I helped a buddy do a condenser and point on is '74 Yamaha DT175A Enduro (2-stroke) about a month and a half ago. We got it running but a few weeks later it died.. which forced him to to go to Mid-Ohio Vintage Motorcycle Fest bike-less.. With the plethora of cheap enduros there.. he picked up a '73 Yamaha 250 Enduro.

I didn't really have much of an interest in an enduro or the space for one but the the fun to dollar ratio on this is just ridiculous.. So I told him to help me fix it and sell it to me for what he has into it.. $375.

It's got blue spark, fuel, at the plug, and good compression. $35 later crank seals, a carb bowl gasket, and drain plug are in the mail. These things are brutally simple and parts are very cheap.

Otherwise the bike is missing the turn signals, head/tail lights, and rear luggage rack. The tach/speedo/odometer all work, tires are good, seat is in good condition, suspension isn't gone, and it's overall in decent shape.

The bike unfortunately has no title.. but the paperwork is in the mail using this approach: http://www.chinonthetank.com/2014/04/ge ... istration/ The process also works for cars too. A few of our friends have done this with success.

The plan is to get it running, plated, insured, throw a head and tail light on it and rip. Bike inspection in Philly is a non-issue. There's just too much going on for police to really worry about it.

I'll get some real pictures in here when I go to work on it but here's what it looks like with all the turns and other stuff.

_________________

95 SLE... a keeper. 241k miles. Low and Slow.
97 BMW 528i
98 Infiniti vq35'd i30: 13.3@104mph, 30MPG Hwy (RIP)
02 Jag X-type
03 BMW M5
05 Chevy Cobalt LS
07 Infiniti G35s 6MT (Sold)
07 Ducati Monster S2R 800 with DS1000 swap
83 Yamaha IT175K
72 Yamaha DS7: '74 RD250 swap, JL chambers

Info on dropping a 92-99: Here.

Oh...dear...lord...why would you do that to yourself? LOL!

That brings back mamories, so those old DT Yammies, TM Suzukis, CR Hondas, etc. have nostalgic value to me but I don't want one. I certainly appreciate guys who restore them for their vintage value, but when I think back on my Elsinore days I wonder how I didn't kill myself on that thing. The Elsinore, in its day, was a Corvette compared to the DT Yamaha which would have been a Volkswagen Beetle. Of course the Elsinore wasn't dual-purpose either so, while it exceled on the track, it sucked on the road (riding it on the road was illegal anyway). The DTs on the other hand, sucked everywhere. But they could be manhandled on the road as well as off. One thing that could be said about the DT is that they were stone reliable - unlike the Bultaco I had for a while. The guys on the DTs would kick the engine once or twice, it would fire, and they'd drive off. The Bultaco rider had to pray to a particular Spanish deity, "tickle" the Amal carb, kick his brains out, tickle the carb some more, hold the throttle wide open, kick (left side starter, BTW), kick , kick, cuss, kick, repeat. If he was lucky enough to fire it up it would be so loaded up it would take minutes to clear out the crankcase. Compared to today's machines, though...actually... ... there's no comparison. I'll stick with the new stuff.

Nonetheless, I shall follow your restoration of the old DT with nostalgic admiration.

_________________

Resident Tightwad

Screw you, Photobucket.

Haha.

Yeah, by no means do I think I'm going to hop on this thing and destroy trails or anything. I live a few miles from Philly's metropolitan area in a dense city neighborhood. There aren't many places to truly take advantage of a dirtbike or a actual good dual sport bike. Nor do I really want to shell out the coin for a good dual sport atm. I just figure for a few hundred if I can rip on some access roads with friends or take the occasional trip somewhere better, game on.

_________________

95 SLE... a keeper. 241k miles. Low and Slow.
97 BMW 528i
98 Infiniti vq35'd i30: 13.3@104mph, 30MPG Hwy (RIP)
02 Jag X-type
03 BMW M5
05 Chevy Cobalt LS
07 Infiniti G35s 6MT (Sold)
07 Ducati Monster S2R 800 with DS1000 swap
83 Yamaha IT175K
72 Yamaha DS7: '74 RD250 swap, JL chambers

Info on dropping a 92-99: Here.

