79 xr500 camshaft on the xl500s

[nimiz1]

i like to put the xr500 canshaft on my xl500s , i already put the xr carb and flyweel but with not alot of differnt in the power suply feeling.

will the xr500 camshaft make the difference or not??

thanks

[zrxer]

I believe the XR and XL cam are the same.

[79yamdt]

Do you have a supertrapp exhaust on your bike? I would look for one of those. Changing the cam usually comes after some other mods. I don't think the cams differ all that much anyways.

[nimiz1]

the xr and the xl camshaft are not the same at all.

as i said , i did all the mods i can do but i only use the honda OEM parts so no suertrapp exhaust on my bike.

[79yamdt]

Just throw a whole xr/ xl500r motor in it and be done.

[Horri]

the xr and the xl camshaft are not the same at all.

as i said , i did all the mods i can do but i only use the honda OEM parts so no suertrapp exhaust on my bike.

Have they got a different cut or something??,,Far as I know the XL/XR Camshafts are the same for the XL/XR 500 and 250,,I have a spare one,,dunno what it's out of apart from saying it's not an RFVC one.,ie,,it fits your model 500 and my 82 XL500 and any other XL/XR250/500 from the same range of years.,ie,,.79--82

[nimiz1]

the honda catalog part number is not the same for the xr500 camshaft and the xl500

why is thet if they are the same part.

as far as useing the xr motor , maybe if i was living in the US but were i live there are only xl motors and you cant import the xr engine so the only thing i can do is make my xl500 an xr500.

[Horri]

Minor variations in part numbers occur,,doesn't mean some other part won't work,,As I've said an XL500 or XR500 Cam will fit either model and the 250s as well.,Here in NZ you have to make do with what you can get so we sort of know parts interchangability between the older models.,30years ago in NZ engineers were putting shell bearings in XR/XL heads when the Cams seized,,I doubt many other people in the world were thinking of that as a fix for a seized head and Cam.,Was a fairly common occurance to seize the things when they were ridden hot and hard in a two day Enduro.,Same as replacing the Conrod on them,,Honda always said you needed to buy a whole new crank when the big ends went,,Untrue,,The engineer just needs to know the tricks and all you do is replace the rod,,not the entire crank,.

[nimiz1]

i already now all thet , all i asked is will i be able to notice any difference in the xl500 engine behavior whan i will use the xr500 camshaft thets all.

[Horri]

You want my opinion,,I think hot cams are a waste of time,,(I have no idea whether you will notice any difference between an XL or XR cam) We used to stick supposed hotcams in our SL125s 30 years ago ,,I never noticed a power difference if there was one.,Better off going bigger carb and better exhaust on a 500,,Leave you to it.,

[zrxer]

the xr and the xl camshaft are not the same at all.

as i said , i did all the mods i can do but i only use the honda OEM parts so no suertrapp exhaust on my bike.

Evidently Horri and I were under the same impression that all the XR/XL 250 and 500s were the same cam. I was actually told that by my dealer about 25 years ago. I guess we were wrong.

A good friend of mine used to really be into the late '70s early '80s XL/XR500 bikes. He had a ton of engine parts and would swap pistons, cams and whatnot between engines and I could never tell any difference in how they ran.

Have they got a different cut or something??,,Far as I know the XL/XR Camshafts are the same for the XL/XR 500 and 250,,I have a spare one,,dunno what it's out of apart from saying it's not an RFVC one.,ie,,it fits your model 500 and my 82 XL500 and any other XL/XR250/500 from the same range of years.,ie,,.79--82

Horri, I dug up some factory Honda manuals I have and here's a list of camshaft specs.

1978-1983 XL250S and XL250R

Intake Opens 5 BTDC Closes 30 ABDC

Exhaust Opens 35 BBDC Closes 5 ATDC

1979 XR250

Intake Opens 10 BTDC Closes 40 ABDC

Exhaust Opens 40 BBDC Closes 10 ATDC

1981-1982 XR500R

Intake Opens 5 BTDC Closes 40 ABDC

Exhaust Opens 45 BBDC Closes 5 ATDC

So there we have it. Three different grinds for four different models.

Unfortunately I don't have a manual for the XL500.

[Horri]

I have the XL500 shop manual in the garage,,I'll dig it out tomorrow and post what I find,,I don't think any of those differences preclude you using whatever Cam you want or people wouldn't swap them about willy nilly,,Course I'm no expert on all the degrees stuff and what effects it may have on the engine or timing.,

[Motosprtman]

The cams back in the day, on the "evolution" era XR's did not differ from the XL. Later on they do in the RFVC engines. as does the CDI ignition map. Best bet for more power is to increase displacement and use a high compression piston. I guess you could go as far as to flow the head - but would be spendy. Good tight sealed valves and increase compression / displacement = more poop!

[Horri]

XL500s

Intake opens 5 BTDC Closes 40 ABDC

Exhaust opens 45 BTDC Closes 5 ATDC

So the XL500S has the same Cam as the 79-82 XR500.

[zrxer]

XL500s

Intake opens 5 BTDC Closes 40 ABDC

Exhaust opens 45 BTDC Closes 5 ATDC

So the XL500S has the same Cam as the 79-82 XR500.

Thanks for posting this up, Horri.

[baldy110]

No you will not feel any differerance with the XR cam. I know you think you know this already but you are wrong, THEY HAVE THE SAME PROFILE.

[nimiz1]

thank you all for your reply's