flyday58

Somebody slap me. Please. Decided to take the heavy coat of hi-temp paint off the cylinder and head to see if it would lower my temps any. Upon removal of same found the piston varnished, four scribe marks aligned with the cylinder ports down the skirt. I figured it was time for a good autumn tear-down, so off I went. The oil only had about 50 miles on it, but smelled like 5000. Hmm, me sez to meself. There was also a good helping of mud and goo in the bottom of the case, also reeking of exhaust fumes. Hmm, me sez again. And a nagging thought slowly rises as I continue. A thought which had occurred to me before, but in the interest of continued good times and letting them roll I was content to put out of mind. Ya see, while I purchased both crank seals, I never made the down time to open up the clutch-side case to replace the right side seal. When I removed it I found the inward-facing spring broken, the seal surface cut. So exhaust was blowing into the case, dirty air was getting sucked in, leaning the mixture. I probably added fuel to the fire with the bigger main jet, allowing the thing to cook hotter and hotter. So the DT mill is in boxes awaiting parts. Will be replacing the crank bearing to rid meself of that nasty harmonic vibe that was getting stronger of late. Wife absconded with the camera but I will post a pic or two when she gets home with it. On the plus side, the CS5 runs very perky so have been out on it a bit. Will be at the Red Lion in Langley Saturday after 4 if anyone local wants to come and slap the out of me. (not really Cockney rhyming slang but I'm USian...)

Willkommen from the States!

Once you have it all together again, try rotating the upper shafts of your fork tubes with the pinch bolts still loose. If that causes the lower tubes to move in or out on the spindle shaft... Cos I just discovered the shiny, unpitted original forks I went to the trouble of rebuilding on my CS5 are both bent.

Good battery shops over here have testers that put a load on the battery to do a full check on it. Do your shops have that ability? I am just wondering how the battery could be dying when It's only had a RAC re-charge and been seemingly fine since. How far do you reckon you'd gone when it quit, or is that the 5 miles? If so, I would think the battery good, keeping you running until the battery charge got too low to keep it going. But I don't know your bike either, so don't know if you have an alternator/ charge light/gauge. Is this a solid-state regulator or points-type?

Yeah, accidently misplaced my filter last night, (oops) and the pep was quite evident. Right up to the point at which it seized. Again.

It's a wonder that there were such big differences between country requirements even back in the good old 70s. Here's my airbox without: and with the snorkel: reverse angle: Intake was already this small: Then the snorkel cut it down to this: Not much breathing room here. Would seem to make things overly rich.

OemParts#/Yamaha/DT175E_-_1978/INTAKE/DT175E_(1978_MOTORCYCLE)/INTAKE_(DT175E_-_1978) Also agree, so I have to believe the formulation of the petrol available today has alot to do with our issues. I never had a prob back in the day, thought a jet was the thing I wanted to fly one day. Anyway. V, my airbox is this jewel: The bit I installed then removed is #23. I am currently caught in the Relations Matrix: something is wrong, alternately or sometimes simultaneously, with my wife; son; daughters; father-in-law; mother-in-law. I have hardly had time to myself, except when at work. I really want to thoroughly map out different set-ups on the DT but, as I've said elsewhere: I run and I run to catch up with the sun, but it's sinking...

Use WD40 or a similar oil-based spray on the crank seal while the engine is running. You want something that will temporarily close any gaps between the crank boss and the seal that might be allowing air to be sucked in, thinning the mixture. If the engine speed changes while spraying, the seal is shot. The gaskets for the side covers will probably be semi-welded in place, and usually to alternate sides so that part of it stays with the engine case and the other part sticks to the cover. Careful scraping it off so as not to gouge the casing or cover surfaces. Carb bowl gaskets sold seperately. Impact driver is a must-have, along with a torque wrench. I don't own a torque wrench, I'm an American Idiot (cue Green Day )

What fancy posh airboxes you MX guys have! I guess the Japanese were getting back at Americans and just bodged together the snorkel-looking intake on the State-side DTs. Mine was missing, found one on ebay but when I installed it, the bike started 4-stoking between 5500 and 6000 rpm and wouldn't rev higher. As it sits now, the bike is very spry up to 4000 revs. At that point it suddenly hurls itself forward similar to what I had on an RM125 back in the day. I back off at 4500 as I'm still breaking in the new ring set, but I'm itching to find out what's going to happen in the higher revs. I'm also going to keep an INTENSE watch on my Autolube feed tube as this seems more and more like lack of oil causing the seize. Stay tuned...

On mine the carb won't come out without partially removing the air cleaner assembly. The old air cleaner and carb joints aren't flexible enough to just yank it out. So it's remove the 2 air cleaner bolts, pull the box out of the keeper under the battery and work the box out far enough to get the rear of the carb out. Then the carb comes out easily enough. 4 bolts and the reeds are out and I agree, no sane reason for removing the cylinder. Having the tank off improves visibility but also not necessary. Re your related thread, did you ever check the resistance of your coils, and did you try the spray-check of the left-hand crank seal behind the magneto? Unless the reeds are obviously damaged, bent, rusted through or missing, your poor running probably won't be caused by them. But in the interest of being thorough it won't hurt to check them.

