Author CBF Winter Project: Bike with engine woes  (Read 5190 times)

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  • Offline keithriley   gb

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    Offline keithriley

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    CBF Winter Project: Bike with engine woes
    on: 01 April, 2023, 09:52:57 pm
    01 April, 2023, 09:52:57 pm
    Please bear with me this is a long one, itís been a bit of a journey so I thought Iíd share my experiences. Even if one snippet of this becomes useful to anyone else in the same predicament then itís all been worthwhile.
    So, to start. I bought a high mileage 2006 CBF1000 A6 as a non runner just into Winter 2022 as something to keep me busy in those dark wet non biking days. I joined the site and was looking forward to reading lots of similar stories of woe as well as tips, hints and advice.
    I was told a hose had blown off, all the coolant was lost whilst riding, a repair was facilitated but any consequential damage was unknown. Anyway the bike ran again, and was even re-motíd, for a short while then one day just refused to start, the owner throwing the towel in and just selling it on. In steps me.
    Bought and transported home, I could indeed confirm the bloody thing would not start. A compression test then showed cyl #1 was good at 170psi, #2 not brilliant at 80psi, #3 at 20psi, yes 20, and #4 another not brilliant at 60psi. Time to remove the head, well it was after removing what felt like every other part of the bike first. The head gasket had definitely failed, breaking through cyl #3 on both sides into #2 and #4, but rotating the engine then revealed cyl #3 bore was FUBAR, lovely heavy scrapes all up the front edge. ĎFlippin eckí I said, I went on to say the same many times during the project. Time to weigh up options. New complete engine? Repair to the existing? Cry?
    Now Iíve never had an engine apart before but how hard can it be, look at all the pretty pictures in the Haynes book of lies, itís a doddle. I will admit I am an engineer and in the course of work stripped and rebuilt many axles and transmissions, including prototypes so I feel I could find my way around an engine no bother.

    Determined to keep the cost down, and the bike as a whole didnít warrant lavishing too much on it, I aimed to do a repair as cheaply as possible, thatís not to say cutting corners that shouldnít be or doing anything that I wouldnít be happy with if I was keeping the bike. I do actually intend to keep the bike, for how long I donít know but four in the garage can get in the way.
    Engine out and fully stripped, apart from the bore walls the only other damage was to the piston and rings, luckily a breaker nearby had a CBF he was mid-way through splitting and had a piston with rings and conrod. Refitting that piston and rings to the bikes original conrod I thought would be the better option for longevity. Maybe around then I fell lucky, a seller on ebay had bare SC58 engine cases for sale so I snapped them up, and took my cyl head to be skimmed to ensure a nice clean flat surface. Around the same time I found a forum member that was also breaking a bike following an accident. He had a complete engine and the asking price meant Iíd be silly to pass up on it. It will sit in the garage under cover, a nice bit of insurance should my rebuild fail abysmally.

    With everything in bits a massive cleaning program to all other internals revealed nothing else of concern. The bike with 60k+ miles was in remarkable condition internally, crankshaft bearing journals and transmission components looking non the worse for all those miles. Of course, various seals were scrapped in the process of stripping the engine so these were replaced, generally just from their size / part number. Only one was unique, the transmission output shaft seal has a large metal backing plate, of the sort Iíve never seen before, so I bought a pukka one of those. I think it was over Xmas 2022 I started the rebuild of the engine, in the dining room as it was so cold in the garage (I do hope my landlord isnít reading this), crankshaft dropped in and torqued down, then flipped over and the corresponding piston with conrod pushed home and attached to the big ends, all was going well. Having to do this on my own I took the approach of putting the engine back in the frame at this point, it was light enough to manage and could be finalised in-situ. Transmission in, clutch rebuilt and in, timing chain installed loosely. Then the fun began.

    I couldnít wait to get the head back on and do a compression check once again, on with a new head gasket and then the cylinder head bolts, an odd M9 thread, lubricated as per the workshop manual. Following the tightening procedure I worked my way to the target 42Nm but had that stomach churning feeling some of the bolts werenít actually getting any tighter. Sure enough one gave way in the mid to high 20ís of torque (flipping eck! once again). Removing the bolt brought with it a nice spiral of aluminium wrapped around the threads. Pressing on to see what else developed a further three bolts gave way not longer after, confirming a serious rethink had to be undertaken. Thread inserts were the most obvious solution but required drilling the block first to take the helicoil insert. Another option was to open out the M9 stripped threads to a more common M10 without needing to drill, and if those threads failed in the same manner, then M9 thread inserts were still a possibility. I made sure the M10 thread was all the way to the bottom of the existing hole in the engine case, giving me the option to use 115mm long bolts. I had to go for cap heads as the hex heads would be too large and sat them on hardened thick washers. Two issues arose here, I had to trim the diameter of the washers to sit in the counterbore on the cylinder head, which was no big deal, but then also found the shank of the new bolts fouled in the through holes in the cylinder head. I gingerly opened the holes up to 10.50mm where all bolts cleared and engaged in the threads easily. To say my heart was in my mouth as I torqued them up would be a massive understatement, but they all went to 40Nm without issue, and I didnít want to push my luck any further. Will it work, will it last, will it survive? Who knows, but I pushed on with the rebuilding of the engine once again and
    with the engine in a state where it could be started, no coolant, no exhaust, no fuel tank, I chanced my arm and went for the plunge. A few squirts of easi-start and she started up without hesitation, sounded nice whilst running smoothly, albeit loud, for around 10 seconds when I quite happily switched it off feeling elated and confident enough to carry on.

