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I'm considering buying a DT175/125, but I have a few questions
- 1PistnRng2RuleThmAll
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I'm considering buying a DT175/125, but I have a few questions was created by 1PistnRng2RuleThmAll
I'm considering picking up a DT175/125, but I've never owned a 2t and have a few questions. How often should I be rebuilding the top end/bottom end if it sees a mixture of commuting and trails? Which brands/websites should I be using for rebuild kits? How is general parts availability for these bikes? How happy are the bikes cruising at 45-50 mph when geared appropriately?
Thanks for any advice.
Thanks for any advice.
15 Jan 2023 20:28
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- Vinduroman
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Replied by Vinduroman on topic I'm considering buying a DT175/125, but I have a few questions
How far is your commute? How many miles of 45-50 MPH will it be called upon to run?
My wife owned an AT3 125 that she rode right at 1000 miles, and I also rode about 200-300 miles myself. She took delivery of it toward the end summer of '20 w/2200 miles on the odo. Solid little bike. FUN to ride.
Her AT3 was most comfortable at 45 MPH. I felt it could do extended miles (4-5 miles) at such speed.
When she sold it this past summer, she/we had put on another 1100+ miles (total of about 3300 on the odo). The engine still sounded very good with no significant piston slap. I do not know what the sprocket gearing was on her AT3. First gear felt very low, and I suspected it could handle 1 more tooth on the counters shaft sprocket. If it could have handled that, it could have been a 50+ MPH bike.
I just recently (like the past 2 weeks) took delivery of a '75 DT125 with only 740 miles on the odo. It too, is most comfortable at 45 MPH, but CAN run over 50 MPH.
However, it is running right at 6200 or 6400 RPM (can't remember) at 50 MPH. The red line is at 7500 RPM. As you can see, 50+ MPH is an RPM range I would NOT want to keep the bike buzzing within for more than a short distance.
FWIW: Yamaha claims top speed of the AT/D 125 series bikes to be about 65 MPH, but that is MAXED OUT and you do NOT want to ask a bike to run miles at such RPM.
I do not have any personal experience with a C/D series 175 so can't help you there. Unless Yamaha put taller gears on it, I suspect the RPM vs speed will be about like the 125, only a 175 will work less to attain 45-50 MPH.
As for service life for piston/rings/cylinder, I have no hard data. I would be inclined to think that somewhere around 3500 - 5000 miles is going to be the norm for a small bore before it's going to require some top end attention.
With 53+ years of "enduro" type bikes under my belt (among my stable of bikes I currently own 4 vintage enduro type bikes), I suspect if your future bike is going to be called upon to run 50+ MPH for extended stretches often, I would suggest you consider a larger bore bike that can carry the gearing to run 55 MPH in its RPM "mid-range".
Good luck!
Vinduroman
aka Andre
My wife owned an AT3 125 that she rode right at 1000 miles, and I also rode about 200-300 miles myself. She took delivery of it toward the end summer of '20 w/2200 miles on the odo. Solid little bike. FUN to ride.
Her AT3 was most comfortable at 45 MPH. I felt it could do extended miles (4-5 miles) at such speed.
When she sold it this past summer, she/we had put on another 1100+ miles (total of about 3300 on the odo). The engine still sounded very good with no significant piston slap. I do not know what the sprocket gearing was on her AT3. First gear felt very low, and I suspected it could handle 1 more tooth on the counters shaft sprocket. If it could have handled that, it could have been a 50+ MPH bike.
I just recently (like the past 2 weeks) took delivery of a '75 DT125 with only 740 miles on the odo. It too, is most comfortable at 45 MPH, but CAN run over 50 MPH.
However, it is running right at 6200 or 6400 RPM (can't remember) at 50 MPH. The red line is at 7500 RPM. As you can see, 50+ MPH is an RPM range I would NOT want to keep the bike buzzing within for more than a short distance.
FWIW: Yamaha claims top speed of the AT/D 125 series bikes to be about 65 MPH, but that is MAXED OUT and you do NOT want to ask a bike to run miles at such RPM.
I do not have any personal experience with a C/D series 175 so can't help you there. Unless Yamaha put taller gears on it, I suspect the RPM vs speed will be about like the 125, only a 175 will work less to attain 45-50 MPH.
