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Thread: ESE's works engine tuner

  1. #34696
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    2nd April 2012 - 00:54
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    Quote Originally Posted by wobbly View Post
    A few cylinders are simply a bad design ( 4DP Yamaha TZ ) that crack no matter what , but the weld material is stronger than the cast alloy , so usually the weld is more reliable.
    Without knowledge of the cylinder material, heat treatments or weld metal material & associated weld heat inputs that may / will actually anneal the cylinder about the weld reworks, nor knowing if the welding has been performed correctly I’m not so sure your statement is correct ��*♂️
    One thing for sure is the shrinkage stresses of the solidifying weld / welds upon a heat treated cylinder rework is akin to over tightening a con rod bolt & expecting it to still perform its role adequately, it can not.
    However normalising & reheat treatments may fix these issues from welding, although then the correct weld metal filler wire would be required & I’m yet to know of a cylinder plating / repair shop to having adequate knowledge of welding to do anything other than create a soon to fail rework whilst billing the owner for the privileged of at best a rework but certainly not what I consider the meaning of the word repair is.

  2. #34697
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    3rd January 2012 - 01:25
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    Quote Originally Posted by JanBros View Post
    it 's just for having some off-road fun, not to ride it at max like a pro.
    Why not just leave it as it is?

    I have done the exact same thing in the past and ran a cylinder with such a crack in the exhaust bridge for two seasons. It has been running with the cracks like this before for some time at the previous owner and without problems anyway. On mine, I just made sure it would keep doing it by relieving the bridge in the cracked area with some sandpaper.

    After that, I put some more work into the cylinder and also had the crack repaired at the plater. I ran the cylinder for another couple of seasons without any issues afterwards. Plating and repair was done at http://www.langcourt.com in GB which is also a bit closer to where you are located. They are experienced with such kind of repairs, just tell them NOT to grind / deburr your transfer port windows after the re-plate, as they (or one of their staff) are / were usually quite generous in doing it.

  3. #34698
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    19th June 2011 - 00:29
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    Quote Originally Posted by Haufen View Post
    Why not just leave it as it is?
    don't think I would feel comfortable, always thinking that at the edges of the crack the plating would start to come of.

  4. #34699
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    20th June 2020 - 07:10
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    Quote Originally Posted by Haufen View Post
    They are experienced with such kind of repairs, just tell them NOT to grind / deburr your transfer port windows after the re-plate, as they (or one of their staff) are / were usually quite generous in doing it.
    I always engrave cylinders in an obvious place “plater no chamfer”. If I forget, they come back with a massively aggressive radius. Some guys are good, some are braindead. Also I would not be afraid of welding cracks. If done correctly they will not have issue. Bevel away as much as you need then repair. Bridges can be built up from nothing and be plated. Had better luck with 4043 filler not getting ruined by the stripping tank FYI, but if you are having the plater do all the labor you do not even have to know that. I would 100% go for the weld/repair/replate unless you know your plater is a hack. You could always go welded in aluminum sleeve too.

  5. #34700
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    Quote Originally Posted by JanBros View Post
    don't think I would feel comfortable, always thinking that at the edges of the crack the plating would start to come of.
    So was I. But I as a student, I was short of money, too So I worked the edges of the crack with sandpaper and used the cylinder for dynoing only, at first. But as that went perfectly well, promoted it to the real race engine, soon.

    If you have it repaired at langcourt, they will weld the crack and re-shape to original shape as well.

    I am not sure about the sleeve option. This seems to come with the highest cost and effort and give a compromised result (sleeved cylinder) in the end.

    Maybe just getting another used cylinder would be an option, too? Are these hard to find?

  6. #34701
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    6th October 2015 - 13:42
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    Cracked Bridges

    Quote Originally Posted by JanBros View Post
    bought a KDX200 but sadly there are 2 cracks between the exhaust ports on the left. I'm in doubt as to whether have them welded and replated or have it sleeved. if welded, will they weld it through and through and not leave parts of the crack that can grow again? and if they weld it through, I'm in doubt as to if it will not harm the flow if the weld protrudes, hardly being able to correct that.
    I know the downsides off sleaving, but it 's just for having some off-road fun, not to ride it at max like a pro.

    also first time I've seen a raised exhaust port on a standard cylinder from the early '90ies

    Janbros, as Wobbly mentioned the platers can weld these cracks. The KDX Cylinder Exhaust is very similar to the KX500 with the dual sub ports either side of the main port and notorious for cracking there in addition to the intake bridges. The repair done by most of the platers here in the states are quite remarkable and FAR better than the original casting. I’d have it repaired and replated before a ring could snag itself on that.

