Smoke, Spark, and Second Chances: Reviving a 1983 Yamaha DT80
The first thing I noticed about the old 1983 Yamaha DT80 was the Monster Energy green spray paint job. Next was that unmistakable smell of old gasoline, grease, wet dirt, and two-stroke exhaust. Nice.
The owner swore it “ran when parked,” which, as anyone who buys vintage motorcycles knows, usually translates to prepare for suffering. But underneath the awful paint color, weather-cracked tires, and missing oil pump was a machine that deserved another chance. I handed over a few bills, loaded the enduro into the truck, and began what would become equal parts mechanical education, test of grit, and stubborn obsession.
The following is my “captain’s log” plus a cost breakdown at the end.
But first, some useful links and resources for others embarking on a similar journey —
Motorcycle VIN lookup: http://www.cyclepedia.com/manuals/CPP-VIN/index.php
DT80 specs and info: http://www.mbike.com/yamaha/dt80mx/1983
OEM supplementary service manual
Yamaha DT80 supplementary assembly manual
3/27/18
According to the seller it has new petcock, air filter, fuel filter and sight tube, seat cover. Carb was cleaned with kit and has new seals, but also a makeshift adjuster screw. Some new screws throughout. Spare set of new wheel bearings, tires and tubes.
Tank was rusty, cleaned with parts cleaner and ran epoxy around inside.
Paint from O'Reilly or whatever. Won't dissolve with gas.
Oil pump is removed, didn't trust that it was hooked up and running properly. Just mix gas 40:1
Paid $400, both signed bill of sale and sales receipt.
Carb has air leak, probably at injection point, only runs with choke all the way on.
Last year had trouble and thought it was the carb, hence the clean and rebuild kit. Turned out to be a clog of epoxy at the gas tank.
3/28/18
Shift is N 1 2 3 4 not the usual 1 down.
Shifter was really low angle, couldn't get toe under it. Bent too. Took foot rest and shifter off. Vise and hammer got the bend out. Couldn't get shifter on at better angle because base is behind the foot rest weldment, so unmounted motor from frame. Lifted motor a smidge and put shifter on at a better angle. Remounted motor and foot rest.
Noticed a fluid spot on floor from where it sat overnight. Thinking it's from the transmission. Wiped and dried things off with a rag to see where fluid shows up. Teddy helped clean with a toothbrush.
No nuts for mirrors. Do have mounting for blinkers in front and behind seat. Rear plate mounting too. Need a kick stand.
3/30/18
Got motorcycle permit yesterday (written test and $21), insurance with Progressive at $75 /yr, got registration and plates today ($62).
3/31/18
Used or new kickstands for my bike are $40 online. I used online images for reference and made one for under $5 (weldable steel and a spring from Menards). First welding project a success! Lightly sanded the whole thing after filing, then cleaned with acetone, dried, and painted black with high temp oil based paint.
4/3/18
Tried my old helmet again and it sucks with glasses. They fog up and they don't sit properly on my face. Also have to take them off to put on or take off helmet. The helmet is old and I don't love the look of it, so I researched and bought a new one today. BELL RIOT in matte black for $149 total. Had been considering Bilt, but they had sketchy reviews of their safety and quality.
4/5/18
Bought plastic-coated steel tire levers $16. Still snowing and more coming this weekend so may be good time to change tubes and tires as indoor activity.
4/6/18
Disconnected front brake and speedometer. Put motorcycle on jack stands and removed front wheel. Removed tire and tube, cleaned rim inside and out. Removed bearing, brakes. Need new brake pads. Tightened loose spokes. Replaced spoke tube guard strip. Installed new tube and tire. Broke one tire lever, bent the other.
4/7/18
Ordered new BikeMaster front brake shoes from Parts Giant for $14.
Received new helmet, fits well, looks good-ish.
Returned tire levers ($16), bought set of 3 pry bars from Harbor Freight for $6.
Removed rear wheel, cleaned rim, tightened loose spokes, changed tube and tire. Pry bars worked great! Aired both tires to psi spec (32 rear, 22 front) Removed old wheel bearings, cleaned hub, installed new bearings. Played with old tires in the yard with Teddy.
4/9/18
Scraped and brushed dirt out of the rear wheel well and components. Installed rear wheel, adjusted rear brake and chain tension. New tire looks nice!
4/12/18
New brake shoes came in and fit on with no problems. Installed front wheel and adjusted front brake appropriately. Looks and feels real good! Did some more cleaning, used a bristle brush and a toothbrush to clean off/out more dirt. Adjusted headlight housing so it points forward aligned with wheel, was off about 15 degrees to the left. Can fine tune the angle of the lamp within the housing. Eager to ride but it's still hovering around 32 and rain/snow mix.
