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  1. #16
    apriliaforum expert riot's Avatar
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    Ok, I don't even own an SXV550 anymore, but am dying to know more about those cylinders.

    Some time ago, I attempted to start a group buy to have some stock replacements made:
    https://www.apriliaforum.com/forums/...ghlight=liners

    Are they aluminum w/Nikasil (like stock)?

    Who plated them for you? How much did it cost?

    It looks really neat. Much more like a Diesel Cyl liner. I bet that would improve the cooling on the cylinder walls a bit, but it looks like you cut down the flow from the heads quite a lot (much smaller coolant ports). What was the thinking on this?

  2. #17
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    Quote Originally Posted by SXV_Jack View Post
    holy jesus ... great work.

    is this a sxv 450 ?

    the crf 250 valves are they made by wiseco and does they fit like oem or is some work nesserary ?

    the cylinder is this made by you or is it possible to buy them for everyone ?

    i am looking forward to the piston you will made.

    i think this is all made for more performance and durability ... realy great work.


    ps:

    "...but in the case of a 2 ring piston, it drinks oil hard under closed throttle"

    you mean the oem piston/rings tend to this problem ?
    no they are crf250 valves from Del West
    I think the exhaust were 2010, and the intakes were 2008
    the intake is 1mm larger than stock the exhaust is 0.5mm larger than stock.
    the keeper location and tip length are also different.

    2 ring pistons work all right. but aside from space constraints they are not better than using a taper hook groove/napier second ring and lowering oil ring tension. The required oil control tension for an optimized 3 ring is less than that of a 2 ring.

    but the issue with mine is that i had the mfg drill holes in the top ring land
    Name:  lateral gas port.jpg
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    this pressurizes the ring faster allowing a quicker seal with a low tension ring.
    it works fine on compression, power, and exhaust strokes. but on intake stroke the ring moves to top land and with the holes it is not sealed, and oil is free to transfer around the bottom, the back and then out the top, where on a standard setup the ring being on the top of the groove would block the oil.

    Or with a 3rd ring, the 3rd ring would be scraping oil, and assisting the gas ported top ring on the intake stroke by holding the "vacuum" I have successfully used these in other engines, 2 other 2 ring, one of them doesn't see much run time because its a speedway engine and is full throttle most of the time. The other is mx and it somehow doesn't use a tremendous quantity of oil but it does use some. Thinking back on it, it baffles me how i got away with using the lateral ports on those engines.


    the cylinders are actually 4032 cylindrical forgings and they would cost around 800usd each. The problem is getting the height right for the cases, If you look carefully at the top photos, the case has a counter bore at the top where the sleeve sits. I machined the case, and I worked with two mfg to get the sleeves done to mach the machine work of the case there were many many complications. Its absolutely critical to have the fire dam protrude 0.001" to 0.002", I left the rest of the cylinder 0.001-0.002 below deck.
    the engine also is converted to external cylinder head oiling as the extra width of the sleeve intruded upon the oil feed and return passages. Initially I wanted to be able to modify cases and sell the system but in the end its too complicated. I have simpler theories and beliefs on appropriate solutions.

    The idea behind these sleeves is to create a TOP STOP sleeve vs MID/Bottom stop sleeves.
    My sleeves have the load of the cylinder head directly transferred to the top flange, and thermal expansion is allowed downward, uninhibited.
    the stock sleeve, I believe expanded too much in relation to the case loading and unloading the head gasket as you rode then turned off the bike over and over. The stock sleeves are also somewhat loose in the cases allowing piston side load to join the problem. Some people have ridden XX amount of miles and think there is no problem with the stock system. I am not one of them I bought the bike and rode it maybe 2000 miles and was loosing 100cc of water per 50 mile ride. I took it apart and both gaskets were missing the black viton coating between the water ports. To me the problem is real so I set on solving it. I do stuff like this a lot since I was a kid actually thanks to my dad and his tools. In fact I built probably 10 other engines and 2 race cars while this was apart :/

    funny I just remembered i had a place in thailand make me gaskets to allow an even larger diameter flange for my sleeve. It takes many many pages to dimension all the curves and radi of a head gasket in autocad what a pain that was. the gaskets were junk. I had already machined a case for very large sleeve flange.... that case is good as junk now.

