Rear mount studs broke, any good fix???

Discussion in 'Frame Mounted Engines' started by danlandberg, May 15, 2010.

  1. danlandberg

    danlandberg Member

    This is the third time the rear mount studs have sheared off at the block (case halves). :ack2: The second engine I used 8.8 grade bolts, worked for 25-30 miles. Then failed again! I removed all studs from both engines, and replaced the studs on the engine I;m running with stock studs, broke again in 10 miles. I'm thinking of shuffle pins, or 8x1.25 studs. One other thought is to add a cold role aluminum plate under the mount spacer (between spacer & case) And adding two more mount bolts into block (case). :thinking: Will have to file the mount spacer (flat end) to accept the plate so I can keep the distance between the engine and seat tube the same. Any one have a sure fire fix for this problem?? :confused: ('' NEED INPUT'').........Dan :banghead:
     

  2. add muffler strap to hold muffler and engine to bike frame, this keeps the engine from moving and helps to take the stress off the mounts.
     
  3. Al.Fisherman

    Al.Fisherman Active Member

    Dan, there are only a few reasons I can think of that the studs for the engine mount will break, other then a accident.
    1. Engine not installed on frame correctly.
    2. Torque not correct.
    3. Engine twisting on the frame.

    I have a solution for all three...

    1. Was your engine mounted correctly, the mounts (both front and rear)) were flush with the frame? No binding what so ever. Perfect angle is 75 degrees, between tubes.
    2. What torque were they torqued to? I use 50 inch pounds
    3. Does you engine twist on the frame, to the left?

    I don't think that 8mm would be a good idea, due to the thickness of the mount base.
     
  4. danlandberg

    danlandberg Member

    I agree that 8x1.25 is a little large in diameter. The left case half (drive sprocket side) does not have much material to work with. The engine is mounted as close as you can get to a "happy medium". These MICARGI bikes are junk! :poop: Much less put an engine on them. Now you have double trouble! :ack2: The front mount is an adapter mount for large down tubes. I had to go with the billet intake & slant head To get the engine to fit. Don't know how much the engine twists. I do have a SBP x chamber, that does give me more torque & hp! I don't know if the mount angles differ between engines. RAW, GRUBEE, and Flying Horse. All I know is I have spent more on asprin than parts!!!:banghead: I'm going to do a second set of mount screws. I will see if it works:whistling:
     
  5. Al.Fisherman

    Al.Fisherman Active Member

    Dan, stay with the 6mm studs, going any larger even to 1/4" might be asking for trouble you can't fix. Since the stud broke and not the case you are lucky. I've said it before and I'll say it again, mount the engine to the frame, and not the frame to the engine. Start with mounting the rear mount to where you need it to be mounted. Then work on the front mount (I don't feel that the adapter mounts that are mass produced are one size fits all, although they are good for most applications)..the clamp is a standard muffler clamp, followed by the engine brace (4 picture in second link) I designed. Use double nuts, nylon locking nuts or both. NO washers between the nuts. I'm sure that these steps are why I haven't broken a mount. haven't broken a stud, and haven't had to tighten the mounts since installed. With the mount standoff (pictures in first link) you can attain the proper torque on the mounts. I lock tite all studs. I use red but most use blue. If red is used and stud needs to be removed heat will be needed. Having the equipment is no issue for me. And you already upgraded Grade and stay with grade 5 (metric 8.8).

    http://www.motoredbikes.com/showthread.php?t=27147

    http://www.motoredbikes.com/album.php?albumid=1018
    Keep in mind the measurements here are for Chinese HT's
     

    Attached Files:

    Last edited: May 16, 2010
  6. Don't forget the muffler strap.
     
  7. Al.Fisherman

    Al.Fisherman Active Member

    Correct and I'd recommend that the muffler be secured to the engine and not the frame, this way if there is movement with the engine on the frame there won't be additional stress on the exhaust studs. Both will move as 1 unit together.
     
