself because well, it sucks riding a motor without the preparation of porting.

    MY QUESTION IS: Even if I am to replace the studs, with stainless steel ones, lock tight the crap out of them,and order all new gaskets WHAT OTHER THINGS CAN I DO FOR MY MOTOR to ensure that I'm not working on my ride EVERYDAY and ensure that it lives a LONG happy life? Are there any other concerns that I should address as well? (ie. things to consider about the crankshaft and flywheel etc.) BTW, I also have the SBP expansion chamber and am planning on picking up their shift kit.

    I really want this rebuild to go flawless so all your collective expertise is very much appreciated. At the same time, I hope your answers will help other readers and lurkers build the most efficiant bike possible so that they don't encounter the pitfalls I have.

    Thanks Guys.

    Wasabi:-||
     
    #1 wasabi805, Jun 27, 2010
    Last edited: Jun 27, 2010
  2. oylavabeer

    oylavabeer New Member

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    Re: I need your guys' 2 cents on durability/ longevity issues on HT motors and.....

    One of the most common reasons I have broken down is the throttle cable end coming off at the carb end . Silver solder a new end on
     
  3. 2door

    2door Moderator
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    Re: I need your guys' 2 cents on durability/ longevity issues on HT motors and.....

    Number one on the list: DO NOT USE STAINLESS STEEL FASTENERS.
    Yes, I know, it's hard to cut and work with but it is not the best material for fasteners.
    Go with a grade five or grade eight Allen head capscrews to replace the studs and nuts. Do Not Overtorque them and if you want to use LocTite, use only the blue lable stuff, never the red. Thread locking compound is not necessary if you install and tighten correctly. Snug things down until the lockwashers are flat then just a little, very little more then STOP. Do not tighten after every ride! Do not try to get a turn or partial turn on the fasteners after they have been tightened intially.
    One of the biggest mistakes that plague the new builder is overtightening or constant retightening of fasteners which results in failure of the fasteners. Even the kit supplied fasteners (studs & nuts) will work just fine if you keep the wrench in the tool box and away from them.
    As for your proposed modifications and upgrades; get the bike running well without them first then you can look for improvements. Master the basics first and you'll be money and time ahead before moving into the advanced stuff.
    Tom
     
  4. wasabi805

    wasabi805 New Member

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    Re: I need your guys' 2 cents on durability/ longevity issues on HT motors and.....

    Thanks for the input: Part of my problem i have to admit was over tightening. I was using the red stuff because it's what my roomates use on their cars. Going to pick up the blue.

    As far as getting down the basics, I've gotten my bike other bike to purr like a kitten and run like a champ. I think my problem of trying to over due "a perfect job" lead me to foul up this last build.
    I brought up the pipe and the shift kit because without a doubt, they're going on. I mention this because I just wanted to see if there are any special concerns or particular things to pay attention too when putting them on that come to your mind. (Mainly more so the shift kit). Just want to be prepared that's all.
     
    #4 wasabi805, Jun 28, 2010
    Last edited: Jun 28, 2010
  5. wasabi805

    wasabi805 New Member

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    Re: I need your guys' 2 cents on durability/ longevity issues on HT motors and.....

    Hey 2Door, (Or anyone else, please chime in), what's your take on the head bolts? Is it safe to say that overtime they are likely to snap? Is it better to replace them with steal studs or bolts instead?

    BTW, this is the bike that mounting stud broke on today. I wish i had a better picture, but all i have is my outdated iphone to take the picture. Still a work in progress but slowly getting there..
     

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  6. millard52english

    millard52english New Member

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    Re: I need your guys' 2 cents on durability/ longevity issues on HT motors and.....

    It looks grtttttt......
     
  7. millard52english

    millard52english New Member

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    Re: I need your guys' 2 cents on durability/ longevity issues on HT motors and.....

    would like to have an adventurous ride on it.......
     
  8. millard52english

    millard52english New Member

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    Re: I need your guys' 2 cents on durability/ longevity issues on HT motors and.....

    I love adventure n this bike is grttt for it.......
     
  9. bairdco

    bairdco a guy who makes cool bikes

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    Re: I need your guys' 2 cents on durability/ longevity issues on HT motors and.....

    if you tighten your headbolts down right the first time, you should never have to touch them again (unless you want to take the head off for some reason.)

    the only way they'd snap is from trying to torque them everyday, or a defect, or if you throw a rod and your engine explodes. if the latter happens, headbolts are the least of your concerns.

    as Tom pointed out, stay away from SS fasteners. not only are they brittle, but the hard threads will (not might, but will) cut into the aluminum and seize. i've seen this happen a lot, and once while i was hand threading a bolt in (working on a microwave antenna, not an engine.) the bolt stopped, and wouldn't back out. had to break it off and just skip that hole.
     
