Tillerman6

Needing a few adjustments is probably par for the course. If all I have to do is the one slow speed jet, I will feel lucky. The B model motor I think is about the same bore and stroke, but other stuff like the expansion chamber or air box might be different. Do you remember what you had to do to the OKO's to get them dialed in? and who did you buy them from?

Feetupfun, Yes mine looks just like that now except for the OKO logo being in black ink or laser embossed. You may be at an altitude closer to the OKO distributor's location at 700 feet which is why you didn't need any jetting changes. I live at 2000 and go up the hill to 4500 or 5000 when the snow melts, so it seems like my tests were showing a too-rich mixture on the idle speed jet test with the air bleed screw. There was one K50 slow speed jet in the kit, so I put that in today- no issues with the slow speed test now. Roger at Mid- AtlanticTrials is great to work with and very knowledgeable

I will do that motovita- are they "dog leg" type? my efforts to find the dog leg mate for the brake side have met with failure and I have to return my brake side part to the dealer for some kind of replacement or store credit.

motovita- I was aware of the Yamaha kit to move the pegs back and down, because I have a set of heavy steel triangle shaped brackets that do that job. I haven't used them for a couple of years, as you can't get your foot on the brake lever without taking your foot off the right peg, and having the pegs so far back is not comfortable for riding anything except trials riding- which I don't do anyway. I also have the other style break lever which I think is shorter and is probably for when you have the trials brackets installed down and back. But I have never seen or heard of any pegs that could be moved forward from the stock position. If you have such an animal, maybe you could shoot a picture of them and I will know if it is the same thing I already have. If it is something new to me I might be interested in buying them from you. But what I really need is a trials seat pan and a trials seat.

So with part of the tune up sheet completed- the procedure has you peak the rpm's with the air bleed screw and then count the number of turns out you are- Mine were somewhere beyond 2.0, so I opted for the 50 size idle circuit jet that was included in the kit. Hard to tell for sure, but I was able to adjust the air bleed screw down below 2 turns out and still had a good idle and good throttle response. Just FYI - the carb for the TY 250 is a 26mm and comes with a 52 size idle jet installed. If you live at higher elevations than the factory (700 ft) it might be better to go ahead and install the smaller 50 idle jet and save yourself the time it takes to swap them out. I was not familiar with jet sizes or what was installed originally when I called Roger at USA-OKO 443-821-6154 but he helped me figure things out straight away. Overall I would give them a 4 out of 5 at least for their customer service and a good product. If you want to check out the installation page it's here: www.usa-oko.com/installation.html

Well, it's tomorrow now and the bike is running well- I got to the middle part of the tuning instructions that came with the OKO 26mm and adjusted the air bleed screw to maximize the rpm while keeping a minimum setting on the idle speed screw- now it pulls well up to half throttle- my test area around the house is not suitable for WFO testing, so I will have to wait on that, and right now it seems to still be a tiny bit too rich on the idle jet (because of my home altitude being higher than the factory 700 ft) but I'm a bit lazy about changing the jet size right now. With that boot being barely large enough to stretch over the intake, it takes a lot of patience to get it back in place if it comes off or has to be removed. I have had to un install the rear wheel, seat and air box to get the carb body and boot all situated and happy, so it's not too much of a fun idea to be changing jets right now.

Feetupfun-, As far as the kick- There are several factors involved. And some days it starts right up without a fuss and other days it will kick back repeatedly. However, I have found that starting the kick from TDC or "the notch" which is just my guess- the chances of getting a good start are increased about 60%. Also how warm the engine is makes a big difference and the throttle position- although putting on the new OKO carb did not help or change the tendency to kick back. New electronic ignition- I ordered the Clubman ignition from Rex's Speed Shop yesterday (6/08/21) which is advertised as having a timing curve and a strong spark. It should be here in about a week and looks fairly easy to install. Rex's makes a "pro" version that has an external switch for an even more advanced "hill climb" sort of timing, but I did not think I needed that option, so I just got the standard Clubman version. Rex's has a pretty impressive web site and it looks like they have the expertise needed to dial in most anybody's ignition situation with their specialized kits. I was glad to see that they had a special kit for the TY 250, and their prices are a bit more reasonable than any of the competition- ( I think because the installation uses the original rotor) plus the fact that Partzilla did not have an OEM set of standard points available, plus the cam on my rotor may be worn out, it made sense at the time to try the RSS kit. We will see in about 2 weeks if this was the right decision, but I have a good feeling about it right now.

