Tillerman6

No doubt. The power was starting to fade and it was getting hard to start. I will figure out how to do the surgery on the front box, but I was hoping that someone has already done a TY 250 and they had the inside knowledge to help me not cut in the wrong place. I have been washing out the back box (silencer/spark arrester) with some purple power and most of the crud is coming out pretty easily. There is a restriction near the mid point with a metal cone that points towards the engine, and around that there are some small orifices that let the gasses in, but they are very restricted and the pipe has a weld close to the restriction. I am trying to poke some wire down the oriifices but about the largest wire that can make it thru there is an .035" piece of mig wire. Could be the design or it could be more crud. The Degreaser fluid seems to pass by easy enough, but that is moving slow compared to what the gasses will be doing when the bike is back in one piece. It is soaking for a day or so to see if anything else will be freed up enough to release itself into the bucket of degreaser. So far I have gotten out about 4 chunks of carbon about the size of a peanut and the rest has dissolved into the degreaser and turned it black. If I get brave enough or if someone comments with direct knowledge of where the best place is to cut the front box open, I will tackle that too. It looks like someone has been in there before me and re-welded the sheet metal shut again. I don't know if they left the insides stock or just took everything out and left it empty. Totally black inside and can't see a thing. But it feels a little heavier than it should if it was just a shell with nothing inside.

So where do you get new packing from? And is there ANY MORE packing anywhere else that has to be changed out? Like in the main expansion chamber?

OK we are getting warm now. Do you mean remove the glass packing from the big expansion chamber and then burn it out with all the guts removed or what? I am talking about the large expansion chamber, not the smaller tail pipe. The smallerspark arrestor/ tail pipe did have a small tube inside that was full of crap, and it was wrapped with fiberglass, (see other thread) but it just slides right out of the spark arrester. Are you saying that the large expansion chamber has a second tube inside with packing around it and it is all welded into the big expansion chamber? I really need X ray vision to see what is going on inside there! I hate to cut into mine unless I know it HAS to be done. The only real restriction that I can sort of find is the one in the spark arrester. It was almost blocked. maybe 75% blocked. How do you tell when the expansion chamber itself is blocked or needs to be re-packed if air will still flow freely thru it? Or is it just one of those things that you do while you are cleaning the whole system out?

So what is inside there that has to be re-packed? I can see where someone has re-welded part of a seam, but it is only about 5 inches long and it's on the tail end under the round exhaust exit hole. There again hard to get a good picture of it with everything being black already. I have a mig welder of my own by the way. Sounds like you have already done that job a few times? Tell me all about it please! So are you saying that it is a waste of time to soak it in anything? or just try to bake it /burn it out?

So here is the last part to be burnt out or cleaned in some way. I was thinking maybe some drain cleaner? Drano or something like that? MEK? As you already may know, the exit hole is very small. So this does not lend itself to cleaning with a scraper or screwdriver. I have to go and get two more gallons of degreaser and soak this thing again overnight. but any thoughts are much appreciated.

This part of the tail pipe accepts the end plug assembly you see in the last thread above. It is also steel construction. It looks like there is a baffle inside there that is most likely welded in about half way down the length of the tube where the diameter starts to change. .? The baffle has several "spokes" to it and makes it look like the center of an old mag wheel. This is where I think the main part of the obstruction for the exhaust gasses was located. I have already poked down in there with a coat hanger and not much is coming out now Sorry for the poor image quality, but it's hard to take pictures in a black hole! . I also soaked it with degreaser over night, But I can see that it is still clogged up. If there is any part that looks like it needs the flame treatment to clean it out it would be this one or the main expansion chamber itself. I took all the rubber parts off the outside and all the mounting hardware.

Thought I should start a new thread for this one. The pictures tell the tale better than I can. All the parts on this one seem to be steel unless there is some aluminum tubing inside the Stainless Steel mesh between the large washer/baffles.? This stainless mesh is spot welded onto the inner tube and the inner tube is full of about 1/4 inch holes. You can't see the holes unless you hold it up to the sun light. I won't burn this part out just to be safe. It is not caked with carbon deposits anyway. Just another dip in the degreaser shoud clean it up well enough. The only problem (and it may not be much of a problem) is the fiberglass packing that was oil soaked. It lived in the "cup" at the forward end of the assembly. As you can see it is a mess. I am leaning towards removing it all together because about the only thing it seems to do is collect oil residue? One of the photos shows it pryied out with a screwdriver. I could push it back down if you think it needs to be in there to keep everything from rattleing?