    Other Ideas I had were to use 450 case, and machine deck spacer to go along with my sleeve, my flange could sit on top of the stock deck. I have 2 new/bad 450 cases that might get a treatment like that.

    I hypothesized the simplest fix, or rather the most bang for the buck is to get rid of the stainless steel layer in the center of the stock gasket, Nobody else is using this folded over center. its thin, and the doubling/forming leads to an inconsistent thickness and surface. If I were starting from scratch I would have sleeve spacers lazer cut 0.004" 0.005" and 0.006". I would machine the sleeves for a fire dam. I would remove the middle gasket layer, and I would get all protrusion from sleeve. The doubled layer is 0.004" thick and creates 0.004" preload on sleeve. I would create that preload entirely from the sleeve. I dont know If i would call it fixed, but I would call it MAJOR IMPROVEMENT. The only modifications would be a simple turning operation to the sleeve, and modification to gasket. Very easy safe modification in contrast to the shit that I did.

  3. #18
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    Quote Originally Posted by levisik View Post
    The main thing which is missing on those engines is oil spray on bottom of pistons. And generally durbality of pistons is not that great (compared to some bigger bikes like CBR600/Ninja...p etc.)
    at 120PSI and going by the bearing codes 0.002" rod bearing clearance, the rod is throwing as much 60wt oil as a 2mm oil ring can handle.

    I am divided on jets. I believe the primary application is cooling piston crown. Particularly useful in forced induction applications. With my current situation I would not want to add oil jets.

  4. #19
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    Quote Originally Posted by riot View Post
    Ok, I don't even own an SXV550 anymore, but am dying to know more about those cylinders.

    Some time ago, I attempted to start a group buy to have some stock replacements made:
    https://www.apriliaforum.com/forums/...ghlight=liners

    Are they aluminum w/Nikasil (like stock)?

    Who plated them for you? How much did it cost?

    It looks really neat. Much more like a Diesel Cyl liner. I bet that would improve the cooling on the cylinder walls a bit, but it looks like you cut down the flow from the heads quite a lot (much smaller coolant ports). What was the thinking on this?

    They are 4032 aluminum forgings.
    Plated by company B.

    Now I called company B when I set out on this project and was advised on alloy and their capabilities as a plater.

    What I paid and what they would actually cost were very different.
    I actually had company a making me the sleeves at first. It took a "few" attempts to get them right.
    Finally having THE set. They were damaged in the plating process by company B.
    Company B told me they would replace them by making them and I said OOOHHHHh boy are you sure?
    took company B like 6 tries.
    The eventual solution was to machine the ID, plate, then finish machining the OD.
    So I have about a dozen wrong sleeves.
    I paid company A, 450usd for 4 "correct sleeves" 2 of which got destroyed, and 2 of which would be destroyed if plated, nice dimensionally perfect unusable paperweights.
    I paid company B, 800? for 3 correct sleeves.
    Company A price, was like 2xx per sleeve
    Company B price, 3xx per sleeve and 2xx for plating.
    Due to difficulty i believe the sleeves would cost around 800$ each


    The cylinder wall fining was just for shits and giggles.
    The water ports well.
    Just look at a stock gasket Name:  gasket.jpg
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    Priority is to cool the exhaust side of the head, and take into account the locations of water inlet and outlet.
    also those ports are hard to machine. and I wanted the sleeve stiff as possible.
    also I ensured that the flow area was still greater than that of the water inlet and outlet ports. so there is no restriction.
    in hindsight holes and a groove are much much simpler
    Name:  sleeves.jpg
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  5. #20
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    While I agree with what you have said the reality is that these motors have to come apart at 20,000km - 30,000km to replace rings and do a good check over...

    I just use a 0.10mmm shim under the cylinder to raise cylinder then lap down to my preferred protrusion...

    With that and using copper gasket sprayI have never had a head gasket failure on any of the XV engines I have built...

    No doubt your cylinder is beyond awesome, but is it needed in a motor that has to come apart so often?

