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Old 08-26-2011, 11:33 AM   #24151
SteveO
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Originally Posted by Machtig View Post
Yes. Though I'd stay away from the Athena kit as the increase in mass of the piston is substantial. Go Thumper Racing big bore. I beat mine like a red headed stepchild and she runs like a top. All of this is subjective, however, except for the increase in mass part.

So the Thumper kit has a shorter stroke to make a larger displacement of volume?
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Old 08-26-2011, 11:42 AM   #24152
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Originally Posted by SteveO View Post
So the Thumper kit has a shorter stroke to make a larger displacement of volume?
It's a piston and cylinder, that makes about 280cc. Because of the lower weight, there is no noticeable difference in vibration, unlike what I've heard about the 290. Thumper Racing's kit is also less expensive, but you need to reuse your existing cylinder.
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Old 08-26-2011, 11:49 AM   #24153
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Originally Posted by RichardU View Post
It's a piston and cylinder, that makes about 280cc. Because of the lower weight, there is no noticeable difference in vibration, unlike what I've heard about the 290. Thumper Racing's kit is also less expensive, but you need to reuse your existing cylinder.

hmmmm....

Does 30cc really make that much of a difference? That's only a 11% increase in engine size. I'm not so sure the money is worth it.......
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Old 08-26-2011, 12:08 PM   #24154
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Does 30cc really make that much of a difference?
It does to me, but I'm fairly aggressive. I've ridden these bikes back to back:

My 280 with FMF Q4 Silencer with Powerbomb Header, FMF Programmer, K&N Air Filter, AIS Removal Kit, Ultimate Airbox Mod, EXUP Eliminator Plug

My wife's 250 with bored exhaust, FMF Programmer, K&N Air Filter, AIS Removal Kit, Ultimate Airbox Mod

The 250 feels like it's dragging an anchor.
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Old 08-26-2011, 12:13 PM   #24155
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Re.: Post 24063... What kind of rear rack is this?

Hey RUFJEEP!

I could not help but notice your different-than-seen-before rear rack... is it a homemade one or purchased from a store? Any chance at more info and more detailed pics? Would be very much appreciated! Thanks in advance! P.S.: I tried to attach your pic here but it wouldn't work!
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Old 08-26-2011, 12:28 PM   #24156
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Quote:
Originally Posted by RichardU View Post
It does to me, but I'm fairly aggressive. I've ridden these bikes back to back:

My 280 with FMF Q4 Silencer with Powerbomb Header, FMF Programmer, K&N Air Filter, AIS Removal Kit, Ultimate Airbox Mod, EXUP Eliminator Plug

My wife's 250 with bored exhaust, FMF Programmer, K&N Air Filter, AIS Removal Kit, Ultimate Airbox Mod

The 250 feels like it's dragging an anchor.
Hmmmm, interesting analogy...

Anybody else out there feel like they had cut the anchor loose after upgrading to a Thumper 280cc ?
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Old 08-26-2011, 07:26 PM   #24157
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Hhhhmmmmm.....some interesting comments regarding big bore results. I find the statements about (against) Athena rather odd. Maybe even unfounded. But whatever....

Today was THE DAY I made my Dyno 3 run on my Athena 290, no less. And it didn't even blow up!

But what it did do, was blow up the HP & Torque charts. Check out my latest post at Highfives Athena Big Bore Thread here: http://www.advrider.com/forums/showt...7#post14052077

Cheers

HF

p.s. But caution.....its bare naked truth. Viewing could be hazardous to your wallet, but soothing to your heart & soul.
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Old 08-26-2011, 08:33 PM   #24158
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Quote:
Originally Posted by HighFive View Post
I find the statements about (against) Athena rather odd. Maybe even unfounded.
Thanks for posting the dyno runs. Even though you were not testing the same big bore I have, you certainly showed some impressive gains are possible.

Which statements about the Athena did you think might be unfounded? All I see is that it has a negligible effect on gas mileage, and compared to Thumper Racing it's more expensive, heavier and might add vibes, which you seem to confirm. Maybe I'm not looking back far enough.
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Old 08-26-2011, 09:52 PM   #24159
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Quote:
Originally Posted by Machtig View Post
Yes. Though I'd stay away from the Athena kit as the increase in mass of the piston is substantial. Go Thumper Racing big bore. I beat mine like a red headed stepchild and she runs like a top. All of this is subjective, however, except for the increase in mass part.
This is the statement I found rather odd. Maybe it just surprised me, I'm not the best wordsmith.

I don't care what people choose for themselves. I just share what I've done firsthand, and how its working out.

I've enjoyed great results with my Athena....in spite of rooting around inside it with a stick at least twice now. I'd have to say my "extra mass" is serving me quite nicely. But that's just my opinion.

HF
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Old 08-27-2011, 08:10 AM   #24160
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Quote:
Originally Posted by HighFive View Post
This is the statement I found rather odd. Maybe it just surprised me, I'm not the best wordsmith.

I don't care what people choose for themselves. I just share what I've done firsthand, and how its working out.

I've enjoyed great results with my Athena....in spite of rooting around inside it with a stick at least twice now. I'd have to say my "extra mass" is serving me quite nicely. But that's just my opinion.

HF
Thanks for the additional view points !

Can you contrast the before and after results relative to the "increased vibes due to piston mass" ?
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Old 08-27-2011, 11:58 AM   #24161
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Originally Posted by Florida Lime View Post
Thanks for the additional view points !

Can you contrast the before and after results relative to the "increased vibes due to piston mass" ?
I didn't have a gram scale, so I never weighed my pistons to compare. Granted the Athena piston is larger diameter than stock....that's the primary point...isn't it? But it feels very light in my hand. Maybe lighter than the stock piston, but I'm not certain. Technically speaking, there is a difference between mass and weight. They are not the same thing. But not to digress, I'll try to answer your question.

