hi this Jeff slaves racing this video is about Justin two-cylinder clearance how to measure it and about ring end gap so what is piston to summer clearance all about well obviously the piste the hole here has to be a little bit bigger than the piston or the piston can't go up and down and so what is that optimum clearance well that's determined by the manufacturers and for this size of a bore on this style of the cylinder with the nikah cell coating I didn't look it up on this but I'm sure pretty sure it's probably around 1.2 to one and a half thousands would be on a brand new fresh cylinder with probably up to three thousand spin their tolerance you know you they can actually go bigger than that through having four or five but let's get started you're pretty loose and once when pistons get loose then that's when you get cracked pistons you know they'll go crack up the skirt and break a chunk off and blow those pieces in the bottom and sometimes take the rod out with it so you don't want to let them get to that point so and why we have clearances different clearances for different types of engines is because how they're built this is aluminum and this is aluminum but they're different types of aluminum and they're different thicknesses and so they swell they expand at different rates so when the engine heats up this expands and the piston expands and they calculate those rates and figure out what is going to take to keep the engine alive and so the clearance as I mentioned before we're pretty typical of a cast piston which is what this is with a forged piston like a wast nor a lie scale then the clearances need to be larger because they are denser and they swell more they expand more so how do we measure that clearance so if you're tearing the top end down and you've got 100 miles on your engine or 100 hours excuse me on your engine you think it's time to put on your piston kit in it maybe you want to do some further checks besides just slapping piston well what a lot of guys do in the garage but I don't agree with because it's really something useless check that is you know take the feeler gauge these long periods and have both rings off of the piston and then set the feeler gauge again and slide the piston down with the feeler gauge to get the piston down in the hole and you kind of figure out what your clearance is well that's really really crude it really doesn't tell you about it much especially if you've got a big clearance because the bigger the clearance the thicker the gauge you have to use on a thicker the gauge is less of bends and conforms so the numbers get farther off so I don't recommend that although whatever if you want to do so another way to do it is with a telescopic gauge which is what this is they move in and out like this and you typically put them in the cylinder at an angle and then you lock this down here and then you rotate it on in pull it out and measure it with micrometer so then you would measure this gap with a micrometer and you'd measure the piston with the micrometer and subtract one from the other and that your clearance this is not quite as easy as it would seem there's a certain amount of feel involved you know most experienced machinist can do it with no problem that's another mesh another method to measure the piston and cylinder clearance then we have this device which is made by mid Toyo and this is called a cylinder bore gauge and its primary job is to measure a hole and it comes with a number of different spindles go with it for different bore sizes and you slide it then some wonder the same way you do that on an angle and then you know this gauge up here moves and then you can move it up and down in the cylinder bore and watch the gauge to see the trueness of the cylinder bore so what is trueness trennis is how straight it is and how round it is so straight going up and down around the circle obviously so that's what you can do with this kind of a gauge but I don't use Monte strokes because they're almost useless on a two-stroke because a two-stroke has so many holes in the zone of the ports you can only measure a very small you can only basically measure from the exhaust port up with this gauge so it doesn't tell you enough also two-stroke cylinders after I don't know we'll say 20 30 40 hours of of use they just get more and more untrue anyhow because of all the holes in I mean they're like a piece of Swiss cheese they they work easily and they get out of round and and not as straight as they should be but they still run just fine when they're that way so the quick and dirty method to do it at home is and it's the one I'll use here all the time just because I've looked at so many cylinders thousands of these cylinders I can look at one and in seconds tell you whether it's in good shape or not and so on one that has we'll just use the hundred hours number because that's pretty common timeframe to tear one down 150 125 really if you reach in here and this is a band but this has recently been recoded so this with this perfect condition but if you reach right in this top section here about two millimeters down from the top two or three millimeters that is where the ring stops during its travel so during its stroke the ring doesn't come all the way to the very top it comes just a few millimeters down so it's going to wear up until that point and then from there up is going to be untouched territory so the wear is going to be below that section so if you reach in here and you feel a lip that's where that's how much where you have if you can feel a lip it's not good now if you feel a big lip it's bad so that's kind of that make or break of it there if there's a big lip it needs to be replayed if there's a small lip yeah maybe you can get by also you would want to check the condition other parts of the sound of work for condition and typically were there whether they'll get damaged first where the plating will come off first is right above the exhaust port and sometimes between the exhaust ports because there's the main exhaust port then there's the sub ports and some pencils bridges there will get damaged even get cracked and but the severe wear will always be above the exhaust port so those are some methods for measuring at home like I said the down-and-dirty quick and dirty way to do it if it's got a lip if it's a bad lip I mean of course that's a judgment call then you've got a problem at that point you know if there's no other bad spots in the cylinder it's reusable yeah you can stick any piston in there and write it by writing for the rest of the season and be fine will it have the power that should have will be as good as a fresh one absolutely not but also you have to consider your budget to replay two cylinders about $200 I use a company in Fond du Lac Wisconsin called us chrome there's also another good company there called millennium technologies blobbies u.s. chrome for many years they do excellent work they come back looking like a brand new cylinder and you just send it in with the new piston that you get up Slavens racing comm preferably a vertex that's the best one to use for these cylinders and they'll replate it and make it right make it right back to there takes about three weeks to get that done typically you might want to call them if you're going to send one the end to see what their turnaround time is they also have a rush fee for 50 bucks or they'll kind of put you towards the front of the line and speed speed up the process but that's the way you do it I think that's about all this for now Joe