  7. #34702
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    19th June 2011 - 00:29
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    also had a response from Jan Luyten (from Luyten import in Belgium and the son of the Luyten 125cc engine) and they say they most of the time re-crack.
    gonna leave it aside for a while and see if a 200 or 220 cyl pops up somewhere.

  8. #34703
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    8th February 2007 - 20:42
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    The replating process is full of pitfalls , but most are well versed in what is needed.
    Yes , 4043 is the welding rod of choice , and that works very well.
    The important deal is getting the cylinder up to a temp , high enough to prevent excessive stress from weld pool shrinkage , but to not destroy the heat treat.
    NZ Cylinders here , heat , then weld , then run thru the bore and or grind away most of the added excess filler , then prior to final hone they do a micro piening process to reduce the localized stresses.

    One big issue may platers dont do properly is that as they VERY rough hone the bore ( for nicasil adhesion ) this removes much of the chamfer on the Exhaust port alloy timing edges.
    So I have to give written instruction every time , for them to rechamfer this in the alloy prior to plating - if they dont , then as soon as I remove the chrome flash lip inside the port
    then there is insufficient chrome depth within the bore to put on the required vertical chamfer.

    And as all you guys on here should know by now , you dont need ANY chamfer on transfer ports - instant power loss , and no effect at all on ring life.
    Ive got a thing thats unique and new.To prove it I'll have the last laugh on you.Cause instead of one head I got two.And you know two heads are better than one.

  9. #34704
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    23rd March 2015 - 21:24
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    I'm still toying around with my Bidalot RF50 cylinder. Thats the best we got so far with the Bidalot pipe, w/o another pipe I doubt we hit the Dutch power figures

    Click image for larger version. 

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    Recently we tested several aftermarket reed cages. Is there any theory on sizing? I suppose carb area (in this case dia = 30 mm), projected area and power are the main factors? Should the carb area vs projected stay the same, decrease or increase?

  10. #34705
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    20th January 2010 - 14:41
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    Quote Originally Posted by koenich View Post
    I'm still toying around with my Bidalot RF50 cylinder. Thats the best we got so far with the Bidalot pipe, w/o another pipe I doubt we hit the Dutch power figures

    Click image for larger version. 

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    Recently we tested several aftermarket reed cages. Is there any theory on sizing? I suppose carb area (in this case dia = 30 mm), projected area and power are the main factors? Should the carb area vs projected stay the same, decrease or increase?
    If you are going for Dutch power levels it should not have a cage but have a spinning disc instead.
    Quote Originally Posted by Katman View Post
    I reminder distinctly .




    Kinky is using a feather. Perverted is using the whole chicken

  11. #34706
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    8th February 2007 - 20:42
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    This again brings up the question I am struggling with re 35cc RC boat engine design I am working on.

    Assuming an engine dyno , giving sprocket Hp with a 5% factor for chain/gear friction etc.
    My personal benchmark is the current TM R1 - that makes 53.3 Crank Hp at 13500 = 14.17 Bar bmep with a piston speed of 24m/s ( still not even in the ballpark of Jans rocketship ).
    The 50cc graph shows 18Hp +5% = 18.9 Crank Hp at again around 13500 = 12.6 Bar at only 18m/s.
    This surely isnt even remotely exciting power/rpm/bmep numbers at all , and to me means that the real potential of the 50cc isnt even close to what could be done
    if you started to push the boundaries ( lets face it thats why we are here isnt it ? ) .

    If it was reved to the same level as the TM with the same bmep ( this being very limited by a straight line ignition and a tiny carburetor ) the 50cc should be doing 29 Crank Hp at 18500
    giving the same limited bmep of 14.17 Bar. Put it on a DynoJet and thats 25.4 Hp Rear Wheel.