4/17/18
Got some sun finally and took a ride around the block! Shifting was easier than expected. Speedometer is inaccurate. Did a second loop around the neighborhood. Managed to lock and skid the rear wheel once. Maybe I'll loosen the brake pedal a bit. Gonna need to be careful of sand where melt off runs and dries. Any shady spots that might be icy too. It's still cold so I used my full face helmet. Made a leather dongle for my key. Red tape on the key to help me remember it.
4/18/18
Returning RIOT helmet, don't love it. Never rode with it, just tried it on in the house. I want full protection and a warm dry face.
Bought some deerskin leather gloves from Menards $14. Fit and feel real nice.
Might ride to work tomorrow. Nervous about stalling at a light, being cold in the morning, my hair looking crazy at work, and something going wrong/breaking and wiping out.
4/19/18
First commute! Sort of. Forgot to get the clamp-on bike mirror from shed so had to look over shoulder, but no biggie. The morning was 35 and sunny, would be 50 coming home. Wore my loose-ish grey jeans as overpants, blue bandana to keep hair presentable after helmet. Wore old full face helmet. Bobbie got video of me leaving. Shifting and brakes were good. Was loving it.
Max speed past the golf course, redline in 4th gear once crested the hill, picked up more speed, and broke something. Engine died. Coasted to side and into driveway. Should have used clutch going down hill. Little smoke. Let cool. Wouldn't start but sounded normal trying to kick over.
Called Bobbie who came with kids in truck. Wheeled it up into bed. Now do I fix the engine or part it out for money to fund an electric conversion?
4/26/18
Spent last Saturday taking things apart, cleaning, and looking for troublesome parts. The carb is clean although the float isn't perfect and the two adjuster screws are questionable. The carb was working fine before though, and dude told me he cleaned it out which seems to be true. Could be reed valves, but those are not likely to break. Installed new spark plug which came with the bike, and checked for spark. Looks good. Bought feeler gauges today and the gap is within spec too, so spark isn't the issue. Gas feeds fine and the air intake is good. Figured it was the piston or rings. Opened the cylinder up this evening, and sure enough a ring is broken! Plan to take the cylinder in to be bored the next size up. I can then order new piston and rings to match that size.
5/1/18
Flipped the reed valve which had a small gap, now its nice and tight. Took the piston off... it's in worse shape than I thought, glad I ordered a new one. The sides are so scraped up the rings are jammed and aluminum galled over them on two sides. One of these sides is where the ring broke. The new one says 25 on the head and the old one doesn't so hoping it was original 47mm. Cleaned around the case being careful to not drop debris in (used plastic bag stuffed in around rod). I have new gaskets on order too, and clips for the piston. Hoping all this damage was from the previous owner or before who was messing with oil pump. Need to make sure getting enough oil in there. Cleaning should help with cooling too. I have a 36-tooth rear sprocket on order to increase top end speed.
5/3/18
Cleaned cylinder (steel) and head (aluminum) last night. Called about 10 places today to see if can bore it, ended up with Bill Bune Enterprises in Anoka who specializes in this stuff. Said I could mail it up with the new piston and rings so am doing that tomorrow. Driving is 40 mins each way. Said they're busy and it might be a week before done.
5/11/18
Got call from Bill Bune in Anoka that cylinder was done. Left early from work since Friday and got it. Bore and hone looks amazing! Def a little bummed that the piston has a broken corner. Didn't notice that when I first got the piston. Not sure now if it arrived broken, got broken when I shipped it, or got broken at the shop. Guessing it got dropped somewhere. Anyway, Brogan at Bill Bune's rounded off the jagged edges for me and recapped the break-in procedure.
This evening after dinner cleaned out the cylinder ports with hot soapy water then I put the new rings on in the piston (left the expander ring off intentionally), and mated it up to the cylinder after putting a little 2-cycle oil on. Fits so nice and snug but not too snug! Scraped off old gaskets, added oil to bearing, installed piston (arrow forward), clips, gasket, cylinder, copper seal, aluminum head. Put on the refreshed reed valve assembly, carb (after fixing leaking bowl screw), oil hose, (with clip in place this time), fuel line, gas tank, exhaust, spark arrestor, seat. Backed it up to the garage door which I opened about 3 feet for exhaust to escape. Noticed something dripping, found the fuel filter had wiggled loose. Hand tightened that did the trick. Put some red electrical tape in the kill engine switch indicator with a spot of clear coat over it. That should keep me straight.