Can't afford that, but CDI and compression release are in the mail.

Jon V8 and Feetup fun-, Still having that kickback issue- timing is spot on as far as the measurements on the flywheel. Could be the points are worn out-? with the opening timing set perfectly, you can't see that the points are open at all. At any point on the wheel openings- you can't see any gap in the points faces. Electrically, though there is a gap, or the plug would not be firing. Before I put this old set of points in, I noted that the bakelite? strip had worn down to about 1.5mm high. I don't know if that is part of the problem, but there is no way to get anything like the .012" max gap that I have read about on here. The only other thing that could wear out would be the cam itself, but it does not look worn when I had it off the bike last time. The timing light shows that the timing is spot on for about a 22mm setback from TDC. Any ideas? I'm about ready to give up on the points and order a CDI unit for the bike. If the cam is worn it would cost as much as the CDI unit from Rex's Speed Shop to replace it along with a new set of points. Jon V8- That's a great picture of the compression release, but what model of engine is this head off of? It's not an A model anyway. Looks like it came standard with 2 spark plug holes from the factory!

Tony 27- Had a time with the OKO install today. First thing was that the fitting on top of the new carb has a fine pitch thread that is different than what was on my TKO throttle cable. That may not sound like much, but I don't have another cable kit to draw parts from, so I had to mill off the old fitting and cable ferrule and keep the inner stranded part of the cable intact. That went well, but not everybody has a milling machine and a lathe, so depending on what threads are on the end of your existing throttle cable, you might have to do some scrounging for parts. The OKO fitting has a large Inner Diameter that fits over the carb end of the cable, so that was a plus, but the main thing is not to have to wait on another delivery. So with that done I started getting the OKO carb body mated up with the new rubber boot from Claus Studios. This was a bit more of a challenge as the opening on the OKO is larger than the TKO by about 4mm. I ended up making tapered plugs that were oversized for both ends of the new boot. These tapered plugs are inserted and left in the boot while the whole assembly is warmed up and then boiled with a lid on it for about 2-3 minutes. I had more trouble with the carb end than the airbox end and I would say that if you clamp the carb end first and leave the tapered plug in the airbox end till the last second, you stand a better chance of getting everything assembled correctly. I also had to take all the mounting bolts out of the airbox and let it float around as much as possible. After the carb is hose clamped to the boot, and the boot is hose clamped to the air box, you can insert the front end of the carb into the rubber manifold and I'm hoping the airbox will still bolt back down to the frame. The instructions with the kit are OK, but don't say what to do in case you can't get the new boot stretched over the carb intake diameter. I had to take the hot boiling pan and all out to the bike to keep it hot enough so that the boot didn't shrink down before I could get it in place. You only have about 5 seconds to get this done. There are also a couple of considerations that you might want to think about if you are going to install an OKO on your TY 250 A. #1 is that with the standard (furnished) metal float bowl- it is large enough that it touches the top of the gearcase. However, if you ordered the clear plastic float bowl, there will be more room under because there is no access plug for changing the jets. #2- It might be necessary to have on hand another throttle cable kit. _ I was lucky to have the machinery to re-work the one I had- there is another work around - you could re- tap the carb cap to accept the threads of your existing throttle cable. I should have the bike running tomorrow if all goes well- wish me luck!

Guy- you replied but did not say what gear teeth you are running now. Also what mods does the bike have that would affect performance?

Well, It's made in Taiwan with all the other OKO's and the original OKO's are knockoffs of the Keihin PWK's but apparently these knockoffs are not directly from China. Still waiting on the rubber boot that goes to the air box- it might come in today. - I noticed that this one has a metal float bowl as opposed to the clear plastic one that was mentioned in one of the previous posts.

If u are in the states it might be easier to just buy another used crank on ebay

Ordered the decompression kit from Venhill in the UK today. That should help with the ankle once I get the kit installed. It's a bit pricey, but cheaper than a doctor's visit and less painful! Thanks very much for the tip- I knew that compression releases did exist, but didn't know where to buy one- in this case it will be backordered, but at least it's in the pipeline.

