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Thread: Adding compression and head porting ideas

  1. #1
    apriliaforum Member
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    Adding compression and head porting ideas

    Hi to all,im thinking to make an effort to improve the performance of my engine.
    I was thinking to follow the big-bore route,but i'm not entirely convinced about the reliability of a big bored engine.
    It takes a lot of experience,and a very competent mechanic to make a good reliable big-bore.
    With that in mind and aiming for max reliability,i'm thinking to modify only the cylinder head,and do a proper porting with flow bench and some head shaving for a little more compression.
    After i will send the bike to a dyno for a proper mapping
    Any ideas about the amount of skimming of the head?
    Somewhere i read about 0.3mm shaving.Is that safe?Can i go for more?
    What to expect in terms of performance gains?
    In current state the bike have open filter,evo 6 exhaust,and pc5 with autotune
    Any idea or help will be greatly appreciated
    Thanks
    Last edited by geobarb777; 06-18-2017 at 11:20 AM.

  2. #2
    apriliaforum expert kzmille's Avatar
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    Honestly a 1060 engine with very little else would give way more performance and be as reliable as trying to tweak compression, etc. Just installing the kit without shaving the heads raises compression a bit. The ports are very good already but no harm cleaning things up a little. Doing more than that without a lot of specific RSVR experience could easily do more harm than good. Timing the cams properly and good tuning on top of those should make you quite happy.

    Anyone capable of shaving the heads and properly building the engine should be capable of installing the 1060 kit.
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  3. #3
    apriliaforum Member
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    All of the 1060 big-bore kit supliers,told me that a very competent mechanic is needed for the 1060 install.
    I dont think that head porting and skimming will give near as much performance gains as the 1060,but will be reliable considering the fact that no motor opening required,and is a job pretty straightforward
    Is the head shaving job requires that much capability?I think that to know the amount of shave will want experience and knowledge.
    The cam timing is necessary for this amount of works on the engine?

  4. #4
    apriliaforum expert kzmille's Avatar
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    Quote Originally Posted by geobarb777 View Post
    ...Is the head shaving job requires that much capability?.......The cam timing is necessary for this amount of works on the engine?
    1) I think so.
    2) Yes.

    When you shave the heads you effectively lengthen the cam chains so precise cam timing is a must. By any reasonable definition these operations certainly fall into the description of "opening the engine". If your engine does not have high mileage I don't know why it would be necessary to split the cases to install a 1060 kit unless there is interference between the pistons requiring some attention. It could be said that when installing a 1060 kit the cases should be split so that everything receives a thorough inspection but it could also be said you should do the same for the modifications you are asking about. A lot depends on the mileage of your engine. I would definitely ask Amauri. He'll be able to answer all your questions.
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  5. #5
    apriliaforum Member
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    Thanks for your inputs kzmille.
    I asked amauri,and he told me while ago that for big-bore building,competence and great experience on rotax motors required.
    My motor have 60000 km.With that in mind and seeking max reliability made the choice to go the header way.
    Any other suggestions?how much head shaving without problems is permitted

  6. #6
    apriliaforum expert kzmille's Avatar
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    With that kind of mileage I wouldn't even consider the changes you desire without a complete rebuild.

    I basically agree with Amauri that good mechanical skills are required but that is true for what you propose as well. Understand, you cannot remove just the cylinder heads from these engines. The heads and cylinders are bolted together and must be removed and installed as a unit.

    Obviously a big bore kit involves much greater expense for the pistons and sleeving the cylinders but anyone capable of removing and replacing the head/cylinder assemblies and adjusting the cam timing should be capable of this work as well. In other words, if they are not capable of fitting the big bore kit I wouldn't trust them to shave the heads and adjust the cam timing.
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  7. #7
    Honest always, feared often Micah / AF1 Racing's Avatar
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    The hardest part of doing the big bore properly is actually installed mg the pistons without damaging the oil control rings. While you can do it successfully the traditional way for bike from the bottom of the cylinder need, it works WAY better and WAY easier and less likely to break an oil ring if installed from top deck of cylinder. I use or prefer to use steel liners from LA SLEEVE set to .0025-.003" piston to bore clearance in final honing. I prefer to leave flywheel weight attached to stator, that is two pounds of taking idle weight well worth it imho IF you go big bore and increase power by 15-20%. I prefer either on high compression or big bore motors to use can timing backed down to 106/109 for upper midrange power or 108/112 if you only care about top end. Stock velocity stacks are best from rsvr as are stock throttle bodies and airbox with 440cc injectors and use the stock air filter too, that alone is worth 1.5 bhp bottom to top.

