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Thread: ESE's works engine tuner

  1. #27706
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    7th October 2015 - 07:49
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    honda ns 400
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    Lithuania
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    Honda NS250/400 std. cylinders from factory have free space under EX duct, but after drilling two holes can be very easy filled with coolant. It looks like Honda engineers wanted filling cooling all around EX duct, but for some reasons decided block passages in casting.
    Maybe it looks too much, but that open space under exhaust duct and transfers A, gave much better power and 1500 rpm more (on standing bike without load before was max 13000rpm , now 14500rpm ). On the road, before modification, power drop after 12000 rpm , now after 13200 rpm. But not tested in 5 and 6 gears. Angle, head, carb, reed all is the same.
    Bottom and mid power not changed , but after 11000rpm feels stronger. I dont know why, but maybe, like Frits wrote, more volume for exhaust suction, or maybe temperature under exhaust duct. And power feels better with longer load , but maybe in 5 and 6 gear would be different.
    Maybe someone had experience.
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  2. #27707
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    8th February 2007 - 20:42
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    TZ400
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    tAURANGA
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    Many engines have the water inlet directly under the Ex port duct.
    Jan tried the idea of stopping flow directly cooling the duct bottom, by filling it with epoxy,and the engine lost power and detoed badly.
    Franco at TM has decided to not use at all the holes in the case and cylinder that would allow ALL of the flow into the cylinder to enter under the duct.
    I cant believe that he did not test this back to back against the original method of supplying water from the case via a hose that enters up high above the Ex port.
    I am about to do this test, along with ceramic coating the duct,as there is still a belief by some that a hot duct will help the pipe work better.
    This is very wrong in my opinion,as overheating the duct will overheat the plugging mixture pushed back past the rising piston, but the only way is to test this back to back.
    My other test will be to do the cooling "properly ",that is to have the cold water enter the cylinder at the back ( opposite the Exhaust ) then flow over the transfers,cooling the Ex last.
    In the TM homologation papers there is no hose shown, so having one around the back is not going to be illegal.
    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.

  3. #27708
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    7th October 2015 - 07:49
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    honda ns 400
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    Quote Originally Posted by wobbly View Post
    Many engines have the water inlet directly under the Ex port duct.
    Jan tried the idea of stopping flow directly cooling the duct bottom, by filling it with epoxy,and the engine lost power and detoed badly.
    Franco at TM has decided to not use at all the holes in the case and cylinder that would allow ALL of the flow into the cylinder to enter under the duct.
    I cant believe that he did not test this back to back against the original method of supplying water from the case via a hose that enters up high above the Ex port.
    I am about to do this test, along with ceramic coating the duct,as there is still a belief by some that a hot duct will help the pipe work better.
    This is very wrong in my opinion,as overheating the duct will overheat the plugging mixture pushed back past the rising piston, but the only way is to test this back to back.
    My other test will be to do the cooling "properly ",that is to have the cold water enter the cylinder at the back ( opposite the Exhaust ) then flow over the transfers,cooling the Ex last.
    In the TM homologation papers there is no hose shown, so having one around the back is not going to be illegal.
    Thanks

    Exactly in this cylinder cold water enter at the back then flow over the transfers to EX.
    Yes, heated mixture not good thing and that why higher power surprised me. But maybe on long run power will change.
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  4. #27709
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    27th October 2013 - 08:53
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    variety
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    usa
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    wob do you think ktm got it all wrong with cold water going in under the exh passage first, then around the cylinder sides to the rear and exiting at the front of the head ?

  5. #27710
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    8th February 2007 - 20:42
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    Well that is how dozens of motors have the water flow.
    But TM could do that, and have plugged the holes - opting to have the flow in above the Exhaust duct.
    Why that is I will know soon.
    But as I said, the best way I believe is to cool the transfers first and I can easily do that by rerouting the side hose to a fitting on the back.
    But as Jan found out, not cooling under the duct sufficiently causes power loss and big time deto, so I plan on trying to drill out the plugs to say 5mm
    and see if that makes any difference ,along with the main flow in at the rear.
    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.

  6. #27711
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    22nd November 2012 - 23:14
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    Chonburi, Thailand
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    Interesting about the water inlet position, flow and so on. Especially the bit about cooling the plugging mixture.

    Having the cold water cool the transfer ducts makes sense, as does tapping off the inlet flow to also flow in under the exhaust duct.

    Wobbly, you've shown your 3 port exhaust duct design, with a length of 2x the bore diameter. So how much of this duct are you looking to cool? All of it? Let's suppose the first part of the header pipe was also jacketed and cooled, would you then be cooling the pipe too much? Change pipe dimensions to suit?

    Much testing required I suspect, and as always creates more questions than answers.

