4G T drive bearing conversion

Discussion in '4 Stroke Bicycle Engines & Kits' started by cobrafreak, Mar 3, 2012.

  1. The_Aleman

    The_Aleman New Member

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    It's been posted several times that the "5/8" shaft is really 15.8MM, or ~0.622".
     
  2. Keeponkeepnon

    Keeponkeepnon New Member

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    Thanks for clarifying. Is the whole motor made with standard specs rather than metric then? I assume it is if the crankshaft is, but it goes against my logic so I have to ask.

    Good call on using spacers. If anything it should decrease resistance to have less bearings in there.
     
    #102 Keeponkeepnon, Mar 17, 2013
    Last edited: Mar 18, 2013
  3. Senetor

    Senetor New Member

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    Why not use a 6702-2RS Bearing 15x21x4 Sealed Ball Bearing
    You just need to touch up the shaft to get it to fit, and get the inside of the clutch drum turned out leaving a shoulder for the bearing to fit against and an interference fit in the drum for the outside diameter of the bearing.
    You could go to the next sized bearing if there is enough material that can be removed which is a 6802-2RS Sealed Bearing 15x24x5, it would make it more reliable with a larger bearing.

    Senetor.
     
  4. recumbentbill

    recumbentbill New Member

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  5. cobrafreak

    cobrafreak New Member

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    Better to have the stack of bearings in it. It will last much longer the more bearings that are in it. These bearing are SO CHEAP, there is not a reason to put less of them in.

    I've got so many thousands of miles of mine so far I've lost count. It's really a do-this-once-and-forget-about-it-set-up. My bearing conversion still to this day runs as good as the day I first developed it.

    At this point I expect the bearing conversion to outlast the actual engine. Which is what we all want.

    -Cobrafreak
     
  6. darkcobra94

    darkcobra94 New Member

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    Hello, after a bit of reading and learning, I decided to try this conversion.
    I contacted Cobrafreak about the bearings that I will be using.

    These are the bearings, and only priced at a $1.00 a piece + around $3.50 for shipping!

    http://www.avidrc.com/product/1/bearings/334/13x20x4-Rubber-MR2013-2RS-bearings.html

    I just ordered them so I am preparing to do this.

    My clutch is off and the engine shaft is bare. I thought my transmission was dead, but this conversion may save me :D

    The person who built the bike before me had it rigged using washers instead of the bushing. XD

    Since my engine idles, do you think I can use 100 grit sandpaper to grind down the shaft to 13mm then use 160 grit to make it even finer?


    I will update you guys whenever I try this :D
     
    #106 darkcobra94, Jun 30, 2013
    Last edited by a moderator: Jun 30, 2013
  7. radaracer285

    radaracer285 New Member

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    :-||I am new to the site. I am installing my new 7g ghost racer kit from gasbike.net
    The clutch seems to be the weakest link in this Honda GXH50 knock off (Yes sarcasm).

    Would these sealed bearings work and keep me from milling the shaft on the HS 142f motor?
    High Performance and RoHs Compliant Miniature Bearing MR2015ZZ 15X20X4

    http://www.alibaba.com/product-detail/High-Performance-and-RoHs-Compliant-Miniature_1475291754.html

    I just contacted the supplier for the price on 12 bearings (2 jobs) min order is 10

    The video is correct that it is not a one way bearing and there is drag when you pedal the bike. I have a 2 stroke engine and it is a maintenance nightmare and breaks down often. I carry needle nose pliers to remove the clip and chain to pedal home. I am looking into a quick release thing for the rear sprocket. I firmly believe the 2 stroke clutches are also weak and if you do not remove the chain to pedal long distances it accelerates clutch wear (2 strokes and maybe even the 4 strokes).

    Finally has anyone looked into the racing kart clutches? Seems you could use the bell housing of the 7g for the belt sprocket and the centrifugal clutch part from the racing kart.

    Lastly...The 7G engine shaft appears to have 2 different shafts called straight and the other is called tapered. It seems they use these terms almost universally and makes ordering transmission/clutch parts difficult.
    :-||My kit cost $283.xx with shipping....Why do I need an aftermarket tranny that costs more than the engine and complete kit itself?
     
  8. radaracer285

    radaracer285 New Member

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    The 15mm bearings do exist....Here is the answer I got from China:

    Many thanks for your inquiry, please see our qutation as below:

    Size: MR2015ZZ
    Description: chrome steel bearing 15X20X4mm, metal shielded both sides
    Price: USD0.45(FOB/PC)
    MOQ: 5000 Pieces
    ( So sorry to tell you that because it is non-standard size, the minium order quantity of it should be 5000 pieces.).
    Standard Min. order was 100 bearings!
     