As for service life for piston/rings/cylinder, I have no hard data. I would be inclined to think that somewhere around 3500 - 5000 miles is going to be the norm for a small bore before it's going to require some top end attention.
With 53+ years of "enduro" type bikes under my belt (among my stable of bikes I currently own 4 vintage enduro type bikes), I suspect if your future bike is going to be called upon to run 50+ MPH for extended stretches often, I would suggest you consider a larger bore bike that can carry the gearing to run 55 MPH in its RPM "mid-range".
Good luck!
Vinduroman
aka Andre
'71 Zundapp GS125
'72 DKW GS125
'72 CZ 175 Trail
'75 Yamaha DT125B
'02 Yamaha XT225
'12 Yamaha WR250R
'21 KLX 140L DS (Wild Child's!)
'72 DKW GS125
'72 CZ 175 Trail
'75 Yamaha DT125B
'02 Yamaha XT225
'12 Yamaha WR250R
'21 KLX 140L DS (Wild Child's!)
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- Vinduroman
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Replied by Vinduroman on topic I'm considering buying a DT175/125, but I have a few questions
An addendum:
Without more info concerning the commute distance/roads, I am inclined to feel that a 2s would NOT be a good choice. Instead, I would be considering a 175-200 cc four stroke such as Honda's XL 175, 185, 200cc bikes.
The 4s engine will run thousands (THOUSANDS) of more miles on a top end compared to a 2s. It's just the inherent nature of a 4s vs a 2s.
Again, best of luck!
V-man
Without more info concerning the commute distance/roads, I am inclined to feel that a 2s would NOT be a good choice. Instead, I would be considering a 175-200 cc four stroke such as Honda's XL 175, 185, 200cc bikes.
The 4s engine will run thousands (THOUSANDS) of more miles on a top end compared to a 2s. It's just the inherent nature of a 4s vs a 2s.
Again, best of luck!
V-man
'71 Zundapp GS125
'72 DKW GS125
'72 CZ 175 Trail
'75 Yamaha DT125B
'02 Yamaha XT225
'12 Yamaha WR250R
'21 KLX 140L DS (Wild Child's!)
'72 DKW GS125
'72 CZ 175 Trail
'75 Yamaha DT125B
'02 Yamaha XT225
'12 Yamaha WR250R
'21 KLX 140L DS (Wild Child's!)
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- Tom P
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Replied by Tom P on topic I'm considering buying a DT175/125, but I have a few questions
My '71 CT-1 cruises very comfortably at 55 MPH, doing 5500 RPM. I went one tooth up on the front sprocket to 17 teeth, with the stock 45 tooth rear. I run 60 MPH in certain areas and that's fine as well, but it just seems real "comfy" at 55. Max speed on mine is 65 MPH at 6500 RPM on a level road (I weigh 180 lbs). I'd never take it on a freeway, where the traffic flow around here is usually 70 to 85+ MPH, but it's great for cruising around town.
16 Jan 2023 09:07
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- nhsteve
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Replied by nhsteve on topic I'm considering buying a DT175/125, but I have a few questions
I would have to second what vinduroman has said on both posts. Shop I worked at sold a '76 DT175 to a young man who used it for just this kind of thing. Seized it up right solid on one of the hottest days that summer when he rode it down to Old Orchard Beach (summer tourist trap) from Lewiston Maine (roughly....35-40 miles?). When asked how fast he was going, he indicated he was on the turnpike at "the regulated 55 MPH".
If that would be your potential usage, then the advice to go bigger and 4 stroke makes more sense.
If not, then the 175s are neat little bikes, and definitely capable and fun off road.
If that would be your potential usage, then the advice to go bigger and 4 stroke makes more sense.
If not, then the 175s are neat little bikes, and definitely capable and fun off road.
16 Jan 2023 09:13
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- MarkT
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Replied by MarkT on topic I'm considering buying a DT175/125, but I have a few questions
These bikes don't seize unless jetting, timing, or maintenance is off significantly. Air leaks are common, sometimes even on new bikes. (I worked on a brand new YZ85 a few years ago that had a major air leak right off the showroom floor.)
