Joined Aug 23, 2011 Messages 348 Location Re: T500 crank seal fitment. A leaky crank seal could be allowing air or gearbox oil into places it doesn’t belong and causing all kinds of issues. After we described our RD’s running problems to him, Brad offered to spend a few hours showing us the steps he goes through diagnosing 2-stroke … I don't currently have the top end installed, so there's no chance of creating a pressure/vacuum situation in the crankcase. Bike Chat Forums Index-> The Workshop Topic moved: from General Bike Chat to The Workshop by Kickstart (31 Aug 2012 - 20:37) Seals exposed to moisture can weld themselves to a bearing surface (i.e. The bottom cylinder is running lean as a result of leaking seal.. Use the pneumatic wrench or clutch tool to remove the boss nut from the crank and the primary gear. When I did Paul's RD build, the previous shop put BOTH seals in BACKWARDS! 80LC & 125LC chat. For starters, there is no need to drain the oil or fluids when replacing this side only. If you are still struggling with following this process, watch this YouTube video that gives a complete walk-through: If you already own the various necessary tools and wrenches and are used to performing this sort of maintenance, then the cost is limited to new seals, oil, and your time. You’ll need a seal pick tool set (link to Amazon) for these next steps: This YouTube video offers a great little hack on the removal process: Be sure to grease the new seal lightly with your preferred mix. If your crankcase gasket, cylinder gasket or crank seals fail, then your crank case is no longer sealed. You’ve now successfully replaced the seal on both sides! ... Crank seal would most likely cause rough/poor running if leaking, not a 7k wall on load And if everything went smoothly, then you should be all finished! I believe on the 400 that the impulse runs off of the pto side. 2-stroke crank seals are double-lip, meaning they need to hold pressure and a vacum inside the crankcase. Remove the clutch cover and set the bolts aside, making careful note of where each one came from. Just as before, pay close attention to where each nut and bolt belongs so that they can be replaced properly at reassembly. Go. Technical Info, Carburation/Jetting looms etc. Now you should be able to move on to removing the stator/ignition assembly. Take a photo of the position of the clutch and primary gear so that you can replace them as they were later. Reactions: treesmith. Then use the claw end of the hammer to pry the seal out from its home. He shares what he learns along the way. And Crank Seal on A 2 Stroke Dirt Bike Checking the condition of a 2 stroke dirt bike's LH crank bearing and crank seal is something that should be done occasionally and this is true whether riding motocross, off-road disciplines or FMX. I've spent most of my life repairing engines big and small, from string trimmers to diesel tractors. Next, drain the oil and coolant from the engine. Just use some mix oil on the rubber parts of the seals that come in contact with the crankshaft, no other lube or sealant is required. Would slipping 2-stroke oil in behind the seal via injecting it through the PTO-side crank bearing work, as well, to sufficiently lube the seal? Try Audible Premium Plus and Get Up to Two Free Audiobooks. Start by poking the screw through the seal, just enough that it catches. Specializing in 2 stroke performance services, such as nikasil plated cylinder coatings, Ontario Crank Service also offers many other performance services like porting, cylinder sleeving, cylinder repair, cylinder plating, crankshaft and engine rebuilding for all ATV, watercraft, motorcycle, outboards and Snowmobile engines. Read on to learn how to do this, one step at a time. TreeSurfer ArboristSite Operative. If a crank seal is leaking it can allow gearbox oil to enter the crankcase and causes the bike to run rich. For Sale 50, 80 & 125cc Bikes or parts. 2 stroke crank seals. Suzuki 2-Strokes: '75 T500M since '93 Ridden it over 100,000 mi Location: Galveston County, Tx. Chainsaw Making Sparks: Reasons and Solutions. If the crank seal goes it will cause a lean condition on that side. After you’ve cleaned and drained things, it’s time to grab some tools and start disassembling. Thread starter NicholasA; Start date Feb 19, 2014; 1; 2; Next. To replace the crank seals on a 2 stroke engine, there are several steps to follow, including cleaning/draining, disassembly and removal, replacement, and reassembly. Use a rag to clean any dirt or crud that may have accumulated around the clutch cover. The RD LC Crazy UK 2 Stroke Forum . If you look at the mag seal, there is a open side and a closed side to it...CLOSED side faces crank. The RD LC Crazy UK 2 Stroke Forum . crankshaft seals have a limited service life and whilst a worn seal will not always show any visible sign of leakage, the effect of a worn seal/s is critical to the performance of a 2-stroke motorcycle. The impact wrench (link to Amazon) is part of that equation but the compressor is often considerably more than that. Primary seal has nubs on it, they will face the main bearing to use as a location and squaring up the seal when installed. Having the right tools is crucial to being able to accomplish this on your own for a reasonable price. NicholasA. It happens almost every working day. A 2-stroke fan and RD350/400 fanatic in particular, Brad has acquired a great deal of knowledge about Japanese 2-strokes. 2 Stroke Design Spreadsheets, 2 Stroke Tuners Info My last two bikes: '89 Honda CR250R (stock), '89 KDX200SR with PC pipe. For this next step, you’ll need a pneumatic wrench or a clutch holding tool (link to Amazon). This site is an affiliate for companies including Amazon Associates and earns a commission on qualifying purchases. First, remove the rotor nut and then remove the rotor cover. 