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  #1  
Old 04-14-2006, 12:14 PM
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Default Athena cylinder head kit.

well i put off doing a top end for over a season and....it fianlly gave up one and it thrashed my cyl. head. so any way i want a little more power out of the bike (pc pipe short silencer v force3) so does anybody kno the quality of the Athena Works cyl head kit. all the OEM parts needed for top end are like 400, Athena race is 450, and the athena works is 500. any hel appreciated.
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  #2  
Old 04-14-2006, 12:38 PM
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Default Re: Athena cylinder head kit.

The Athena is worth it for the better exhaust valves in my opinion. Only been on one,,but it is a good kit it seems like.
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Old 04-14-2006, 11:31 PM
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Default Re: Athena cylinder head kit.

i had the kit on my 125, and it works great, if you use the high compression dome you will need to run race gas to prevent detonation, but it will be FASTER than your bike is now, you might have to buy a new pipe though because of the way the athena flange is. on my 97 i had to buy a 99 pipe to use it on that cylinder
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Old 04-15-2006, 09:18 PM
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Default Re: Athena cylinder head kit.

im pretty sure my pipe will still fit, the flange looks similar. neway i put the order in tonite so it should be here in a week or so. sweeeeeet
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Old 04-15-2006, 09:40 PM
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Default Re: Athena cylinder head kit.

if i dont put the bronze insert in can i run on 93 octane pump gas with a lead additive (44:1)?
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Old 04-15-2006, 11:25 PM
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Default Re: Athena cylinder head kit.

probly
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Old 04-16-2006, 12:31 AM
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Default Re: Athena cylinder head kit.

If you could get an actual lead additive you could run about anything with it. A real tetraethyl lead additive will turn about anything short of drip gas into the octane rating you would want. I haven't owned the kit you are buying, but I would imagine in the configuration that is suposedly stock or close to it (they don't say which year in the literature I have seen) you would likely be able to jet it to run on 93. We can't even get 93 here, but most stockers will live on 90.

As for the lead substitutes, I have tried several and you might as well save your money. When they talk about raising your octane rating by 7 points, well their idea of a "point" is .1 of a point of octane rating. I have tried the Klotz HiTrate which is a concentrated race fuel mix. You mix one gallon to 9 gallons of pump gas. It worked for us in a variety of types of engines, 4 stroke and 2 stroke. Moneywise it doesnt work out any better than Sunoco race fuel or Trick which I can get pretty easy when I am in town. I use it when I am out of town.
Eric Gorr suggested it some years ago when I got a cr125 144'd from him. PM me if you want to know which "boosters" I tried.
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Old 04-16-2006, 10:39 AM
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Default Re: Athena cylinder head kit.

just a thought, have you thought about mixing 50/50 pump gas and race gas? 110 is like 30$ for 5 gallons and you could get 10 galons out of it if you mix it with pump gas. ive never done this but have read and heard that it works pretty well.
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Old 04-16-2006, 05:01 PM
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Default Re: Athena cylinder head kit.

i will only run 110 leaded fuel in my bike. it's stock so it isn't neccessary but regular pump gas is not always the purest, and i find the jetting stays move consistant with race fuel, and on all my tear downs there was always plenty of lube. So why mess with what works. I run 110 cam 2r from speedway at 3.49/gal which isn't bad considering premium is like 3.05/gal now, and i mix it 40:1 with maxima castor 927.
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Old 04-16-2006, 09:41 PM
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Default Re: Athena cylinder head kit.

At $3.50 a gallon it makes reasonable sense to go overboard on the octane. You can get more consistency in your jetting for sure. Most of us jet on the safe side, which in my case is 1-2 sizes richer when I use pump gas or the HiTrate mix. With the mix I get adequate octane for even my big bore kitted stuff, the key is that I am using pump gas as a base, and therefore kind of have an unknown, as it changes from week to week. Not a lot, but enough that I don't feel as comfy running it to the limit on the jetting. Even a lot of the magazines and tuners suggest the mix of 50/50 though. Again, though it wouldnt make any sense to me at all to do that if you can get race gas for $3.50.
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Old 04-17-2006, 07:43 PM
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Default Re: Athena cylinder head kit.

yea well id have to use race fuel for the insert (it rases the compression to 14.8:1!) but if i cant use pump gas with out the insert i can always machine the squishband out a liitle bit to lower the compression a bit.
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Old 04-17-2006, 08:26 PM
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Default Re: Athena cylinder head kit.

: :
Quote:
Originally Posted by YZ125motoracer
yea well id have to use race fuel for the insert (it rases the compression to 14.8:1!) but if i cant use pump gas with out the insert i can always machine the squishband out a liitle bit to lower the compression a bit.
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Old 04-18-2006, 09:15 AM
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Default Re: Athena cylinder head kit.