    The rebuild continued and at various stages have started her up briefly, quite often experiencing the refusal to restart after that short initial run, but she starts and Iím more than happy with that. With the fuel tank on, coolant in the system the radiator semi fitted I went for a full warm up to engine temp, and this is again where my hopes were dashed. A leak from the water pump to begin with but then Niagara Falls from the radiator when fully warmed up. I wonder if Iím now just finding whatever the root cause was that lead to the engine failure in the first place. A new radiator ordered off eBay, £100 and looks the business, but the water pump, according to the manual at least, is unserviceable. Donít say things like that to an engineer, itís like a red flag to a bull. Iíve found itís only unserviceable because the mechanical seal is in a blind hole so thereís not really any way to push it out from behind. Well if itís leaking itís about as much use a chocolate teapot anyway so that got mullered in its removal from the housing. A new mechanical seal was £10 and the oil seal that sits behind it £4, both from eBay. One cautionary tale though, because the water pump is Ďunserviceableí the manual does not delve into it at all, the bolt holding the impeller on is a left hand thread. Donít do what I did and try to unscrew it Ďnormallyí. It will come off, just not how youíre expecting it to. Thankfully I could get it drilled out on the lathe and being a l/h thread when the drill bit in, it unscrewed itself. Another eBay purchase, one M6 left hand thread bolt.
    A few weeks later that turned up so with the water pump rebuilt and refitted I finally got the chance to fill the cooling system and run the bike properly. At first I thought the fan wasn't kicking in but with nerves of steel and when the water temp hit 104 degrees in the top hose it finally ran. Throughout the day I have started the bike up, ran up to temperature and all seems well, with only one leak on the drain off pipe to the reservoir tank. Once that was sorted all was good.
    Last Edit: 01 April, 2023, 10:03:54 pm by keithriley

  • Offline oldtimer03   england

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    Offline oldtimer03

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    Re: CBF Winter Project: Bike with engine woes
    Reply #1 on: 02 April, 2023, 09:49:37 am
    02 April, 2023, 09:49:37 am
    Keith, what a brilliant story, and hopefully a permanent happy ending! Congratulations on your skill and perseverance. Your story reads like some of Allen Millyardís youtube videos!

  • Offline keithriley   gb

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    Offline keithriley

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    Re: CBF Winter Project: Bike with engine woes
    Reply #2 on: 02 April, 2023, 09:58:25 am
    02 April, 2023, 09:58:25 am
    *Originally Posted by oldtimer03 [+]
    Keith, what a brilliant story, and hopefully a permanent happy ending! Congratulations on your skill and perseverance. Your story reads like some of Allen Millyardís youtube videos!
    Ha ha ha thanks Oldtimer03, I'll take that.

  • Offline Froggymanny   fr

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    Offline Froggymanny

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    Re: CBF Winter Project: Bike with engine woes
    Reply #3 on: 02 April, 2023, 12:04:47 pm
    02 April, 2023, 12:04:47 pm
    Very pleasant reading indeed, thanks a lot Keith for taking the time to share.  One day, maybe, I will go down that courageous route of taking an entire bike apart, but for now I keep learning from accounts such as yours and its extremely interesting. Thanks again!

  • Offline keithriley   gb

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    Offline keithriley

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    Re: CBF Winter Project: Bike with engine woes
    Reply #4 on: 02 April, 2023, 12:36:57 pm
    02 April, 2023, 12:36:57 pm
    *Originally Posted by Froggymanny [+]
    Very pleasant reading indeed, thanks a lot Keith for taking the time to share.  One day, maybe, I will go down that courageous route of taking an entire bike apart, but for now I keep learning from accounts such as yours and its extremely interesting. Thanks again!

    It's been my pleasure to share, as it was also my first time in, so to speak. Thanks for taking the time out to read.

    Keith

  • Offline pedro   england

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    Offline pedro

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    Re: CBF Winter Project: Bike with engine woes
    Reply #5 on: 03 April, 2023, 02:33:07 pm
    03 April, 2023, 02:33:07 pm
    Excellent work and a good read too. As a non-engineering type, I stand back in awe.

  • Offline keithriley   gb

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    Offline keithriley

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    Re: CBF Winter Project: Bike with engine woes
    Reply #6 on: 03 April, 2023, 03:24:40 pm
    03 April, 2023, 03:24:40 pm
    *Originally Posted by pedro [+]
    Excellent work and a good read too. As a non-engineering type, I stand back in awe.
    With the online manual it wasn't that bad at all, working through it all methodically and a set of half decent tools it was all achievable. I must post some pics.

  • Offline edger   gb

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    Offline edger

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    Re: CBF Winter Project: Bike with engine woes
    Reply #7 on: 03 April, 2023, 08:34:36 pm
    03 April, 2023, 08:34:36 pm
    Bloody mindfulness ! I love it  :001:

  • Offline keithriley   gb

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    Offline keithriley

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    Re: CBF Winter Project: Bike with engine woes
    Reply #8 on: 03 April, 2023, 08:36:24 pm
    03 April, 2023, 08:36:24 pm
    *Originally Posted by edger [+]
    Bloody mindfulness ! I love it  :001:

    I wouldn't go that far lol

  • Online Rev Ken   england

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    Online Rev Ken

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    Re: CBF Winter Project: Bike with engine woes
    Reply #9 on: 03 April, 2023, 10:50:18 pm
    03 April, 2023, 10:50:18 pm
    MANY years ago I enjoyed taking engines apart, but they were simpler and I wonder if I would have your perseverance to-day. I doff my hat to you!
    Last Edit: 03 April, 2023, 10:52:40 pm by Rev Ken

     



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