Update: New piston came today so back together she goes. Fired on the 2nd kick and let it tick over with the Autolube held wide open to get the oil to the cylinder, at which point the beautiful blue cloud surrounded me. Great to have at least one bike that runs again! I've fitted a 160 main jet and gone back to the mid clip position as I try to sort things going forward. I rode maybe 2 miles just up and down my neighborhood's road keeping it under 4000 revs and everything went fine. Seems boggy right now but how much can you tell from an initial run? I will experiment with the jetting as I get the time. Unfortunately, in the West we have this thing called "jury duty", and my tour came up for next week, so the DT may languish again. Languish? Hell, the CS5 won't even look at me anymore and the RT3 just screams, "why did you even buy me, you ?" 70s Yams, so needy! Paul the Fabulous, I fitted your temp gauge/gage/gay ja but only saw 180˚C on my short ride. I am going to be paying alot of attention to it as I go along. It's a great addition, thanks for the post about it.

String gasket 248-14623-10-00 supersedes the -00 part number. It goes into the groove of the exhaust pipe collar #14. Clean the collar as best you can then pack the new gasket in with a screwdriver blade or similar. I used the entire length and just kept wrapping around the inside of the collar. Here you can see the groove: http://i.ebayimg.com...yo4g~~60_35.JPG I only see one part # for the springs at the site I use most, Yamahasportsplaza.com. That's where I got mine. Hope this is heppfull.

Great link, helps me with all the junk I've got in my shed. Thanks Sin Nick. Let's get pissed sometime.

It's worth dissaembling to know what you got, no guessing. Gasket should be reuseable no prob. All the parts in the aftermarket I bought were de-identified, so no way to adjust jetting and such. So I ended up finding a Mikuni on ebay and rebuilding it. IMO carbs and like parts on these bikes are like some parts for American vehicles: there's just some things Ford, GM, and Dodge know how to do right.Went thru 3 NAPA lifetime warranty alternators on my F250 before someone on the Ford forums suggested going with OEM. Been happy since I did. Went thru the same thing with igntion coils on another truck. And I am really glad I bought the OEM Mikuni as I can fiddle with the jetting to get it right for today's ethanol-based varnish they laughingly call gasoline. That said, I repeat that Oldbikerehab is satisfied with his aftermarket unit.

WHAT?!?! How could this happen?? Paul right about something? What is happening to my normal sane world?? Somebody slap me, I gotta wake up!!!

What condition are your wheels, tires, brakes and front forks in?

Was this parts, or pieces of parts? Which part of the motor did they come from, the cylinder or the transmission? Lots of spares on ebay at any given time, from parts to complete motors. 72 or 73 will work, along with some parts from the DT2 and DT3.

Keep us advised. Also, while my icon is NOT who I am, I resemble that dude cos I'm, well, old. More than a few of the chaps here have seen at least 4 decades, 5 in my case. My kids didn't have to help me with vids and pics only because the help on this forum is stellar. Get back to us, we are one with The Force!

Any chance of a short video, upload to photobucket or similar, then copy and paste the link here?

All good stuff. I'll just add: When the revs stall at 3500, does the engine sound like it is 4-stroking, firing every other or even every 4th time? Mine was rescued from a junkyard after 20 years; it wouldn't accelerate much over 3 grand. Ended up water had been getting into the magneto for awhile and had compromised the hi-speed coil. This is it, the small one: If the fuel issue doesn't pan out, keep this in the back of your mind. Since you haven't had the flywheel off yet, I'd pursue Airhead's route and sort out your fuel supply first.

You're going to need a flywheel puller for the left side. They're widely available on fleabay and other places for not too much scratch.

This is what one guy found: Member Posted 30 September 2011 - 05:32 PM it turned out to be the same problem I had on my replacement ignition switch This post from shows it in detail..... Its just that I purchased a new ignition switch from yambits the other week, fitted it and the bike would NOT start, no matter what I tried. everytime i turned the key to ON it was being grounded, yet everything checked out fine until I turned the key... you can see the culprit arrowed, I simply moved the leg away from the solder and it all worked. whats the chances of it happening twice??? glad to have been of service! So removing the ignition switch and giving it a thorough check would be worth it.

Full agreement with my illustrious colleague. Being from the sounds of it, all original, all the organic bits will be shot or nearly so. It would be worth it to do a full disassemble and replace all the seals you can get, most of which the parts houses have. The ones they don't tend to show up on ebay frequently enough, so a bit of patience is in order to wait for them to show. Again I can personally vouch for changing the crank seals, as can many others on the forum. We live for this stuff, so take lots of pics as you go, both during the disassemble and reassemble. You will have a fairly permanent record and we all dig seeing an old duffer brought back to how they looked way back when.