The Honda CR250 is well known as the bike that helped make Jeremy McGrath a motocross star. If you give your CR250 the kind of hammer McGrath gave his, or even if you ride yours with great care, sooner or later you may need to rebuild it.
HPP Rebuild Tips
According to master mechanic Eric Gorr, if you are rebuilding the Honda Power Port on a 1988 to 1991 CR250 and you find that the valves are not completely opening when you rev your engine, this is probably because the HPP mechanism is not completely engaged. To fix this, remove the valve cover and the round-slotted access cover under the water pump. Insert an 8mm T-handle through the access hole and onto the detent bolt and do a 1/4 turn counterclockwise. Then insert a straight-blade screwdriver into the pinion slot and turn the shaft counterclockwise 1/8 turn. Then turn the detent bolt 1/4 turn clockwise. Release the spring tension from the pinion shafts in the cylinder to engage the detent bolt. This should engage the HPP mechanism without risk of damage to the fragile cam spindle.
Tips For Installing Ignition Components
The stator plate has a mark at the bottom. When installing it, take care to match this to the casting mark on the case. Apply Loctite liquid threadlocker, or similar thread-locking agent, directly onto the two mounting bolts. Then tighten them securely. Install the woodruff key, also referred to as a half-moon key, into the crankshaft spindle slot. Fit the rotor, washer and hexagonal nut. Then set your torque spanner to 40 foot-pounds and tighten the nut. Fit a new gasket in the ignition cover then replace the cover and use four pan-head screws, with washers to secure it. Pan head screws have a head shaped like a disc with a chamfered outer edge. Fit the kick-start lever upon its splined shaft, which has a series of ridges, called splines, for grip. Tighten the bolt to 20 foot-pounds. The countershaft sprocket has a recessed side, which should face towards the engine. Bear this in mind when fitting. Fit the cone washer over the sprocket and tighten the bolt to 33 foot-pounds.
Shock Rebound Adjuster Tip
When rebuilding a 1986 to 1989 CR250, you may find that the shock absorber's rebound adjuster has seized up. The adjuster consists of a screw with a fine thread, on which sits the familiar ramp-shaped nut. If you cannot turn the adjuster screw, it may be because condensation has caused corrosion on the fine threads. To tackle the problem, carefully remove the rebound adjuster cartridge. Discharge the nitrogen gas pressure from the shock absorber bladder. Then clean the threads with an old toothbrush, or fine wire brush before refitting.