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Old 11-08-2011, 09:23 PM   #11311
Garthe
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Quote:
Originally Posted by Frapper View Post
Cheers man.
So what do you guys reckon is the highest compression ration I can run in my bikes.
I've owned a few CRF's that i bumped the compression right up with only power and a little extra heat as side effects.
The XR650R head ,in my opinion should hold at least 13 to 1.
http://advrider.com/forums/showthread.php?t=736864

PM this guy (Cycle Wizard)...he know his shit about Honda 4 strokes.

Cheers Frapper.
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Garthe screwed with this post 11-08-2011 at 09:25 PM Reason: splleing
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Old 11-08-2011, 09:38 PM   #11312
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Quote:
Originally Posted by Garthe View Post
http://advrider.com/forums/showthread.php?t=736864

PM this guy (Cycle Wizard)...he know his shit about Honda 4 strokes.

Cheers Frapper.
Dude i know the Wiz,we're cyber good ole boys.
Just after what most guys would use or believe in here.
The Euro guys are retarding(motarding) and going around 12 to 1 but not much more.
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Old 11-08-2011, 09:48 PM   #11313
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Ever since Johnny 55 posted his picture of the ammo box on his skid plate. I can't stop thinking about doing the same thing...well sorta.



I have a few projects that I have to take care of first. But then, I'm going to use the above measurements and mock up a aluminum box. I don't care for the lid in the above design. I don't want it hinged and I will use the skid plate as one of the sides of the box.

When I get the XRR on the lift and have the box mocked up...I'll post up pictures.

Can anyone weld aluminum?
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Old 11-08-2011, 10:59 PM   #11314
larryboy
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Quote:
Originally Posted by Garthe View Post
I have a few projects that I have to take care of first. But then, I'm going to use the above measurements and mock up a aluminum box. I don't care for the lid in the above design. I don't want it hinged and I will use the skid plate as one of the sides of the box.

When I get the XRR on the lift and have the box mocked up...I'll post up pictures.

Can anyone weld aluminum?

May as well hang a coupla ammo cans off the thing.







You can rivet a box together like that pretty easy and it will stay together if you use a pneumatic rivet popper.
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Old 11-08-2011, 11:04 PM   #11315
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One post newb doing a ride report about an XRR trip:

http://advrider.com/forums/showthread.php?t=740400


Let's give him a warm welcome over there.
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Old 11-08-2011, 11:30 PM   #11316
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Quote:
Originally Posted by Garthe View Post
I don't want it hinged and I will use the skid plate as one of the sides of the box.
One of the constraints is the proximity of the exhaust above the box...make sure your access is such that whatever lid you use, whether opening it or operating it, does not go near that hot component.

For water/dust proofing it is better to not use the skidplate as a back wall for your box.

A point of failure is also adviseable, you don't want your box to hook up and rip of everything...much better to just lose the box. Mine fastens with 4 8mm bolts (quite weak) but to date, I have not lost it...just a thought.

Would be interested to see what you come up with.
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Old 11-09-2011, 12:16 AM   #11317
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Frapper,

bumping the c/r means you'll have to bump the octane rating of the fuel, thus your Q can be A-ed with 'what fuel you're going to run?'
12 will require a 95 octane with 30 C-ish ambient, but possibly you'll get away with 93. 13 in a big pot is looking for trouble unless you put avgas (100+) in. Nice, sure, but I'd hate to carry that 210L drum on the back in the outback



RF,

I, sortof, definitely formulated different in tone than XRr did, second the idea of telling us about your sandrail which you, zero offense intended, meant or even suggested, 'home-built' yourself. It looks a work of art, and now that you've admitted you built it yourself you may as well show it off properly.
Not here no, but somewhere else where you think it proper, and then posting a link here no-one will hold against you, most certainly not me.

