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Nummie

XL600R, XR650L, XR600R bore & stroke ?

15 posts in this topic

I couldn't find a thread that spells out what the bore and stroke are for the XL600R, XR650L, and XR600R.

Can someone either point me to the right thread or clue me in ?

I am just wondering what works with what.

Thanks.

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OK, so after some more searching I found the following specs:

Model bore stroke

XR600 98mm 80mm

XL600 100mm 75mm

XR650L 100mm 82mm

Can someone confirm this stuff for me?

I read that they all use the same connecting rods, but the difference in stroke is made by changing the deck height of the piston with different locations of the wrist pin. Is this true ? (I don't think so)

I also read that the different stroke is gained by changing the centreline distance of the connecting rod big end bearing to the main crank bearings. (this sounds more likely)

If the above specs are true, then I am assuming that it would be possible to use an XL600R head on a XR650L cylinder and bottom end.

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that looks all about right and yes the 600 head will work. i thought about doing the twin carb 600 head on my L, then i bought a 500 dollar fcr!

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Yes that is my understanding. Not sure if they all use the same con rod though. the pistons all have different dimensions from the top of the piston to the center of the wrist pin.

The older XL used smaller diameter cylinder bolts. It is my understanding that the older dual carb XR600 heads will mate to the XR650L cylinder.

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The con rods are the same...the problems with combining cylinders and heads from different models stems from different size head bolts. I tried tapping the XL cylinder to 9mm from 8mm, but the bolt length is considerably different. this is still not a big problem, but be very precise when machining the dowel pin holes to 12mm. If you don't get them exact, your head will not sit correctly on the cyclinder. See this thread:

http://www.thumpertalk.com/forum/showthread.php?t=472106

It's very doable to combine top and bottem ends, but it's never as straight forward as it seems, even though all these RFVC engines are VERY similar. Crmc33 knows lots about this stuff. For more info on the differences between all the RFVC engines (GB, XR, XL, NX, XRL) do a search for GB500 FAQ on google and the first page that comes up explains it all.

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Stay tuned. I'll be attempting to install an '84 XL600 top end to a '93 XR650L next week. I'll review all the parts used and if I was successful. Wish me luck! Bruce

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Stay tuned. I'll be attempting to install an '84 XL600 top end to a '93 XR650L next week. I'll review all the parts used and if I was successful. Wish me luck! Bruce

you got my ears! good luck.

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OK, so after some more searching I found the following specs:

Model bore stroke

XR600 98mm 80mm

XL600 100mm 75mm

XR650L 100mm 82mm

Can someone confirm this stuff for me?

The XR600 has a bore of 97mm, not 98. The actual displacement is 591cc from a 97 x 80mm bore and stroke; a 98mm bore would yield 603cc.

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Hi Guys,

I am a newbie to this forum so fogive me if I have placed this in the wrong thread.

I have a PD03 xl600r 100mmX75mm bore and stroke. The piston and barrel are beyond repair.

Spares are difficult to find over in the UK (I am currently sourcing parts from the netherlands)

I have managed to get hold of an xl600lmf barrel. piston, and crank assembly, Having researched I believe the heads are interchangeable (previous thread) will they fit straight in to the PD03 crank cases? or is that just wishfull thinking.. I know the later lmf was electric start but were the cranks similar bearing wise? thanks guys.

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it seems everyone with a XR600 is boring it out for better horsepower. however as my xl600 already has a large bore, could i make whatever change the XR has to get its longer stroke? (connecting rod, whatever it is) and get some better torque?

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You would need to change the crankshaft and piston, but I have been told that the longer stroke XR600 crank does not fit in the XL600 cases. I haven't tried the swap so I don't know how or if that is accurate information. It would probably be easier to just get a complete XR600 bottom end anyway.

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FWIW I just put a 90's 9mm xr600 head on an '85 xr600 8mm cylinder.

I used the old 8mm head bolts. For the locating dowels, the newer big dowels fit over the old smaller dowels, so I sawed one in half and used it to sleeve the holes in the head.

I've only put about 5 miles on it so far, but it's running good so far. I'll post back if it grenades.

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the xr crank and piston will fit right in there, bore the cyl to 102mm making654cc with porting and you will be amazed.

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