LOL, I wouldnt worry about that 14.8 number. Not to wind anyone up again, but Racer,,just consider it somewhere in the
9's. If you really did have a compression ratio that high on a twostroke, I would bet it won't live a moto, and maybe not a full minute on gasosline you can buy. Anyone curious as to why using a compression gauge won't work to figure your compression ratio (I had a science teacher that thought it should too) should read ALL of Boyle's Law first. Then they should get closer to how an engine works and how inertia affects air flow. Finally, they should compare the reading given on one revolution to the one they get on "several kicks", or just have an actual knowledge about what is happening and how the gauge works.
Then a good pinch of reality (make sure you are awake if anything)should be administered; as you wonder why the factories and the engine builders go to all the trouble to CC or pour a head and cylinder to determine it rather than to just "use a compression gauge".
Or just don't worry about 14.8 to 1 LOL

Last edited by ossagp1; 04-18-2006 at 09:23 AM.
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Old 04-18-2006, 01:09 PM
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Default Re: Athena cylinder head kit.

i cant do a compression test because i dont have the cylinder yet. those specs are from the motosport outlet catalog. as for boyles law (pressure, volume, and temperature are all directly related) how would that help me find out if i can run pump gas in it?
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Old 04-18-2006, 01:32 PM
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Default Re: Athena cylinder head kit.

Racer,,you ask good questions: Neither a compression gauge or the numbers given by the manufacturer here will do you much good. I like that you know the full implications of the physics involved,,,most especially the temperature part of the supported theory. When you see a compression ratio like 14.8 on a two stroke you can bet it is not one that is derived by what is called the "corrected method" among some. Ie, the portion of the cylinder that exists above the exhaust port/power valve or the transfer ports (whichever are higher, as some have built engines where the transfers are closer to the combustion chamber than the exhaust is). That is really the only meaningful one. That area is also referred to by some as the "effective stroke". When considering fuel and other limiting factors it is the one that manufacturers and builders are more likely to look at.
The reason I mentioned the compression gauge was that ironically enough another poster stated that his Athena kitted bike had a 14.8 to one compression ratio, and that he derived it from the fact that it had 210 lbs of compression. If you divide 210 by atmospheric pressure it seems that you should be able to get the true compression ratio. In truth you can't. When you compress a gas it heats up. Pure and simple. That is one of the biggest reasons besides overfill and the way the compression gauges are made to begin with that keeps the two groups mentioned above from simply taking a compression reading to determine compression ratio. For instance,,according to Honda an 88 XR250 has a compression ratio of 10.2-1. They say compression readings should be 185-213 lbs. Divide those last two numbers by 14.7 (a popular representation for atmospheric pressure is anywhere from 14.4 to 15 lbs) and you get numbers above 12.5 to 1. Do you think Honda missed on what the compression ratio really is on their engine?? Do you think many teenaged boys could out think them on that? (I know when teenaged boy described me I thought it was pretty likely that I could.)
Compression ratio alone does not give an ironclad means for determining fuel requirements either of course. Want to talk more about that?? We can. Tryce is more current than me on that, as he deals with fuels which are more highly oxygenated than I do. Such things as ignition, a cooling capacity, shape of combustion chamber, material of construction, atmospheric conditions, and type of use have much to say about what will work for you.
Again,,don't get too stuck on the 14.8 to 1 number. I think as does the actual user of that kit that you would like it a lot.

Last edited by ossagp1; 04-18-2006 at 01:35 PM.
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  #16  
Old 04-18-2006, 01:40 PM
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Default Re: Athena cylinder head kit.

oh, ok. ive never seen those calculations before. so theyre measuring from the bottom of the stroke, instead of from the point at which all of the ports are closed?
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  #17  
Old 04-18-2006, 01:44 PM
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Default Re: Athena cylinder head kit.

Yep. Forever it seems the Euros were big on that. I recall the 125 Husqvarnas having something rediculous like 15 plus to 1. One particular monthly fiction book that masquerades as a motorcycle magazine was really impressed by that.
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  #18  
Old 04-18-2006, 01:48 PM
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Default Re: Athena cylinder head kit.

wierd.lol. well the cylinder kit should be here next week some time, ill keep u updated on it and tell u wen i install it. it should really fly now
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Old 04-18-2006, 01:57 PM
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Default Re: Athena cylinder head kit.

Ok here we go...several points to consider.
Calculated CR...total swept volume is in the equation. BDC to TDC vs head and squish volume.
Actual CR...2stroke...swept volume from the time the exhaust or transfer closes to TDC vs head and squish volume...intake velocity can also be equated into the formula, but a bit much for the average guy.
4stroke...Calculated CR...total swept volume vs head and squish volume.
Actual CR...swept volume from the time the intake closes vs head and squish volume...intake velocity can also be a factor as stated before.
NOW...
On a YZF450 for example, we could have a Wiseco 13.5 CR rated piston with a radical WebCam timed for a high lobe center(late opening/late closing) with a ProCircuit port job(sucks, low flow/low velocity) and end up with an actual CR of around 9-1. The fuel requirements for this engine configuration could easily be in the 87 octane range with no trace of detonation, especially if you the tuner went by the more mods/more fuel way of thinking.
Not as explicit as some of the other explanations, but hey, I am a simple thinking kind of guy! Tdub
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Old 04-18-2006, 03:49 PM
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Default Re: Athena cylinder head kit.

LMAO, should be simple enough for most to understand!

Ossa and FFR, I can't believe that you finally found someone that will listen to you two! Great explanations, you two are the best.
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