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Not sure what "a 2005 loom" refers to? If no spark... Check key switch and kill switch, especially if corroded Check the plug wire follow it to coil, everything look right? Remove the gear shift lever Pull the flywheel cover. Inspect the flywheel, corrosion remove with emery cloth check for spark after cleaning. still nothing, pull flywheel and inspect /replace stator plate.

Installed crank, and transmission bearings in both cases. Had bearings in bags in freezer overnight and then put cases in the over at 300degree temp. When they reached the point when water vaporized, turned off heat in oven. Then each side crank bearing. I had to supplementally heat the case with a propane torch to get bearing to slide into case. Wipe the bearing, that you just pulled out of the freezer, quick wipe and into the correct position. Both crank seals went smoothly. Both blind bearings required physical seating, which I did with a rubber mallet and impact socket where the outer edge of the bearing (race) matched with the socket size. Again, heated the case with torch first. Bearings seated well, with some persusion. Then I placed the case halves on a wooden bench with cloth below and covering each case half and bearings, to keep dust or dirt from getting into bearings. Bearing install 1.5 hrs, with bake time. I warmed cases for about 15minutes in the oven @‌ 300 degrees. Suggestions - dry fit the bearings onto the case, noting location of each bearings with a tag/map - the tranny bearings. - put each bearing and them into individual ziplock bags in the freezer, which includes a part reference - so you know which individual bearing fits each slot... it will speed it up and keep the bearings cold... mine were altogether and they "warmed" as a group. - keep torch moving and heat both inside and outside of case at bearing location... quick on the bearing move from freezer to case.. I watched video and tech was using dryice, which might help by lowering the bearing temp further. Next steps are bearing seals, crankshaft, transmission.

I broke the engine free when I removed the flywheel. The flywheel puller threads into the center of the flywheel and is hollow so a ram bolt pulls flywheel off the crank shaft. When the crankshaft rotated, chunks of piston were revealed lodged in between the two metal discs on the crank. Removed all visible fragments and could only achieve 270degrees of crank rotation without "force" Then, attempted to flush out crank case with diesel fuel using an drill powered transfer pump spraying into an inverted engine. That actually flushed out most all of the piston metal fragments. Crank shaft would achieve 360 degree rotation. It seemed like a cheap fix. Let engine drain overnight. Next day, the crank turned but there was a catch about every third of forth rotation. I knew one of the crank bearings was impacted... and that may have been the cause of it all. I then split the cases. At that stage, it only makes sense to change all the bearings and seals. It proved that the crank bearing on the flywheel side of the engine and one of the transmission bearings were both not spinning like they should. The crankcase does not have much free space around the edge of the crankshaft, less than I thought. Case is in excellent condition, no cracks or gauges. Used automobile aluminum rim cleaner and then a water bath and the aluminum cases look like factory new. So, after research and consultation, here's my recipe for a total engine rebuild on a YZ 125. - hotrod lower end kit to include crank shaft, crank shaft main bearings and wrist pin needle bearing and seals - hotrod transmission bearings & seals - hotrod water pump rebuild kit - hotrod top and bottom end gasket kit - namura piston, wrist pin The cylinder bore has a small nick, about 3mm length and 1/2mm depth extends from top of a port, left side of bore. I was advised that a light hone and performance will be minimally impacted, if at all. The reasoning provided was the imperfection is low in the chamber so excellent compression can still be achieved. I plan to compression test after build. If poor, then I'll go for a re-chromed cylinder exchange. Cost is $290 gross with a $70 core charge after you send them your cylinder. USChrome was recommended by more than one source. Hidden costs of exchange are the cost and time to remove/reinstall the head studs and power valve from your core and install back into new cylinder. Was advised that namura, though less cost than wiseco, is a solid if not better piston. Learned that Vertex piston is OEM on the KTM bikes. Hotrod has the best crank and bearings and the cost is slightly more as a result. All in for the recipe of parts - $350, with cost saving of almost $200 achieved by sourcing on-line versus local dealer for same parts. Had I went with Wiseco, I could have done it for about $285. Tools that I've had to purchase for this project; - flywheel puller $20 - case splitter tool $60 - crankcase puller (tusk) $66 - blind bearing puller $50 So, $550 between for parts, tools. 2 cycle is a pretty simple engine and the 125cc motor when out of bike is quite small. Cases are stripped of bearings, cleaned of oil, gaskits, and case sealant residue and prepped for the oven... Bearings are in the freezer. My first engine rebuild is about to begin. I'll track my hours and share the lessons learned.

