So you think this is more feasible/going off the crank? If i go off crank/what sort of join? welded? sleeve and pin?
When I modded the tank to fit a radiator fan it was pretty easy, I took a heat gun and warmed up the area slowly not getting too close with the heat. As it softened I pressed it with the wooden handle of a hammer and it slowly gave way, it wants to return to shape so you have to keep pressing it as it cools. I never felt like it was on the verge of making a hole or ruining the tank, if anything I felt like I needed to heat it more. It never got real soft, more like it got flexable. I took a fair amount of pressure to deform it where I wanted but I was being carefull. The FCR is slightly bigger than the stock carb so there's not much deformity required. I would verify the different size carbs the Sudco bell adapter fits before committing to purchasing any carb. I don't know if the XRR cables bolt up but the CRF450 has a similar throttle as the XR and uses an FCR so it's cables should work fine. I just sent off my 39mm FCR to a guy who's boring it out to a 41 and doing some other mods to the carb, for that it runs $200, less if you stripped the carb but it's fairly complex for a MC carb so I left that to him. The RMZ runs the larger 40 or 41mm FCR, that's probably a better carb to look for. As for the specifics of the FCR conversion, I think Jesusgatos wrote some details much earlier in this thread (about 2 or 3 years ago). He might be willing to share more info if you PM him. It's also talked about on thumper talk. I liked my TM40 for the most part and it does make the bike come alive due to the accel pump, nice wheelies. The 650 really responds to the squirt coming off idle, almost like a different motor. But like I said, after running an FCR I'm a believer in that carb and that's the route I'd go if I was swapping carbs on the XR. It's a more refined piece of engineering compared to the Mikuni, if you look at the parts breakout, there's about 2x as many pieces to an FCR. It's crazy expensive in a kit but with some research and finding a good deal on a used carb it can be done pretty reasonably. You'd want one off a 450, it's going to be the closest to the what the XR needs but it's still going to need some different jets and probably a needle to work right. Here's some info: http://www.thumpertalk.com/topic/891049-xr650r-fcr-conversion/ http://forums.dustdevilsmc.com/forum/index.php?topic=404.0 http://www.supermotojunkie.com/showthread.php?119801-XR650R-keihin-FCR-40-pls-help-!
I just wanted to point out that's how they typically do it. As for the details, you'd probably want to get over on a flat track forum and ask those guys specifics. It's done with some kind of extension on the crank that extends past the stator cover and the cover is modded with a seal. It takes quite a bit more power than a cordless drill or impact to fire one up, I've seen the tool at the races and it's a big honkin thing with a crossbar so the operator can hold it against the torque of the tool. Beyond that, I don't know much about it, sorry.
Please let me know if you find out any info about running a 39FCR on a XR650R. I've got one sitting at home that I'm looking to fit to my XR... Already got the adapters made to fit the intake manifold and airbox. Just need to get home for a holiday so I can finish it up. A reputable bike mechanic/tuner I know of reckons the XRR pulls better with the 39 than the 41! We'll have to find out. Apparently the acerbis tank works fine with the FCR, no heating required. Sent from my LT25i using Tapatalk
Grego, you got the hot start button, I think that would really help get the XR running after a fall. Adam, The 39mm is off my KTM 525, we're at 5K' here so all our motors take a pretty good hit on HP, almost 1/5th which really sucks. On this motor I just put in big valves, a 540cc kit and a mild cam. The 41mm carb compliments that build with the extra flow. The guy who did the work has a some other mods he does to them, it's supposed to feel like FI. I know that crazy statement but apparently he's really good at getting that carb to work perfectly with that motor. It already did pretty damn good. DS mileage usally runs right at 50mpg on these bikes. I expect to loose a couple mpg but it won't be far off as long as don't get carried away with the throttle.
Anybody see that swingarm tool that just sold on eBay for $66? Yikes!! Somebody didn't do their research! Sent from my iPhone using Tapatalk
yeah... not sure if the hot start and choke knobs are accessible with the tank on (got a clarke 4.3g fitted now but looking at getting a 7g IMS for long trips). might have to convert them to cable operated. i originally bought the 39FCR to use on my '81 XR500R. unfortunately it doesn't fit due to clearance issues between the throttle assembly and the frame. i'll give it a bash on the XRR, as is, and see how it goes. the guy who will be setting the bike up has dyno'd another XR650R with similar mods and a 41FCR... it will be interesting to compare results.
anyone got details on making a set of tools? what size sockets do you need to use? i did a search but havent found the details yet... thanks
13/16 inner and 1-1/8 outer there is a right up if you google "borynack xr650r" or something like that. Sent from my iPhone using Tapatalk
Here is a link to the tools on Pig Pen http://www.xr650r.us/preload/ Sent from the depths of my pockets
I was way off! Haha. And I just made the tools two weeks ago too. I'm a dork. Sent from my iPhone using Tapatalk
The XR's only have found few HRC high compression pistons , they are pricey but very rare , so if you want one dont miss your chance .