True on all that equipment except the snake bite kit. No snakes up here. The hand gun is too heavy to lug around. I will take some pics of the innards of the tail pipe and you guys can tell me if there are any parts missing as far as a spark arrestor. I did not see anything like that inside, but there was just the oil soaked packing material that looks like fiberglass and the tube assembly that holds it in place. The scenery is awesome. Might need a bee sting kit this summer. They are bad and can ruin your day for two weeks. The advice on bears- If it's a grizzly you can play dead and they might just wander off. If it's a brown bear or a black bear you have to try and fight it off with whatever you can they are unpredictable. But the thing with them is don't make eye contact. They take that as a threat and then they want to defend "their territory" A good camera- Yup. I will try and put some shots on here for you guys to drool over. No problem.

This one is steel outside including the tail pipe, but i will check to see if any of the end covers are something else. I think there is a rubber gasket and a rubber flap just at the joint between the two pipes?Maybe that is part of the air box, and there is a rubber shock mount thing on the tail pipe that will have to come off before the fire gets lit. And some hardware etc etc. No problem, but thanks for the heads up. I think I did see one TY at the last trials event with an aluminum tail pipe "box" and yeah that would not be something I would put in the fire anyway. I have some 15 years as an amateur machinist and now I'm getting into aluminum foundry work so I have a pretty good idea of how thin aluminum can be damaged by heat.

It all depends on your point of view. I could stay home and watch TV and be real "safe" and then die of cancer or a heart attack. Something is gonna get you one way or the other, so why not enjoy yourself while you can? I do pretty much stay on the fire roads so there is usually a car coming by in a few hours anyway. I don't go blasting thru the trees like I used to so the biggest worry is probably a bear or a pack of wolves. But they are pretty scarce too. No rattlesnakes this far North. The wife would just say "well he died doing what he loved to do" and that would be that. I am working on the buddy thing. It's a lot more fun that way for sure. but then you get into a situation like "hey watch this" and you do something really stupid. I'm almost 70 years young so I have been there done that and I have the scars to prove it. I sort of ride to go exploring. If the trail drops off the edge I just turn around and laugh. Some of the trails up here are so steep you would have to have ropes to climb them on foot, so even though they are marked for motorcycle use I have to wonder what kind of a motorcycle they are talking about when they put the signs up! Maybe a Rokon with chains on both tires. And is a cell phone really that good anyway? Two months ago my step daugher was hiking and almost fell off the side of a mountain. She fractured her leg and had to be carried out on a stretcher which I made out of stuff I had in the shop. She was with her sister, but there was no cell service up there. Her sister walked down the trail back to her car and drove 20 miles to where she could get cell service and then called 911. No answer. Tried several times No ANSWER. So she called home and we rescued her ourselves with the home made stretcher. She had to make camp that night with her sister but we came with some help in the morning and it took most of the day to carry her off the mountain. As far as the bike it will be in fine shape again pretty soon. I feel much safer on it than any of the taller bikes they make these days. And I don't have to have a ladder to get on. And I don't have to mortgage my house again to buy one, so that's why the antique bike. Just exactly the way I want it. If you have friends to ride with that want to go when you want to go then consider yourself lucky! I still have the old friends but they gave up riding years ago. Sad for them. They think I'm crazy but the truth Is I really don't care what they think. What doesn't kill you makes you stronger!

Guy, So I could try to understand that several different ways. What do you mean exactly?

My cylinder is already sent out for repairs, but I will definitely be cleaning the hell out of the tail pipes. And lubing all the parts well with 2 stroke oil on re-assembly The pipes were clogged to some degree.I haven't got around to burning out the pipes yet, but that will happen soon.

100% agree and I won't be running like that from now on. Point well taken. But the bore is at the outer limits with this stock piston. Time for plan B.

Feetupfun and guys, Well, yes if I was close to anyone that could bore a cylinder I would walk it in there and have them tell me what piston to order, Don't have that option. And I want the shop to fit the new bore to the new piston, not the other way around. It's a whole new can of worms to me. They have to bore until the cylinder wall cleans up plus enough for clearances on the next size piston that is available. Nobody knows at what dimension that is going to happen until they start making chips. I don't know if they can do all that in one setup. I would not want to try it without having the new pistons in my hand to measure. Even then it would be a guess the first time. Tough job to get it right. I am not friends with Millenium Technologies in any way. If it turns out that they let me down, I will be the first one to let you guys all know it. If they do a fine job, then that too will be widely known on here. If the other guy that had the Nikasil work done on his bike would like to comment on his experience (who ever that was) I would be very grateful to hear all about it. Wish me luck!