  10. rohmell

    rohmell Active Member

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    Re: I need your guys' 2 cents on durability/ longevity issues on HT motors and.....

    I would upgrade the crankshaft bearings to the type with a seal or shield on one side. 6202-RS or 6202-Z. The open end would face into the engine to get lubrication and cooling from the fuel-oil mix, and the other end would face towards the outside to give a helping hand to the external rubber seal to help seal the engine from air leaks.
     
  11. Bikeguy Joe

    Bikeguy Joe Godfather of Motorized Bicycles

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  12. rohmell

    rohmell Active Member

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    Re: I need your guys' 2 cents on durability/ longevity issues on HT motors and.....

    Here's a list of replacement plugs- do it today!

    NGK B5HS or B7HS
    Champion L86C
    Autolite 4093 or 425
    Gap it at .025"-.028

    Bikeguy Joe, how come you skipped over NGK B6HS?
     
  13. Bikeguy Joe

    Bikeguy Joe Godfather of Motorized Bicycles

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    Re: I need your guys' 2 cents on durability/ longevity issues on HT motors and.....

    I think I was trying to say B5 THROUGH 7hs. I'll have to edit that, thanks!
     
  14. huckersteve

    huckersteve New Member

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    Re: I need your guys' 2 cents on durability/ longevity issues on HT motors and.....

    Shoot! Red locktite is fine in many applications. if you need to remove a bolt that has been red "locktited", just use a propane torch to warm things up (unless its painted of course). melts right out 60% of the time, every time.

    My bike has 2000+ miles on the build and I have only broken a chain a time or two, never been stranded once, and I bring it when I ride, if I do say so myself ;) Of course, I over tighten my stuff all the time lol. Probably just jinxed myself with this little comment too!
     
    #14 huckersteve, Aug 7, 2010
    Last edited: Aug 7, 2010
  15. beentryin

    beentryin New Member

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    Re: I need your guys' 2 cents on durability/ longevity issues on HT motors and.....

    i think longevity of these motors is not over reving ive put over a 1000 miles and only clutch has started to go
     
  16. Allen_Wrench

    Allen_Wrench Resident Mad Scientist

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    Re: I need your guys' 2 cents on durability/ longevity issues on HT motors and.....

    You shouldn't have to actually WORK on the bike every day. BUT: if you allow to for a pre-ride checklist, you can avoid mishaps that will cause more work. This is just my own personal example:
    1. Lights, head, brake & tail. Working?
    2. Drive chain tension & allignment.
    3. Tire pressure.
    4. Fender brackets, look and feel (if you have fenders).
    5. Any black oily gas leaking out of tailpipe or carburettor?
    6. Choke nut tightness? (There's a good reason for this one too.)
    7. Was petcock shut off after last ride?
    8. Got enough gas in tank to get where you're going and back??? (!!!)
    9. Brief but thorough general visual inspection - bike overall.
    Sometimes I even add things to the list if I think I need to. Keep in mind: I'm pretty anal. I'm pretty sure not everybody here goes quite this far, but some do - I'm sure. This sort of thing keeps me out of trouble. And I don't have to work too much on the bike. Works for me. That, and I agree with getting a better aftermarket plug, and don't overwork or overrev the engine. Just give it the work it was meant to handle in the way it was meant to handle it and it should last as long as any other. Just my 2 cents.
     
  17. Al.Fisherman

    Al.Fisherman New Member

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    Re: I need your guys' 2 cents on durability/ longevity issues on HT motors and.....

    I'm not going to read through all the replies, so this is my $0.02

    ..making them last!

    So just as I thought I was out of the woods in regards to working every technical issue on getting my second build to run, I got her going and the one of the studs used to mount the back of the motor to the seat post tube on the bike cracked in the block. After working diligently for an entire day to get her to this point and having that happen, somebody give me a "bro hug" and tell me things will be okay.

    When mounting a engine ..mount it to the frame and not the frame to the engine. This is the most common mistake and causes both front and rear mounts/studs to break.

    Replacing the studs was always on the back of my mind but, just never got around to it. Boy do I regret that.

    SO......I'm planning on just getting a new base, cyclinder, and piston rings. I'm gonna port and polish it myself because well, it sucks riding a motor without the preparation of porting.

    MY QUESTION IS: Even if I am to replace the studs, with stainless steel ones, lock tight the crap out of them,and order all new gaskets WHAT OTHER THINGS CAN I DO FOR MY MOTOR to ensure that I'm not working on my ride EVERYDAY and ensure that it lives a LONG happy life? Are there any other concerns that I should address as well? (ie. things to consider about the crankshaft and flywheel etc.) BTW, I also have the SBP expansion chamber and am planning on picking up their shift kit.

