HarleyTechTalk

Much easier to do if one used the '99 - '00 trans case as it allows any year FXR inner primary to bolt on (one threaded hole must be drilled to a through hole).

To answer the mail, if an aftermarket oil pan is used, the entire drive train will bolt in without mods for the most part.

- The swingarm pivot hole requires a decision about which swingarm is being used. The critical dimension is the bearing ID in the swingarm pivot and the ID of the hole in the trans case. Lots of ways to solve this. I have not ever met anyone that did not have 'The Best' way. On one of my bikes I bored the trans case to accept the larger late model shaft, the other bike uses uses adapter bushings in the swingarm.

- If an adapter oil pan is used, the right side foot peg mounting block will have to be clearanced.

- If the oem oil pan is retained, the crossmember will have to be removed to clear the pan. The low cost solution is to use the crossmember and mid controls from a dyna (Barf). 

- If the '99 - '00 trans case is used, the FXR inner primary will have to have a hole drilled through.  There is a bolt that attaches a ground strap to the back side of the trans case. In OEM form, the bolt is accessed from the right side of the bike and is under the transmission. This bolt goes through the trans case and threads into the inner primary. The FXR inner primary will have to have that threaded hole drilled to accept a 5/16" bolt. This bolt will be the third bolt that goes through the inner primary and into the trans case, located at 6 O-Clock behind the clutch basket.

- If the oem FXR inner primary case is used, nothing else is required to the right side. All OEM mid controls and floorboards will bolt on in their factory configuration.

- Conversions using trans cases other than '99 - '00 with require some fabrication to use factory mid controls or floorboards. The will require a vertical mill.

- The oem top engine/coil mount will work, but not really ideal as the TC coil mounts differently. I made a small run of top mounts that accept the oem TC coil. Looks factory.

- Throttle bodies will require the bracket on the top tube that the upper stabilizer link to be cut off and a different one welded in its place. In its oem configuration, the mount and link prevent throttle bodies from being installed.

Electrical and ignition requirements are outside of the scope of the OPs question so I am limiting my response to only the mechanical requirements to put the drivetrain into the chassis. 

Best of luck with your project.

Quote from: Shep236 on April 16, 2024, 08:05:52 PMThanks for the replies.  I ended up scoring a pair of 2017 xl 1200 heads for 300 bucks for the pair.  I'm gonna utilize those along with the 1275 big bore kit, and a hsr42 Mikuni carb.  Just haven't decided on what cams to run with it yet.  Was thinking the andrews n4 or n8s.  Just for ease of use really.

Either of those cam grinds will work with the 10ish:1 compression ratio you get with stock EFI 1200 heads over a flat top 1275 kit. But keep in mind that both of those are very old cam grinds, designed around the small valves and much inferior 1986-2003 hardware. The later heads have larger valves, 7mm stems, and a factory beehive spring pack, with an entirely different set of capabilities and limitations.

Let me give you an example. The last Buell product to use the old hardware was the 2002 X1 & S3 models. They came from the factory with "B" cams (.497 lift) and a 6800rpm rev limit, and at 6800rpm, the valve train was already starting to lose control, it was really marginal.

The very first HD product to use the new 7mm/beehive hardware was the Buell XB9, which came out in 2003. It had a factory 7500rpm rev limit and a two year warranty and valve train failures were almost unheard of, it was stable all the way into the limiter. This despite the new springs having roughly the same spring pressure as the old stuff. The "E" grind cams (.551 lift) in those motors had a lot to do with achieving this, with a lobe design that took advantage of the higher lift ceiling to ease the transitions between the ramps and the nose, making for a more stable valve train.

HD really showed the way on this, but they are not the only ones making cams like this for the new hardware. I'll stop there because I don't want to sound like an advertisement. My main message is that when you use cams that are made for the old hardware, with heads equipped with the new hardware, you're leaving a lot on the table.

But yes, using low lift cams does simplify installation with respect to cam box clearances. Clearancing a cam box is not difficult however and personally I would not let that deter you. It's just not that big of a deal.

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Found this for the Wood Performance WM-22XD

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This video may help understand the physics or ring rotation too.  One good takeaway is the description of how the common 45 degree crosshatch angle is calculated.  the other is what deviation from the prescribed angle does. 

I picked up several of these gauges at their SEMA booth about 10 years age.  They have a thin pad on the back to stabilize then while you inspect the angle.

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I had a phone conversation with one of the techs at Total Seal last summer. He confirmed that rings do rotate by design. He said if for no other reason to keep from having a score mark in the cylinder if the gap of the ring never moved. I do remember that two cycle dirt bike motors that I owned as a kid were pinned to not rotate. But I always assumed that was to keep the ring end from grabbing a port in the cylinder.

This was just the first video I've ever seen that just spells it out. Like the link to the Motortrend article, they speak to ring rotation if you read down to about halfway.

Cool quick video. My first thought before watching was: "Then why does it matter that the ring gaps are oriented they way they are when being assembled". They addressed that.

Zach

Quote from: FSG on April 16, 2024, 09:25:32 PMa good pic is worth a 1000 words   

Speaking of pictures...I measured the old vs. new rotor and found the below numbers.
When I installed the new rotor a couple weeks ago, I left the shim in and therefore the sprocket would have been 0.020" more outboard than the previous rotor..... Would that have been enough to cause the knocking I was hearing? or is it still more likely tied to the comp either being too little torque or the nut bottoming out?

Regardless, I'm going to shorten the comp nut today. Then I'll reinstall, torque properly, and make doubly sure the sprocket alignments is correct.

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