I reckon a lot depends on how much cabbage ($$) you have to stuff into the old scooter. Most of the ones I've seen have blown shocks, pitted forks, rust in the gas tank, need new tires, seized and broken spokes, toasted chain & sprockets, an air filter that's turned to powder...and that's just the chassis. By the time a guy dumps the money to make it work, that $50 bargain bike winds up costing more than when it was new. The exception to this rule is if you're going to build it into a vintage museum piece (and money is no object) or if you start out with a functioning machine to begin with.

If you're working with the latter, it sounds like the old DT might be the ticket for your situation. Perfectly fine for tootling down to the Sev for a Slurpee or rolling down a fire road or powerline - both cases that wouldn't be ideal for the Monstro. And for short distance commuting it's much more manly than a scooter. Sorry scooter people, no matter how practical or cheap or convenient they are, scooters are GAY. Honestly, if a guy pulls up to the house to date my daughter and he's riding a sport bike or a cruiser I'd be a bit concerned (and maybe a little impressed). If he's sporting a scooter, meep meep, I'm thinking this dude is no threat to my daughter's virtue.

_________________

Resident Tightwad

Screw you, Photobucket.

Well, here it is:




I have the magneto cover but the head and tail lights are my buddy's.

_________________

95 SLE... a keeper. 241k miles. Low and Slow.
97 BMW 528i
98 Infiniti vq35'd i30: 13.3@104mph, 30MPG Hwy (RIP)
02 Jag X-type
03 BMW M5
05 Chevy Cobalt LS
07 Infiniti G35s 6MT (Sold)
07 Ducati Monster S2R 800 with DS1000 swap
83 Yamaha IT175K
72 Yamaha DS7: '74 RD250 swap, JL chambers

Info on dropping a 92-99: Here.

Appears to be in decent shape - I've seen a lot worse, anyway. Is the baffle missing from the exhaust? I think they actually run better with the baffle in, and are much quieter. That's a bonus when you're sneaking down a fireroad you probably shouldn't be on.

_________________

Resident Tightwad

Screw you, Photobucket.

Baffles are missing.

I'm hoping the rest of the gaskets for the crank seals come in before the weekend. The magneto side was easy with an impact screw driver. The clutch side proved a little more difficult without a basket holder or an air impact. I got it down to the crank gear nut but couldn't get it off without an impact. (buddy's 1-car storage garage doesn't have one) I bought the service manual for $7 off ebay and found out what they use to break that nut loose.. a folded up rag.. to bind the gears. lol. 'at least 16 layers'

I've been having fun learning more about oil injection and carbs. I've never messed with either before.

_________________

95 SLE... a keeper. 241k miles. Low and Slow.
97 BMW 528i
98 Infiniti vq35'd i30: 13.3@104mph, 30MPG Hwy (RIP)
02 Jag X-type
03 BMW M5
05 Chevy Cobalt LS
07 Infiniti G35s 6MT (Sold)
07 Ducati Monster S2R 800 with DS1000 swap
83 Yamaha IT175K
72 Yamaha DS7: '74 RD250 swap, JL chambers

Info on dropping a 92-99: Here.

Those old oil injection systems are pretty rudimentary by today's standards. They were effective, but added waaay too much oil to the mix. That's why there is always all that spooge around the exhaust joints and at the tailpipe. The guys who used to like to "tune" the old DTs would chuck the oil injection system and premix the gas instead.

The carburetor should be pretty simple. Those really haven't changed much on 2-strokes. Yeah, there are flat-slides, D-slides, oval-slides, etc., but the basic operation is the same. What did they put on the old Yammie? Mikuni, Keihin...? I can't remember.

It may not be possible to find, or not even worth the effort, but if you can dig up an exhaust baffle you might find the bike will run better. 2-strokes need a certain amount of exhaust back-pressure to run most effectively. This back-pressure helps to seal off the exhaust port during the down stroke (exhaust/intake) of the piston. I'm sure the factory took this into consideration when they designed the exhaust system with the baffle. I believe the exhaust baffle also acted as a spark arrestor.

_________________

Resident Tightwad

Screw you, Photobucket.

From what I've read these oil injection systems were decent for their day. I do like that it's throttle regulated. A few have said you'll loose power down low depending on the premix.

This guy apparently has a vm24ss Mikuni. Seems pretty simple.