Engine seized up as result of exhaust side of piston's skirt breaking apart and falling into lower end of engine. Yes there was engine oil and also coolant, both before and after the "seizure"... or that would have been a big lecture to the boy! I read on another blog this is usually the result of running to lean, thus too hot and pop??? In hindsight, the bike was accumulating some oil/sand at the exhaust port/muffler connection on the cylinder. It was initiated by an over full oil condition, which was corrected, weeks before. But, maybe that popped the seal. The bike started, ran well, plenty of power, it was odd. Another blogger suggested it is caused by too much tolerance in the crank bearings, causing piston slap? I have torn down the engine to lower end engine case splitting stage. Cylinder has small gauge (about 3mm length, maybe 1mm depth and 1-2mm width) from top of port upward. Thus, top 50 - 60mm (about 2") of cylinder are perfect... which is combustion chamber. Metal piston shards remain in lower end of engine. Although when I pulled the flywheel, crank broke free and permits about 200 - 270 degrees of rotation. And, rotation exposed many shards of piston skirt metal wedged in between crank, removed accessible metal shards, yet crank will still not complete full revolution. So... Questions are; 1. does the cylinder need rechroming or can I simply hone it to remove any high edges as the nick is so low in combustion chamber? 2. looking for guidance on how much to change out... lower end bearings and seals (about $60) or crank too (about $75)? top end kit (about $125) (depending on brand) 3. any experience/recommendation on engine rebuild kits; wiseco, nomura, hotrod cranks, moose racing - all offer a complete lower and top end rebuild kits from $260 to $400...? 4. any recommendation on cylinder rechroming companies? (us chrome)?? About 10 manhours to get top end, clutch cover, clutch housing, flywheel, flywheel cover and stator plate off, and remove engine lower end from bike frame... including all the requisite steps to begin those tasks. Likely a shop would do it faster. Only mention the manhours to give an idea to other weekenders considering the task. Thanks in advance.

Engine seized up as result of exhaust side of piston's skirt breaking apart and falling into lower end of engine. Yes there was engine oil and also coolant, both before and after the "seizure"... or that would have been a big lecture to the boy! I read on another blog this is usually the result of running to lean, thus too hot and pop??? In hindsight, the bike was accumulating some oil/sand at the exhaust port/muffler connection on the cylinder. It was initiated by an over full oil condition, which was corrected, weeks before. But, maybe that popped the seal. The bike started, ran well, plenty of power, it was odd. Another blogger suggested it is caused by too much tolerance in the crank bearings, causing piston slap? I have torn down the engine to lower end engine case splitting stage. Cylinder has small gauge (about 3mm length, maybe 1mm depth and 1-2mm width) from top of port upward. Thus, top 50 - 60mm (about 2") of cylinder are perfect... which is combustion chamber. Metal piston shards remain in lower end of engine. Although when I pulled the flywheel, crank broke free and permits about 200 - 270 degrees of rotation. And, rotation exposed many shards of piston skirt metal wedged in between crank, removed accessible metal shards, yet crank will still not complete full revolution. So... Questions are; 1. does the cylinder need rechroming or can I simply hone it to remove any high edges as the nick is so low in combustion chamber? 2. looking for guidance on how much to change out... lower end bearings and seals (about $60) or crank too (about $75)? top end kit (about $125) (depending on brand) 3. any experience/recommendation on engine rebuild kits; wiseco, nomura, hotrod cranks, moose racing - all offer a complete lower and top end rebuild kits from $260 to $400...? 4. any recommendation on cylinder rechroming companies? (us chrome)?? About 10 manhours to get top end, clutch cover, clutch housing, flywheel, flywheel cover and stator plate off, and remove engine lower end from bike frame... including all the requisite steps to begin those tasks. Likely a shop would do it faster. Only mention the manhours to give an idea to other weekenders considering the task. Thanks in advance.

I did have both the bearings and the seals changed, which required a teardown of the engine. So, this "reverse" condition only happens occasionally with the "tell" being the failure of the tachometer. Then, turning off the engine and restarting it usually puts it back into forward. I agree, the timing is probably off too as it runs well at high rpm, but not well at lower rpm. Thanks for the info and confirmation of my thoughts. I didn't tackle the seal/bearing replacement job. He charged me $400 for both labor and parts. I suspect the parts were next to nothing. But, that job is beyond my skillset. I sure hope it isn't another $400 of labor to get to this woodruff key...

Dec 1975 (build) DT 175 Enduro Trials and tribulations later, the bike is running, not perfectly, but running well. The "perfectly" part will be a function of the carburator. Anyway, here's the "first" in my life and not sure if anyone else has ever heard of this oddity... So, my son rides this bike. Arrived home from work and decided to try it out. So, upon starting it, the tachometer was not functional, cable was connected on both end, and then I engaged the first gear with clutch in... slowly release and I swear the bike's motor/gear pushed drove backward. Was this an anomoly or is sum-ting-wong? Bear in mind, I recently had the bike torn down and camshaft seals and bearsing on both sides replaced to eliminate air sucking issues diagnosed with help of this forum. Bike runs well, but this oddity of "reverse" on the bike is either a figment of my and my son's imagination (flat ground) or a loose "cog" in the machine that should be addressed before bigger problems develop. HELP! Thanks Beautiful in Michigan in July!