  9. radaracer285

    radaracer285 New Member

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    The .99 cent Abec 1 bearings may work for awhile. But all these mini bearings are for the little rc toys. I am going to use the Abec 3 rated ceramic bearings ($6.97 for one) from http://www.rcbearings.com/products/6702-2rsc-15-x-21-x-4-ceramic-bearing.html
    I am going to cut into the bell housing and use the 3 bearing method. Makes no sense to cut the output shaft and the 15x20x4 mm bearing are available from the slow boat to (from) China. By the way, if its got a woodruff key then its a straight shaft and not tapered. The 7g ghost racer is a straight shaft. The Oilite bushings need to be re-soaked in regular oil after 4 hours of use. I have a spare Oilite coming but nothing seemed to match the OEM part from my measurements.
    I put the 7G kit in a Kent Del Rio because of the huge amount of space the Del Rio frame has. Chain alignment is a bear since you have to remove the mounting plate to adjust the engine mounts. Toss those screws out and get good hex bolts with large washers (plus the lock-washers) to mount the engine (underneath the mounting plate and the side bolts to the mounting plate. Its ironic that very few places are selling the 7G kit and spare parts; and not all the 4G stuff is interchangeable with the 7G kit. Why are they pushing these other kits when they have been discontinued? Loctite is nice for internal engine stuff, but the FAA, CCS, and WERA use safety wire. In 13 years of motorcycle road racing I never had anything vibrate loose after I used safety wire and/or Shoe Goo'd/silicone sealant something. Make sure the chains master-link is facing (open end part) in the opposite direction of forward travel! I would assume most of the chain failure is the result of frame (or other surface)/chain contact that pops the master-link off! And most racers add thin safety wire to that clip. The washer trick on the inside of the frame can widen the frame enough if you are experiencing chain/frame contact. The Wright Brothers were in fact bicycle makers, but don't tell the police that or they will make people using these bicycle kits get a pilot's license.
     
  10. scrollerguy

    scrollerguy Member

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    Well, after all the trepidation, not wanting to mess anything up, I did it. I took it slow, and wala, it is finished.

    Great way to get rid of that lousy bushing.

    I would reccomend this to anyone, just take it slow and steady. You will love the results.

    Kudos goes out to Cbrafreak!!!

    Thanks.
     
  11. MotoMagz

    MotoMagz Active Member

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    Yep if you think about it you will shy away...great job going for it. Slow and steady.
     
  12. KCvale

    KCvale Active Member

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    I tried all these things back when this topic was started.
    The bottom line is trying to mount the bell on the same spinning shaft as the clutch is and always will be a poor design so I quit using it.

    All I use are engines with a short shaft with the clutch attached, and a transfer case that isolates the bell on it's own bearing shaft to drive the reduction system.
     
  13. scrollerguy

    scrollerguy Member

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    Some people don't have the money to do your expensive alternative.

    Being on a fixed income and having to save month after month for the large purchases, it is quite refreshing to find a fix that is inexpensive and quite affordable.

    My littlebike has over 1500 trouble free miles on it. I am glad I did the conversion.

    I also did all of the safety mods, my fenders will not fall off, and my bike has all the bells and whistles, from 3 sets of brakes to the 12ga spokes, and a horn loud enough to be heard. Granted, most of this stuff was nickel and dime, but that was the only way that Social Security would allow, so till next month when my check comes in, I'm set.
     
  14. MotoMagz

    MotoMagz Active Member

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    Yep conversion is a great mod...and after you've completed it it's a good feeling. Any time you can do mods like your safety mods it's a great feeling and way better than bolting on something.
     
  15. KCvale

    KCvale Active Member

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    Expensive is a relative term, compared to say a Q-matic for example a 4G is ~$100 less and a better design.

    It is also relative to how you value quality.
    Everyone wants quality, but to make something right costs more.

    That's where outfits like gasbike come in.
    They cut every corner on the quality of the parts to sell more.

    Of course money is ALWAYS an issue for most, even more so here where it is factor #1 for many.

    My point is, there are all kinds of things in the MB world out there with no quality at all and fail so in short no good at all, a waste of money.

    If your bike is a hobby no problem, something to fix.
    But if you have to rely on it for everything you just don't want to use 'cut corners' parts.

    Any 'savings' in initial price evaporate in a hurry when you not only need to repair/replace something, but how much it screwed you when you really needed it.

    Being retired I have no idea where you fall in there scrollerguy, but I do know how important RELIABILITY it is to many and there are options out out there for everything that will do the job.
     
  16. scrollerguy

    scrollerguy Member

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    Cobrafreak are you still on this forum? I have PM'D you and no response.

    Thanks in advnce.

    Scrollerguy
     
  17. Dave31

    Dave31 Moderator
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    He's profile says he has not logged in since June of 2014 :(
     
  18. malatious

    malatious Member

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    I just did the upgrade. Was a little concerned that I might wreck my shaft, but once I got close I went very slow and measured with my calipers to make sure it was even. I used a 4" grinder with a cut off wheel on it, using the flat side of the disk. When I was close used a fine file and Emery cloth to finish up. I have not installed my engine yet but just on the bench you can tell how much better this will be, spins nice and smooth with no effort.
     

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  19. KCvale

    KCvale Active Member

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    Yep, I tried this 'fix' for the clutch bell on a long shaft engine a few years back.

    [​IMG]

    To me it was just a colossal waste of time and money for failed design to start with and since only use HS 142F-1G clutch attached engines and isolated clutch bells in the transfer case like the 4G.

    This is of no help to Honda engine owners, they all come that way, but maybe for a new engine buyer.
     

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