Why? I lurve wheels, 2 and 4, especially when connected to a toy for boys, even more so when it's not a neat off-a-rack toy. And no, I don't expect to see or find a set of cad-files to enable anyone to copy & paste, such would ruin the uniqueness of your built.
Please?
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Old 11-09-2011, 12:25 AM   #11318
Beserker
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Frapper,

It looks a work of art, and now that you've admitted you built it yourself you may as well show it off properly.
+ 1...It is a boy an' their toys thing...
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Old 11-09-2011, 01:04 AM   #11319
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[QUOTE=BuRPsa;17264441]Frapper,

bumping the c/r means you'll have to bump the octane rating of the fuel, thus your Q can be A-ed with 'what fuel you're going to run?'
12 will require a 95 octane with 30 C-ish ambient, but possibly you'll get away with 93. 13 in a big pot is looking for trouble unless you put avgas (100+) in. Nice, sure, but I'd hate to carry that 210L drum on the back in the outback


There's good fuel available everywhere in OZ so yea no issue.
I'm goin to go 12.5 or 13 to 1 like i said the head on the big XR is an awesome design so it'll hold some comp without having to pull too much ignition or go a little rich..
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Old 11-09-2011, 01:40 AM   #11320
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Wonder about that (having to bump the octane up). Have put hi-comp pistons in all my bike except the XRR, and none of them have had any problems whatsoever with the cheap 87 octane?
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Old 11-09-2011, 05:54 AM   #11321
BuRPsa
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Well Frapper,

it's your bike, by all means do, and pls keep's informed.
Just wondering how you're going to control the timing though, your ".. without having to pull too much ignition ..", as I dunno any way to fiddle with that lil' black boxie.


Burning any midnight oil perhaps Gatos? Or busy with maybe?
With some engines, especially liquid cooled squished designs, one gets away with shite fuel, but pls keep in mind that some ems' adjust settings to save the engine. Actually, I think to remember that the GS1150 does, put in catpee & it'll get you to the next filling station.
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Old 11-09-2011, 06:37 AM   #11322
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Frapper, I look forward to hearing how it works. It may be worth ceramic coating the top of the piston for that extra little bit of detonation protection. Of course make sure to chamfer all sharp edges before coating as well.

There's more to it than just the head/piston/combustion chamber though, cam timing/profile/lift and bore/stroke also play a part. I would guess that more aggressive cams paired with the high compression would work out well. I know that on a TL1000S (996cc v2) you can run 14:1 CR and big cams on pump gas no problem. Still smaller pots than an XR-R, but not hugely so. I haven't tried it, but I've heard it won't run that compression with stock cams on pump gas all that well due to pinging at low-mid rpms.
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Old 11-09-2011, 08:02 AM   #11323
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This is a proven cure for high C/R motors pinging(fuel with not enough octane to resist detonation) and need for excessive timing advance. You can dimple the tops of the pistons and/or the combustion chambers. Simple to do and not super picky on where and ow much it is done on most chambers. I have used this method to knock almost 10* of timing advance on small block chevy race motors. Should work very well for the XRR. The nice thing about this mod is the is not ill-effects if you do it wrong. As long as you do not crack the head or piston! That is hard to do as you are not hitting the head or piston with much force. I have used a drill with a 3/16" bit to make small dimples about 3/32" deep. Take a center punch and make out your area and then dimple it. I have used just the center punch aswell. It works just fine but requires too much "hammering" to get a deep enough dimple to be effective. Anyways, there is a solution that drag racers have been using since the 70's


EDIT: Be sure to file down any burrs as they can create hot shots that cause detonation as well.






Here is the area you dimple on the pistons. There is no real need to dimple the lower landing of the piston, just the top of the dome, unless you high comp piston has no dome but most do. Not 100% sure on the XRR.


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Old 11-09-2011, 08:29 AM   #11324
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^
so, it seems to me that you're effectively increasing the size of the combustion chamber by doing this. yes?
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Old 11-09-2011, 08:38 AM   #11325
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^
so, it seems to me that you're effectively increasing the size of the combustion chamber by doing this. yes?


Very slightly. Mostly it alters the flow of fuel and air to promote a better burn rate. After doing this mod of my last 383, the static c/r was only .04 less then the c/r before I started. So you are really not losing anything.
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