Well, thanks for the heads up, but I think that's bad news. I played with the carburator and it runs well when cold - revs up and will idle down to a steady 1500rpm idle (attempts to idle lower than that and it stalls out). So, the bad news is once it warms up, it starts to smoke, white smoke. And, then it will not run, it just stalls out and goes back to the up/down engine rev. From your diagnosis, I'm guessing the right seal is the issue. Given that I'm "advanced beginner" mechanic, is this job within my skillset? I'm not afraid of the task, but this appears to be an almost complete teardown to repair. Bottom-line, what kind of timeframe are we looking at for a professional? (Which I would guess requires about 3X as long for me.) Thanks for helping me...

what does the plug look like? does the "fuel" residue on the plug seem excessively oily? does engine sound different - knocking, for instance, when you first start it and exhaust is smokey? has there been depreciation in engine power noticed - when it does run? and, when you ride it now, does it quit/fail during ride or you arrive and shut it off? does it prefer full throttle or idle when cold or hot - anything you notice there?

So, adjusted the float tang to 21mm (although it may be +- 3mm from 21mm as float "bulbs" are not the exact smae shape), verified idle screw at 1.5turns and air jet at 1/2 turn. The DT starts on first or second kick, cold with choke on. It revs up, sounds good - UNTIL it warms up and choke is turned off. At that point the engine runs irratic... meaning the rpms jump up to 7k rpm, then nearly cuts out, then back up and finally it stalls. I'm getting to be a carburator removal expert. But, I know I'm not a carburator expert. Manual suggest that "engine performs worse as it warms up" is a rich mixture problem. Frankly, I don't know whether the float is still off, another jet needs adjustment, or??? The only portion of the carb I did not tear down was the choke. This carb has the side choke and when disassembled I can see the hole/choke mechanism engage and disengage the opening. Thanks

This is a great community - thanks so much!

Hello All, I thought I'd say HELLO from the Great Lakes state of Michigan! I have a 1975 DT 175 Enduro that was my bike beginning in 1978. It was ridden quite a bit until the mid 1980's, then stored away. It is like new. Now, my son wants to ride and I pulled it out of the barn and we're working on it together. I just ordered a Yamaha repair and serivce manual for it, which will help. Everything on it works, and I've had it running. Except, I "cleaned" the carburator a bit too well and the configuration/adustment of the jets, is now off. I have another bike in the barn too. It is an early 70's (I think) AT2 125. We have that in "rough running" condition too. The bikes are aestetically like new. Just have to work the gum out of them. I'm kind of excited. I'll touch in occasionally and share what I know. My dad is the better mechanic, but some things require precise setting and carburators and timing are two of them. It seems you can find just about anything on the net. Though I'm a bit suspicious of some aftermarket parts, especially when the reviews indicate "wrong and won't accept returns..." Anyway, the internet is a great way to link up with folks and glad someone had the time and passion to start and support this site! Thanks.

Based on other posts, I believe my terminology is correct calling it the pilot jet. Inside the float area of the carburator (bottomside of carburator housing, not float bowl) there are three jets. A long wide jet in the center that the end of the throttle cable extends into from the top side, another that I believe is the pilot jet. The pilot jet screw access is "bottomed out", meaning it is turned completely into the carburator. The third orifice in the bowl side of the carburator is the gas supply "shut off", which is actuated via the float. I adjusted the tang on the float and it no longer is spilling fuel via overflow. And, the plus is wet, so I know I'm getting fuel. I did try a different plug too and it didn't solve it - just saturated another plug. My understanding was always, gas, air and spark. I have gas, have spark, have air - so the mixture must be off. Again, this bike was starting and running rough prior to the carburator removal, cleaning and reinstall. thanks for the assistance.

I had this bike starting, but running poorly. Removed and cleaned carburator and all jets. Initial reinstall, the carburator was spilling fuel out of the bowl overflow drain. So, I bent the tang on the brass float and reinstalled. Now it is no longer spilling fuel, but will not start. So, the current set-up is; - pilot jet in bowl is bottomed out - air jet is at 1/2 turn out. - idle is at 1 1/2 turns out Plug is wet and there is good spark. The float tang is set so when carburator is upside down, without pressure, the floats are slightly inside the carburator housing. But, again, the carburator is not spilling fuel through overflow and there is fuel on the plus, so the float is likely not an issue, I would think.... Anyone have a service manual to share the jet settings... Thanks