  6. #21
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    I know there are people who say that they never had an issue. But when I look at the system all I can see is an eminent issue. The engine was built by a prominent member here before I bought the bike. with copper spray, without a shim. both head gaskets were missing the coating between the ports on the exhaust side.
    your 0 for 0 good for you. the bike within 1500 miles was 2-2. I checked fluid levels every ride......... it only used 25 or 50ml every 50 miles but I don't consider that acceptable.

    There is a reason diesel cylinders are top stop, and not bottom stop.
    there is a reason you will find no other split horizontal with bottom stops.

  7. #22
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    Quote Originally Posted by aaron9696024 View Post
    I know there are people who say that they never had an issue. But when I look at the system all I can see is an eminent issue. The engine was built by a prominent member here before I bought the bike. with copper spray, without a shim. both head gaskets were missing the coating between the ports on the exhaust side.
    your 0 for 0 good for you. the bike within 1500 miles was 2-2. I checked fluid levels every ride......... it only used 25 or 50ml every 50 miles but I don't consider that acceptable.

    There is a reason diesel cylinders are top stop, and not bottom stop.
    there is a reason you will find no other split horizontal with bottom stops.
    Yet again, I totally agree with you but...

    Those diesels you are comparing it to are designed to be build, give them regular maintenance and you don't open them up for thousands of hours...

    The XV motor design is not for long life, the manufacture recommends opening it up every 6 hour?

  8. #23
    apriliaforum prov-nov Mekis's Avatar
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    Attachment 387866

    Can you tell us about the pipe design? cone, power bomb, chamber...?
    Last edited by Mekis; 09-11-2019 at 02:29 PM.

  9. #24
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    I have been working on exhausts since I was a little kid fascinated by 2 stroke expansion chambers.
    I have done them for scooters, speedway bikes, stock cars and sprint cars.

    Many people get fixated on equal length being the most important factor, others get an idea that an engine needs backpressure.
    the truth is, what does equal length do some how magically make it the same, NOPE the firing order is already off on most engines that aren't inline 4 cylinders.
    fully developed race engines have optimized ignition and fuel maps per cylinder because of the charge robbing, and cylinder dilution from the next cylider blowing down while the previous is in overlap (cross plane v8s are really bad for this one)
    The screamer is actually ok, but big bang is really bad for this aspect.
    what is important is the RIGHT length, but people have such a fixation on same that they will abandon one right and one ok, for two wrongs.
    for example, if you were targeting 20" and you get 18" and 22" with few, and wide bends, you gladly accept and consider successs, while the misenformed adds more bends, flow restrictons, weight and hurts wave tuning by running them out to 30" to make them the same.
    The sxv would quite enjoy a 16" primary length, but the problem is that you cant get the two pipes to join up when they are that short.
    Everyone thinks the exhausts that they bought are all designed by some great wizzard engineer. No what the engineer wants never fits on the bike............................. ever..........
    the pipes are designed by a guy who makes pipes fit the bike, maybe they make two a couple different size tubes and steps. I mean just look at them..... silmoto and arrow have no secondary after the collector, just muffler, Secondary length tuning can always be beneficial, but it wont fit on the bike easily. Nobody likes to bother with cones as hydro forming or pie cutting them is a pain, and even with mufflers, they have extremely loud closed throttle reverberation.

    now others have this idea about back pressure. The entire point of exhaust tuning is to time the arrival of a low pressure "wave" at the exhaust valve in the useful rpm range. There is multiple reflections going on in an exhaust, peaks and troughs,
    totally hypothetically, if you had a 22" header, your likely to say have beneficial low pressure at 8000 rpm, high pressure at say 9000, and again low pressure at 10,000, arriving back at the valve during overlap creating peaks and valleys in the torque curve, a secondary collector length can be used to fill these troughs and attenuate the peaks, while a a cone can be used to diffuse them, taking the short sharp waves, and spreading them out over a length of time allowing a larger useful range at a weaker amplitude. all of which aimed at reducing pressure during overlap. no room for back pressure here. we need velocity, we need a reverse cone end cap to prevent atmosphere form entering the cone, but pressure, we do not need

