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Thread: ATC 250R coolant leak leads to enlightenment - Hand Lapping and Time Serts

  1. #1
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    ATC 250R coolant leak leads to enlightenment - Hand Lapping and Time Serts

    I had been working on my 85R, getting ready for the dunes this spring. In the last leg of this rebuild I put all new gaskets on the top end, tightened everything down and filled up the radiator with coolant. I let the bike sit overnight only to find a puddle of antifreeze under the bike the next morning. I double and triple checked all of my hose fittings and was perplexed as to where this fluid was coming from. Finally, I touched one of the "nodules" on my three piece TRX gasket and I notice a little tear drop of fluid weep down the side of the cylinder. Hmmm, this isn't good. When I was done inspecting I had found that fluid was weeping 360 degrees around the cylinder.....well crap.

    What to do? Well, three options, mill the head/cylinder top deck, hand lap head/cylinder top deck or splooge the crap out of the cylinder head with RTV (btw, please don't do this one, unless you have no other option).

    I thought I would try option 2. Hand lapping is something that I have always wanted to try. Do I have access to a mill?, yes. Call me nuts, but sometimes I like the satisfaction of doing something myself. Gives me a whole new appreciation for a hard job and afterward, I treat those parts with more respect after all the hard damn work I put into them...LOL

    And here we go....I hope the following steps help out others when considering to hand lap a cylinder head.

    First items I purchased were a custom cut 10x12" piece of glass, 150/320/600 sandpaper and some elmers spray glue. Note, when doing this make sure you are on as flat as surface as possble. I made my benches so I knew they were relatively flat and my level agreed with me. The glass makes for a VERY flat surface on an already trued work bench. If you are lucky enough to have access to granite, I highly suggest using that instead of glass. But don't fear! Glass works!
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    Step 1: Create a stationary jig out of 4 scrap pieces of 2x4, screwed down to a bench and lay the glass in the center
    Step 2: Spray the glass down with Elmers glue and let it dry for 2-5 minutes (this allows for the sandpaper to come up easier when changing out grits)
    Step 3: Start with 150 grit paper and lay it down on your tacky glue laden glass
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    Step 4: Get some blue dykem out...what the hell is that?? Don't have any? I didn't either, so I used a sharpie and coated the cylinder head. This helps in finding low spots.
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    Step 5: Generously coat the sandpaper with WD-40
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    Step 6: Now comes the fun part. Starting with a PROPER grit, (I used 150 because I had some serious warp and low spots) start sanding your part in a different patterns. I prefer the figure 8 pattern. The key is NEVER TO SAND IN THE SAME DIRECTION.....EVER. Circles are fine, straight sanding I don't recommend. Figure 8 is the most safe IMO. I set a timer to 10 minutes at a time. And i still went through 4 cycles with the 150 grit. This is what it looked like after 4 cycles of 150.
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    Step 7: It was at this point I felt safe moving onto the 320 and ultimately the 600. I ended up doing 4 cycles of 320 at 10 minutes a cycle and then 4 more cycles of 600 at 10 minutes a cycle. This is what it looked like after I was finished. Was it 100%? No, but it was damn close and definitely six sigma worthy!
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    So after that was finished I decided that I was going to do my cylinder top deck. Well, as one might imagine those pesky cylinder studs leave something to be desired. I began removing the studs and to my surprise they were all coming out! That is until the last one. You guessed it, snap. We will keep this PG-13 and pretend I said crap. In reality, my wife heard me yelling profanities through our garages into the house. I went ahead and removed the cylinder head and decided to worry about the stud replacement at a later time. I still had some hand lapping to do!

    The steps for the cylinder are the same for the head. Get your jig, glass, glue, paper and marker all ready. I started with 150 grit on the cylinder top deck as it was also way out of whack.
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    This is after 4 cycles with the 150. My fine tip sharpie is highlighting the low spots still left after an hour.
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    This is after another 4 cycles with the 150. At this point I am thinking holy crap, this cylinder was warped beyond repair.
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    Finally I could see the light and began working with the 320. this is after 5 cycles with the 320.
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    After that I moved to the 600 and here was the finished product. Was it 100%? No, but damn close with a straight edge.
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    At this point I was finished with the hand lapping and ready to move onto fixing the cylinder stud. You have two options here, helicoil and timesert. Everyone has their preference and after a bunch of research and experience with helicoil, I decided to go with a time-sert. I ordered the M8x1.25 kit from the thread doctor on Ebay. Note that this kit comes with 11.5 MM inserts and you also need to order longer inserts. I opted for the 18mm as the lower shank of the head stud measures 17mm. Here is a picture of the kit below. You get a bit, counter sink, tap and insert installer. You also need to get the oil for the insert installer and 266 loctite.
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    A few words of warning when using a time sert or helicoil. If you don't have access to a drill press, please for the love of all things holy have an extra guy or two around to "assist" you if you must use a hand drill. They can watch if you get off center and give you a good smack in the back of the head. If you are using a drill press ensure that your press plate is absolutely dead nuts level. I took an extra 45 minutes to ensure level on mine.