Noisy is one thing but this was more noise than I wanted to deal with. I could hear it with my helmet on and the sound was bouncing off the trees in front of me. Not normal at all. Then when I looked at the small end bearing it was missing a roller! WTF? I am leaning heavily in favor of the Wossener pistons right now. They have 4 oversizes available in the Germany warehouses and the pistons are forged which is supposed to be stronger. Millenium Technologies will decide which size to order. I did find out that the same part numbers are used from the DT250 series if someone wants to use a factory piston and rings, But I don't know where all the sizes would be available on short notice in the States. It's up to the technician to tell me what size I need after they get the boring process finished. Thing is from my perspective, you can't save any money trying to jury rig a piston yourself. You have to have the cyl bored, and that is what introduces some variables. If the tech decides that the bore should go past the 1st oversize, then any stock or 1st oversize pistons that I might have stupidly assumed that were going to fit would now be useless. So how are you going to save any money? If you guess it right you are home free, but if you guess it wrong you have to go out and look for another piston and rings and try to sell the one (s) you bought? Nahhhh!

All the other edges in the cylinder line up perfectly. It was just this one spot that was low (high) because the pic was taken with the cylinder upside down. I am not a 2 stroke authority at all, but I know that the rattle was getting LOUDER the more I ran the bike. And I usually have to ride alone, in the middle of an area with sketchy cell service, so this thing HAS to work or I have a 10 -20 mile hike out of the woods. AND a teardown when I get it home!- If the piston had come out of that bore clean, then I would not worry, but it had an area on the rings and directly below that about 1/2 inch wide and extended down the piston most of the way to the edge of the skirt. In that area the piston had seized before. I don't know when, but it had seized at one time or another. I don't have pictures of the rings, but they were nicked in 4 places near the ends where they pass by this red arrow area in the cylinder. Also some micro beads of metal were stuck to the inside of the intake port. (same area) Knocking - I think that was my fault. The more I read on here the more it sounds like a bad idea to do any engine braking with a 2 stroke. And I was definitely doing that. Rattling- Well the rattling was getting louder and added to the loud bang when the cylinder would fire with the throttle closed. It seemed like a good thing to go inside and have a look. As it turned out, the piston to bore clearance was at the max limit after I had the bore honed to remove the glaze. So at a minimum it would need a new piston and rings and an overbore anyway. There are no cylinder boring services anywhere around where I live (North Idaho) and stock oversize pistons are not something you want to buy off of Ebay in advance of knowing what size you are going to need! the Nikasil process is about 120.00 and I have read on here that the fellow that had his TY nikasil'ed liked it a lot, so why not try it? It's supposed to reduce the friction and make the bike run smoother. They would not offer that service if it was going to make things worse, and they do hundreds of cylinders a month of all varieties. And they guarantee that the Nikasil will not flake off. Anyway, I think it was good to have a look and it was time for a re-bore at a minimum. The bike is from 1974. As I said before, I was trying to prevent being stranded in the woods and or blowing up my motor. The damage during a seizure can go way beyond just the piston/cylinder in a heartbeat, so not being one to let it all hang out, this might be the way to go for me.

Guy, Now that makes more sense than anything I could think of. Reason I'm asking is that I have that cylinder sent out to Millenium Technologies for a rebore and Nikasil. I don't know how many hours it has had on it, but when I had it in a local MC shop they ran a hone thru it to take out some of the scuff marks from the piston and rings. The shop owner said the cylinder was a little out of round and you could hear the hone speeding up and slowing down presumably from the out of round condition. I measured the bore in one spot above the output port and it was still right at 70mm, so I think the sleeve that is in there now has not been re-bored oversize. But since that area on the right has been modified with a rotary file or some abrasive tool, it does probably mean that the aluminum outside the sleeve was not touching the liner so they ground down the liner until they had full support from behind. I wanted to get as many eyes on that as possible before they call me from Millenium and say whatever they are going to say. I am about 50-50 on trying to find a better cylinder to put the money into, and I think a re-sleeve would be several hundred dollars where maybe a cylinder that was worn but in better shape could be re-bored as is and end up costing much less out the door because it would not need to be repaired first.

Old thread, but could it be that since the carb body does not sit level with the ground, they had to make the float sit level with the ground and not the carb body. The fuel level might flood the carb if the float was level with the carb body since it is on an angle when it is mounted on the reed cage manifold.