    so specifically
    The exhaust is made from mandrel bent 0.035" or 20GA 304 stainless steel. The Spigots are machined and tig brazed onto the header with silicon bronze. The attachment flanges are milled from aluminum.
    all bends are on a 3" radius, or in other words they are very sweeping no tight bends.
    Primary diameter from cylinder head is a small 1.25", but only held for 5" - this is described as the blow down length the exhaust here is kept as small as possible as long as possible without introducing losses
    It is possible to replace 1.250" section with 1.375"
    primary diameter 2, 1.375" for 8"
    Primary diameter 3 1.5" for another 10 or so inches. I stepped up one size near the point which I would have ended the header if it were physically possible.
    the collector is 1.5 10* shallow collector. the choke for the collector is 1.700"
    The megaphone is 6* and tapers to 3.5", with a 2.25" reverse cone, but it is possible to place smaller choke.
    the muffler has 2.25" core.

    design goals, were to make the header lengths as short as possible, which were something like 24"
    the megaphone is designed to "blur" the header length to the engine, essentially make it think it has a 24" and a 50" header and everything in between. But the way it works is it it scavenges less strongly than defined length would at its optimal rpm which is ok, as over scavenging is easy to do. The idea is that you can make very smooth torque curve starting very low.

    in a perfect world I would have used the following
    1.250 for 6"
    1.375" for 10"
    1.375" to 1.625" collector
    6" cone
    but no way in hell you can make it happen, only if the exhaust was in the valley.


    In the real world, things aren't so simple, nothing can be fully optimized as there are always compromises, its a matter of selecting the correct ones.

    heres some others i have builtName:  P3281111_zpshwprnc42 (3).jpg
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    these made 800hp, no tubes are the same length...., was very hard to get them even close on the 4-2-1, with strict firing order requirements.
    the dyno operator commented that he was shocked how close in dimension they were to what they developed running a 50,000$ header development/testing program.

  10. #25
    apriliaforum Junkie SXV_Jack's Avatar
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    the pipes are designed by a guy who makes pipes fit the bike, maybe they make two a couple different size tubes and steps. I mean just look at them..... silmoto and arrow have no secondary after the collector, just muffler ... Secondary length tuning can always be beneficial, but it wont fit on the bike easily.
    What do you mean with secondary after the collector ?
    What do you mean with muffler ?

    What do you think about the "powerbomb" on the late version on sil moto ... is this a spoof or is there a real benefit ?

  11. #26
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    Quote Originally Posted by SXV_Jack View Post
    What do you mean with secondary after the collector ?
    What do you mean with muffler ?

    What do you think about the "powerbomb" on the late version on sil moto ... is this a spoof or is there a real benefit ?
    jim fueling patented an AR chamber

    he sold the patent to hytek exhaust before he died.
    the FMF is kind of a knock off as it goes straight through and typically has two 1/2" holes inside.
    the megabombs are sort of like a premuffler,
    the cansiters also are like a dampener or attenuator, sort of dampens the pulsation smears the header length, weakens beneficial and unwanted pressure waves, possibly reduces sound.
    they all do that, but jims original AR chamber also acts as a (rudimentary) one way valve. I made some for speedway but series promoter decided to be jerk about them

  12. #27
    apriliaforum Junkie SXV_Jack's Avatar
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    okay i understand (the most).

    You say the exhaust from arrow / sil are not the optimum.
    yes that can be but he must fit on bike (like you say) and better than OEM are they sure.

    Have you been on a dyno with your modifited sxv to check ps and nm ?

  13. #28
    apriliaforum expert levisik's Avatar
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    I see some good knowledge here, do you know if stock crank in Aprilia is forged or not ?
    2006 Aprilia SXV 450
    Tuneboy Cable available in Poland

  14. #29
    apriliaforum Junkie SXV_Jack's Avatar
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    @aaron9696024

    you made other pistons and cylinders in the engine but
    i think what is missing are titanium rods .... ?!

    what do you think about this ...

  15. #30
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    Fantastic! Love it!

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