flyday58

Already went around retightening. The forward mount was slightly loose, the rest were fine. I did find the drive sprocket very loose, also producing a leak. With everything torqued back correctly I still have the harmonic vibration.

Hey Paul, As you see, the air screw is pretty much spot on, altho I will check it again. The varnish in the carb combined with what I can only assume is the ethanol-based petrol available here caused what looked like intergranular corrosion within the float chamber. One of the pillars holding the float pin broke off, so really there was nothing salvageable. I could have removed the jets, but I tossed it before joining this forum with all the excellent info available. Had I known I would have removed the jets, at least. I just returned from the petrol station down the road with a 5-gallon can full of no-ethanol 87 octane petrol. I drained the old stuff and added the new, but had to get under cover due to severe weather moving in. I don't think it will impact the sputtering but at least it should cut down on corrosion of my metal parts. Also going to purchase some of that see-thru vinyl tubing for the fuel and oil lines so I canobserve my petrol and lube oil status. Great idea. If I figure out how I will post a short vid of the sputtering I mean. Maybe it's just a two-strokeism...

Why yes. Yes I did. I didn't like the "slop" the rotor had when I installed the magneto stator I got on ebay, so I bought a new woodruff key for the shaft and that took care of most of the slop. I WILL go back and check the torque on the rotor nut. Ran outta time just now as severe weather is moving in and needed to get under cover. Come to think of it, I should get off the computer,too...

Heidi, The DT is doing pretty well these days, just a few issues. One of these is that under leisurely acceleration, she kind of sputters along, always increasing revs but acting like I just woke her up and she's reluctant to respond to my gentle carress. Ooh. If I insist and dial on the throttle, she responds willingly, indeed, voraciously with no hesitation. Clean, smooth, robust acceleration. The original carb died from varnish cancer, so the one I have now is one of those ebay $40 specials, ostensibly for my model. I did install the correct slide and needle, which survived the old carb and the clip is in the correct position. I wouldn't think my woes are electrical or cdi in nature, given the performance when I wrap the twisty-thingy to go fast. Throttle. Couldn't remember for a sec... Also cruising at 30, 40, 50 mph is sputter-less unless I feather the throttle. Also also, mine doesn't idle nearly as smoothly as oldbikerehab's does, and if I adjust the idle much below 1500 it will bog and die. Played with the idle air screw but standard to 1and a half turns works best. Also also also, after riding a bit then coming to a stop, idle will be around 2000 rpm, then drift down to 1400-1500 after 10 to 20 seconds, sometimes revving a little to 1600 on its own before decreasing again. I've looked for air leaks around the carb, reeds, crank, cylinder. Do to the wonderful ETHANOL MANDATE in this country our petrol is not it's all cracked up to be, but I saw a station down the road today advertising 100% petrol, no ethanol, so that's what I will put in the tank for the forseeable future. So. Ideas on my sputtering? Should I try to procure an OEM carb? Anything I might have missed?

Thanks for the reply. This bike sat in a junk yard out in the elements for a number or years before I purchased it and started the restoration. I disassembled the the cases to give it a good cleaning and check for damage, and all seemed well (I worked on C-130 props and engines for 22 years, cars starting in '79 and bikes back to '72, so somewhat familiar with things mechanical, just your basic gear-head). I did not document anything for reasons which escape me. Normally I photo everything I do, but not this time. So I've got nothing to refer back to. I know the con rod had side play but don't know about up-and-down. A main bearing seems more likely to me, as I don't think the gear bearings turn as fast. I'm going to try putting it on the stand, going thru the gears and seeing if I can narrow this thing down. Cheers. Richard

K (sniff) Kinda makes ya proud to be a guy!

Mello Greetings. With 100 miles on the rebuild of Ole Red, time to do some searching. I am noticing a vibration that I am associating with bearings. It becomes very pronounced at 3100-3200 rpm, then again around 4100 rpm. If I vary the throttle just a little, the vibes decrease to what I consider normal for a two-stroke. When I pit my palm on the flywheel casing I can feel the vibes as the rpm changes, but it's not scary, just I know it's there and wondering what the long-term import may be. Please, I must have your thoughts...