I have couple simple carb questions for ya.

The pilot jet - That's always open to the bowl right?

The choke, if on the engine side of the carb, does it open another path from the bowl for more fuel?

And what does an air vent pipe do? At first I thought it was so the air had somewhere to go when filling the bowl but the overflow pipe would do that.

_________________

95 SLE... a keeper. 241k miles. Low and Slow.
97 BMW 528i
98 Infiniti vq35'd i30: 13.3@104mph, 30MPG Hwy (RIP)
02 Jag X-type
03 BMW M5
05 Chevy Cobalt LS
07 Infiniti G35s 6MT (Sold)
07 Ducati Monster S2R 800 with DS1000 swap
83 Yamaha IT175K
72 Yamaha DS7: '74 RD250 swap, JL chambers

Info on dropping a 92-99: Here.

That is correct. The pilot jet along with the air/fuel mix screw control the fuel charge at idle and just off idle.


Yes. Most 2 strokes use this method of enrichening the mixture for cold starting as opposed to a butterfly on the inlet side of the carb (which, obviously reduces the amount of air, effectively enrichening the mixture).


You are essentially correct with your first thought. The primary purpose of the air vent pipe is to equalize the pressure in the float bowl with ambient pressure outside. If you didn't have air vents you would either have overpressure in the bowl when you fill it with fuel, or a vacuum as you remove fuel from the bowl. Either condition would result in a non-running condition.

A secondary purpose of the air vents is to drain excessive fuel when the bike is tipped over. This helps prevent filling the crankcase with fuel (flooding) and puts a nice film of gas/oil mix on your engine cases which, in turn attracts every particle of dirt in a 13 ft radius.

_________________

Resident Tightwad

Screw you, Photobucket.

Awesome. Thank you!

_________________

95 SLE... a keeper. 241k miles. Low and Slow.
97 BMW 528i
98 Infiniti vq35'd i30: 13.3@104mph, 30MPG Hwy (RIP)
02 Jag X-type
03 BMW M5
05 Chevy Cobalt LS
07 Infiniti G35s 6MT (Sold)
07 Ducati Monster S2R 800 with DS1000 swap
83 Yamaha IT175K
72 Yamaha DS7: '74 RD250 swap, JL chambers

Info on dropping a 92-99: Here.

Nice Mike! My dad has an old Enduro 400 in the shed that I really need to do something with. It leaks and doesn't run, and was 2 bikes assembled into 1 when he got it in the late 80's. I should really tear the whole thing down and start fresh, but that'd require time and money...

_________________
Bye Bye:

RIP sandrock

Also, note that your idle mixture screw is on the inlet side of the carb. That means it is an air screw. So as you screw it out, you add more air and lean out the mixture. If the screw was closer to the outlet (with respect to the throttle slide), it would be a fuel screw and to lean out the idle mixture you'd screw it in (close off the fuel supply). Might help when you're fine tuning after getting it running again.

...and more money.

_________________

Resident Tightwad

Screw you, Photobucket.

Yeah that whole time and money thing.. lol. Loose time making more money or spend more with free time.

Yep. Understood on the idle air screw. I was reading same is the case with the choke, if its on the airbox side, it blocks (chokes) the air vs adds fuel. - edit - as mentioned already a few posts up

Factory is 1.5 turns out. I'll make sure I at least start there.

_________________

95 SLE... a keeper. 241k miles. Low and Slow.
97 BMW 528i
98 Infiniti vq35'd i30: 13.3@104mph, 30MPG Hwy (RIP)
02 Jag X-type
03 BMW M5
05 Chevy Cobalt LS
07 Infiniti G35s 6MT (Sold)
07 Ducati Monster S2R 800 with DS1000 swap
83 Yamaha IT175K
72 Yamaha DS7: '74 RD250 swap, JL chambers

Info on dropping a 92-99: Here.

Yeah. I still need to get my license and a bike to ride...

_________________
Bye Bye:

RIP sandrock

Part of the deal buying this thing was it would stay in my buddies storage garage till it's running. I have zero room to work on it in my garage. This means I need to coordinate schedules with someone else who pretends there's 36 hours in a day. So, linking up has been a little difficult. We were able to link up last night and tonight.