    Use Grade 8.8 studs (close to US grade 5) NOT stainless. Anything over a grade 8.8 is overkill because the cast aluminum can't take the torque that the 8.8 stud can. 8mm studs torque to between 150 and 204 INCH pounds, the 6mm studs torque to between 50 and 65 INCH pounds. I use 150 and 50. Have NEVER had a broken stud/mount or pulled thread. I use red lock tite on all cylinder/mount and both intake/exhaust studs. Double nut ALL studs. I use a standard nut followed by a nylon locking nut on everything besides the head nuts. 50 inch pounds may not be enough to keep the engine from twisting on the tubes so I make a small anti torque bracket.

    I really want this rebuild to go flawless so all your collective expertise is very much appreciated. At the same time, I hope your answers will help other readers and lurkers build the most efficiant bike possible so that they don't encounter the pitfalls I have.

    http://s982.photobucket.com/albums/ae309/Ron-Becker/Engine Mounting/
     
    #17 Al.Fisherman, Aug 9, 2010
    Last edited: Aug 9, 2010
  18. xen

    xen New Member

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    Re: I need your guys' 2 cents on durability/ longevity issues on HT motors and.....

    If your kit was the one that comes with a bicycle chain, not the bigger (#415) moped chain, buy a new one! I have done three builds so far that have come with very low quality bicycle chains. After about fifty miles you start finding multiple stiff links in the chain, even when its been lubed. I bought a decent quality BMX chain and the bike runs faster and noticeably smoother. Thats my 2 cents.
     
  19. xen

    xen New Member

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    Re: I need your guys' 2 cents on durability/ longevity issues on HT motors and.....

    Just another thought, but I dont think locktite would do much good on the studs for the cylinder because of the temperature of the engine.
     
  20. BarelyAWake

    BarelyAWake New Member

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    Re: I need your guys' 2 cents on durability/ longevity issues on HT motors and.....

    I jus' thought I'd share a lil experiment I've been doing & my take on "durability/longevity issues"...

    Roughly following the advice found here: http://motorbicycling.com/f30/guide-bicycle-motor-preparation-care-354.html with only a few minor deviations (personal preference) as well as the modifications found here: http://motorbicycling.com/f13/bicycle-engine-basic-porting-16646.html (it's actually the same engine used for that tut) I built the 66cc Chinese two stroke for the Rollfast found here: http://motorbicycling.com/f38/rustoration-build-off-13144.html and after the first week or so of initial dialing in...

    I then proceeded to "neglect" it, deliberately ignoring my urge to tinker & constraining myself to just any failures that may come up...

    There's been absolutely no engine related issues at all in the roughly four and a half thousand miles I've put on it so far. I have not "upgraded" the head bolts, I've had no clutch pad problems, nor have I changed out the bearings, I've not even swapped out all of the fasteners with better ones. I did however use some of SBP's grade 5 fastener kit in the more critical applications such as mounts.

    ...and no, I'm no "Sunday driver" heh .wee.

    It's all about the initial care while building, excepting the occasional "dud" engine (which should be covered by warranty if purchased frm a reputable vendor) I can't help but think the vast majority of "reliability" issues complained of are in fact owner oversight, misuse and inexperience, compounded by (in my opinion) one small misrepresentation made by advertisers...

    These are not "motorized bicycle engine kits" they're "motorized bicycle engine kits" as in the engine itself is a kit, only loosely assembled as to not loose the parts in transit and any all accessories (like throttle, tank, sprocket & chain) included as the very minimum - to be upgraded as necessary, thus their ridiculously low cost. That tiny distinction makes for a world of difference in expectations.

    Not to sound harsh as I really don't mean it that way - but the fact of the matter is that due to that low cost these two stroke kits are by far the most popular kit sold - period. As a result they're somewhat misrepresented in that for many, they're the very first engine they've ever had - let alone the complexities involved in modifying something that was never meant to be motorized in the first place. Consequently you'll see what appears to be a disproportionate amount of failures associated with such kits when in fact the vast majority of such can be directly attributed to installation errors.

    IF installed correctly, following the basic advice as outlined in http://motorbicycling.com/f30/guide-bicycle-motor-preparation-care-354.html I've found the cheap Chinese two stroke to be a wonderfully simple & reliable little motor. If you don't wish the initial prep work and really do just want to "bolt it to the bike and go" then you'll hafta spend a bit more money for a more "finished" engine built to higher standards... it's a simple matter of spending your money or your time lol





    BTW - that engine of mine is no "fluke", I've another with well over six thousand miles on it & have helped locally with a number of others. None have had any engine related issues that can't be attributed to simple owner inexperience with engines in general ;)
     
    #20 BarelyAWake, Aug 29, 2010
    Last edited: Aug 29, 2010

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