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eschonda

XR 600 head ,on a XR650L ??

16 posts in this topic

Will the xr600r head, fit on a XR650L ?? And is there any performance gains to be had?? Looking for more performance out of the L motor? Thanks!! : :thumbsup:

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I think the xr600 head would fit on the 650l wouldn't think you would gain any thing on performance Unless one cam is better than the other different duration higher cam lobes. Check out the specs on both before you do any Changes. :thumbsup:

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from what ive heard the xr600's motor is the same as the L's just the L has wider bore and a longer stroke

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I'd look at ways to increase the flow in what you already have.

Such as a cam with longer duration, more open flowing exhaust ,

and some jeting to match, and maby a port job.

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The L has lower compression and more mild cam... Fix that first to get to XR600R status before going all custom.

If im not mistaken, the 650L has smaller valves. A 600 head has a hotter cam, and slightly larger ports too. Although I'd do the head on the 650, port it stage one cam, new guides and bigger valves with 3 way seats.

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I thought that I read somewhere that the 600r head,had bigger ports, and possibly larger valves as well. That's why I asked. But I need to know for sure ,before I chase one down, I already have a Webb cam, with hardened rockers, 101mm ,11.5-1 piston, white bros stainless header with a Thunder Alley silencer.Edelbrock pumper carb from the xr650r. I know that the head is my limiting factor at this point.I just want the head that will net the most performance .The package rocks at this point already, Just want to put it over the top. :thumbsup:

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That piston compression is no small issue if you are trying to match the XR600R performance... I have both bikes and have been turning my XR650L into an equal performer to the XR600R. Valve and port size alone won't get you there. Cam, Piston & Head are what you need. I'm swaping out Carb as well instead of living with Dave's Mod.

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Would the XR600 cam fit the XR650L head? And would the decompression business work for the e-start? I would seriously consider getting an 600 cam if that was the case. The hot cams do away with the compression release and I've heard it makes the E start work a lot harder. I know once I disabled my compresison release and the bike barely turned over.

And are there mid range compression pistons. I think someone said that stock an L is less than 9.0 to 1. 10.0 might not be bad but wouldn't want to go much higher than that for a general purpose bike.

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Will the xr600r head, fit on a XR650L ?? And is there any performance gains to be had?? Looking for more performance out of the L motor? Thanks!! : :thumbsup:

I would have to say no, not without some machine work. I woud suspect that with the bigger bore on the L you would get some piston contact.

Since you'd have to machine it anyway, why not just ship your L head off and have it ported?

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The XR 600 gearbox will fit in the 650L. Dirt Bike did this a couple years ago and said it improved the performance off road mainly. It was done to an older 650L that had a blown gear box. :thumbsup:

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Like it's been said, raising the compression is going to give you the biggest bang for the buck.

A buddy of mine spun his countershaft sprocket on his '02 XRL at 10K miles (long story) & destroyed the countershaft splines so the cases had to be split for it to be replaced. He took it to Al Baker 's XR's Only for the repair work & had is head machined down, using the same cam & valves, & only replacing the cam chain. I think it's at 10.2:1 now, & still uses (premium) pump gas but the power increase is VERY noticable.

That'll be the way I go when I need to rebuild my '98. :thumbsup:

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I would think that machining the head would loosten the cam chain and retard the valve timing requiring an adjustable chain sprocket to re-time the cam. I just put in a JE 10.5:1 piston at 101mm.

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I would think that machining the head would loosten the cam chain and retard the valve timing requiring an adjustable chain sprocket to re-time the cam. I just put in a JE 10.5:1 piston at 101mm.

That's what the automatic cam chain tensioner is for, taking up the slack. Think about it. All these bikes, stock or otherwise, would have that problem as you stated as the cam chain strectches during it's designed service life.

I don't think that would be an issue until the cam chain has stretched beyond it's wear limit or the if the cam sprocket teeth somehow became worn. :thumbsup: If I remember correctly, it doesn't take very much milling to increase compression. :thumbsup:

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