    Step 1: After leveling the press spend an extra amount of time to measure once, twice...hell ten times if necessary to make sure the bit will be drilling at the correct depth. The "well" of each stud pocket in the cooling jacket differs...great huh. So I took a conservative approach and drilled my to 21MM. Use plenty of oil.
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    Step 2: Hopefully step 1 went well for you because its the hardest. Step 2 is nothing more than chucking up your counter sink bit and counter sinking the hole you just drilled because the insert has a lip that will ride on this "shelf" you create.
    Step 3: Tap the hole. Again, have a buddy watch you do this so he can slap you when you are not tapping at 90 degrees to the cylinder top deck. Take your time and use plenty of oil.
    Step 4: Oil up the insert driver and screw the insert onto the driver. Add locktite 266 to the insert, don't need to go overboard here. 266 is some strong stuff. Thread the insert into the hole and eventually you will feel it tighten up. Keep screwing and you will feel it get loose again and that's when you know the insert has seated properly. If all goes well, you should end up with something like this.
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    And that's about it. I have put the engine back together and "knock on wood" it is holding all the antifreeze and the stud torqued down to proper specs. I hope this thread helps someone else out in the future.
    Last edited by yaegerb; 04-26-2015 at 10:22 AM.
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  2. #2
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    Quote Originally Posted by yaegerb View Post
    Tap the hole. Again, have a buddy watch you do this so he can slap you when you are not tapping at 90 degrees to the cylinder top deck.
    Nice write up. I'm glad all your hard work paid off.

    When I need to tap a hole, that I just drilled on the drill press, I keep the drilled piece clamped down to the table, remove the drill bit, install my tap into the chuck, tighten it down, then I start threading the tap into the drilled piece by turning the chuck by hand. Once it is threaded in an acceptable distance, I loosen the chuck and raise it up out of the way, leaving the tap partially threaded into the drilled piece, install my tap wrench, then finish the tapping by hand. Doing it this way, I'm assured the tap is started at the same angle that the hole was drilled to.
    Red Rider's Sand Machine Updated 07/23/14

  3. #3
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    Quote Originally Posted by Red Rider View Post
    Nice write up. I'm glad all your hard work paid off.

    When I need to tap a hole, that I just drilled on the drill press, I keep the drilled piece clamped down to the table, remove the drill bit, install my tap into the chuck, tighten it down, then I start threading the tap into the drilled piece by turning the chuck by hand. Once it is threaded in an acceptable distance, I loosen the chuck and raise it up out of the way, leaving the tap partially threaded into the drilled piece, install my tap wrench, then finish the tapping by hand. Doing it this way, I'm assured the tap is started at the same angle that the hole was drilled to.
    Another great tip!
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  4. #4
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    Great job, good read- yaegerb

    I do the same thing, but start at 240/320/600 wet & dry sandpaper with a granite plate, WD40, Dychem. (I found 50 cans at a dollar store in 2001 and still have a ton)

    I just duct tape the edges tight with Gorilla Duct Tape, never thought about spray glue.

    This is a proper way to resurface a head/cylinder.

    I surface using a figure-8 motion, the turn 90 degrees, over and over.

    Eric Gorr showed he how to do this many, years ago. He came out with a VCR tape about it and other engine tricks in like 1990.

    It works wonders, never had a head gasket leak, except that pesky 1985 Suzuki Quad Racer, but those gaskets are crap!

    This works on cleaning up washers, nuts, bar clamps, spacers & shims too.

    *Note- This is NOT how you mill a head, so don't get any ideas!
    Last edited by onformula1; 04-26-2015 at 05:42 AM.
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  5. #5
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    Quote Originally Posted by Red Rider View Post
    Nice write up. I'm glad all your hard work paid off.

    When I need to tap a hole, that I just drilled on the drill press, I keep the drilled piece clamped down to the table, remove the drill bit, install my tap into the chuck, tighten it down, then I start threading the tap into the drilled piece by turning the chuck by hand. Once it is threaded in an acceptable distance, I loosen the chuck and raise it up out of the way, leaving the tap partially threaded into the drilled piece, install my tap wrench, then finish the tapping by hand. Doing it this way, I'm assured the tap is started at the same angle that the hole was drilled to.
    Nice, I do the same thing.

    So many people, so far away, doing the same tricks...To cool!

    Lets write a book- 10,001 tricks to save your Money & frustration.
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  6. #6
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    That was a great write-up Yaeger! Some good advice on the time-sert install as well. I have done the same thing many times on small engine heads, and 2-bolt carb flanges. I read how to do it in a small engine repair book from the public library when I was a kid. I did this once to the carbs off a Honda 305 scrambler that were so bad the slides would stick when the carb nuts were tightened!

    BTW- I love the suggestion on the time-sert install of having a friend around to smack you if you drill crooked. I have to do that with my students, only I can't smack them.
    1985 Tri-Z 250
    1985 ATC250R

  7. #7
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    Great write up. Iv done this several times with cylinders,heads side cases ect. When I remove the head studs I tap each stud a couple times with a and they come right out.
    250r rules

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    great How-to thread.

    I REALLY REALLY think 3WW would benefit from it`s own "how-to" Subforum. This is just another example of a clear and concise skill thread I`ve been seeing on here for years now and I think this stuff needs preserved before it disappears ten pages back in Trikesyvania.

    I never have as good of luck using the search function as one would think.

    I hope someone will start stickying threads like this in a new subforum for tutorials

  9. #9
    Billy Golightly's Avatar
    Billy Golightly is offline Always finding new and exciting ways to not give a hoot in hell Catch me if you can
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    That is kind of what the "World Class Help" section started off as ,but over the years its been hard to keep up with good threads and get them in there. Plus, once its in there, no one ever looks at it or replies to them again...


    yaeger I like your spray glue method alot! Here is what I did on my rotax center-case -



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  10. #10
    poolieZerUK is offline At The Back Of The Pack Arm chair racerFirst time rider
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    Didn't this affect the squish value?
    Suppose it depends on how much material you had to remove to flatten it.

  11. #11
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    Quote Originally Posted by poolieZerUK View Post
    Didn't this affect the squish value?
    Suppose it depends on how much material you had to remove to flatten it.
    I am sure it effected squish and UCCR. I will be doing a compression check on it later this week and I will report back how much it changed, but I highly doubt it will change so much that I would need to increase my octane to race fuel. Plus I am using the really thick 3 piece TRX gasket, so that will take up some room as well.
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