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The content below is 100% taken from http://www.geocities.com/MotorCity/Downs/6164/page72.html/. All credit is due Dave Jakeman!
PREAMBLE: 1988 KLR650: last spring, @ 36,000 miles I started experiencing fuel system difficulties - loss of throttle control, inability to use reserve fuel, etc. After some fooling around by the dealer in Bountiful and myself, throttle response went away completely, and the bike wouldn't come off choke. The dealer in SLC called it a plugged pilot circuit, so February this year, @ 39,000 miles, I decided to remove and clean the carb myself, and upgrade to a K&N kit and air filter. This article and check list is offered as a guide for the first-timer attempting removal, service, and reinstallation; who may not have a service manual to help him through it. The list looks formidable; I've included other observations and reminders to myself, but don't be afraid to sail into this task. The sense of accomplishment and self-sufficiency you'll feel when the bike fires right up at the end, can't be bought at any price, but it's yours for free if you're thorough and systematic about it. The Bountiful mechanic was able to remove and replace the carb without swinging the sub frame out, but I felt more comfortable doing it by the Service Manual.
( ) Remove side covers, seat, tank. Only the two top radiator shroud screws need to come out. An ice cube tray or muffin tin is handy to keep the fasteners from migrating all over the bench.
( ) Remove the rear brake reservoir cover and retainer, leaving the front reservoir bolt in place.
( ) Remove the muffler: two hanger bolts and the clamp bolt, slides out to the rear.
( )Remove the Tywrap holding the battery leads to the frame tube (near the upper sub frame bolt) and the battery, loosen the wire bundle clamp on the frame cross tube.
( )Disconnect the wiring connector on the rear fender, that feeds the rear light group. I drilled a new hole for the retainer two inches forward of the existing hole, to allow the sub frame to come out a little farther.
( ) Loosen the strap clamp which holds the soft boot from the air box to the intake horn of the carb. At this point, I ran a tie down strap from the front tire to the crossbar of the center stand, to prevent it from folding up while the work was in progress. I also ran a camlock strap from the branch in the frame top tube, rearward to the frame cross tube to allow me to inch the rear sub frame away just enough to clear the intake horn of the carb.
( ) Remove the upper sub frame screws and loosen the camlock buckle until the soft boot clears the carb horn.
( ) Remove the plastic cover from the side stand switch/solenoid.
( ) Left side: Remove the choke fitting: curved metal tube leads to a black plastic nut. I used a long curved hemostat (also handy for retrieving fasteners that fall down into deep recesses) available at medical supply houses.
( ) Remove the overflow and fuel supply hoses.
( ) Right side: Remove vacuum hose from the outlet horn, and the throttle cables: loosen the top nut until the bottom nut can can drop out of position. This is a good opportunity to lube the throttle cables and the choke cable.
( ) Loosen the remaining strap clamp, and twist the carb out of the cylinder boot: check to see if there is a dump hose on the bottom of the float bowl, carb is out.
At this point I drained the float bowl and cleaned the grime from the carb body, using a 1" paint brush, Stoddard solvent, and air. The Bountiful dealer had set the pilot screw 1 1/2 turns out. I removed the float bowl and float, and checked the float needle for wear. Look at the way the main jet fitting protrudes into the main throat; it can be installed upside down. Remove the main jet holder and that plated nozzle. If the carb is to be cleaned, unscrew the pilot needle, taking care you don't lose the tiny flat washer and "0" ring near the tip. At this point, a roll of 2" masking tape makes a handy work stand for the carb. The top cover, diaphragm, and slide can now come out. I had varnish deposits everywhere, so I used some NAPA carb cleaner to soak everything not made of rubber or plastic. I use a metal "tea ball" from the grocery store to soak tiny parts, so they don't get lost in the soak solution. I removed the plate on the left side that holds the coasting enricher and the two hose fittings, for cleaning. I followed the K&N directions: installed the leanest main (136) and set my pilot screw 3 turns out. NOTE: I have developed adjuster tools for the pilot mixture screw on KLR's: available through my shop: allowing the idle mixture to be set while the engine is running. I replaced the main needle with the K&N needle, clip in the middle groove. Float height was 19mm, I reset it to ServMan: 17.5mm. I removed the cylinder intake boot & cleaned it. Because the engine had been running dirty, the tops of the intake valves were a mess. Using the battery, I rotated the engine until TDC, used a little spray carb cleaner and soft fuel line to my Shop Vac to remove the worst of the gunk.
