Mr. Dune's Sandbox/Quadzilla Zone

Nov. 01, 2005 By Mr Dune

   The procedures outlined below are not  recommended for inexperienced mechanics working without proper tools, Do not attempt a repair you do not have the tools and manuals to complete. You risk severe damage to your precious Quadzilla, not to mention busting your knuckles, throwing your wrench, only to realize you just put a dent in your wifes new truck! At which point you'll have to sleep in the garage with your bike. Which of course may be the lessor of two evils...

    While Mr. Dune is copyright protected please feel free to copy any of these tips to save or to distribute to your riding buddies.  If you don't see it here just click here to Ask Mr Dune!

Very important note: Before trying to diagnose an internal engine or jetting problem and after an engine top end reassembly, ALWAYS perform a leak down test! If you do not know how to perform this test... Click Here!
  • Engine leans out at high RPM, excessive vibration, bottom end noise, premature failure of crank seals, piston seizure.

    All Suzuki LT500's will require this fix!

       The crank bearing bosses expand at a different rate than the bearings allowing the crank bearings to become loose, thus cavitating the bosses. This leads to crank seal failure, sucking air into the motor leaning out your mixture and potentially causing your piston to seize. It can also cause primary drive gear failure.The 100% fix for this is to have your crank bearing bosses machined out and bronze bushings pressed in, the crank bearings are then pressed into the steel sleeves and voila! Your all set-forever!(The steel bushings expand faster than the steel bearing or the aluminum case, creating a tighter grip
    as the temp increases.)

       To determine if you need this fix, remove your flywheel side cover, grasp your flywheel and try to lift the bike/push down on the bike in a back and forth motion. If your flywheel has any perceptible movement whatsoever you gotta do it. the best spot for the repair is Tudors Performance. They guarantee the fix for a couple of years. Although I know of a couple dozen bikes they have done, besides four for for me with no reported failures. So you should be completely satisfied.

  • Leaking or blown gasket at the cylinder base, under the reed cage:

       Operating your bike with a blown base gasket can cause severe engine damage! This is a common source of trouble on LT500's as your bike ages the cylinder base and case mating surfaces warp. The area under the reed cage/ intake port is the most susceptible to warping as the gasket surface is only about 6mm wide. In severe cases you may need to have the surfaces re-machined. However, I suggest you remove the cylinder, clean the gasket surfaces thoroughly,  then inspect the surfaces for burrs or nicks. (Only the narrow area at the intake port is of real importance, you need not be too concerned about burs on the wider areas unless they are large.) If the intake port area is damaged, lightly deburr the area with a fine grade of emery paper. Remember, this surface is aluminum and can be easily damaged beyond repair! When you reassemble the cylinder use a high grade liquid gasket adhesive on the intake area going about 10mm into the wider surface near the base studs. First apply a small amount to the engine case, wait a few minutes, then fit the base gasket. Apply another small amount to the top side of the gasket and refit the cylinder.DO NOT APPLY ADHESIVE TO THE ENTIRE GASKET, YOU WILL HAVE A BITCH REMOVING IT AGAIN! This should fix your problem or at the least give you better gasket life.

  • Coolant leaking from the weep hole under the water pump cover:

       This is an easy fix, the water pump has a spring loaded mechanical seal behind the impeller that is prone to failure. Simply remove the pump cover, remove the impeller, (The bolt that retains the impeller has left hand threads, DO NOT screw this up, this bolt is extremely soft metal and will break off in the water pump shaft if over tightened, you will never get it out and have to replace the shaft/bearing assembly which costs about $60, not counting the shaft seal and the possibility of replacing you clutch side cover gasket!) using a small screwdriver and hammer pry up the lip of the mechanical seal part of the way around until you can can get a good bite on it, give it a good whack so the soft metal bucket distorts enough in it's bore that you can grab it with needle nose pliers or vise-grips. Replace the seal  (part # 1740-46A00) with a new one, lightly coating the bucket with hi temp silicone and tap it in using an appropriate sized socket as a driver. Replace the rubber seal and ceramic bushing on the back side of the impeller with the new parts provide in the kit and re-install the impeller. It's a good idea to also replace the rubberized steel washer at this time, it's a cheap part. Remember do not over tighten the impeller bolt and do not use Loc-Tite on this fastener. This problem is so common I carry a spare kit in my goodie box.