    What am I missing here , especially as these engines are essentially square and all the technology in the world is readily available to do sintered cylinders etc.
    EDIT - in both the examples shown above we have a 50cc and a 125cc engine with the same carb @ 30mm , so maybe just one element of the 50cc is close to optimum - why ?
    Ive got a thing thats unique and new.To prove it I'll have the last laugh on you.Cause instead of one head I got two.And you know two heads are better than one.

  12. #34707
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    2nd March 2013 - 15:04
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    My Honda 50 has a bore of 39.5 and stroke of 41.4. The single Exhaust port opens at 84° for a total open period of 192°, and the A-transfers open first at 117°.
    I planned to have peak power at 13,000RPM, and I guessed at 500°C for the average EGT, so that's a speed of sound of 557m/s.

    With these parameters, using the pipe dimension calculations we're all now familiar with, I made a pipe with LT = 724mm. Baffle cone angle is 28°.

    The engine has a 26mm OKO carb with the power jet disabled, and HPI ignition which starts at 30° advance and retards to 14° by 11,000RPM.
    Compression Ratio is 14.0 (full stroke), running 98 pump fuel.

    The cylinder has huge Boyesen ports and a large reed block, and lots of work has gone into smoothing or removing all sharp edges and obstructions on the intake flow to the transfers.
    The exhaust duct has been extended to twice the bore and water cooled.

    On the track, after much jetting etc., peak power appears to be around 11,000 and it won't rev past about 12,300. Quite good mid-range power though.

    I tried various stinger nozzles from 15mm down to 13mm to try and elevate the EGT but with no improvement.

    Clearly I've done something wrong. Any clues please?

  13. #34708
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    20th June 2020 - 07:10
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    Diffuser too efficient for your engine? I built many sets of FOS pipes with different variations and none worked well with my single exhaust port elevator shaft transfer duct engine.

  14. #34709
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    22nd November 2013 - 16:32
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    Quote Originally Posted by wobbly View Post
    This again brings up the question I am struggling with re 35cc RC boat engine design I am working on.

    Assuming an engine dyno , giving sprocket Hp with a 5% factor for chain/gear friction etc.
    My personal benchmark is the current TM R1 - that makes 53.3 Crank Hp at 13500 = 14.17 Bar bmep with a piston speed of 24m/s ( still not even in the ballpark of Jans rocketship ).
    The 50cc graph shows 18Hp +5% = 18.9 Crank Hp at again around 13500 = 12.6 Bar at only 18m/s.
    This surely isnt even remotely exciting power/rpm/bmep numbers at all , and to me means that the real potential of the 50cc isnt even close to what could be done
    if you started to push the boundaries ( lets face it thats why we are here isnt it ? ) .

    If it was reved to the same level as the TM with the same bmep ( this being very limited by a straight line ignition and a tiny carburetor ) the 50cc should be doing 29 Crank Hp at 18500
    giving the same limited bmep of 14.17 Bar. Put it on a DynoJet and thats 25.4 Hp Rear Wheel.

    What am I missing here , especially as these engines are essentially square and all the technology in the world is readily available to do sintered cylinders etc.
    EDIT - in both the examples shown above we have a 50cc and a 125cc engine with the same carb @ 30mm , so maybe just one element of the 50cc is close to optimum - why ?
    Wob,
    Here’s my basic calc:
    (35/125)*53.3*(18500/13500) = 20.45
    "Success is the ability to go from one failure to another with no loss of enthusiasm.”

  15. #34710
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    18th April 2017 - 23:08
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    Quote Originally Posted by wobbly View Post
    This surely isnt even remotely exciting power/rpm/bmep numbers at all , and to me means that the real potential of the 50cc isnt even close to what could be done
    if you started to push the boundaries ( lets face it thats why we are here isnt it ? ) .
    The little experience I have from 50cc, I experienced that when you set up a pipe and tried to get enough time area on the intake(rotary)
    For peak around 16000k it became a hell to start and below 8000 it wants to get stuck.
    I think that will be one of the biggest challenges with the engine I am working on.
    Have seen here that people have worked on variable intakes but have not heard how it went.
    have myself wondered if it would be possible to make some kind of centrifugal solution so you can run crazy open times.

    Edit: Sorry saw that the arms were put wrong in this picture! but as long as you understand the principle
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    No amount of experimentation can ever prove me right; a single experiment can prove me wrong.

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