My motor is producing significantly more HP and Torque now. So naturally, that additional "force" is going to be transferred throughout the motor and anything connected to it. Barring any other counter-measures to compensate for said additional forces, they are going to be felt in places where they weren't felt before. That is a common, even expected, result which was anticipated. The further I go, the more likely it will manifest (be felt) at an increasing rate. For me, 50% more HP & TQ is worthy of putting up with extra vibes. Others, maybe not....or, they need to relax their grip, I donno.

My bike, when stock, in original condition did not produce any significant vibrations. I stand by my statements in the original Shootout Article, when Krabill and I were comparing bikes.....what got all this mess started in the first place. With each progression of power increases, I could feel vibrations building. The primary points of contact being the hand grips and foot pegs. Most of the vibes are noticed in the hand grips....the harder I squeeze those grips. But, I ride loose with the hands, preferring to leverage my palm pad and fingers as pressure points, instead of maintaining a stranglehold on the grips. It comes from many years of Observed Trials competition, I'm sure.

The vibes are more now, but not significantly noticeable until I get it above 60 - 65 mph. Under 60 mph, there just isn't enough to spend time discussing. So, riding trails, two track, and fire roads at leisurely paces is no vibe issue at all. Holding the motor at peak HP, around 7,500 - 8,500 rpm I feel a lot of vibes. Strong vibes from strong power. I like the feeling...its good on the trail. Says to me, bike is "ALIVE" and pulling strong. Holding the throttle like that on the slab at 70 - 85 mph is a LOT buzzier. Yes, I hold it in those speeds for long periods sometimes. I live in "No Man's Land"......also known as Wide Open Spaces. You can do that around here, just watch out for antelope, buffalo, and Indians on bareback.

Its a lot easier to maintain those kind of slab speeds now (specifically 70 - 75 mph) when loaded and running into headwinds, crosswinds, or up and down hills. Yeah....we've got hills too, if you can believe it. And even trees and rocks! The original stock motor felt very smooth (vibe free) to me, even at these speeds. But it could struggle to maintain it under similar conditions. It doesn't have vibes, because it simply lacks power....for its weight (IMO). That doesn't make it necessarily less worthy, or uncapable, or less fun. The stock bike will go faster than any posted speed limit I've seen anywhere in the USA....with grace, style, and comfort.....and no vibes.

I wanted something more. I've built up to it. I'm very pleased with the results.....which includes the trade-offs that come with it. What's grand for me, may be unacceptable to another. It really comes down to understanding what you want to do with the bike, and how you want to use it. I'm tuning it for me, not someone else. I'm an expert level rider who can push it hard, but who is spending more & more time casually exploring with each passing year. The bike is now as good as it will get, for me. I'm through tweaking it, more or less. And, I still lust for others.....who doesn't?

If you're losing sleep over wondering what it does to the bike, hear me now and believe me later: it makes more vibes, a LOT more vibes everywhere, more vibes than you probably want to feel, or CAN EVEN HANDLE. It may simply be too much power for you. Accept it as the gospel for someone who knows firsthand.

Now then, if you ever make this type of change to your motor, maybe you'll discover that it isn't so bad and doesn't bother you as much as you had anticipated. Wouldn't that be a blessing? Things could be good as they are, no doubt. But what if, they could be better?

That's all I have to say about this issue.....cheers.

HF
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Old 08-27-2011, 03:35 PM   #24162
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Cry Stuck in 1st Gear

Biffed on the trail, came down hard on the left side. Left peg was packed with dirt and stuck up, but I got that squared away. Until I tried to shift into 2nd gear. Or even neutral. Have tried with engine running and not. Do I need to tear into it, or do I try a bigger hammer first?

HALP!?!?!?

Thanks.
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Old 08-27-2011, 04:43 PM   #24163
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Quote:
Originally Posted by Oblivion View Post
Biffed on the trail, came down hard on the left side. Left peg was packed with dirt and stuck up, but I got that squared away. Until I tried to shift into 2nd gear. Or even neutral. Have tried with engine running and not. Do I need to tear into it, or do I try a bigger hammer first?

HALP!?!?!?

Thanks.
I'd pull the left side cover. Somethings clearly bent. Possibly the shifter fork but you won't know until you tear into it. Lay the bike on it's right side so you don't have to drain the oil.
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Old 08-27-2011, 05:17 PM   #24164
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Quote:
Originally Posted by Oblivion View Post
Biffed on the trail, came down hard on the left side. Left peg was packed with dirt and stuck up, but I got that squared away. Until I tried to shift into 2nd gear. Or even neutral. Have tried with engine running and not. Do I need to tear into it, or do I try a bigger hammer first?

HALP!?!?!?

Thanks.
First check to make sure the shifter isn't bent into/under the case. I dinged mine pretty good and had to straighten it by removing it then beating it with am axe against a rock. Got it straightened well enough to ride. YMMV. I hope it is something simple and would check the shifter before taking anything further apart.
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Old 08-27-2011, 05:46 PM   #24165
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Quote:
Originally Posted by HighFive View Post
......
Its a lot easier to maintain those kind of slab speeds now (specifically 70 - 75 mph) when loaded and running into headwinds, crosswinds, or up and down hills. Yeah....we've got hills too, if you can believe it. And even trees and rocks!

HF

This is what is most important to me. With my current gearing (13/48) I have plenty of power, torque and speed for single track. My current gripe is when I hit the slab and I'm loaded down. That's when I need more passing, head-wind, and hill power.

Looks like this may be my next upgrade...
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