Husaberg Motorcycle Engine Tolerances and Blueprinting

This information about engine tolerances and engine blueprinting is for the Husaberg 400/450, but should work for other Husaberg motorcycles. For your reference to incorporate into your Husaberg engine rebuild:

Engine Tolerances

Wear Limits and Tolerances

Rocker Arm Differences

There are different rocker arms for the big valve heads compared to the SV heads. The easiest way to check what you have is to measure the valve diameters first. Are they 37/30 or 35/30 (some 400’s had 27mm exhausts)? Next the rockers then. Measure to the outside of the screw threads with a vernier.

Small Valve Rocker Inlet: 44.3mm; Exhaust: 40mm

Big Valve Rocker Inlet: 45mm; Exhaust: 43.2mm

Oil Level

Con Rod Side Clearance

Con rod side clearance should be set at 0.4 – 0.5mm. (Ausberg)

Head Gasket Thickness

Thickness of standard gasket is always .056″ or 1.4mm. A thicker gasket is available than standard.

Piston Skirt to Barrel Gap

OEM Husaberg Piston / Cylinder clearance is .002″ – .0025″ (Lineaweaver).

Little End Sizes

All have a little end of 20mm EXCEPT the 350/40 which has an 18mm little end bush. The bushes are interchangeable. (JBS Racing) However, all 20mm bushes spin regardless (Lineaweaver) because the bush material is thinner and looses it’s compressed state.

Crank End Float – Axial Clearance

You can measure this by tightening the cases and using a ‘deadlead’ hammer and slapping the crank from left to right. Two or three efforts like this and the crank will be as free as it’s ever likely to be. Slap the crank one way, then, using the foot of a vernier, measure the lip or drop from the bearing to the crank. Now slap the crank the other, measure, and the difference is your float! The KTM clearance for the very same bearings is 0.21mm and this should be used for the Husaberg. (Lineaweaver)

450 501 / 550 650
0.45 – 0.55 mm 0.45 – 0.55 mm 0.55 – 0.65 mm

Skim the Barrel / Engine Block

Want to skim the engine block to increase compression or because of engine warpage? Here’s the correct way to skim a Husaberg motor. The spigot should be flush with the block or can be proud by up to .005″ (Lineaweaver). It may pay to have the spigot and crankcase machined separately.

Rocker End Float

Is .15mm (.006″) (Simon). Don’t have this? Fit the rocker cover screws then tap the black end caps inward till you do!

Engine Blueprinting

Crankcase Alignment

Both halves can be out of line. Lineaweaver made an arbor and changed the tolerances to a KTM specifications of 0.1-0.2mm float. Due to extremely tight fit-the bearings should still be “snug” after machining lightly.

Arbor Tool
Arbor Tool (Lineaweaver)
Crankshaft Clearance
Crankshaft Clearance (Bergoroadracer)

How True Runs the Crank?

Dial indicate crank (mounted between centers)
Dial indicate crank (mounted between centers) (Neil_E.)

Thicker Head Gasket – OEM

  • 21 200 319-01 Cylinderhead gasket 400 (thick) -01
  • 21 200 231-01 Cylinderhead gasket 400 -02
  • 21 200 320-01 Cylinderhead gasket 501 (thick) -01
  • 21 200 232-01 Cylinderhead gasket 501 -02
  • 21 200 321-01 Cylinderhead gasket 470/550/650 (thick) -01
  • 21 200 233-01 Cylinderhead gasket 470/550/650 -02 (JoeUSA)

Linar Ovality

The linar on all the 100mm bore engines is exceptionally thin. It means that over a period of time it gets pulled oval by the action of the piston driving into the front and back walls. Check for ovality. The spigot – less the ‘O’ rings wants to turn freely in the cases.

Installed Valve Spring Height

Installed valve spring height standard springs should be (1.320″). Seat pressure should be 75 lbs. -0 / +10. Installed spring height is measured from the retainer bottom to the steel spring seat. 1.320″ (33.4mm) should give you near 85 LB seat pressure. .7mm is roughly = to a 13 lbs. reduction in seat pressure so make shims to fit under springs. (Lineaweaver)

Valve to Piston Gap

The absolute minimum should be measured at 1.25mm on the exhaust, 1mm inlet. preferably another .25mm should do it.

Valve to Piston Gap

The absolute minimum should be measured at 1.25mm on the exhaust, 1mm inlet. preferably another .25mm should do it.

Valve Timing

Lobe centers for cam timing are:

  • ’53’ cam = 112° (Measured with zero lash). From 1mm lift the ’53’ cam’s -inlet valve timing is: Opens 10° BTDC, Closes 54° ABDC. I could not get Dale’s cam timing figures using the 1mm lash but could get them without it perfectly though! so the simple rule is to have both lobes pointing up at 11 and 1 o’clock.
  • ’01’ cam = 110°
  • ’55’ cam = 117.5° (Lineaweaver)
  • LRX1 = 284 / .414″ / 106°
  • LRX2 = 272 / .407″ / 107° (Lineaweaver)

OEM camshafts 820.36.010.000 and H-200.342.08 share identical profiles. The later unit is shipped with a matched auto de-comp lever. 1mm lift / 0 Lash / Straight Up.

  • Intake Open 19°
  • Intake Close 67.1°
  • Intake CL 114.9°
  • Exhaust Open 98.8°
  • Exhaust Close 17.9°
  • Exhaust CL 115.1°

Installed Valve Height

Installed valve height should be (1.320″ or 33.4mm) whether conical or dual springs. Seat pressure should be 75 LB -0 / +10 with the conical. 1.320″ (33.4mm) should give you near 85 LB seat pressure. .7mm is roughly ~ to a 13 LB reduction in seat pressure so make shims to fit under springs. Installed spring height is measures from the retainer bottom to the steel spring seat. (Lineaweaver)

Cranking Compression

The auto de-compression bleeds only a fraction of the trapped charge engaging near 85 BTDC and closing near 15 BTDC with a peak valve lift of less than .040″. “E” Cranking compression should be approximately 130 psi. (Lineaweaver)

Oil Pressure

Engine oil pressure; 15psi @ 3,000 RPM (Lineweaver)