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Project The Neglected Honda project...

Discussion in 'Your 250cc Projects' started by Joker, Jan 9, 2016.

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  1. Joker

    Joker See "about me" for contact details. Contributing Member

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    Got one on the way. Don't think I'll need to replace anything else given the KMS so I'll take a gamble and lap in a new valve. Longest wait is the parts. Aint gonna touch any of the others, the old adage if it aint broke dont fix it probably applies!
     
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    Joker, Jan 24, 2016
    #61
  2. mishdog20

    mishdog20 Active Member

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    Wouldnt hurt to whip the other valves out to inspect em / de-carbon them though bud.
     
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    mishdog20, Jan 24, 2016
    #62
  3. Phil

    Phil Senior Member Contributing Member

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    Completely agree with your thought process, if it ain't broke...don't fix it !!!
    Having said that once your new gadget arrives it probably wouldn't be a bad idea to de-coke the other valves and have peace of mind.
     
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    Phil, Jan 24, 2016
    #63
  4. kiffsta

    kiffsta Senior Member

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    I have one of those kits, works a treat
     
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    kiffsta, Jan 24, 2016
    #64
  5. Joker

    Joker See "about me" for contact details. Contributing Member

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    Hmm not having much luck taking the carbon off with threebond. Any tips? It will take some of the surface stuff off pretty well but the hard cakey stuff I left it to soak for a bit and not really coming off.
     
    Joker, Jan 25, 2016
    #65
  6. GreyImport

    GreyImport Administrator Staff Member The Chief Contributing Member

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    Leave it on for awhile and give it a help along with a tooth brush .... I just reapply the run off in the container with the brush when Ive done carbs and pistons

    Gloves help as it gets in your skin and stinks
     
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    GreyImport, Jan 25, 2016
    #66
  7. mishdog20

    mishdog20 Active Member

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    You blokes have more patience than me..lol, i just hack into em with the wirewheel
     
    mishdog20, Jan 25, 2016
    #67
  8. Joker

    Joker See "about me" for contact details. Contributing Member

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    Quick update, got the replacement valve direct from Honda in 48 hrs ($29.95) but still awaiting the valve spring compressor kit. Looks like it will be next weekend now as I didn't get it by today.

    Pretty keen to rip into it though, get this thing going. :crazypilot:
     
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    Joker, Jan 29, 2016
    #68
  9. mishdog20

    mishdog20 Active Member

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    Your a more patient man than me Joker...lol. Id be modifyiing somethin to get that valve out. Ive used a G-Clamp and a socket with a slot cut out of it before...Worked well, hahaha.
     
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    mishdog20, Jan 29, 2016
    #69
  10. Phil

    Phil Senior Member Contributing Member

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    Patience is a virtue....so it is said!! Trouble is when you've got the "PART" you just want to get going :thumb_ups:
     
    Phil, Jan 29, 2016
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  11. Joker

    Joker See "about me" for contact details. Contributing Member

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    Yeh I have stopped myself from using a few backyard tricks I know about to get the valve out. Would rather do it legit as this is a good condition bike that I'm hoping to flog for moderate coin in order to invest in FZR upgrades lol
     
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    Joker, Jan 29, 2016
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  12. Marcus

    Marcus Member Premium Member

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    Mate had pretty much the same issues with a spada i was trying to do up. Found that there was old fuel in the system so would not ignite no matter what i did, had to push start it over and over to get the fuel to pass through but eventually it started up and ran fine. The smell from the fuel was sickly sweet and stayed for weeks if i spilled some. Hope this helps
     
    Marcus, Jan 29, 2016
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  13. Joker

    Joker See "about me" for contact details. Contributing Member

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    Progress again!!

    This $20 fleabay spring compressor was worth the investment. Easy as pie.

    IMG_3374.jpg

    Yep, valve is just a little bit rooted...

    IMG_3375.jpg

    Seat looks OK which is good news.

    IMG_3376.jpg

    One of my favourite tools, kept this after the kids moved off bottles... use it heaps haha. Bit of threebond down the hole...

    IMG_3377.jpg

    Now the lapping. When I bought the tool & paste it comes with two grades (bought from REPCO). A knowledgeable mate informed me not to use the coarse paste (pretty much ever) but to work with the fine paste. So on that alone I took his advice, I haven't really done it before but it seems simple enough. I suppose working with the finer paste probably makes sense as it lowers the risk of over doing it or something... The tool I got from supacrap auto at some stage, the rubber is already perishing but it was just enough to get the job done.