2 Stroke Replacing Crank Seals 97 Cr 125. Be careful not to misplace any hardware. Now that the new seal is in place reassemble the housing and parts in reverse order. Sep 26, 2012. Check the ring end gap and replace those while in there. Here's the backwards pic's Chuck Note: Do not refill using the previously drained fluids. Stroke, Custom Order, Chevy, 350, 400. are low cost to replace and the cost of replacement is largely labor which you are already doing to get to the crank seals. Most of the consumable parts, seals, bearings, rings etc. Its job is to make sure that oil and gasoline don’t leak out of the combustion chamber into adjacent sections of the engine case. Rotax engines, like many 2-strokes, are known for their propensity to run away instead of idle if an appreciable air leak is present. You should be able to see the crank seal at this point if you’ve removed all the various housing pieces correctly. I'm Teddy, a small engine enthusiast, and occasional guitar player. Replacing the crank seal on this side is very similar and maybe even a bit simpler. While they are a relatively simple component, they serve an important purpose in keeping the oil that is constantly being used and tossed by the crankshaft as it rotates from leaking out of the engine’s crankcase. If the crankshaft seal dries out, cracks, or breaks, it can cause an oil leak. The poor guy on the other end of the phone is giving me every intimate detail about his modified engine in hopes that I'll be able to rattle out the exact cause of his most recent piston seizure. Most crankshaft seals are made of rubber and metal and are round in shape. If you lack the tools, like a pneumatic wrench and an air compressor, then the cost goes up quite a bit. Originally Posted by boyoboy actually, its not my bike. Bike related chat. Once clean, remove the brake pedal and kickstarter and set them aside. Next Last. You can jump right into some disassembly. At this point, you should be able to remove and replace the crank seal, just as discussed previously. Once you’ve replaced the seal, carefully reassemble the pieces in reverse and start the bike, letting it idle for a few minutes to ensure that things are running smoothly. On a 2 stroke dirt bike, the seals on each side serve different functions and involve slightly different processes. ABOUT AIR LEAKS - The engine you save could be your own. Using a chainsaw can be dangerous even under the most ordinary circumstances. It seems to be peculiar to 2-strokes though, because there are millions of cars out there which have the crank/gearbox/diff seals exposed 24/7 without spewing their guts. Teddy is always fiddling with small engines, picking up thrown-out string trimmers or tearing apart dirt bikes. The crank seal, otherwise known as the main bearing oil seal, sits deep inside the two stroke engine right next to the main bearing. Blown crank seals are usually a symptom of another problem. To replace the crank seals on a 2 stroke engine, there are several steps to follow, including cleaning/draining, disassembly and removal, replacement, and reassembly. older 125cc dirt bike, 70's, rare, honda, and i just wanted to inform myself before going to check it out. 1 of 2 Go to page. LC / YPVS & 500 Chat. The exact process will vary depending on your machine and which side needs replacing. 80LC & 125LC chat. You don’t want any of that falling inside your machinery once you start to open it up and take things apart. Hopefully, you'll have less headaches than he has had by learning from his mistakes. Better safe than sorry! BU0DaÆrŽ¥R`¹˜\YÿÅ:ZÂ|ÊZa«“9LÂߕW¯è몃4džr„ There may not be a part called a crankcase seal, but the crankcase must be sealed to allow the saw to run properly. Here's Why. Feb 19, 2014 #1 My bike has recently started losing trans oil and running rich and i have diagnosed it a a leaking right crank seal. A typical sign indicating you need to replace a two-stroke crank seal is an oiled plug or oil dripping from the exhaust pipe. Reply. i thought i had the problem solved with the xc with the high idle problem but i guess not i started it up today idle at 4 grand i hit the gas a few times hoping it would drop but didnt so i shut it off. One example is a failing PTO bearing causing the seal to elongate and allow air to enter the crankcase leaning the fuel air mixture on that side eventually detonating the piston. Let’s jump to the other side of the bike and replace that side too. 42 responses to “Replace Yamaha 2 stroke crank seals” Carson says: 09/18/2014 at 8:26 am. Crank seal . If the cover is stuck, try tapping it with a rubber mallet to loosen it. the crank journal) and when you turn it the lip is torn off, leaving a thin black line of rubber on the journal. Remember to pay careful attention to the placement of different nuts and bolts. Part Number: CRO-LW95119 Not Yet Reviewed For Sale 50, 80 & 125cc Bikes or parts. Wanted 50, 80& 125cc Bikes or parts . Can be installed without disassembly of crank. I'm hoping that the troubleshooting guides on this site will save you a lot of time and headaches when it comes to fixing engines. If you’re noticing a strange smell coming from your 2-stroke or experiencing an issue with it revving up, it might be time to replace the crank seals. This isn't true in my experience, every leaky crank seal I've found was causing terrible idle mixture control. Optimal crankcase pressure is a major factor of a 2-stroke engine’s design and any deviation from specs will upset performance. If the seal pick is proving to be too difficult to use, some people recommend using a drywall screw and hammer to remove it. If you’re serious about committing to small engine repair, then invest in the quality tools to get the job done, and after a while, jobs like these will be much easier. The seal on the magneto/left side keeps air from getting into the combustion chamber, while the seal on the clutch/right side keeps crankcase oil from getting into the combustion chamber. Countershaft seal should get done while in there otherwise inspect and replace as required. Like any engine parts, they take some damage over time and need to be replaced. If you never have, then probably. A fairly affordable operation for the home mechanic. whats up with this thing could it be bad crank seals i just replaces the hole top end pistons/rings and all. ... on page 60 there is a technical drawing of he crank and it shows the seals for the centre bearing. While its running you'll be getting more oil to the engine parts but it won't change the jetting (rich/lean). Here's Why. BlueDevil Pro says: March 19, 2020 at 11:18 am.