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So I was doing some digging around on the interweb for a winter project and i found this local company out of Plymouth, WI that offers a 90" bore kit specifically for the XR. Was just wondering if anyone has attempted this yet or what your opinions on this were. Also was wondering if anyone has found a 6-speed upgrade for the transmission on these bikes. I know Baker makes something but haven't checked compatibility for the XR. THANKS GUYS
 

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Whistling Dixie!
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Got a link?
 

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Whistling Dixie!
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Dayum! 1474... The answer to your question is way above my pay grade.
 

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It will be just like installing an 88" cylinder kit, albeit with their 90" Nikasil plated cylinders and their pistons that fit the jugs. The cooling fins will be a little bigger and fatter than HD jugs. It looks like they have the XR kit, so you can use the XR's oil-cooled heads - but you would want them ported to optimize to the new jugs. You should plan on new cams too, to get the most out of the build. You may have to tweak the oil lines to the heads, to get them to fit around the jugs. You'd probably want to go to an XL clutch with something like a Bandit clutch pack to handle the power. Plan on doing the crank too, to handle the power. Tuning would be just like for any other build, but you will expect to plus up the maps a bit from what an 88" would take, because of the extra cubes. I like the SEPST, TTS, or TMax for it. Slightly larger fuel injectors will probably help it.

You'll find lots of opinions out there about the Nikasil cylinder kits. The cylinders cannot be honed, so they are pretty much one-time use. They can be replated by RevPerf, but that is expensive. Many people don't like this, so they don't like the idea of Nikasil. Piston choice is limited because of the extra size of the jugs. You don't have to worry about over-sized pistons later, because as mentioned, you can't hone worn jugs.

Some people claim short lives for the Nikasil jugs, others run them for quite a while. My thought is that many people that have had problems with the jugs have had other problems with their builds that contributed to the problem. You'll see a number of pics in big twin forums re vertical wear marks in Nikasil jugs. It does not always happen.

Personally, I don't think I would do Nikasil 90" jugs on the XR. Unless, of course, one rides the XR like a Big Twin HD - that is low rpm. Pushing those pistons constantly between 4k and 6k rpm would scare me.

That said, I have run a RevPerf 98" Nikasil kit in my FatBoy for about 8 years now. Early on I had a crankshaft problem that took out the bottom end and I ended up with scored cylinders. (The problem with a pressed crank and extra HP - the cure was a trip to Darkhorse for the crank.) That resulted in getting a new cylinder kit from RevPerf. They did discount the replacement. The 98" builds a respectable 105 to 110 HP in my big twin, and about 100 ft-lbs of TQ. I've run the Nikasil for quite a few miles, including a three week, 6,000 mile cruise through the northern states. I like my 98" build, and I do run it up to 6,000 rpm quite a bit both on the drag strip and banging through the gears on the street. That said, I ordinarily cruise that bike in the 2k to 3.5k range. Also, the 98 was just the core of a full build in my other bike - you want to think this back from a full build perspective, rather than just thinking about piecemealing in a piston kit.

So, try it out and let us know what you think! :scooter:
 

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Jack of all trades...master of none.
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For that price, if it produces good numbers on the dyno, that's a pretty sweet deal. I would definitely be interested in a kit like that!
 

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For that price, if it produces good numbers on the dyno, that's a pretty sweet deal. I would definitely be interested in a kit like that!
There is really nothing cheap about it. You're talking $1200 plus tax and shipping, just for cylinders and pistons. Then head work, cams, pushrods, a clutch upgrade, and exhaust at a minimum. Not to mention splitting and machining the cases. And preferably pinning or welding the crank. Throttle body work, or replacement and fuel injectors may help it. And one needs a full tuner and a bit of dyno time to get it tuned right. This is not a quick parts swap for a few extra HP.
 

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There is really nothing cheap about it. You're talking $1200 plus tax and shipping, just for cylinders and pistons. Then head work, cams, pushrods, a clutch upgrade, and exhaust at a minimum. Not to mention splitting and machining the cases. And preferably pinning or welding the crank. Throttle body work, or replacement and fuel injectors may help it. And one needs a full tuner and a bit of dyno time to get it tuned right. This is not a quick parts swap for a few extra HP.

I'm thinking, even if you have the skills, physical facilities, and special tools needed to do the labor yourself, realistically this is at least a $4000 project. If you are paying labor you are prolly looking at $6k. Minimum. :yinyang:
 

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Live life like u mean it !
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Seems like a great idea at first glance, but I think in reality, well, the way I see it, is that it doesn't make any sense to spend that sort of money in the pursuit of more power and performance on a road going XR.

It's still a hefty, mildly sporty road bike, what ever you do to it.

The main thing is to get it to handle as tidy as possible and rev as smooth and cleanly as possible...then just enjoy the character and the attitude of the thing. :scooter:
 

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www.jp2code.net
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Also was wondering if anyone has found a 6-speed upgrade for the transmission on these bikes. I know Baker makes something but haven't checked compatibility for the XR. THANKS GUYS
Nope. There is no 6-speed option for our transmissions. It seems there is no room inside, from what I remember.

Your easiest option to drop the engine speed by about 500 RPM is the Scotty Mod. It even retains the speedometer's accuracy.
 
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Go for it man, you can do this, a torque monster XR, put a big arse windscreen on it, panniers, floor boards, a nice comfy seat and tow a trailer all over the country side with it.
 

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