Vital Tech Tip: Keeping Your 2-Stroke Alive

everybody this is Scott Gustafson with vital MX today we're going to show you how to keep your two-stroke alive there's been a resurgent two-stroke interest in the last few years especially from a lot of riders that never rode two strokes before and there's a couple things that you really need to understand about a two-stroke that makes it different from a four-stroke just to keep the thing alive the thing I find commonly is that riders don't quite understand the bike and how simple some of the checks are and you can cause some premature wear or damage on your bike if you're not in tune with these things so let's go about showing you a couple of different things you can do okay the first thing we're gonna show you is how to do a compression test on your bike you'll need to buy a compression tester you can find these at auto parts stores on the Internet motorcycle retailers they're real inexpensive and they're real effective so the compression tester is just gonna tell you how much compression that your bike will have and tell you the condition of your bike the other thing you'll need before the test is a wrench to undo your spark plug one of the nice things about working on a two-stroke is they're so simple you can get in there without having to remove a bunch of things many times you can do this test without removing the tank so I'm just gonna undo the spark plug next thing I'm going to do is I'm going to match up my connector with the spark plug threads here and real basic this is a common thread so I'm going to put this 14 millimeter thread in here now I'm going to connect my compression tester okay now that you've got your compression tester all hooked up you're gonna end up what you do is you kick the bike over five to ten times until the gauge comes to a maximum reading and while you're doing this you're gonna hold the throttle wide open so this bike is reading a hundred and sixty psi and normally for most bikes this size we're going to be between 150 and 175 so shows the bike is in good condition whenever you go below that that's when you know you're going to be putting new rings in new breed's in maybe main seals maybe there's other underlying problems maybe you have a head gasket leak or something but the compression tester is the first thing you want to do with a two-stroke to see the condition or tell the condition of your bike one of the major issues I like to check on a two-stroke is a leaky main seal when someone comes to me and they say my bikes not running right this is one of the first areas that I go to what will happen is this will create a lean condition the bike will feel like you can never get it right and it's by creating a lean condition it's also going to make the bike run really hot and you could cause all kinds of problems with that seizures etc so I'll show you how to get in there now your ignition side cover on a two-stroke is dry so there's no oil in here you don't have to worry about draining oil or anything you just take the cover off so I'm just gonna remove these eight millimeter bolts on the outside here now I'm going to remove the flywheel seventeen millimeter nut here remember to take this washer out to remove the flywheel you're going to use a flywheel puller the nice thing about two-strokes is almost all of them use the same thread flywheel puller so what you used on your 1992 rm125 is probably gonna fit your KTM 150 from 2020 so you're gonna screw this in this one happens to be reverse thread and then using your impact gun okay now in order to better see the main seal down here we're gonna need to remove our wiring here just remove these two four millimeter allen screws now what I want to do is I want to look and just make sure there's no oil coming out of this seal right here if there is I know there's a leak and this could be causing problems with the engine like I was saying before you run into jetting problems you running into you also run into heat issues so this is something that probably needs to be replaced or checked periodically some of the downsides are there are some engines like this one where the main seal can't be removed from the outside a lot of the bikes you'll just be able to pick the main seal out of here this particular one you actually have to split the cases - to replace it so it's a bit of a job another area to check if you're having problems with your two-stroke are your reeds they wear out they chip so they're definitely something - you need to replace them periodically and you also need to check their condition sometimes a retool break and go into the cylinder and cause some problems there but otherwise the bike won't run real well if your reeds are bad so let's show you how to check these real quick now the KTM has really rigid manifolds here so we're gonna end up doing a little bit extra work to get the carburetor off first thing we're gonna do is loosen up the carburetor clamps I'm just gonna loosen up these six millimeter screws right here I'm gonna remove the subframe bolts on either side that's a 245 bolt then I'm gonna remove the bolts that hold the muffler on and then I'll remove the seat and then we're just gonna lift this up a little bit to give us a little extra room that pulls of the carburetor away from the manifold in the front here in order to get the read cage off I'm just going to remove these four eight millimeter bolts that hold it on once you have your read cage out you're gonna want to inspect it for chips along the edges and inspect it on all sides you're also going to visually check to see if one side is up you can see if you look real close this side has lifted up a little bit and you can tell by flipping it this way if you were to look into the light you could see the light shining through now here this is a classic scenario with a two-stroke you do your compression check and it's good and everything is checking out good the last time you wrote it it's in great shape but you check your reads and you notice hey they're not quite sealing good so this is something you can get some more performance out of by just replacing the reads on this okay so that's just a couple ways to troubleshoot your two-stroke you saw that we checked the bike had good compression we checked the main seal it was fine and then we finally checked the reads and we found out hey the reads could be replaced they're starting to get worn out so we actually add a bike that's not performing the way it should and it's always a good thing because sometimes you might think that the bike is a hundred percent and it's a little bit less than that simple check like that periodically will really help anyways if you liked that video or you want to see any other videos just let us know in the comments below if there are some different videos you'd like to know about if there's some tech tips you'd like to hear about let us know and we'll see if we can do them in the coming weeks for you thanks a lot from vital MX you

Channel: Vital MX

Views: 68,286

Rating: 4.9761577 out of 5

Keywords: Vital MX, VitalMX.com, motocross, supercross, dirt bikes, mx, motorcycle, Tech Tip, How To, Two-Stroke, 2stroke, KTM 150 SX

Id: hDOjc2YWy0k

Length: 8min 35sec (515 seconds)

Published: Fri Apr 24 2020