Shippy, I would have to assume that your changing of the pilot jet size did fix the problem with the dong-dong noise?, and I have that same noise on my TY250 A - when on a deceleration of more than say 30 feet with the throttle closed, especially if the engine is fully warmed up. But now I am thinking that I simply should not be using the engine for deceleration at all! The idea is that the rings will scrape the cylinder wall dry in just a few strokes with the throttle closed and the cylinder and piston and head are possibly still hot from the last uphill run. If there is any glowing carbon stuck to the piston crown or the exhaust port or anywhere that fuel and air can get to, and that starts glowing hot enough to ignite the tiny bit of residual fuel that gets sucked under the carb slide when the vacum is high and your have a sort of unwanted pulse of power which may or may not co-inside with the spark plug timing. (or a tight downhill section that you need to keep your speed down to an absolute minimum) What I am getting is almost a diesel type of ignition or pre-ignition. It also will push the bike sharply for one piston stroke and yank on the gears and chain because the chain was putting slack on top of the chain loop but all of a sudden the engine fires once and takes all the slack out of the system! But then immediately the engine stops firing again and the slack moves back to the top of the loop! So what could possibly go wrong with this scenario? The engine will not ever make that noise unless the throttle is closed while on a down hill, so I have to think that what I was doing was abuse. I would also get 30 seconds of piston slap noise along with the dong! dong! so I don't think if was doing the engine any good. But all that being said, if you could stop this dong - dong stuff entirely by changing the pilot jet size then at least you are not yanking on the gears and chain every 10 feet. I don't understand how increasing the pilot jet size would help this situation because you would think that if there was any residual weeping of the carb with the throttle closed, that it would weep more fuel with the larger jet size but I must be missing something? I guess it all boils down to my stupidity for wearing out my engine and gears rather than some brake shoe material. By the way- I am a newbie on here and I appreciate all the help you guys are dishing out! Please let me know if anything has changed in the way your bike is performing or your riding style since this old thread was created? Thanks for your input!

Guys, I started a thread asking about cleaning the tailpipe and got side tracked a bit. Can anyone look at these photos for me and see if that intake side port opening looks damaged or modified or normal? in some way? It looks to me that one side of the opening is lower than the other, and somehow it might have been caused by someone in there with a grinder? The right side of the image is much shinier than the left side as well, so I don't know why that would be the case. All I did was wash the whole jug with water and a solvent and I did not scrub this area on the right any more than I did on the left side. So something has been in there either with a lot of heat or what is your esteemed opinion? Before it was washed there were also tiny beads of silver colored metal stuck to the intake port surfaces but only on that same side. These beads were on the order of .005" in diameter and resembled weld spatter from a MIG welder. Any ideas? I had some detonation issues while decelerating with the throttle closed (My bad) as I was thinking that the engine would cool itself down better with the throttle closed than by blipping the throttle with the clutch pulled in.

I did the kickstarter spring adjustment years ago, but I would put in enough preload so that when your foot comes off the kick starter it whips up and dis engages the starting pauls with some authority. You will hear it rattling until the lever is almost verical and you have to get beyond that or risk damage to the gearbox parts.

TY 250A wiring myths solved!. There are three ground points used in the TY250A wiring that are important for the spark ignition system. At the source coil- inside the magneto- one end of the source coil is grounded to the frame. At the High voltage Spark coil- one end is grounded to the frame. And at the kill switch- If you slide the kill switch to the red position it grounds out the primary input side of the high voltage spark coil and the output of the magneto. And since both coils are just copper wire, the resistance measurement is very low. You might think you had a short to ground somewhere if you had only a garden variety ohm meter to work with. - For instance, if you measure resistance to ground at the output of the magneto (female black wire) - there is hardly any difference between the readings for engine "kill" and engine run. (Even with the points held open) you will get about 0.1 ohms in kill position and 0.75 ohms in the run position ! But the bike was designed that way and it runs fine if everything else is in working order. And since the two coils are in parallel electrically, the two of them together is lower than either one separately. So on my bike, the two coils in parallel measure just three quarters of an ohm. You need a pretty good volt-ohm meter with a low ohms range to even be able to measure that. And that reading is taken with the points open and of course the kill switch sett to 'run" (not showing red} FYI- on the 74 model there is no blocking diode in the system.

Tony27 I have the A model 250 1974 I took the oil pump out and blocked off the inlet tube and put in the plate but I'm wondering if the oil in the gas would call for a larger jet because of the thicker gas mixture?

Oni nou, Thanks for that. I have been abusing the engine no doubt. Probably picked up bad habits from running 4 strokes back in the day. The engine braking is smoother and less likely to dump you on your head, but it is harder on the engine for sure.

shakenstirred, I am thinking you are right. About 50 :1. The break in procedure might be a little richer than that, but the Amsoil Saber does not burn completely in the engine because it has a higher flashpoint. I have no idea what oil was used by the previous owner and I have run the bike on Amsoil Saber since I've had it, Sometimes richer and sometimes leaner, but I noticed that the piston slap was a little louder with the 80:1 which I tried briefly. I was trying to save having to teardown the engine for a new piston for as long as possible, but the recent detonation/ banging changed my way of thinking. I am also going to stop using engine braking as a means of slowing down on long downhills. It just wipes all the oil off the cylinder and piston. And it still tries to fire about every 30 feet at least once or twice with a loud bang. That was the only time I heard any banging/detonation anyway was going downhill with the throttle closed. It's kind of ironic about the closed throttle position causing this problem because the engine will not start with an open throttle. The closed position is also the recommended position for starting! I am thinking that the carb slide must be a tiny bit open even if there is slack in the throttle cable. I also took the oil pump off the engine shortly after i got it because having an oil pump failure would be the end of the road for this engine and I only have one.