HI, I've got a 1975 DT 250 enduro pretty much restored. Noticed I'm only getting about 40-50(55)MPH max at the moment (hitting 6K RPM at 55MPH). . I'm hearing people talk about 60-70MPH max on these bikes but i don't feel anywhere close to that. Maybe those conversations are not apples to apples this bike but I feel like i should be able to hit 65 with a 250 on flat roads? 

I believe on a Google search I did a while back I found info/specs on my DT2 that stated mine should hit a top speed of 67mph. I've had it to 65mph and she's screaming, but does it right up against red line.

Thanks for your reply 
mines screaming at 50 mph

Do you have the stock sprockets on it? If so, you should go faster than that. My '71 175 (that I just got running) will easily do 60 at 6,000 RPM, and that's after I put a 17 tooth sprocket on the front (one tooth more than stock). I think it will get up to about 65, but I usually stop at 60. That's fast enough for around town on an old bike. In fact I put the larger front sprocket on because now it'll cruise comfortably around 45 to 50 mph on city streets without winding out.

I actually haven't fine-tuned the timing. I took the points off and cleaned them, then put them back on, set right where they were. However it seems to run pretty well, and Idles nicely around 1300 RPM.

When I first got it running, it would bog down at 5500 RPM, but I eventually discovered that I'd neglected to clean out the main jet. After I cleared that out, it revved great.

But if I were you I would count the teeth on your sprockets and see if the previous owner maybe put a larger rear sprocket on it. That's what I did to my old CT1 back in the day, when I was using it off road more.

If gearing is correct, then gauges may be inaccurate.  I had that happen on my RD350 hanger find...  a friendly police officer let me know how fast I was really going.  

Thanks for getting in touch
front sprocket 15
rear sprocket.  45
what size are the stock sprockets 
Thanks

I believe 14 and 40, but wait for others to confirm.

75 DT250 has a short .86 5th gear.
They came as 44/14, gives about 57mph @6000RPM in 5th.
Your bike, 45/15 gives about 61mph @6000RPM in 5th.
If you change to 45/16, You have around 65mph @6000RPM in 5th.
If you want a street bike to cruise at highway, consider changing rear to 39/15, you have 65mph@5500RPM in 5th.

Top man
thanks for your reply and help
much appreciated