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84 XL600R Cylinder Heads: What other models/years will fit?

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My brother in law's 84 XL600R is needing a set of cylinder heads. What other models/years of bike will fit? I see on ebay they have a 85-87 XR600R heads for sale, will this fit?

Edited by D0T-C0M

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XL600 1983 through 1987. 1983 head will require a different valve cover gasket and possibly a valve cover. It has a reed valve connecting the primary and secondary intake ports. There maybe other heads that will work, not for sure though. Maybe others can help.

DSCF0001a.jpg

Edited by kmequint

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Thanks for the info. Does anyone know if the 86 XR600 heads will fit?

Edited by D0T-C0M

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I know the bore and stroke are different between the XL and XR. The XL is 100mm bore x 75mm stroke. The XR is 98mm bore X 80mm stroke.

Edited by kmequint

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I'd say an 86 XR head will fit..Problem is the locating dowel sizes are different so it'ill need machining to put in the correct dowels. Might then be some problem with the head gasket fitting correctly then again there might not. Also dunno how the carbs will react to no reed..XR,,no reed,,,also don't think there's a tacho drive on an XR,,so no rev meter.

Might also be a problem with the carb manifold and porting to it between XR/XL,,something else to consider there. The earlier XLs vary a bit in the porting to a later XR..

Never seen that reed before,,good picture Quint.

Edited by Horri

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Well then I guess I'll stick to a XL600 heads if it isn't bolt on compatible. There were 3 last month on ebay but as luck would have it nothing yet has been posted since last week.

Thanks for all the info guys.

Edited by D0T-C0M

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Thanks for the info. Does anyone know if the 86 XR600 heads will fit?

Yes, they will. '83-87 twin-carb XL and XR600 engines all use the same 8mm head bolts and dowels. '88+ single carburetor engines have larger bolts and dowels.

If you have an early "reed" bypass head like the one kmequint posted and replace it with a later non-reed head, then you also need a carburetor boot with the crossover passage from a non-reed engine.

'83 XL600 heads have the intake largest ports. They were also the most powerful production RFVC 600.

Edited by HeadTrauma

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Yes, they will. '83-87 twin-carb XL and XR600 engines all use the same 8mm head bolts and dowels. '88+ single carburetor engines have larger bolts and dowels.

If you have an early "reed" bypass head like the one kmequint posted and replace it with a later non-reed head, then you also need a carburetor boot with the crossover passage from a non-reed engine.

'83 XL600 heads have the intake largest ports. They were also the most powerful production RFVC 600.

Thanks for heads up. I've found a 1987 XR600R head, so just to confirm your saying this will fit on a '84 XL600? Also just to confirm that the cam and rocker cover from the '84 XL600 will fit with no problems too?

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the squish perimeter is slanted on the xr , but you ll have the remaining 1.5 mil strip (97 vs 100 bore) flat ..it s too thick a squish area to work properly on the xl anyways .

XL heads went from big ports, big carbs (30s) 36/31 valves to small ports, small carbs  (28s)34/30 valves in 85 i think.(we re talking pd03 her , not 04)

At the same time , the xr twin carb had the small ports but the big valves 36/31

should work ok

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just checked the centering dowels on a 84 XR and a ???? early XR (so happens i have 3 radial heads on my bench) same size , will fit , just use a 100 mill XL gasket ;-)

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FYI, the valve sizes never changed for US-market bikes. They are the same for all RFVC 600s and 650s from 1983-2014 that were sold here.

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Ok  , thanks HT , i wonder why ?

i thought it was  for more low end smoothness by speeding up the flow , dunno , maybe it was done to accomodate  more restrictive "environmental" jetting ?

 

heard that Canadians also had a 34/30 head at one point .

i have several configurations and dont find much "seat of the pants" difference - in uncorked stock motors that is

 

sorry to bring back that old tread , i was just messing with some ported head i m trying to save

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Ok  , thanks HT , i wonder why ?

My guess is that it's because the US does not have any laws limiting engine output or for basing insurance premiums and/or rider licensing on it.

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