Reassembly: I wiped the dirt out of the choke control housing, greased the wave washer, and reassembled the control. I also cleaned the brass barrel fitting at the other end, and wiped it with a little anti-seize, before inserting it hack into the carb. Remember, don't over tighten the fitting, it may break.
Reassemble the carb; clean the o-ring slot in the float bowl, and apply a little Vaseline to the O-ring before reattaching the float bowl with my magic stainless steel socket head cap screws. Wipe the soft boots clean where they surround the carb horns, and apply a little Vaseline, then the carb can be inserted into the cylinder boot, and the clamp tightened.
( )The sub frame can now come forward. Stand on the right side, left hand on the luggage rack, and pull it upward and towards the front of the bike, pulling up on the camlock strap. Hold the sub frame while you tighten the strap buckle. Bring the sub frame up in small steps: as the air box boot approaches the carb horn, make sure the soft boot swallows the carb horn all the way around. You're ready to re-insert the sub frame screws and tighten them, and remove the strap.
I cleaned the muffler clamp screw, together with the hanger bolts, and applied a little anti-seize. Reattach the muffler, loosely for now. Temporarily block the vacuum fitting on top of the discharge horn, attach the overflow hose, tighten the float bowl drain screw. A temporary fuel reservoir can be made from a spray can, some brass swamp cooler fittings, and fuel line, or a line from a jerry can works well. Wire brush the threads on your spark plug, squeeze a dab of anti-seize on the threads, and install. If you Tywrap the throttle cables to the frame top tube, they won't snag the saddle fitting on the tank next time you remove it. I temporarily hooked up the battery, installed the air filter, and it fired right up. Huzzah!!
( )Reconnect the taillight harness, tighten up the engine mount screws, and the sub frame screws, muffler screws, etc. Replace the tywrap for the battery leads, and retighten the wire bundle clamp on the frame cross tube. Take some fine steel wool and shine the battery cable lugs, coat them with a little Vaseline, and reinstall the battery all the way.
( )Loosen the throttle cable adjusters at the twist grip to give some slack below: there should be enough threads for the upper nuts on the carb ends to allow the lower nuts to drop out of the bracket on the carb. Secure the lower adjusters, then adjust the twist grip ends until there's about 1/8 inch of slack at the twist grip.
( ) Finish tightening the soft boot clamps, reattach the vacuum hose to the discharge horn, and you're ready to install the tank, seat, and side covers, and the rear reservoir retainer and guard. Install the left side cover for the side stand switch, remove the center stand strap, now ready for road test.11 April: The results of the first fill-up after the rebuild: 20-75 mile runs, out & back to average out the ascend/descend and wind, no duffel, mean altitude 5000ft. 5th gear running, speed ~ 55-65 mph. Throttle response is more linear, acceleration is better than stock, small amount of lean surge. First tank went onto reserve @ 240 miles (downhill): @ 253 miles, fill up took 4.28 gal. Yield was 59.1 MPG.
Fascinating. I would recommend the 140 main jet to eliminate lean surge. Loaded trips now average
56-59 MPG, all wind conditions and grade.Editor's Note: Dave has developed adjuster tools for the pilot mixture screw on KLR's allowing the idle mixture to be set while the engine is running. This is a very handy tool - simple but effective! Contact Dave (Jake) at his shop listed below for details and ordering information.
DAVE JAKEMAN
SAGEBRUSH MACHINE SHOP
49 SOUTH 400 WEST
P.O. BOX 339
MILFORD, UTAH 84751
(435) 387-5575
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