These engines will run full throttle at redline for extended periods at full load without any issues at all... I raced desert with air cooled two strokes for years. Temps were often over 100F... plus deep sand and high speeds really load the engine.
The smaller engines are especially very reliable... I set a 24 hour desert race endurance record with an air cooled two stroke... and ran the the rest of the year on the same engine.... used to get thousands of race miles out of modified two strokes.
If you run a good oil ratio and keep out dirt (poor air filter maintenance is a huge reason for premature failure... and Yamaha had leaky air boxes in the mid-70's that allowed dirt in) there is no reason a two stroke can't run for thousands of miles. I have a 1980 or 81 DT175 I bought from original owners in Utah. Had over 20,000 miles on it and was still on standard bore. It rattled, but ran okay. They took good care of it and used it for commuting to school for several years when it was new, racking up most of the miles in the first few years. Engine had never been apart.
That said, these bikes are from a different era... VERY slow compared to modern vehicles. They fit in back then when many cars were even slower... a VW bug struggled to get to 65 mph... most cars back then couldn't hit 100 mph... and 0-60 times were in the 20+ second range for a lot of vehicles.
Today, there aren't many cars that won't easily go 100 mph or more... or that won't hit 60 in ten seconds or less.
Any of the old bikes can be great fun around town or on shorter commutes... if you want to ride a lot or at modern freeway speeds, get a new bike.
These engines will run full throttle at redline for extended periods at full load without any issues at all... I raced desert with air cooled two strokes for years. Temps were often over 100F... plus deep sand and high speeds really load the engine.
The smaller engines are especially very reliable... I set a 24 hour desert race endurance record with an air cooled two stroke... and ran the the rest of the year on the same engine.... used to get thousands of race miles out of modified two strokes.
If you run a good oil ratio and keep out dirt (poor air filter maintenance is a huge reason for premature failure... and Yamaha had leaky air boxes in the mid-70's that allowed dirt in) there is no reason a two stroke can't run for thousands of miles. I have a 1980 or 81 DT175 I bought from original owners in Utah. Had over 20,000 miles on it and was still on standard bore. It rattled, but ran okay. They took good care of it and used it for commuting to school for several years when it was new, racking up most of the miles in the first few years. Engine had never been apart.
That said, these bikes are from a different era... VERY slow compared to modern vehicles. They fit in back then when many cars were even slower... a VW bug struggled to get to 65 mph... most cars back then couldn't hit 100 mph... and 0-60 times were in the 20+ second range for a lot of vehicles.
Today, there aren't many cars that won't easily go 100 mph or more... or that won't hit 60 in ten seconds or less.
Any of the old bikes can be great fun around town or on shorter commutes... if you want to ride a lot or at modern freeway speeds, get a new bike.
1963 YG1-T, 1965 MG1-T, Allstate 250, 1970 CT1b, 1971 R5, 1973 AT3MX, 1974 TS400L, 1975 RD350, 1976 DT175C, 1976 Husqvarna 250CR, 1981 DT175G, 1988 DT50, 1990 "Super" DT50, 1991 RT180, 2017 XT250
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16 Jan 2023 11:27
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- Ht1kid
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Replied by Ht1kid on topic I'm considering buying a DT175/125, but I have a few questions
+ 1 MarkT I’ve never had any of my Yamaha’s seize I did do maintenance on my bikes when I was 14 yrs old on my HT1 I would run wide open for over 15 miles on the highway to go to the fire roads
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16 Jan 2023 16:15
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- darinm
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Replied by darinm on topic I'm considering buying a DT175/125, but I have a few questions
I'd lean DT175 over the 125 for what you want, and as others have said it should do fine. Will it need a top end before a four stroke will? Absolutely. But it'll be cheap and easy to do.
1972 Yamaha CT2 175
1972 Suzuki TS185 Sierra
2000 Suzuki RM100
2003 BMW F650GS
2009 Yamaha WR250R
2013 Yamaha XT250
1972 Suzuki TS185 Sierra
2000 Suzuki RM100
2003 BMW F650GS
2009 Yamaha WR250R
2013 Yamaha XT250
16 Jan 2023 17:51
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