Just crossed 100 miles on my rebuild, new 66.5mm piston, rings, fresh bore. Put a little grease on the head gasket per Clymers with no ill effects (so Far). Also placed the gasket ridge-up, as it just seemed right. Put a light coat of oil on the cylinder walls and put it all together. The first 20 to 30 miles had a fair amount of blue smoke above 3000 revs (not going over 4000 revs for the first 50 miles) but that gradually cleared as the rings seated. After 50 miles I did short bursts to 5000 rpm before settling back to 4000 or less, and today I took it to 7000 for the first time. All good so far... I after 50 miles I purchased a 45-tooth rear sprocket to get the top speed up. Here in the good ole Estados unUnidos alot of us live in rural areas, with four-lane and divided highways/ motorways prolific. At 40 mph with the 49-tooth standard sprocket I was only doing about 35 or 36 mph at 4000 revs, way too slow with a jacked-up Ford Super Duty riding your taillight. Or a Prius driven by an over-anxious cellphone-weilding teen, for that matter. I now get 41 mph at 4000 rpm, so I'm pleased with the arrangement. The clearance issue on the front forks: mine is nearly identical, maybe a tad wider around 2mm. Hasn't been an issue riding. I did have a problem on initial start-up. This was 5 or 6 years ago, and the bike ended up sitting in my shed in a forgotten corner until the petrol in the carb turned to a lovely varnish. The problem was the engine would not rev over 3000 rpm, no matter what I did. When it got to 3000 it just sounded like it was firing once a second or so, just kind of a pop-pop-pop. I rode it around the yard but of course, not very quickly. Tried all kinds of adjustments, ohmed everything I could think of. Finally threw it in the shed and forgot about it. When I decided to re-resurrect the project this December, I did a lot more research but didn't discover this forum till February, so didn't have much good intel. I decided compression was keeping the thing from revving, as I could pit a stick of gum between the cylinder and the piston. Needless to say I was a trifle upset when the machine still refused to rev! THEN I discovered this site and was steered to the source coils. Mine were pretty smarmy-looking, the pulser wire had a bare spot near where the flywheel turned, causing a possible short, and source coil #1 was giving me strange readings on the meter. So I purchased a stator that looked in good shape from that place we all get this stuff, and EUREKA! Revs all the way up now. I just wish I had documented everything I did, and that my last computer hadn't died and taken the early pics with it. I am currently shopping for a DT 360 or RT-1 to restore and will definitely document document document. Can't wait to see your beast run...

Thanks, I will check it out on my layover Tuesday.

Indeed, Sir. Got my very own copy last week. Also picked up the supplement and downloaded the parts manual, so I am now well-armed, shop-wise! Still(slowly) moving towards a 12-volt convert, the gents at the local bike shop GAVE me the 6 volt turn and stop bulbs they had because they had been on the shelf so long the stocking numbers had vanished! They mostly laughed me out the door...gits!

I agree with all, oh Sage One. 2N5 covers the '79s but evidently Mr. Hasigawa Yamaha decided to put 'em on end-of-the-line '78s to screw with guys like me 30+ years on. That worked out just fine. Anyway, I will leave things as they are and hope, five years from now, that I will remember this discussion and not ask the whole thing all over again. Thanks for all the help ,Paul et all.

Ahh. Sure you can't take good ole American Greenbacks? Wish I could get paid in just about ANY other currency than U.S. Dollars. The exchange rate in the UK, Netherlands, Japan, Hong Kong, Damnnearanywhere kills me when I travel which, oh yes, is my job! Lately $1.00 is worth only about $.70 in the UK, $.65 in euro countries, around $.70 in Japan. Plus fees. Sorry for that, the price is actually excellent, count me in.

On further search, it appears that there was a switch mid-year from the separate lights/dimmer arrangement to dimmer only. Parts houses list two looms, one with the '2A7' designation and one with the '79 '2N5' number. But wait! My loom has the 2A7-82590-50 number right on it. Appears to have a 77-09-25 date code also. Curiouser and curiouser.

Okay, I've looked all over for how or where to create a photo album for the Gallery, no luck. Help a poor brother out, please!

Agreed. Looking at pics available around the net, the '79 loom has a single 4-pin plug plus three individual wires, which is what I have. The '78 loom has a single 6-pin plug plus 7 individual wires, so WTH? Then there's this guy: http://www.ebay.com/...11cf4bb&vxp=mtr Even shows the red DT as a contributing source. Makes me think Yamaha pulled a switcheroo mid-year on this model. Sure would like to have control of the lights(bloody Americans ) but not enough to change out the entire harness. BTW, thanks for the link to the Thumper site, they've got some good tech over there. I just feel comfy over here!

I would tend to bow to your expertise in this matter, except that the matched engine and frame serial numbers begin 2A7, which everything I've read says is a '78 vintage. Prithee?

Here are iphone pics of the ignition and light switch: My U.S. spec ignition switch has only the Off-On positions. Oh, I've tried the U.S. yamaforums but again, they are mostly for jet-propelled motorway terrors, not much in the way of Enduros.

Reg- I could not find Yokohamas for a reasonable price for my restoration, but after diligent search I purchased Kenda tyres with a very similar profile on ebay. I looked at Michelins but liked the profile on the Kendas better. A quick search did not reveal any in the size you are looking for, but I did not search for long. You might have better luck. Cheers, Richard

Good day all, In looking around the different manuals available, I see that in one place the light switch console for my 1978 DT has an on-off switch and a dimmer. In another place only the dimmer is present. My original harness seems to support the latter single-switch set-up, so I'm wondering if the two-switch is incorrect or a mid-year changeover. Loosing precious brain cells on this one, gents ( and ladies, if present )).

Now THAT is a capital idea! Thanks for all the input, me hearties. Our maintenance guys will most likely help out on this one. Cheers, Richard

My "other" scooter. Arriving Terminal 4 Heathrow.

Note to self: instead of endlessly sifting web sites for things like parts lists, just ask Old Git. Will save a lot of time/anguish. Thanks for the link!

Pics are from today, false Spring in Mississippi. I do not have a parts list, but I think I will compile one, kinda curious myself. I know I've got pics from the day I brought it home, but two searches of my computer have not revealed them. Gonna have another look though, she was definitely an Ugly Betty back then.

Yuniparts sez no shippi to les estados un-unidos so on to plan B...whenever I figure it out.

Finally riding after four years .Recovered from a junkyard and restored to running condition by a card-carrying U.S. Old Git.