yet another new bike 81 DT175

[Dr Rockso]

well the xl didn't pan out ....but i got a pretty good chunk of change for it and picked this thing up in md for $350 , by far the cleanest dt i've ever seen , low miles , runs great , clean title . it's a little on the small side , but i ride slow off road and i wanted something small that i could zip up to the 7-11 on since it's kind of a pain to get the fzr out every time i wanna ride 4 blocks . plus my insurance said it would be $1 more a month to add it to my insurance , i couldn't say no ...woo hoo , new dt

[sweekster]

Nice find.

[YAM93]

Hard to believe Yamaha made a 175 2-stroke with forks that thin. And in 1981 for that matter. Those look as thin as my XR80, jeeze. May just be the photo though. How's the power and sound ?

Yeah, it IS in pretty awesome condition for being so old. Most guys that had those back in the day ran the crap out of them and let them sit outside and rust.
Nice find.

[Dr Rockso]

it's more of a trail bike than a dirt bike , but i'm used to throwing the heavy old enduro's around so it's nothing new to me . i don't really do many jumps or anything , i just like cruisin thru the woods and this will do that fine . it's actually pretty quiet , and once i get some new packing for the muffler it'll be even quieter . i'm just stoked that it came with a title , i used to ride around on one of these back in middle school and highschool

i can't tell you how many times we crashed that thing , it wouldn't die , the dt series was possibly the most reliable 2 stroke bikes yamaha ever built next to the rd series . but i was always riding it around on the street and the cops were always trying to get me . this time it'll be street legal , i just wish it was a 250 , but i'll live . not to mention if i get tired of it i can sell it for WAY more than i bought it for .

[YAM93]

Sounds good. Those bikes were one of the best ALL-DAY trail bikes you could get back then. Very comfortable, and would take a decent beating also. This one looks like it would be good on the street as intended also. My XR80 did fine on the asphalt but it didn't like it, and would wear the tires out quick. I spent most of the time in the air anyway.

[yamaha_george]

Sounds good. Those bikes were one of the best ALL-DAY trail bikes you could get back then. Very comfortable, and would take a decent beating also. This one looks like it would be good on the street as intended also. My XR80 did fine on the asphalt but it didn't like it, and would wear the tires out quick. I spent most of the time in the air anyway.

Hi,
Nice find and GREAT condition, better than the two I still have for sure but then mine go in the Jungle on a regular basis over the last 30 years.

You can see one of mine that i sold at:-

http://www.saltmine.org.uk/kgb/patriot.html.


There is a full list of blurb of what it got modded to <BG>

[YAM93]

wow, talk about a lot of trouble to go thru for doubling the gas tank capacity. Nice bike George, I bet it was a blast to ride. Side note: I never see any Bultaco's any more. Lots of Taco Bell's though.

[yamaha_george]

wow, talk about a lot of trouble to go thru for doubling the gas tank capacity. Nice bike George, I bet it was a blast to ride. Side note: I never see any Bultaco's any more. Lots of Taco Bell's though.

Yam,
The ONLY regret is that I sold my Bultaco Alpina 350 to fund my first RD project "Red Arrow"

I had replaced the Bing carb (which is a crap carb ) with a 34mm Mikuni and all of a sudden the MPG doubled ( I kid you not ) and the top end opened up by about 10 MPH.

I know I made alot of money from my Rd (dragging & servicing others ) but I miss my Bultaco. I have advertised several times in Trinidad to find it , but to no avail

[Dr Rockso]

i'm still trying to get my dt175 going 100% , but i'm having some issues . you can give it as much gas as you want and it does fine untill you hit 6k , then it just flutters there . i checked the float height and it was off so i set it to factory spec . the slide needle isn't adjustable , the autolube pump seems to be adjusted right (peg lines up with the dot) , all jets clean . once i'd done all that i could get it to go to 6.5k rpm and sometimes a little higher but it would start gurgling . then i thought hey , maybe the air cleaner isn't as clean as it looked , so i took it out and found the back side of it sopping with oil and pretty much falling apart . i removed it and i took it for a spin up the street and now i could get it up to 7k maybe a little higher but not up to the 8k red line so i'm guessing the clogged up old air filter had something to do with it (i have a new one on order) . but shouldn't i be able to get her up into the red (not that i plan on riding in the red , but theroetically shouldn't it be able to get there ? atleast to the 8 ? ) and if so what could be holding it up ? there's nothing else adjustable on here . compression is good and she starts first kick , idles great , the plug looks a little wet but the tip is somewhat tan .


i just noticed that in the diagram for my air box there's a small snorkel that you set into the box before screwing the cover down and mine doesn't seem to have that ...that couldn't cause this could it ? i wouldn't think that an inch long plastic snorkel would make that much of a difference tho . anyone else have any ideas ?

tomorrow i guess i'll check the reeds and make sure they're good . and i'll try running it with the fuel off to see if once the fuel level gets lower if it'll rev all the way up . if neither of those pan out i'll run it wide open up a hill and hit the kill switch and then check the plug . i know it's something dumb but i'm running out of ideas .