Turned the fuel on, ignition on, did a few slow "kicks" to turn it over, then 2 kicks and it started!!! Let it run for about 2 minutes to get up to temp, then killed it, to let it cool. Need to do this a few times to break it in. So pumped it's running. Just need to make sure it doesn't overheat and scour the cylinder or break a ring again.
5/14/18
Ran it around a little over the weekend. Real smokey and not as responsive as used to be. Took to work. Died 3 times in when up around 45 mph straight. North valley park, new construction after Robert St, new construction at Eagan border. Length of run seemed to be dependent on time given to rest. After died 3rd time on way home I called Bobbie cuz it was raining and miserable. Theory: too much oil meaning not enough gas and gunked up spark cant fire, or gas isn't feeding fast enough from clogged filter, carb, pinched hose, vacuum in tank.
Once home took out spark plug and dripping oil. Gas line seemed fine, no vacuum. Drained carb bowl, got and added more non-oxy gas to dilute oil mix. Swished tank to mix, let carb bowl refill. Fuel filter has very very slow leak.
5/15/18
Took it out for 30 minute ride to evaluate. Backside of O'Reilly, stop at bike king for mirror, up cahill, behind airport, Dawn, home. Did great! Idles, responds, pretty steady power. Fun looks and conversation at Bike King and staff from food place next door. Optimistic for commute tomorrow.
5/16/18
Commute was successful! Cop at 4-way stop let me go by. Speed was good although I was nervous. Engine speed didn’t come down right away, like maybe throttle was sticking? Need to lube that to be sure. Died once when coming down from 4th gear, just put into 2nd and popped clutch after turned and came right back. Walked it over curb and down through ditch to shortcut parking lot. I’m sure it'll leave an oil drip where I parked it. I brought ratchet & socket & lite rag for cleaning spark plug if I needed to. Should use the rag to clean oil when parking.
Had a nice chat with other motorcycle commuter when leaving work. He knew it was a DT, asked if 80 or 125. Said he really wanted one in high school. Chatted for a good 5 mins. Leak is coming from carb bowl drain screw. Ride home was nice. That shortcut is great. Also went down right side of road past traffic at 4-way stop, hehe.
5/26/18
Got Bobbie to ride it around the yard once! Used the EDGE method to teach her (Explain, Demonstrate, Guide, and Enable). She was nervous because people were in their yards and might see her make a mistake. Did well, wobble going around the tree, and stalled it when stopped.
5/31/18
Couple more successful commutes! Installed mirror on left handlebar. Silicone sealed bolt in carb bowl, stopped the drip. Trip to Ace Hardware for a bolt (kayak rack mount) and throttle is def sticking now. Wont ride it again til fix that. Walked it home the last block.
11/10/18
Was idling super high so adjusted carb screws. Screw on engine side is fuel mixture - backing the screw out allows more gas so runs richer, turning screw in restricts gas so runs leaner. Screw in middle of carb is idle speed - backing it out slows the idle speed, turning it in speeds the idle rpms. I got it running, warmed up, and adjusted. Rode it around the backyard a few times since there is snow on the roads.
3/11/19
Been storing it in the garage through the winter and running it once per month to keep it from getting gummed up. Just letting it run idle and warm up all the way, then riding it around the driveway and back yard. It's finally getting above freezing and I took it up and down the driveway a few times with no snow. Love this thing, so much low-end torque and fun to ride.
Time to move on to the next project though and see if I can turn a profit on fixing this thing up. Plus my tags expired end of Feb and my motorcycle permit and insurance expire this month. Posted to craigslist and facebook marketplace.
Hoping I can at least break even on this adventure. Problem is now that it's running well and warming up outside it's hard to let it go. I don't want to spend another $100+ on government stuff just to keep it another year though. Original plan was to just use the frame for an electric conversion, but it's too small a frame for that.
3/23/19
Sold it for $850 to a guy for his daughter to learn on. Nice dad. She liked it too and its a great fit. Sent him a link to download the manuals.
Final cost breakdown:
$400 for bike, new tires, spark plug, wheel bearings
$75 insurance
$21 permit
$62 plates & tags
$5 kickstand materials
$14 new brakes
$80 cylinder machining
$20 mirror
$61 custom sprocket
$14 piston
$77 gaskets, rings, clips
Not counting tools, because none were specialized
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$829 Total out of pocket expenses (total parts spend was $671 ignoring all the government stuff)
$850 Sale price
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$21 “Profit”