    Porting: the only benefit I have seen on these heads is concentrating on increasing port velocity, match seats to castings do a very nice valve grind for sealing evenly on all valves. If you wanna spend the money to modify valves you can see more compression and flow from non own valves without a loss of lifespan. Stock valve stems are unnecessarily large in potion exposed in ports. I prefer not to flush port the valve guide extensions as while flowbench numbers will go up valve stability will go down. I use very coarse intake port grinding and mirror polish exhaust ports for max heat rejection on hot side and max laminar flow on cold side.

    The reason big bore kits work so much better than they should on paper is the They increase in port velocity which leads to higher volumetric efficiency in your target rpm range. NEVER go under .9mm squish FYI. Do not deck heads to set squish only to make certain they are flat, and match chamber volumes this way. Deck cylinder top decks to set squish at .9-1.1mm.

    When tuning, and you will need to with all these changes make sure to tune both cylinders first with single lambda and then redo each cylinder individually. No afr offset needed as water cooled. Following this roadmap will result in 150-158 rear wheel bhp at 1060cc ported and degrees with proper tuning on a relatively low octane fuel like say 93-95'octane. More can be had on exotic oxygenated high temp fuels but only about 4% more using $25+/gallons racing fuels.

    Hope this helps.
    Diminished expectations is the key to happiness in life.

    Micah Shoemaker
    AF1 Racing
    9900 IH35N
    Austin, TX 78753
    micah@af1racing.com
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  8. #8
    apriliaforum expert kzmille's Avatar
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    Interesting stuff, Micah. I've never built my engine that I did so much preliminary work for. Life has a way of intruding on the things we want to do. I'd like to finish it someday but at 65 now I wonder if it will ever happen.

    One of the reasons I never before considered a 1060 kit was just the trouble of tuning. No one here I would trust with that. The idea of thrashing - my impression - a new engine on a dyno has never set well with me either.

    Anyway, this thread has perked my interest. I mean, if I'm going to build it, why not?

    So I have a question on this. With a 1060 kit, ported gen 1 heads, stock 02-03 cams, mild cam timing, 57's, 2 into 1 modified headers and race can, and standard rev limit, is there any way that the standard gen 1 injectors will be adequate?
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    apriliaforum expert jess67's Avatar
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    I have some Bosch giant green injectors for my 1102 big bore kz, they bump the cc's from the standard 400 to around 440 and I will raise the fuel pressure marginally by doing the fuel pressure mod. That should keep the injectors from maxing out before 100% throttle.

  10. #10
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    Funny, I too have looked into this, but I don't have the finances at the moment.
    From what I have read KZ, most seem to fit Gen 2 heads, as I believe the valves flow better, also Gen 2 throttle bodies and injectors too.
    While I am not certain on this, I am hoping someone more knowledgeable will chime in, so I know for certain. I won't big bore my Gen 2, but I may well do it to a Gen 1.
    My current ride: 2004 RSV1000R Factory, DNA air filter, Arrow pipes, tail tidy, Aprilia alloy muffler brackets, Aprilia Performance open airbox conversion, Carbon fibre dual velocity stacks, Bazzaz Zfi & Afm, EVO1 adjustable/foldable levers. My wife's: 2002 MV Agusta F4 750S Diamante.
    Previous:
    2006 GSX-R1000 Full yoshimura exhaust, Galfer discs and lines, Pazzo levers, Factory Pro intakes, BMC filter, Yoshimura case savers, Vortex rearsets, Toby adjustable steering damper, Yoshimura bar end sliders.
    2004 GSX-R1000,1999 GSX-R750 SRAD full Arrow race system,1998 TL1000R Two Brothers pipes, 1993 ZXR 750,1998 TZ250U,1990 TZR250,1990 KR1S 250,1986 XR250 340 big bore kit,1991 KX250, 1993 KX125,1991 YZ250, TS250X RH,1974 CR250M Elsinore

  11. #11
    Honest always, feared often Micah / AF1 Racing's Avatar
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    Gen2 heads are better up top with their 57mm TB's for sure but not nearly as much better as most people think. Too much compression is doable at low rpm with dual spark heads, the only ones I've ever had detonating issues with and only then at low rpm, under 4K.