    Put the suction cup on the valve, wind it back and forth and now and then pull it up and spin it so you're not always working in the same place.

    IMG_3378.jpg

    Here is the end result on the valve and seat:

    IMG_3379.jpg IMG_3381.jpg

    Just a question for the more experienced parties, the silver "tapered" section of the valve should I lap it so it is completely "grey"? It's about 95% grey at the moment, it starts off in the middle section (you can tell because the grey section contrasts with the shiny new bits) and as you keep going eventually the grey "band" gets wider until all the shiny section is pretty much gone. My logic says it should all be grey because that's the mating surface of the valve to the seat so you want it to have a good firm connection, but thought I'd check for other opinions just in case I'm wrong :)

    Haven't started the rebuild just yet, will start to piece it together maybe during the week and work it into the weekend.
     
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    Joker, Feb 1, 2016
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  14. Linkin

    Linkin The Mechanic Premium Member Contributing Member Dirty Wheel Club

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    Service manual should contain the correct angles and measurements for cutting the valves and the seats.

    If it's a new valve and the seat is OK, just lap the valve face and the seat with the fine paste, wipe it all away, and you're good to go. Did it on the fizzer with all the original valves and seats.
     
    Linkin, Feb 1, 2016
    #74
  15. Joker

    Joker See "about me" for contact details. Contributing Member

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    Yeh that's what I've done. It's how much lapping that is the question. The angled part of the valve is the mating face, my question is should the entire angled part be lapped or should it just be a tiny thin band in the centre of the angled part. The service manual talks about 2mm service limit with the face of the valve mating face somewhere between 1.0-1.2mm. That says to me the width of the band should be that, but that also seems quite small, very small in fact. I'm not sure how to accurately measure it, but I suppose I can always reinstall the valve and leak test it to see how it has gone.

    The manual is translated but pretty poor english to the explanations aren't great.
     
    Joker, Feb 1, 2016
    #75
  16. Linkin

    Linkin The Mechanic Premium Member Contributing Member Dirty Wheel Club

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    It's a small engine. Funnily enough, a smaller valve seating area is actually good. As the valves and seats wear down the mating surface area increases. Recutting the valves and seats sets surface area back to standard. Or at least, that's what I was taught at TAFE.
     
    Linkin, Feb 1, 2016
    #76
  17. Murdo

    Murdo The Good Doctor Staff Member Contributing Member Ride and Events Crew

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    What you've done is about right. The whole of the seat face does not need to be in contact as Linkin said, they wear in. The seat width is quoted at 1.2mm? Leave it at that as going further you are effectively 'wearing' the seat. Exhaust seats are set at a width so they will transfer heat to the head, but without holding too much heat and burning the valve.
    If it holds fuel then it is done. Wash the grinding past out with petrol/kero, then wash it and the whole head with detergent to get ALL the grit out.
     
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    Murdo, Feb 2, 2016
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  18. Joker

    Joker See "about me" for contact details. Contributing Member

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    Bit more fiddling today, leak test - the valve weeps ever so slightly with petrol. Hmm. Tested the other ones - all the same. I lapped the valve slightly more to get rid of a little bit of pitting I spotted in the seat but pretty much the same afterwards when it came to the leak test.

    I've left it like that because I wonder if it's worth gambling with. The low viscosity of petrol may bias the test a bit... do these things need to be 100% leak proof? I'm kinda hesitant to lap it even more and considering it's done such low kms I wonder if it will wear in a bit on its own. Compression should be much better now, if in spec maybe not worry about it?
     
    Joker, Feb 2, 2016
    #78
  19. Linkin

    Linkin The Mechanic Premium Member Contributing Member Dirty Wheel Club

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    Do a compression test and find out... I wouldn't worry about it.

    The fizzer engine had every single valve leaking petrol when testing, before lapping the valves. It was running on a blown head and leaky valves, with out of spec valve clearances... it could be hard to start but it still ran and had decent power after doing the cam chain.
     
    Linkin, Feb 2, 2016
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  20. Joker

    Joker See "about me" for contact details. Contributing Member

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    Yeh I was leaning towards that. compression should be 5 times better now (I hope). Will throw the head back on when I have time and see how we go.
     
    Joker, Feb 2, 2016
    #80
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