difference in xr and xl motors

[honda500]

what are the differences in the xr and xl engines.

[frogman]

Where do you want to start?

[BWB63]

Model: XR650L

Engine Type: 644cc air-cooled dry-sump single-cylinder four-stroke

Bore and Stroke: 100mm x 82mm

Compression Ratio: 8.3:1

Valve Train: SOHC; four-valve RFVC

Carburetion: 42.5mm diaphragm-type CV (street type Carburetor, slide pulled by vacuum not throttle cable)

Engine weight: 102 pounds. Horsepower: 42bhp @crank and 34hp at rear wheel.

XR650R ENGINE

Engine Type 649cc liquid-cooled dry-sump single-cylinder four-stroke

Bore and Stroke 100.0mm x 82.6mm

Compression Ratio 10.0:1 HRC: 11:1

Valve Train SOHC; four-valve

Carburetion Keihin 40mm piston-valve

Engine weight: 88 pounds Horsepower: 55bhp @crank and 44hp at rear wheel HRC Horsepower 64bhp @ crank and 52hp at rear wheel.

[honda500]

what about an 83 xr500r and an xl500l. i know the xr500 from 83 has the RFVC but does the xl500 and will the heads swap.

[BWB63]

They are the same head, different cam

[honda500]

awsome, thats all i need to know thanks

[bluerock5]

The big difference is the "L" has "Electric Start" ? and the "R" is a kick start.

[BWB63]

The big difference ? is the "L" has "Electric Start" ? and the "R" is a kick start.

Yes, along with "L" being air cooled, "R" water cooled,

"L" 42hp, "R" 55hp, @ the crank and "L" 34hp, "R" 44hp @ the rear wheel

"L" being 102 punds, "R" being 88 pounds,

"L" having 8:1 compression, "R" having 10:11 or 11:1,

"L" having a CV carburetor, "R" having a piston slide carburetor,

different cam profiles, different cylinder angles, different head designs, "R" having easy access to the clutch, different air box designs, other then that and the electric start they are almost the same

Someday they will perfect the stator being also a starter. That will fix a lot of bikes

[Jeff Moore]

1.The '83 was the first year for the RFVC motor in the 500's. I believe the 82 and earlier had reed valves.

2.What BWB63 said about the cams.

[BWB63]

1.The '83 was the first year for the RFVC motor in the 500's. I believe the 82 and earlier had reed valves.

2.What BWB63 said about the cams.

"RFVC" = Radial Four Valve Chamber

The valves kinda fallow the radious of the cylinder with the valves all opening to the center. The spark plug was in the center almost pointing down. The head is more like a dome then more flat like most four strokes. The rockers are biult into the valve cover.

XR's were to be the dirt "Race" type four strokes and the XL's were the street enduro's. More and more were changing the XR's to be streetable. Honda started calling the XL's XL"R" to make them sell better (like XL600R like they are doing with the little XR's to CRF's) then they change to XR600L thinking that would be better. Back in the day the "L's" had a steel gas tank, milder cam, lower compression and different swing arm. It was cheaper and easier to pick up a XR600L for the license plate and change the gas tank, cam, piston, swing arm and change the two carburetors to one Mikuni pumper ? I had one of these. Five gallon desert tank, 12:1 piston, cam, 38mm Mikuni pumper, Suspension done, XR swing arm all with lights and plate. Now the XR650R and XR650L have nothing in common but, the bars, brake cylinders, levers, rims, chain and a few other things. The suspension, hubs, everything else is a totaly different bike.

Reed Valves are used in Two Smokes as in Elsinore's and CR's. Two strokes can have no valve, rotory valve or read valve. Two stroke Dirt bikes have read valves (some old Elsinors had rotory, I think it was the 250 enduro?) little two stroke scooters and weed eaters have no valves, and two stroke boat motors have rotory valves. Not four stroke XR's or XL's or XRL's or XRR's

[xXHondaOwnsXx]

Wow, you know your bikes! ?

[Jeff Moore]

BWB- I'm reasonably new at the whole dirt bike thing after a 30+ year absence. Are ALL "X" designated bikes four strokes? If so, do you know if the 82 XL/XR 500 motor is a two valve that sports 2 exhaust pipes? And, are they conventional valves? All my recent knowledge has been from LOOONG sessions of reading TT. I have found in these readings, a lot of very good info, and a lot of inaccurate statements as well.For the neophyte(sic) it's often hard to separate the good from the inaccurate.One has to use their own personal knowledge to intersperse where needed.One has to use common sense when reading torque values in non-factory manuals for instance.

[BWB63]

BWB- I'm reasonably new at the whole dirt bike thing after a 30+ year absence. Are ALL "X" designated bikes four strokes? If so, do you know if the 82 XL/XR 500 motor is a two valve that sports 2 exhaust pipes? And, are they conventional valves? All my recent knowledge has been from LOOONG sessions of reading TT. I have found in these readings, a lot of very good info, and a lot of inaccurate statements as well.For the neophyte(sic) it's often hard to separate the good from the inaccurate.One has to use their own personal knowledge to intersperse where needed.One has to use common sense when reading torque values in non-factory manuals for instance.

The xr500 and XL500 were almost the same engine. The XL500 engine put out 27bhp and the XR500 34 or 36hp at the engine (I can't remember that far back) I had a used one. I had an 84 XR500 also used. With two exhaust into one. I haven't touched one sense 1987. I don't know the first year they change to RFVC I don't know if my 82 had four valves now or not. I thought it did but, wow that was a long time ago. I know mine had one carburetor.

The timing chain was a major pain. It would wear right through the side! I remember that ?

I had a 74' two stroke Honda that was black with a silver tank. I am not sure if it was a MT250, it was street legal. I think it had rotory valves. I had it in 1976 and I was 14. So, I can't remember that well.

[MrShred]

BWB, you appear to be the definitive XR expert. Can you tell me if the XR650L has the same cam as the XR600R, or does it have a smog cam? I have a 93 650L project bike I would like to bring up to at least 600R spec, with a higher compression piston (& cam if necessary).

[frogman]

Four strokes don't have reed valves, they have mechanically opened and closed hard valves,

and it was the old original KX's that had the rotary valves, the first production motocrossers to have reed valves were the Yamaha YZ's, the year they came out with the mind-blowing monoshock rear suspension.

If my memory serves me right.

[XR6's_rule]

There was never such thing as an "XL500L", there was the XL500S twin shocker that had a conventional 4-valve head (non RFVC) and ran from 1979-1981, then there was the XL500R that ran for one year in 1982 and it had basically the same engine as the XL500S. The XR500 and XR500R from 1979-1982 also had this same basic engine. The XR500RB/RC (1981-1982) had a reed valve in the intake which meant a different head but with the same valve layout etc to the aforementioned XL models. The XL600RD and XR500RD were released in 1983 and were the first models to utilise the RFVC head. In fact the engine was new all over. There was never an XL model with the RFVC head so you wont be able to use an "XL500" head on the RFVC XR500RD model.

Hope this clears it up!

[XR6's_rule]

There was never an "XL500" model with the RFVC (Radial Four Valve Combustion). Only the XL600R, XL350R and XL250R. By the way, all of the pre RFVC engine 500 models (explained in my last post, had a cam without bearings, but did run twin exhaust ports in it's conventional (pentroof) four-valve head. There's a lesson for ya!