Jon v8- I could do that with what I have in the shop. I guess there is a cable up to the handlebars? And where did you find this part? - Luckily I now own a new 14mm x 1.25 tap so it should be pretty easy to fit if everything else is available. Thanks very much for the idea anyway! BTW- with the timing as it is right now it will just kick back maybe once before it decides to start up, so since the new shouldered washer was installed, the timing is much closer to being right. Other factors affecting startup- Temperature, a very short (maybe 60 degrees of actual engagement of the starter shaft for each stroke of the kickstarter lever and the old carb seems to leave the plug wet even when I run it dry on daily shutdown. Today I just received my new OKO carb from Mid-Atlantic Trials!

I am running my old factory points set for now. New ones on the way. I had problems from making substitutions and not using a washer under the screw head- my fault totally. But I failed to mention that I am 72 and have managed to sprain my right ankle walking around in my front yard. This is not fun when the bike kicks back during the startup. So I guess I'm looking for perfection and that is probably not going to happen.

I noticed from reading old mail that you have or had two TY 250's with electronic ignition from Trials and Trails UK. You seemed to like the operation of these and thought it was an upgrade or advantage to have these kits onboard. And from looking at prices online recently, it appears that the spark only version from Trials and Trails is not too terribly expensive. But also from reading other mail it seems that people are not getting a response from T & T for whatever reason. Could be Covid related? So I am a little apprehensive about ordering from them right now. Should I be?

The points won't open without the flywheel cam to ride on. You have to be careful when re- installing the flywheel as the cam can get caught on the points arm and bend it. I use a small piece of plastic with a string on it to make the points rise above the cam until the flywheel is back on the shaft and the keyway is lined up and installed. Then I pull on the string and the spring in the points drops the points arm back down on the cam

Can you tell me what brand of electronic ignition you installed on your Ty 175? There are now at least two makers of these and all are quite expensive.

It sounds like you are talking from experience on this? Do you have a bike with the OKO installed? What are your thoughts other than the installation?

Could be- sorry- my mistake!

When I ordered the points for this bike, I think they had to substitute part numbers to get anything. So I will be doing my best to match up old to new. And thanks for the nice diagram, although I do have good spark, just not exactly at the right instant in time. I will be tinkering again today- see what happens. - I want to make a special washer to limit the Z axis travel of the breaker plate assembly around the securing screw. That should minimize the sloppy fit it has now. ( the slot in the plate is for a larger screw) - hope I don't drop anything and have to pull off the flywheel again!

One more possibility - you say the clutch won't disengage- Well mine did that too - when cold and if you put the full 1000 cc's of oil in the gearbox, there is a lot more friction between the plates because of the higher oil level. But as soon as I reduced the oil level to about 650-700 cc's and especially after the engine is running for a few minutes- the clutch would slip fine with the clutch lever pulled in.

I was reading on a site that sells magneto systems as a retrofit for the TY 250 A. It was mentioned in the instructions that sometimes during a crankshaft rebuild that one or both of the main crank ends ends up shorter than it was originally because of the work on the crankshaft. if that happens on the magneto side, it can cause the flywheel to touch or rub on the stator. In your case, I think it's possible that the clutch basket could be sitting too high or low in reference to the engine cases because of the crank being moved out of position. I am not a mechanic, and although my engine has had a complete overhaul, I do not know what the clearance should be behind the clutch basket, There are also several spacers that are close to the same size that go on various points on the crank or the gearbox components. I had a pro bike overhaul guy do mine, so although it was expensive, the job has turned out fine and my clutch is working normally. It might be possible to just measure the length of the clutch shaft in reference to the surfaces where the clutch cover gasket sits. If someone else on here has the clutch cover off you can ask them to measure theirs and make a comparison. That would tell you instantly if there is a crankshaft offset that is causing you problems.

That makes sense in a way- the fuel is ice cold and the spark plug is fairly hot, so the ceramic insulator takes a beating from the temperature changes I would think if there is excess fuel being sprayed onto the business end of the spark plug. I did not have another failure on my newest NGK plug, but I noticed that it was dark brown and more or less wet when I pulled it out today- I ordered a new OKO carb yesterday which will hopefully solve both problems. I have recently been letting the bike run the carb dry when shutting down for the day. I don't think this will change the plug readings towards a false "rich" wet looking plug.