I don't know about the CR rods although I've heard them mentioned but the XT350 pistons would likely not work out. The XT engine is a 4 valve per cylinder DOHC design with valve reliefs molded into the piston crown to match. A better possiblity would be the YFM350/400 ATV piston. That's a SOHC two valve 83mm bore design.
There is a tech note in the XS650 motorcycles, and I can't remember the number but I wrote down the different combos with the CR500 rods (144mm length) 782cc = cr rods with 82mm Honda Hurricane pistons, Xt 350 pistons @ 86mm = 860cc. Halco says, for XT 500 Yamaha pistons you must use European long rods (130mm + 10mm 533 rods) These are 87mm = ??cc. For standard big bore Suzuki SP 370 pistons 85mm high crown. I believe they mean for the CR500 144mm rods. This whole parts bin thing is very interesting to me. The CR 500 rods are 144mm length and you must use pistons that have the same higher wrist pin either 14mm or 4 depending on your present length rods. the rod to stroke ratio for the 144mm is 1.945 Hope I got that mostly right. Cheers, 50gary
XS650Motorcycles.com It's the Bob Bertaut site. I forget which number the piston info is listed under but that's where I found the information. One of the members from the old Garage site posted the info there and email me but that was quite some time ago. Cheers, 50gary
Eric they have those numbered postings and I usually write down what I'm interested in and save it. I just can't locate the scrap of paper. So day I'll actually have to learn how to use this computer. I do some checking. Cheers, 50gary
;D ;D ;D I posted all that stuff originally Honda CR500 MX rod kit fits fine. I have list of pistons that fit with it. All will need some modification, but even a small lathe can cope with machining aluminium alloy and making bushing for small end. I found some more parts that fit, I think a Polaris (watercraft) con rod will go in, its 140mm long, I've got a crank to take apart and get the numbers. Only 'problem' is small end is 25mm so will neeed bushing. It would be same length as european rod so you can use Suzuki SP350 piston to get 840cc.
Last Edit: Jan 22, 2007 0:33:00 GMT -5 by 1crazypj
More cc if you go up in bore diameter. Longer connecting rods will help to elminate side thrust in the cylinder and the piston will spend more time at TDC which is a good thing. Indy cars will have a stroke to rod length ratio of up to 2.4 to 1. Take the stock 74 mm XS stroke and divide into the 130/140/144 mm rod lengths you'll get ratios of 1.756 to1, 1.89 to 1, 1.945 to 1 Cheers, 50gary
r80rt: :)This is a splendid write up, THANK YOU!!!!
Dec 26, 2015 16:54:05 GMT -5
mashermoto: What the what is this shoutbox for? Or should I shout, WHAT THE WHAT IS THIS SHOUTBOX FOR!
May 12, 2016 22:22:21 GMT -5
motormike: Good Day ...just a FYI.. Wild Cat is this Labor Day weekend. Still go'n on. A few 650's still make the scene. Various rides at different skill levels each day.. awards dinner sunday eve. BS in the park'n lot after dinner.
Aug 23, 2016 7:57:01 GMT -5
lsettle: First post in over 6 years!
Aug 28, 2016 19:45:17 GMT -5
kardon: Wow quiet here, where did they all go.
Oct 7, 2016 2:18:13 GMT -5
gggGary: XS650.com LOL
Feb 16, 2017 20:49:02 GMT -5
buell88: Anybody have any idea who built the xs650 tracker used in the Draggin Jeans Ad on Pipeburn?
May 16, 2017 16:24:09 GMT -5
joshua: The regulator/rectifier unit I got from Mikes PMA has closer hole spacing than original. Are we supposed to mill the holes to fit?
Jun 7, 2017 19:25:58 GMT -5
joshua: My bad. I found the bracket they supplied to mount the rectifier/regulator... Uh oh. How is this meant to work? Which way is it meant to mount? Looks like I have to use some spacers or something. Good instructions would be nice.
Jun 7, 2017 22:09:52 GMT -5
craig8johnson: Not sure if this is the right spot or not but oh well...
Jul 11, 2017 18:04:15 GMT -5
craig8johnson: I'm checking the charging system. I'm afraid I might have fried the last battery. With the solid state regulator (after market) what should it be charging at. The book says, I think, 15 volts. I'm hitting 17 when revved. Is that too high?
Jul 11, 2017 18:06:19 GMT -5
gggGary: Yes 17 volts is too high, about 14 volts is max, sounds like you don't have the right regulator or it's wired wrong.
Jul 13, 2017 6:54:33 GMT -5
dean: Just saying Hello, new member who is going to fix up a 79 XS650 that has seen its better days. I will definitely have lots of questions coming up.
Jun 23, 2018 16:45:32 GMT -5
tt650: Trying to breathe life into a 1980 that's been stored (indoors) for 25 yrs. Air filters are dry rotted. Have cleaned carbs but she only runs briefly on choke then stops. Need jet setting info and other ideas that might help her idle and rev.
Jul 3, 2018 19:15:19 GMT -5
trix13: Hey everyone! New to the forum and am fighting those gremlins!! New charging system, ignition switch, coil and fuse box. Resistance is higher than normal on the ignition pick up so I'm trying to find one. No such luck yet.
Aug 16, 2018 8:50:48 GMT -5
trix13: Also, even though all of my connections are clean, I cannot seem to find out why , when at higher rpms, I hit the signals and the rpms pulse with the signals...hahah. same with the brake light. I appreciate all input!!
Aug 16, 2018 8:55:08 GMT -5
bob99: how do I post a question. I am new to the forum
Jun 6, 2019 10:52:10 GMT -5
adlpc: Hello all! Been enjoying your edifying posts and discussions - and as a fan of the XS650 since my early teenage years happy that I now own a 1980 Special which I plan to turn into a vintage half faired racer. Thank you all for being here!
Oct 1, 2019 0:58:56 GMT -5
jimothyj: Hello everyone, I just joined & wish would have known about this site in 2014 when I brought my 1974 TX650A back from the grave. I have spent a good deal of $$ and alot of time on it. Just painted it and working on electrical, I will post pics soon,
Apr 10, 2021 2:14:13 GMT -5
louisvan: trix13 - I had a problem with my 1975 SX650. When I got to highway speeds, the engine lost power. The problem was in the connectors. At a certain vibration and the wind pushing on the wiring loom, the connector lost continuity. A bad crimp to the wire.
May 20, 2021 1:19:09 GMT -5