[yamaha_george]

i'm still trying to get my dt175 going 100% , but i'm having some issues . you can give it as much gas as you want and it does fine untill you hit 6k , then it just flutters there . i checked the float height and it was off so i set it to factory spec . the slide needle isn't adjustable , the autolube pump seems to be adjusted right (peg lines up with the dot) , all jets clean . once i'd done all that i could get it to go to 6.5k rpm and sometimes a little higher but it would start gurgling . then i thought hey , maybe the air cleaner isn't as clean as it looked , so i took it out and found the back side of it sopping with oil and pretty much falling apart . i removed it and i took it for a spin up the street and now i could get it up to 7k maybe a little higher but not up to the 8k red line so i'm guessing the clogged up old air filter had something to do with it (i have a new one on order) . but shouldn't i be able to get her up into the red (not that i plan on riding in the red , but theroetically shouldn't it be able to get there ? atleast to the 8 ? ) and if so what could be holding it up ? there's nothing else adjustable on here . compression is good and she starts first kick , idles great , the plug looks a little wet but the tip is somewhat tan .


i just noticed that in the diagram for my air box there's a small snorkel that you set into the box before screwing the cover down and mine doesn't seem to have that ...that couldn't cause this could it ? i wouldn't think that an inch long plastic snorkel would make that much of a difference tho . anyone else have any ideas ?

tomorrow i guess i'll check the reeds and make sure they're good . and i'll try running it with the fuel off to see if once the fuel level gets lower if it'll rev all the way up . if neither of those pan out i'll run it wide open up a hill and hit the kill switch and then check the plug . i know it's something dumb but i'm running out of ideas .

Doc,
Check out the needle jet which is a brass 1" or so long tube that taps out from the body once you have removed the main jet. Some carbs were notorious for clogging between body and tube as the holes are REAL fine.

You should also check the needle number as the calif . model (which I presume you have was the only one i know of with a non adjustment grooves on it ) and can be replaced thro sudco mikuni state side.

[Dr Rockso]

i just tapped it out and cleaned it , it actually was all clogged up ...unfortunately that didn't fix it . it still gets to 7k at neutral and 6 or 6.5 k under load . today i checked the reeds and they're in great shape , i also cleaned the carb 40 more times , checked for air leaks , set the float to a bunch of different heights (it's at 22mm right now) pulled the whole exhaust off to check for clogs , tried the wide open hit kill switch check plug thing and the plug was wet but the tip was slightly tan . my air filter is dead so i've been testing without it , i'm also missing the little intake horn that sits at the end of the back of the air box , i've got it on order because i guess it could be screwing with it . i'm detirmened to get this damn thing going , every dirt bike i get always has some mystery problem that i can never solve so i sell it . good call on the needle jet thing , i forgot you had to tap those things out . any other ideas ?

[yamaha_george]

i . good call on the needle jet thing , i forgot you had to tap those things out . any other ideas ?

get the needle replaced with a grooved version talk to Sudco Mikuni they will need the needle number of orig. the needle jet number and the carb body casting number.

[Dr Rockso]

i'll call them on monday and see what they can come up with . today i got my boost bottle and intake boot from an rt180 which is the same basic bike without all the street legal stuff . putting it on made my idle way more adjustable (before i had to bottom the screw out for 1000rpm idle . and it feels like it's got a bit more oomph now . i'm still going to have to rejet i think .

[yamaha_george]

i'll call them on monday and see what they can come up with . today i got my boost bottle and intake boot from an rt180 which is the same basic bike without all the street legal stuff . putting it on made my idle way more adjustable (before i had to bottom the screw out for 1000rpm idle . and it feels like it's got a bit more oomph now . i'm still going to have to rejet i think .

Doc,
Glad the boost worked we found that boost bottles were very iffy, and depended on the state of tune on the engine even when straight out the crate. I n the end what I did was make collapsible version ie adjustable and played with that but found the 1 mm length change altered the works even on a 2.25 dia bottle, it was all to sensitive. After that we only used the very discreetly on staff bikes.

[Dr Rockso]

well the rt180 is the same engine , so the bottle , intake , and hose have already been setup to work for mine from yamaha . they even use the same exhaust , actually the only thing that changed on the rt besides the lighting being removed is the jetting . i just have to get it tuned right but i figured i better put on all the stuff i'm putting on it before i tune it . i don't claim to know anything more than basic tuning , i can take it back off if you think it'll be a problem , but i sure do like what it did to my idle adjustability . it didn't seem right to me that bottoming the idle screw into the carb was only good enough for 1000rpm .