I got the right side crank seal done, right cover on, oil pump with new hoses left unhooked so I could prime it once the engine is running. That was yesterday. Today I threw some pre-mix in and oil for the crankcase. My buddy tried kicking it over (I'm still recovering from a broken right calcaneus) and also pop staring it with no luck. The plug was wet and it was getting spark. I tried torching the plug with no luck. I took the carb apart and replaced the bowl gasket and drain washer because we thought they were leaking. 1.5 turns out on the idle air screw. I also checked the reed valves and they were fine. Trying again, every once in a while it would almost kick over but just never did. Played around with the idle speed screw too. Turns out the bowl gasket and drain washer weren't leaking, it was the overflow. I adjusted the float and we tried kicking it over. At first it seemed like it was going to go kicking it and a couple pop starts it would run for a couple seconds then die. Then the float started leaking again.. Repeated the float adjust and got the same almost running results. The overflow was leaking again.. I took the carb off for the umteenth time and checked to make sure the float needle was sealing.

-It was not-

That fellas is I think the issue is. I ordered a rebuild kit and a new choke because it choke stopped staying open after I cleaned everything. Cheap enough, $33 shipped for both. Now the waiting game starts again.

I'm happy I walked away from it tonight with a likely cause. And I got to really play around with a carb for the 1st time. Had I walked away from it with question marks above my head I'd probably be pissed. I'm more excited now that I kept trying to work through it and it feels like I'm pretty close. I can't wait to ride around on this thing.

_________________

95 SLE... a keeper. 241k miles. Low and Slow.
97 BMW 528i
98 Infiniti vq35'd i30: 13.3@104mph, 30MPG Hwy (RIP)
02 Jag X-type
03 BMW M5
05 Chevy Cobalt LS
07 Infiniti G35s 6MT (Sold)
07 Ducati Monster S2R 800 with DS1000 swap
83 Yamaha IT175K
72 Yamaha DS7: '74 RD250 swap, JL chambers

Info on dropping a 92-99: Here.

A bad needle & seat will do it. If the needle doesn't seal and the petcock is on, it will slowly dump gas into your crankcase.

_________________

Resident Tightwad

Screw you, Photobucket.

Yep. Completely makes sense.

Good news. My Vermont plate came in using the registration method mentioned in the 1st post. So when this thing runs, I can legally ride it.

_________________

95 SLE... a keeper. 241k miles. Low and Slow.
97 BMW 528i
98 Infiniti vq35'd i30: 13.3@104mph, 30MPG Hwy (RIP)
02 Jag X-type
03 BMW M5
05 Chevy Cobalt LS
07 Infiniti G35s 6MT (Sold)
07 Ducati Monster S2R 800 with DS1000 swap
83 Yamaha IT175K
72 Yamaha DS7: '74 RD250 swap, JL chambers

Info on dropping a 92-99: Here.

Yessssss!

_________________

Resident Tightwad

Screw you, Photobucket.

The other day I got the head light, tail light, and tag on.

The rebuild kit came yesterday but not all the parts were compatible for some reason. I was only able to use the float needle (with rubbber tip), the float, and pilot valve. I guess it's fine considering I only really needed a new float needle valve. The choke I ordered fit/worked though. I adjusted the new float to 21mm, and put it back together.



Today I slapped the carb in, checked the timing again, put a vac cap on the autolube inlet and it started right up. Woooooo. Muurrriccaaaa.



I went to bleed the autolube system, got the air out of the feed, bled the screw on the pump and pulled the throttle cable at the pump to push the oil through the feed line. but... I broke the nipple on the banjo bolt for the autolube inlet to the engine.. I'll have to order that but otherwise it's a running, driving, legal bike that I can rip on some dirt roads for under $500.

It even barely fits in my 1 car garage.. lol.

_________________

95 SLE... a keeper. 241k miles. Low and Slow.
97 BMW 528i
98 Infiniti vq35'd i30: 13.3@104mph, 30MPG Hwy (RIP)
02 Jag X-type
03 BMW M5
05 Chevy Cobalt LS
07 Infiniti G35s 6MT (Sold)
07 Ducati Monster S2R 800 with DS1000 swap
83 Yamaha IT175K
72 Yamaha DS7: '74 RD250 swap, JL chambers

Info on dropping a 92-99: Here.