KLR 685cc Kit
For 1996-2010 KLR650A
Note – This piston will fit the 1996 to 2010 cylinders only. The liners on 1987 to 1995 cylinders are too thin to use safely. If you wish to use this piston on the early model KLR’s, you must use a 1996 to 2010 cylinder assembly. The cylinder assemblies are interchangeable and require no modification to use.
Measure the piston 7mm from the lower edge of the skirt, 90^ from the Pin. Minimum clearance is .055mm or .0022”. Do not fit any tighter! Bore and finish hone. Use #320 grit finish. This is a bit coarser than most modern bores. Do not use a finisher finer than #400.
Check Ring End Gaps
Fit each ring squarely in the bore, and check ring end gaps. Minimum gap is .018”. The oil ring scrapers will normally be well over that. The 1st and 2nd ring may require some filing to get at least .018”. Do not fit any tighter!
Fit the rings to the piston
Install the oil ring expander 1st, then the oil scraper rings. The oil scrapers have no direction and may be installed either way. Make triple sure the expander ends are butted against each other. If they are overlapped it will damage the rings and smoke heavily! The 2nd and top rings are directional. The 2nd ring is thinner. The lettering must face up! The top ring is thicker and wider it has a stamped “dot.” This dot must face up.
Choose compression ratio
There are 2 included base gaskets. One is .010” the other is a .020” or a stock gasket (stock is .020”). The piston is designed to be 9.7 to 1 when used with only the stock .020” base gasket. That is recommended. The slight increase iin compression over stock is well tolerated. Other options are to use both gaskets together for a 9.55 to 1, or stock compression. Or you can use only the .010” gasket alone for 9.85 to 1. The 9.85 ratio is only recommended with premium fuel, or if cams are to be installed. It is also useful if you live & ride at higher elevations. The 9.55 ratio is best if lower grade fuels are going to be used.
Note – On 2008 models, the compression ratio will be .1 point higher than the above. Thus, with the .010” base gasket compression will be 9.95 to 1, 9.8 to 1 with the .020” gasket. Stacked together will yield 9.65 to 1. Again, the .020” base gasket is recommended in most cases.
Clearance the head gasket
If using a new Kawasaki head gasket, Part# 11004-1158, it must be clearanced around the bore before installing. No part of the gasket should overhang the bore. You can remove this extra material with a dremel tool and a sanding drum. Be careful not to overheat the area you are working. Normally only .010” to .020” needs to be removed. Carefully deburr the edge when finished.
Wash the cylinder in warm soapy water and dry. Wipe the bore clean with WD-40 and a clean rag. Install the piston on the connecting rod. Use a drop of oil on the pin. Install the base gasket. It is easier to lay a couple of dowels under the piston skirt. These will hold the piston square with the base. Set the cylinder on top and screw two of the long head bolts in to help hold the cylinder. Verify the ring end gap positions one lat time. Smear 1 drop of oil on the piston skirt. Use no oil on the rings, or on the bore. Carefully work the cylinder down over the rings. Rotate the engine over a few times by hand. There should be a smooth light drag. Assemble as per the factory, or Clymer service manual. Use stock torques. NOTE – Use no gasket sealer on the head gaskets. (See image below)
Before the first fire up, change the oil & filter. Use a cheap 10w30 or 10w40 mineral based oil. No synthetic. Warm the bike up fully. Ride the bike somewhat easy for 5 to 20 miles. DO as much engine braking as possible. NO steady throttle cruising! Change the oil and filter again using a premium grade, non-synthetic 10w40. Over the next 150-200 miles work the engine progressively harder. Best if done in 2-3 sessions with a cool down in between. Again, use as much engine braking as possible. Go through the gears as much as possible. There are no RPM limits, just “work” the engine a littler harder each time, then back off. Change the oil and filter again after this period. You can now use a synthetic oil (recommended). Use a 15w50 or 20w50. Avoid any extended high RPM runs for another 100 miles.
The head bolts do no need to be retorqued, but it does not hurt to do so. You should recheck the exhaust bolts and other hardware about this time.
The piston kit alone will not require any jetting changes. If it was correct before, it should not change
Note – Because this piston is forged, it should be warmed up a little longer before riding. You may also hear a bit more noise when cold. The PCV valve mod is also recommended with this piston kit.
Also highly recommended is the “thermo-bob” modification. That can be found at http://www.xanga.com/watt_man
KLR-685 Piston Specifications
222 N 3rd Street
Decatur, IN 46733
Motor Type: Kawasaki KL650-A
IMPORTANT CLEARANCE INFORMATION GUIDELINES ONLY
Set clearance to .0024 (.06mm)
Some applications may require more clearance. Measure piston diameter .275 (7mm) from bottom of piston skirt
Minimum clearances (coated) .0022”
CORRECT PISTON INSTALLATION IS THE RESPOINSIBILITY OF THE CUSTOMER
Minimum ring end gap is .018”
Ring Markings face up (dot or letters)
Oil Rings are not marked
Note—Compression height is .005” lower than stock piston at outer edge. Stock piston is dished slightly
Piston Type: Flat Top
Bore: 4.035 (102.49mm)
Stroke: 3.268” (83mm)
Comp. Dist: 1.213 (30.81mm)
Int .156 (3.96mm) 27 Deg
Exh .141 (3.58mm) 28 Deg
Valve pocket dept measured from Deck
Top .48 (1.22)mm) .210 (533mm)
2nd .040 (1.02mm) .140 (3.56mm)
Oil .119 (3.02mm) .110 (2.79mm)
Pin Dia .945 (24.00mm)
Pin Length 2.250 (57.15mm)
JE .073 Wire Locks
Actual Weight 413 Grams
Total Assembled Weight
With Rings–Pin 558 Grams
Stock Assy 641 Grams
Valve Reliefs will clear 40/36mm Valves