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engine death story

Discussion in 'Hangout Lounge' started by ToddMackenzie, Apr 15, 2007.

  1. ToddMackenzie

    ToddMackenzie Member

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    My friend's bike, a 2 cylinder honda cm450 (I own the xj) recently underwent engine failure and so we have been working on it intermittently for some time. The initial symptoms were that the engine seized up on one very cold day. It later did crank over but would not start.
    When we started to tear apart his engine to see if there was any damage, we encountered several issues. We first found that the head gasket was blown, and so, thinking that had found the problem, we let the engine sit for a while as we had my bike which also needed work. We also noticed that there was scoring on one part of a cylinder, but we dismissed the issue as we had a cylinder hone and it didn't look too bad.
    When we recent revisited the problem, we discovered that the scoring was worse than we had thought, but that was ok because the cylinders on the spare engine were fine and we simply de-glazed them a small amount and they were in great shape. We also found out that the scoring was caused by the wrist pin coming loose and scraping the cylinder wall. The wrist pin is usually held in place by a small cir clip, but a very small piece of the piston which was part of the lip that help the clip in place, was broken off. This was also ok as we had spare pistons from the other engine which was suitable.
    My friend was then all ready to get his engine back together with a new piston and cylinders when he discovered that the connecting rod also had about 2mm of play. The bearing between the connecting rod and crankshaft had been completely pancaked and was being squished out between the connecting rod and crank shaft at a 90 degree angle. My friend took some pictures of this and I'll post them once he gives them to me, it is quite a gruesome picture.
    My friend is a student and very very poor (so am I) so we went to see if we could salvage a set of crank bearings from his replacement engine and we found that it suffered from the exact same problem. Luckily, one set was still in great shape, but the crankshaft under the wrecked bearing seems to have some damage as well.
    We haven't got the rod off the damaged bearings of the engine on the bike yet, but we are currently crossing our fingers and hoping that the crankshaft is reusable. We are also hoping to make a 1400km journey back home for the summer in less than two weeks.
     
  2. cruzerjd

    cruzerjd Member

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    Sounds serious. My friend had a 1980 CM400 (looks a lot like my Seca) that suffered catastrophic failure at 26000 miles. The bike looked good and ran well up to the point, but severe highway mileage at high rpm's that the previous owner subjected it to had killed the motor. The pistons were fractured around the skirts but no major engine damage had occured yet. He ended up being put off the project and later sold the bike as a parts bike on ebay. With a new 450 topend and gasket kit in the box ready to install. Hope you can get it all together, cruzerjd
     
  3. Captainkirk

    Captainkirk Member

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    Interesting story. I bet the pictures are even better! My son owns a CM400-I'll pass this on to him.
     
  4. PainterD

    PainterD Active Member

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    I wonder if you should drill out the rod journals a little bigger so it gets better lubrication? Maybe the oil was left in a bit too long and was dirty. causing poor lube to the rod bearings.
    The wrist pin coming out is rare but I've heard of it happening with other engines. It was probably not put in correctly from the factory (built on a friday kinda thing) Just a thought.
     
  5. horowm

    horowm New Member

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    I beg to differ.

    With few exceptions, the Japanese engines are desgined well and are very solid. It takes a great deal of abuse to lead to the levels of destruction that we have read above.

    Further, the Honda Hawk engine was around in many different bikes, for many years, including service as an automatic transmission model.

    I'l bet that somewhere in this one's history, it was abused and/or not kept up. More likely, both.

    My XJ is in showroom shape, but it's still 25 years old. Regular maintenance is critical. And all those rubber and plastic parts seem to have a finite lifespan.

    Just my .02

    Marc the Librarian
     
  6. PainterD

    PainterD Active Member

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    Oh ya, abuse. I forgot about that. You must really have to beat the crap out of these bikes to wreck the engine.
     
  7. ToddMackenzie

    ToddMackenzie Member

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    I know for a fact that my friend drives the bike hard, that's what he likes doing. He also got the bike for 200 Canadian dollars in running condition and has put 10000km on the bike since he got it.
     
  8. PainterD

    PainterD Active Member

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    Riding a bike hard and abuse are different. I ride my bikes hard on occasion and maintain them myself.
    The term "abuse" can be interperated in different ways I guess.
    Riding a bike "hard" can also be interperated in varying degrees, so I'll just leave it at that. I ride for the conditions and if the conditions interperate that I can ride it hard...I DO!! Parts just wear out faster on some bikes I guess.
     
  9. Robert

    Robert Active Member

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    Good issue to point out D, the perception of abuse and riding hard often gives the impression of each being interchangable, and they aren't.
    I'll chip in my 2 cents that I've been regularly pleased with what these Japanese engines can take in terms of thrashing. All of my bikes have been reliable save the expected consumable parts (drive chains and sprockets, light bulbs, etc.).
     
  10. ToddMackenzie

    ToddMackenzie Member

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  11. Robert

    Robert Active Member

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    AAhgh! I'll bet the death rattle that thing was wheezing out was bone chilling! Shoot it and put it out of it's misery.
     
  12. lowlife

    lowlife Member

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    Off topic here a bit , but do any of you guys have links to parts for those little honda twins ? Friend of mine is rebuilding one and can't source pistons . Can't remember if it's a 400 or 450 . Any piston links ?
     
  13. Maan

    Maan Member

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    If the other Crank has some play but is usable i don't see a reason why cant that be installed, There are a number of engines here with lots & lots of crank noises but they run just fine.
     
  14. MiCarl

    MiCarl Active Member

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    Any play you can feel is a lot of clearance. No way the oil would stay in there at the RPMs these bikes run. I wouldn't want to have my engine sieze at 70 mph.
     
  15. MacMcMacmac

    MacMcMacmac Member

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    Crankshaft bearing clearances on a Japanese motorcycle engine should be a couple of thou, max. If you get your hands on any service manual, you will see that there are many different colour-coded bearing sets to keep the clearances within very tight tolerances. You need to get a micrometer or caliper and measure the journals very carefully, checking for ovality (non-roundness) as well as max diameter. Then you go to the dealer and find out which colour-coded set you will need. Excessive oil clearance will hammer out the bearings and crank in short order, as well as starve the rest of the engine of oil pressure. This is an extremely common engine, I doubt it's worth the trouble to overhaul for what you could get a used one for. It was available in the Hawk, The CM400E CM400T CM450E CM450T Nighthawk 450, 450 Rebel and CB450S, and probably a few more.
     
  16. ToddMackenzie

    ToddMackenzie Member

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    My friend was able to replace the piston and rod assembly using parts from the other engine and tells me that there is no bearing play and everything should be good to go. We will hopefully get everything put back together this weekend and get it running again.
     
  17. PghXJ

    PghXJ Member

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    that's some busted up bearings...and crank for that matter.

    So did you run the salvage parts motor yet??
     

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