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Thread: Center cylinder lost all compression - your guess?

  1. #51
    Senior Member ProStock Mac's Avatar
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    New Jersey
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    1 out of 1 members found this post helpful.

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    Ya cant just get half a case. They are machined as a set.
    Most of my drinking buddies got riding problems.
    Snowmobiling..... the most fun you can have with your clothes on.

  2. #52


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    Then Im in big trouble, because I have done it a couple times.
    -------------------------
    1997 Yamaha XTC
    700 Redhead, Mr. Viper ported, CPR pipes, 20CC Domes, boost bottle, SRX reeds, Heelclickers, Dual bulb, LT Ohlins

    1997 700 SX
    Thinned head gasket, Gutted Airbox, Reed Spacers, Bender Pipes, Viper Shocks, 51/43 helix 89L weights

    2004 Viper S
    SLP pipes, peak performance head,

    2001 SRX 700
    Power Inc. Pipes

    1997 Mountain Max 700
    Black XTC Hood, Thinned Head Gasket, Gutted Air Box, Reed Stopper Notch, SLP Pipes

  3. #53


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    The groove is partially gone on both the upper and lower case so going that route I'll probably get a set anyway.

    So you think risk of blowing it all to pieces is considerably higher using it?
    Atleast the groove on the crankshaft bearing is intact, perhaps some kind of bearing fixation paste to lock the stopper ring in position where the groove is intact could help it a bit...

    I know the safe route would be a new case, problem is money vs chance of 2nd rebuild success and parts like that are not easy to come by cheap here in Sweden.
    I'm used to order parts from US already but with import and shipping charges price will atleast double from ebay prices.

    Example from ebay just now:
    Subtotal (1 item) US $149.99
    Shipping US $95.28
    Import charges US $58.37
    Order total US $303.64

  4. #54


    Default

    Wow, thats a lot.
    Maybe a question for Mr. Viper.
    -------------------------
    1997 Yamaha XTC
    700 Redhead, Mr. Viper ported, CPR pipes, 20CC Domes, boost bottle, SRX reeds, Heelclickers, Dual bulb, LT Ohlins

    1997 700 SX
    Thinned head gasket, Gutted Airbox, Reed Spacers, Bender Pipes, Viper Shocks, 51/43 helix 89L weights

    2004 Viper S
    SLP pipes, peak performance head,

    2001 SRX 700
    Power Inc. Pipes

    1997 Mountain Max 700
    Black XTC Hood, Thinned Head Gasket, Gutted Air Box, Reed Stopper Notch, SLP Pipes

  5. #55
    Senior Member ProStock Mac's Avatar
    Join Date
    May 2003
    Location
    New Jersey
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    674


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    Quote Originally Posted by MURDER YAMAHA View Post
    Then Im in big trouble, because I have done it a couple times.

    Bad advice is still bad advice.
    Most of my drinking buddies got riding problems.
    Snowmobiling..... the most fun you can have with your clothes on.

  6. #56


    Default

    Quote Originally Posted by Mac View Post
    Bad advice is still bad advice.
    Easy there big fella, not telling anyone to do it, just telling what I have done.
    but appreciate the criticism...
    -------------------------
    1997 Yamaha XTC
    700 Redhead, Mr. Viper ported, CPR pipes, 20CC Domes, boost bottle, SRX reeds, Heelclickers, Dual bulb, LT Ohlins

    1997 700 SX
    Thinned head gasket, Gutted Airbox, Reed Spacers, Bender Pipes, Viper Shocks, 51/43 helix 89L weights

    2004 Viper S
    SLP pipes, peak performance head,

    2001 SRX 700
    Power Inc. Pipes

    1997 Mountain Max 700
    Black XTC Hood, Thinned Head Gasket, Gutted Air Box, Reed Stopper Notch, SLP Pipes

  7. #57


    Default

    I've been lucky and found an entire engine with a crank bearing failure for a reasonable price.

    I will check it out in the upcoming days. Atleast I'll have some spare parts then since it's an all or nothing deal.

    About reusing base and head gaskets, have you done it and do you use spray like Loctite 3020 or similar? My new base and head gaskets from 1st rebuild still feels new and only got a couple miles on them. Ive got new for crank seal, intake, water pump and power valves. Exhaust gaskets from Winderosa did not survive the teardown so thinking of re using original gaskets there as well.

    I've ordered a leak down tester for monitoring ring wear but perhaps it can be used before first start to check if there are gasket leaks also.
    Last edited by Sidekrans; 08-07-2019 at 09:50 AM. Reason: Phone texting messes with new line wrapping

  8. #58
    Senior Member Stock SRXChris's Avatar
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    Feb 2017
    Location
    Marmora, Ontario Canada
    Posts
    138


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    To bad your in Sweden I have a case with a bad crank I have laying around, centre rod bearing was shot.

  9. #59


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    I picked up the other engine this weekend and as far as I can tell it looks good.
    All three cylinders were in good shape and pistons looked used ofcourse but no failed ones.
    All other parts were also in decent shape so I've got lots of spare part now.

    When I compared the two cases I started to see that the old case had more damage to it. Strange that I didn't notice it before.
    It's clear that the crank has been moving and scraped wear marks on the case in one direction.

    20190812_075938.jpg20190812_075933.jpg20190812_075929.jpg20190812_075818.jpg20190812_075923.jpg20190812_075914.jpg20190812_075919.jpg20190812_075832.jpg

    I'm speculating here but the wear is on the opposite side from the ring groove which could indicate its a direct result of the engine running with the ring alignment out of place.
    I guess this could very well be reason for the burndown since all that friction must have created a lot of heat, and debris.
    Do you guys think that the reason for these marks are the broken ring groove that made the crank become unstable or do you think the reason for both the marks and the broken ring groove is a bad crank?

  10. #60


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    Update: Today I took the crank to a professional mechanic. He will true it and check overall condition. Sent in both cranks so he can replace outer bearings if in better condition.
    Also got the ProX pistons and Threebond 1184 so it's getting close to rebuild time.

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