    Kz, I personally would just use a larger flowing set of injectors, I've seen Stock injectors on healthy motors going as high as 96% duty cycle, this is not sustainable long term. PCV with dual AT300 auto tune kit can be used if you are really patient to self tune, do you have access to a dyno?
    Diminished expectations is the key to happiness in life.

    Micah Shoemaker
    AF1 Racing
    9900 IH35N
    Austin, TX 78753
    micah@af1racing.com
    @ShoemakerMicah
    @AF1Racingaustin

  12. #12
    apriliaforum Junkie
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    There we have it, the knowledgable have spoken!! Thanks for your answer.
    I for on am not at 100% throttle, I am using the high 80 to low 90%, so as far as I can see, I don't need more power yet!!
    My current ride: 2004 RSV1000R Factory, DNA air filter, Arrow pipes, tail tidy, Aprilia alloy muffler brackets, Aprilia Performance open airbox conversion, Carbon fibre dual velocity stacks, Bazzaz Zfi & Afm, EVO1 adjustable/foldable levers. My wife's: 2002 MV Agusta F4 750S Diamante.
    Previous:
    2006 GSX-R1000 Full yoshimura exhaust, Galfer discs and lines, Pazzo levers, Factory Pro intakes, BMC filter, Yoshimura case savers, Vortex rearsets, Toby adjustable steering damper, Yoshimura bar end sliders.
    2004 GSX-R1000,1999 GSX-R750 SRAD full Arrow race system,1998 TL1000R Two Brothers pipes, 1993 ZXR 750,1998 TZ250U,1990 TZR250,1990 KR1S 250,1986 XR250 340 big bore kit,1991 KX250, 1993 KX125,1991 YZ250, TS250X RH,1974 CR250M Elsinore

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    apriliaforum Member
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    Does anybody know what a modification like this can deliver,in terms of performance.
    I read everywhere about how beneficial is head porting for an engine,and the importance of gas velocity
    Maybe on aprilia that is not the case
    So,do you think it is worth it?

  14. #14
    Honest always, feared often Micah / AF1 Racing's Avatar
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    Very consistently using both the The porting I described above as well as cam timing, tuning and 3mm overbore pistons at .9-1.1mm squish I'd see 20-25% gains in horsepower and up to 40+% gains in lower rpm torque even at as little as 20-40% throttle opening. Almost all the big bore ported or unported but all degrees and tuned motors I have done with gen2 starting points ended up making I shit you not, equal to stock bhp, at 40% throttle opening.

    My dyno reads VERY low compared to dyno jet machine. Dead stock small valve Gen 1 motors are right at 100-102 RWBHP witha wicked dip/spike in the 6500 rpm range. My best Gen 1 based motor running stock throttle bodies was 127.5 RWBHP but due to arrow full system a bit lumpy shaped dyno curve. My best 100mm Gen2 using ALL the tricks only about 136.5 RWBHP and 102mm 136.0 RWBHP with simple volcanic explosion torque! The most power I ever saw dead stock on any gen 2 motor was in the 102 range semi restricted and 108 bhp range just intake snorkel restrictions removed and rsvr stacks using stock pipes.
    Diminished expectations is the key to happiness in life.

    Micah Shoemaker
    AF1 Racing
    9900 IH35N
    Austin, TX 78753
    micah@af1racing.com
    @ShoemakerMicah
    @AF1Racingaustin

  15. #15
    apriliaforum Member
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    Hi micah,my question is about the porting and head skimming,and not the big-bore.
    Im convinced about the big-bore performance
    I wanted to know if head porting and if head skimming is worthy for the effort.
    Will i gain anything significant?

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