  7. #27712
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    20th April 2011 - 08:45
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    Quote Originally Posted by Matt@TYGA View Post
    Having the cold water cool the transfer ducts makes sense
    It would certainly make sense if we had cold water, Matt. But apart from outboard engines, the coolant temperature may well be higher than the temperature of the fresh mixture in the crankcase.
    The transfer duct walls are heated by thermal conduction from the hottest cylinder part, the exhaust duct. So if we take away the heat there, the transfer ducts will benefit as well. And it is a lot simpler than convincing the coolant to flow from around the transfers to the underside of the exhaust duct and then upward without mixing with the 'cold' coolant that enters the cylinder from behind.
    In most good cylinders, only the roofs of the transfer ducts are wetted. And in the best of 'm, some of the water that enters the cylinder under the exhaust, is directly guided through the inner transfer duct curvatures before it has had time to be heated by the exhaust duct.

    Wobbly, you've shown your 3 port exhaust duct design, with a length of 2x the bore diameter. So how much of this duct are you looking to cool? All of it? Let's suppose the first part of the header pipe was also jacketed and cooled, would you then be cooling the pipe too much
    Only the part of the exhaust duct that gets temporarily filled with washed-through fresh mixture, needs to be cooled. If we cool a length of exhaust duct, long enough to hold a mixture volume equal to the cubic cylinder capacity, we'll be all right. Cooling the remainder of the exhaust tract would needlessly raise the coolant temperature and entail a loss of exhaust gas energy, reducing the good work of the pipe.

  8. #27713
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    22nd November 2012 - 23:14
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    Very good points there Frits, and plenty of food for thought.

  9. #27714
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    28th March 2013 - 04:29
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    98 Honda NS1, others...
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    Leiria, Portugal
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    Quote Originally Posted by Frits Overmars View Post

    Only the part of the exhaust duct that gets temporarily filled with washed-through fresh mixture, needs to be cooled. If we cool a length of exhaust duct, long enough to hold a mixture volume equal to the cubic cylinder capacity, we'll be all right. Cooling the remainder of the exhaust tract would needlessly raise the coolant temperature and entail a loss of exhaust gas energy, reducing the good work of the pipe.
    I guess it's exacly where the wet part of exhaust flange/header looks taking an exhaust off while doing a plug chop.

    On my case the wet part now is exacly the lenght of the Aluminium flange.

    If this end fresh gases are cooled better, do you think the engine will tend to run richer or leaner?

  10. #27715
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    20th April 2011 - 08:45
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    Quote Originally Posted by RomeuPT View Post
    If this end fresh gases are cooled better, do you think the engine will tend to run richer or leaner?
    How would a difference in temperature change the air-fuel ratio of a mixture that was already prepared in the carburetter, Romeu?

  11. #27716
    Join Date
    18th March 2012 - 08:35
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    Homebuilt chassi, Kawasaki 212cc
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    Sweden
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    As i´m building a new pipe for my 211cc engine, could it be worth it to build a waterjacket, say first 100mm on the header?

  12. #27717
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    6th February 2016 - 06:52
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    ducati
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    usa
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    Quote Originally Posted by SwePatrick View Post
    As i´m building a new pipe for my 211cc engine, could it be worth it to build a waterjacket, say first 100mm on the header?
    I had this same idea, would love to know also.

  13. #27718
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    6th February 2016 - 06:52
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    ducati
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    usa
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    Also, going back to the dyno talking point quick. I noticed that aprillia used an inertia dyno, is this correct Jan? In a 2 stroke application is there any pro's and con's to using an inertia dyno versus a loaded dyno, like a water brake or eddy current?

    I have used both dyno's before, I wont name the manufactures names, but the one dyno was so bad at giving me good data plots that my runs were just not repeatable and believable. The current dyno is an eddy current dyno that works well, and gives me good data plots per run, but I am loading the engine quite a bit.

    It just caught my eye what you guys were talking about with inertia dyno's. Would love to know the experts opinions on the matter.

  14. #27719
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    28th August 2015 - 00:01
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    1975 Hodaka Wombat
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    Eugene, Oregon, USA
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    I'm a long way from an expert, but we used an inertial dyno for all our 26 and 35 cc model boat race engine development. The story of the 35 cc engine development is here. The big advantage is that the runs are very short allowing a lot of testing of various ideas without wearing out the engine. Also due to the short run, we saw beginning failures sometimes before they destroyed the engine. However, we also completely destroyed an engine that seized. An over run clutch might have helped disconnect the inertia wheel more quickly than the clutch. I would always include an over run clutch for larger engine testing. The run time was chosen to approximate the run up to the timing trap for speed events or the time of acceleration from a corner down the straight in oval racing. We held the ultimate gas RC boat speed record of 109+ mph from 2004 to 2016.

    Lohring Miller

  15. #27720
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    28th March 2013 - 04:29
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    Quote Originally Posted by Frits Overmars View Post
    How would a difference in temperature change the air-fuel ratio of a mixture that was already prepared in the carburetter, Romeu?
    If charged with cooler mix the engine makes more power, more power going to exhaust, means it will cause greater depression/pressure, may cause lower pression below piston, then suck more fuel?!
    Also hotter gases may change a little the plugs appearance and burning temp?! Too much guessing probably....

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