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crankshaft , engine rebuild help!

Discussion in 'Modifications and Projects' started by wild_buddha_boy, Jul 19, 2006.

  1. gday guys,

    I have a few problems at the moment on my 03 honda cbr 600rr. Firstly, i recently had a blown up engine and apperantly the top end have been damaged.
    I also, have pulled out the engine and taken out the crankshaft and it appears to have a broken bearing. I went to a crankshaft specialist and said that he would be able to fix it by regrinding parts of the crankshaft, and all i had to do was the find a 30000-40000 1 mm over bearing. I have tried a few places like honda dealers and bearing shops, and they dont appear to have them.
    I live in sydney, and i need help on finding a 1mm over bearing. In addition, what else should i do with the engine rebuild??

  2. well welcome to the forums mate

    now do you mean by the 30000-400000 quote bearing shells or ball bearings ?????

    if you meant bearing shells your crank grinder should have had a big book listing all the sizes of shells it is not uncommon to find bearing shells from some cars can be made to fit bike applications by grinding the crank and resizing the rods and maching new grooves in the rods to take the different shells

    alternatively there is the option of spray welding the affected journal to build up the surface and then regrinding the journal back to stock size

    In the case of it being a ball bearing on a main jounal of the crank you may need to gind it down further and see if a speedy sleeve can be fitted of course this means can only be on the outside of the crank

    More details please ?????????????? which jounal main or big end what number cylinder effected
    and do you mean ball bearing or shells
  3. more info

    I spoke to my mate and a few mechanics and both have different opinions on what i have to do.

    Firstly, my mate who is a car mechanic, said that the big end conrod bearing has spun and needs to be replaced, but has damaged the crank contact surface. And the size of the bearing is 30-40 thou but i need to have a 1mm oversize due to required machining.

    In addition, i went to a few motorcyclist mechanic, and some have mixed opinions on having a oversized bearing shells which can be done. While the others have said to replace a crankshaft which can be found at wrecking yards. Then replacing the bearings with new ones.

    The crankshaft specialist also said that regrinding and obtaining a new bearing shell with a 1mm oversize would cost under $250. While if i cant obtain a bearing shell, resurfacing the crank would cost over $600.

    WHAT TO DO???
  4. another way, could buy a 2nd hand engine... and most wrekcers are asking for 3,500 dollars. Is there anyone that would have a used engine or know of a place that would?
  5. does anyone know of a mechanic who would be able to assemble an engine together, or do i have go to a honda specialist?
  6. Theres not many mechanics that will want to assemble a mtr that someone else has stripped down, there is far to many variables ( unknown's ) to consider with the rebuild.
    Rings / head machining - yes any alloy head/block should at least skimed to make sure the surfaces are flat !
    dodgy threads / missing parts etc etc

    The reason being who ever does the job for you has to warrant the job OR
    Like I used to do ( I wont touch an engine I haven't stripped down anymore )
    Charge at least 3 times what it should to cover any problems encountered in the rebuild, AND get the owner to sign a form stating that there is NO warranty on the labour or parts.

    The reason I dont rebuild other ppls repairs that have got to difficult for them and have to pass em on the the 'professonals' is that in 2 out of 3 as the rebuild is progressing, I find the problem THAT caused the breakdown in the 1st place and then end up argueing with the customer, over more parts that are required to repair it properly or even end up putting it all back in a box and returning to the customer :roll:
  7. Go have a talk to a shop that specialises in engine rebuilds, racing etc,

    Never had a problem getting an engine rebuilt that i've stripped down specially if there needed to be alot of machining done.
  8. Yeah they will and can, they are fully set up for this stuff and you pay though the nose for them to do it too, but the question asked was any "mechanics" that will do the job !

  9. Like youu'd trust your average bike shop to do a job like that , especially one that need maching of parts.

    I wouldn't be going to my local corner store :LOL: :LOL: :LOL:
  10. thanks guys for your replies. i have been through a few motorcyclist in sydney, australia and most have said they had to send it to a honda dealer to put the engine together. I was wondering, is it better to buy a used engine or to fix the problem itself.

    Inaddition, i have looked through ebay, and the engine cost around $600USD and postage would be aprox. $400USD.? Is it wise to import an engine from the US?

  11. you mightn't be able to register the US motor?

    i went through the same thing myself. was not fun. eventually found a spare motor locally.
  12. Grinding the crank for oversized bearings is not such a good idea, mainly due to it will be even harder to repair next rebuild if you plan on keeping the bike.

    Any grinding to that extent will affect crank balance marginaly and is bad on that front due to high RPM of bikes. Counter weights on the crank can get the balance back but you will need a very reputable shop to do it right.

    Spray welding could work but I would be hesitant in a high performance situation. It is preferable not to get involved with dis-similar metals here. Poor workmanship can see stress's added to the crank from HAZ (heat affected zones) resulting in part failure.

    Wreckers are probably your best option, finding a good one can take time.

    If an import motor has a lot of interchangeable parts then that could be an option, use the crank and not the case and have a lot of spare parts left over. Chances are that there will be some differences.

    Absolute last resort is put it back together with a quality piece of shoe leather and sell it as fast as you can.

    Good luck.