  • 1987 model year head gasket failure:

       Most 87's out there will require this upgrade; In 1987 the quadzilla had only six head studs which were 10mm in diameter. These are insufficient to restrain the combustion forces and will over time weaken and elongate causing a blown head gasket. You replace the gasket only to have it happen again, once the studs/threads begin to stretch your head will no longer hold it's torque. Suzuki became aware of this problem and changed the design on 88-90 models to seven stepped studs (10mm upper/12mm lower) and changed the deck height, slightly lowering the compression ratio. Also making the engine a little easier to start. The simple fix is to drill out the stud holes in the cylinder and rethread them to accept the later model studs. While any qualified machine shop can do this, I suggest you send your barrel to Tudors Performance, they have done hundreds, mine included, and I know of no complaints. Since doing this on my own engines I never had any further problems.
    NOTE: When replacing your cylinder on your 87 I recommend switching to the late model (88-90) jug. All the parts are interchangeable except the cylinder head, and intake manifold/reed cage assembly. The cost of a new head is comparable to the head stud mod. and you can take this opportunity to upgrade your reed cage to Duncan's Pyramid Valve or FMF's Ram Valve (you'll also have to get a new rubber manifold from Suzuki).  Either will give better throttle response, most noticeably coming off idle.

  • Wiseco piston problems:
        Burning the fronts off your Wiseco pistons? Leaning out/detonating @ high RPM's no matter how big your main jet is? Is your bike ported? The problem is Wiseco casts its pistons too narrow at the pin boss to accommodate a monster port job. This allows fresh mixture in the crankcase to be forced around the sides of the piston and out the exhaust port on the down stroke, so you get not enough mixture through the transfer ports into the combustion chamber, causing you to run lean and scorch the piston at or near the exhaust port.
      First do a leak down test to ensure your crank seals, gaskets, etc. are all healthy. Bad crank seals or other engine leaks will also cause these symptoms. If you pass the test it's certainly the piston not completely covering the exhaust port. Tear it down and test fit the piston in the bore, you may even be able to see daylight through the exhaust and around the sides of the piston.The only cure is a new piston.
      While a Wiseco rep. has informed me that this problem has been corrected in new production runs, he also informed me they have no intention of recalling existing pistons that are on the shelves at various suppliers. My suggestion is to stay away from their product entirely and use Sudco pistons.
      Sudco manufactures all the OEM  "ART" pistons for the "Big Four" (Suzuki, Kawasaki, Honda, and Yamaha). They originally had a non-compete agreement, preventing them from marketing pistons direct to the public, This expired a couple of years ago. The big news is that while Suzuki tries to force you to buy a new cylinder after going 2nd over, you can buy  the same OEM pistons from sudco to 4th over (same as Wiseco). Plus they are a lot less expensive. A piston alone from Suzuki runs about $70. You can get the same piston with rings, clips and pin for $70.99 plus S&H from Dennis Kirk (800)328-9280. You can buy direct from Sudco but they charge a little more and for us in California they charge us sales tax too. Dennis Kirk also as a pretty good catalog they will send you for free, but watch out their prices on some items can be extremely high, so shop around. Their part #'s for pistons are as follows: 0.0mm(stock) #13-824/ 0.25mm #13-8241/ 0.50mm #13-8242/ 0.75mm #13-8243/ 1.00mm #13-8244.
      If after replacing your piston and squaring away your jetting, the problem still persists, your exhaust port may just have been hogged out buy Satan with a grinder. the only reasonable course of action is to go back to company that did your porting for compensation, Good Luck! 

  • Oil dribbling from your countershaft sprocket:
       Got that nasty drip? There is a very thin O-ring on your c-shaft that likes to fail. I always carry a spare in my fanny pack. Remove your sprocket and sleeve, remove the old O-ring from around the c-shaft. Pop the new one on, replace the sleeve being sure to place it with the beveled edge on the inside. Replace the sprocket and your done! That was easy!

  • Jumps out of gear:
    Usually this will only occur in 2nd and/or 3rd gears. Unfortunately there is no simple fix. Your gears have worn dogs (The little square tits or indentations on the sides of the gears that allow them to grab the next gear on the shaft.) Transmission disassembly is not that difficult but, I would not recommend that it be undertaken by inexperienced mechanics or without the proper tools and a Genuine Suzuki shop manual.

    • You must replace gears as a set ie: If your bike jumps from 2nd to neutral you will have to replace both the driven (countershaft) and drive(input or clutch shaft) gears.If your bike jumps from 3rd to 2nd you will have to replace all four gears.

    • I would also suggest that you replace your 1st gear set when replacing your 2nd gear set these are typically damaged also and if not replaced will cause premature failure of 2nd gear and your shift forks.

    • You must also replace all three shift forks during this repair as they are easily damaged by gear set failures and even a slight distortion will cause premature gear set failure

    • Also replace the shifting drum detent arm and spring. When a gear set jumps it forces the shift drum to rotate, stressing the forks and detent arm beyond their design limits. If these parts are re-used you transmission problems will certainly persist!

    • If you do not feel comfortable performing this repair on your own you should at least remove all your side covers, accessories and cylinder. Remove your engine from the frame and take the bare bottom end to a qualified service facility for final disassembly.
        NOTE: Always ask for your old parts back! BUYER BEWARE!

   There are many , many more tips in the works. If you don't see the info you need just click here to Ask Mr Dune!

   If you have your own tip or suggestion you would like to see published e-mail me [email protected]

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