  8. danlandberg

    danlandberg Member

    There is no place to mount the exhaust to the engine! :ack2: (SBP x chamber) :tt1: I am trying to mod the rear mount for added strength. :idea: :thinking: I'll post some pics tomorrow or the next day when I get done! :whistling: Hope it works! :sweatdrop:
     
  9. danlandberg

    danlandberg Member

    rear mount repair

    Hope this works! I drilled and tapped 2 more holes in the case halves to accept 2, 6 X 1.0 hardened button head Allen screws, inboard the stock mount studs, (just above center line), to hold a piece of cold role aluminum between the mount spacer and engine. :thinking: This might work. :rolleyes7: If not, :thinking: I'm going to use 2, 5mm x 20mm role pins inboard the mount studs. (one above and one below center line of stock mount studs). If both methods fail, that will be strike 3 & your OUT! I'll find a frame that works, and cut this one up to make usable tools, (Forks for truing wheels, tail section for rear wheel truing, V section for engine add ons). I'll make stands out of every thing I can! That's all these MICARGI bikes are good for! SCRAP :poop: :ack2: If anyone has bought a MICARGI DIY kit from B.B. I AM sorry I did not do it first :detective: So I could warn you that they are :poop:
     

    Attached Files:

  10. danlandberg

    danlandberg Member

    I also did an air filter mod for better air flow + another O-ring! Having troubles with pics, AGAIN!
     
  11. AussieSteve

    AussieSteve Active Member

    Overall, Dan, I agree with Ron. Under normal conditions, there shouldn't be a problem with breaking rear mount studs. It must be an alignment issue with those frames
    Sorry to hear that you've had such dramas. My bike almost put itself together and nothing has ever come loose or broken. (509km on the clock so far.) I'm not really supposed to ride any more, but manage to sneak out every week or two.
    I ordered an expansion chamber this morning and a battery for my charging system and super-headlight. (4 x 12V 18W filaments, though normally I'll use 18W for low beam and 36W for high beam, with the full 72W for 'spotlight'.) The cagers will see me coming!
     
  12. engine mount bolts were torqued too much and the muffler was probably not strapped or not correctly
     
  13. danlandberg

    danlandberg Member

    Correctly what? (mufler wise)? Who are you, to TRY to talk tech with people with more experience under their belt, than you are old! If you live in the USA, You will know that you are tooooo young to ride one of these things! OH, and by the way, please post a torque table for all points that need exact torque! So us old guys can get a refreshment course! Kids these day's :ack2:
     
  14. i ride motorcross
    i know a bit about torqueing nuts and engine mounting
    i just turned 16 today and have my permit
     
  15. danlandberg

    danlandberg Member

    I used to ride MC also,+ Road (cafe) So I know a bit about engine propelled cycles/vehicles!!! My MOM raced off road. (Barstow to Vegas). My DAD raced Oval dirt track, When I was 3,4,5, & 6 years old. Sorry if I came off to hot! But I'm having a bad month, (ever since I got this thing running). I apologize! With all my resources (tools) 300 miles away, I'm frustrated!!!
     
  16. its cool i remember something else i run cut peices of popped tube on the clamp
    it allows the engine to move more but stay sturdy almost like a car hope that helps
     
  17. danlandberg

    danlandberg Member

  18. i might tomarrow i have to get a new camera card
     
  19. Al.Fisherman

    Al.Fisherman Active Member

    Dan, I have a engine mounted in a vice that I'm experimenting with...designing ways to better install the rear bracket, fabricating a bracket to repair front broken mounts (not the studs). I have it mounted by the rear mount only. I have a problem with the stock clamps and the lack of room to use a socket/torque wrench to properly torque these studs (aftermarket grade 5). What I noticed was that with the proper torque on the rear. I can pull up or push down on the front of the engine and the rear studs will be in a bind and can see how they can eventually break. With a proper front mount there is no stress on the rear studs and seems virtually impossible to break the studs under normal riding conditions. My son even took his bike to our moto cross track here and ran it like he stole it, jumping hill after hill...afterward I inspected everything and nothing needed any adjustment.
     
  20. AussieSteve

    AussieSteve Active Member

    Dan, have you seen the rear mount for the SBP shift kits? It's similar to what you're making, but longer vertically. It uses 2 allen key bolts and a spacer to mount to the engine, then 2 u-clamps to attach to the frame.
    You could then vary the spacer thickness to get a nice snug fit in the 'v' of the frame and you'd be less likely to strip or break studs.
    I think you can see it in the pics in the album on my profile page.
    (Or buy a shift-kit and it's already done for you.)

    Ron, I think you've hit it on the head. The front mount needs to be solid and also should be properly spaced so there's no gap that the bolts have to pull up. That'll put extra stress on the rear studs.
     
    Last edited: May 21, 2010
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