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cantregister

XR650L piston specs

13 posts in this topic

I recieved a new "high compression" piston from XRs only this week, when I

looked at the box it was for a 600R. I called XRs and was told "it'll work". I called

JE piston and was told it is .060" shorter than the one I ordered. Does anyone know what the comp height on a OEM piston is? I don't know how much compression I will be losing with this piston. I'm reluctant to send it back, as it is the third one they have sent me and is the closest to being right, I'd like to get this project done before spring.

Thanks

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From what you posted I would not use it..

JE Pistons should be able to give you the specs your after...

Do you not have the old one out yet...?

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I haven't torn it apart yet, I didn't want parts strung around all winter, I have been a month and a half now just trying to get a piston. I'll call JE again.

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Definitly look up the part number of the piston. The stock bore on a 650L is 100mm, and only 97mm on the 600. I think that they are the same otherwise, as in the same wrist pin. Going to a 100mm bore is a common mod for the 600, so it might be the right one for your 650L. You just need to check.

I just took a quick look at the JE website and the part numbers appear to be different. The JE part number is after the word "Round." http://www.jepistons.com/pdf/2006-moto3.pdf

1985-2000 XR 600R Stock Bore: 97mm • Carrillo Rod #HOXL6<05276 See Page 32-33

629cc 100mm +3mm 10.5:1 386g Round 128995 XH10000 945-2850-14-51C 945-073-MW JC7896 Bore & Hone

640cc 101mm +4mm 10.6:1 397g Round 128996 XH10100 945-2850-14-51C 945-073-MW JC7828 Bore & Hone

654cc 102mm +5mm 10.8:1 395g Round 128998 XH10200 945-2850-14-51C 945-073-MW JC7957 Bore & Hone

1993-2006 XR 650L Stock Bore: 100mm

644cc 100mm STD 10.5:1 399g Round 130682 XH10000 945-2850-14-51C 927-073-MW JC7959 Deglaze Only

650cc 101mm +1mm 10.5:1 412g Round 138978 XH10100 945-2850-14-51C 927-073-MW JC7960 Bore & Hone

657cc 102mm +2mm 10.5:1 406g Round 139550 XH10200 945-2850-14-51C 927-073-MW JC7973 Bore & Hone

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Sounds like nothings easy, huh! If the je piston is shorter from top of piston to wrist pin I definately would not use it, if the piston is shorter to the skirt I would probably use it. However why they sent you a 600 part to begin with is a bit on the shady side, I would call xrs only and speak with Kamell. I believe he has always given me a straight answer. If its the 100mm piston looks like the 600 part is 13 grams lighter than the 650 part, which is appealing to me. Good luck, let us know what the outcome is. Oh, welcome to TT.

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From what Freddie at xrs only told me the 650l 10.5-1 piston is closer to 11.0-1 and the 600r 10.5-1 piston will lower the comp to 10.5-1 so you dont have to run race gas. Trust xrs only they have been building these motors for a long time.

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If that piston is indeed for the 600, you'll have problems. As the stroke increased on the RFVC motors, Honda "hid" the extra length in the wrist pin to piston top distance because the rods are all the same length. It's easier to do this than make a bunch of new cylinders and rods, etc. So if you use a 100mm piston for an XR600 on an XR650L, you'll definitely have issues with compression to say the least. More like kiss your head goodbye.

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I sent the piston back, when I called the first time they recommended the 650l

piston, when I returned the first two that were for a 650R, I was told, "as soon as the right piston comes in we will send it out for ceramic coating and get it right out to you", makes me feel like they are trying to sell me whatever they have in stock. I sent this one back at my own expense, and will ask them for a credit towards an exhaust system. I don't want to be a shithead to deal with, just want what I ordered.

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If that piston is indeed for the 600, you'll have problems. As the stroke increased on the RFVC motors, Honda "hid" the extra length in the wrist pin to piston top distance because the rods are all the same length. It's easier to do this than make a bunch of new cylinders and rods, etc. So if you use a 100mm piston for an XR600 on an XR650L, you'll definitely have issues with compression to say the least. More like kiss your head goodbye.

A 600r piston will work I just put one in my bike and it runs great. Like cantregister said the JE 10.5-1 piston is .06 shorter (shorter meaning the pin is closer to the top of the piston)then the 650l piston. The 600r is about .03 taller then the stock 650l piston and it dosent have the dish on the top wich puts the compresion around 10.0-1 and it is lighter also and you dont have to worry about what kind of gas you run.

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I just got the JE 101mm 10.5:1 XR600R piston (from eBay by accident). Will it fit in my XR650L? If so, what are ALL the differences, and why wouldn't I just use the appropriate XR650L 101mm 10.5:1 piston from JE?

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The piston will work fine its just like in between stock and a 10.5-1 650l piston my bike runs great. My buddy Had his motor done by XrsOnly and they used the 600r piston to keep the compression down a little so you don't have to worry about what gas you put in it.

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