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  1. #1

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    Brison 4.2 chipped cylinder head

    Hello,

    I bought a Brison 4.2 a few months ago and I was wondering if anybody has a spare cylinder head for it that they can sell. The engine looks clean and not worn out at all, but I am worried that it might overheat with those chipped fins at the rear.

    Thanks,
    Tony

  2. #2
    Moderator w8ye's Avatar
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    RE: Brison 4.2 chipped cylinder head

    In most situations, the broken fins cause no problems from heat.

    The Dolmar 120Si and 6800i cylinders are no longer available but you may find a used one on the E Bay? I found one a couple months ago.

    You can get new pistons of the Meteor brand on the big auction site. The rings are available as the Caber brand on the same site.
    Attended the CutFinger Institute of DirtNap University for years but never did graduate....
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  3. #3

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    RE: Brison 4.2 chipped cylinder head

    someone has a cylinder head on rcu for sale , its a sachs i think , check it out

  4. #4

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    RE: Brison 4.2 chipped cylinder head

    Thanks for the reply guys. The one at RCU sales thread is for a 3.2 or a 6.4

    5 of the 7 fins at the rear are chipped.

  5. #5
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    RE: Brison 4.2 chipped cylinder head

    If you still have the chipped off pieces you can glue them back on with JB Weld. I have a Brison 3.2 that had a good size piece about the size of a quarter that broke off the top fin in a shipping purchase and it fit "jigsaw puzzle" perfectly to the broken cylinder fin so I glued it back on with the JB Weld ( just couldn't stand to see that broken fin on my pretty new engine). It's been holding strong now for well over 5 or 6 years with dozens and dozens of flights. If you do a clean/precise glue job and wipe off the excess with a lightly moistened alcohol dampened cloth/paper towel you almost can't tell the fin was ever broken.. You have to get it aligned and wedge a piece of appropriately sized balsa or similar between the fins to keep the fin spacing even while curing. In your case you'd probably want to do one or two at a time and that's if you still have the broken pieces..

  6. #6

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    RE: Brison 4.2 chipped cylinder head

    Thanks for the tip Bass1. I'll keep that in mind if it happens again on my other engines. I don't have the chipped fins anymore for this 4.2.

    Here are some pic of the engine. I am afraid that a replacement cyl head would be the same cost as the value of the engine with the ignition at the moment. Trade anyone?
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  7. #7

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    RE: Brison 4.2 chipped cylinder head

    I am in need of a muffler for a orange case conversion engine. the bolt pattern is app. 44mm and I was thinking it was a 5.8 but I have a A&M 5.8 and tht pattern is only 40mm.. Turns a Zoar 24-10 at about 6000. has been converted to electronic ign. but is bad about kicking back on start.Should the timing be at about 32 degrees? Could this be a 6.4 as mentioned in a post from above? Thanks Jack

  8. #8
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    RE: Brison 4.2 chipped cylinder head

    Timing should be at 28 degrees before top dead center.

    Measure the bore by putting a pencil or Popsicle stick through the exhaust port and lightly closing the piston on the stick. Then measure mark left on the stick. One of us can tell you which engine by the bore in mm?

    I know the 3.7 and 4.2 had the same muffler dimensions with a 38mm bolt spacing. 
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  9. #9
    Moderator w8ye's Avatar
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    RE: Brison 4.2 chipped cylinder head

    Some combinations on the Sachs Dolmars. As you can see it is hard to pin down an old one at times.

    3.7 has a 46mm bore and a 36mm stroke
    3.7 has a 47mm bore and a 35mm stroke
    3.7 has a 44mm bore and a 40mm stroke
    4.1 has a 49mm bore and a 36mm stroke
    4.2 has a 47mm bore and a 40mm stroke
    5.2 has a 52mm bore and a 40mm stroke
    5.5 has a 52mm bore and a 42mm stroke
    5.8 has a 55mm bore and a 40mm stroke
    6.1 has a 55mm bore and a 42mm stroke
    7.2 has a 56mm bore and a 48mm stroke
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    RE: Brison 4.2 chipped cylinder head

    The cylinder measures 55.18mm to the best of my doings and the timing is set on 33 degrees. I know I have run out of buddies to help flip start it. Jack

  11. #11
    Moderator w8ye's Avatar
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    RE: Brison 4.2 chipped cylinder head

    There are Huskies or Husqvarna 5.8 and 6.0's floating around too and they have wider exhaust than the Sachs - Dolmars

    Their orange color is close to the Sachs color but a shade or two lighter.

    Their muffler bolts are 56.25mm apart and have a 56mm bore
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    RE: Brison 4.2 chipped cylinder head

    The 5.8 will have staggered exhaust bolts ...... not in line with the port.

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    RE: Brison 4.2 chipped cylinder head

    With the information that you have given me I am going with the thought that this is a 6.1 motor. It had a electronic ign. that appeared to have been homemade and the timing was fixed at about 32 degrees. The spark was very weak and not reliable so I changed it out to a new C&H. I left the timing set at the same setting, but do I need to change this to TDC? Jack

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    RE: Brison 4.2 chipped cylinder head


    ORIGINAL: fjs

    With the information that you have given me I am going with the thought that this is a 6.1 motor. It had a electronic ign. that appeared to have been homemade and the timing was fixed at about 32 degrees. The spark was very weak and not reliable so I changed it out to a new C&H. I left the timing set at the same setting, but do I need to change this to TDC? Jack
    Looks like you still have throttle coulped timing control.If your C&H Ign has a built in timing board you will need to lock the timing plate at 28 degrees BTDC and remove the linkage. If no electronic timing module.Set timing at 28 degrees BTDC at full throttle and about 4 to 6 degrees BTDC at Idle or low throttle.
    The more fins you break off the better it will run.
    BCCHI

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    RE: Brison 4.2 chipped cylinder head

    Is it possible these were broken off intentionally?
    Tony Hallo

  16. #16

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    Quote Originally Posted by Tony Hallo View Post
    Is it possible these were broken off intentionally?
    It is possible, but I see no good reason to cut the fins. We usually have problems cooling engines in cowled planes already.


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