Have 77 DT250 Yamaha. No low end power. Will rev up, but not much torque at higher rpm's either. Points or?

Question

Just got the bike used. Nice, but no torque/power. There is no way to adjust timing, only point gap, right?
Or is there a way and I just don't know how to do it??

I had heard that points being worn would make the timing off.
Please help.

Answer 1

Ok well the first thing you need to do is get a repair manual. Read as much about the bike as you can. Get familiar with how the bike was made and how it works. Then get ready to work. I had two bike do the same thing and the one bike(99) it was the timing the other (82) was the a torn diaphragm in the carburetor. But first check fuel, spark, compression. Make sure the spark plugs are good. Then check the compression. if compression is equal or about the same with each cylinder then you know its either fuel or spark. If its not then your looking at valves or piston rings or even worse, a hole in a piston. My opinion, it sounds like valves or a ring. Theres a lot more to do but hopefully this helps. If you need more help just email me.

Answer 2

A small engine doesn't make as much torque. Also, you can get the same total HP by reving up higher in small engines, but what fun is that. from a "drivability" standpoint, there is much more practicality and fun in having an engine that makes it's hp and torque down low in the rpm range. having a car that is a snail off the line and can't do any good until it hits 4 grand isn't really all that useful for driving around town. They are moving to smaller engines now, but at the time when the 350 was at it's peak production, direct injection wasn't really more than a prototype. The small block was the perfect compromise between weight, HP, high torque, longevity (as stated in previous answer), price, and size. Don't forget, cars also weighed more in the 80s and 70's so you wanted that lower end grunt to get the car moving off the line. As a side note, HP is not actually Torque multiplied by rpms, otherwise all cars would have at least 4,000 or 5,000 HP becasue all they would need is 1ft-lbs of torque at 4,000rpm. And your wrong about the camaro 3.6l engines. you can cruise around at 1,500 rpm comfortably. They make their max torque at around 2800 rpm. And no, HP = 2pi x torque x rpm / 33,000

Answer 3

Low power is due to worn cylinder, piston & rings.
1977 - that's the first thing I would check.
Remove the exhaust pipe and look in the exhaust port with a flashlight and mirror.
Any scoring of the piston/cyl wall or discoloration below the rings - rebuild the top end.

Answer 4

T G is right about a repair manual. Clymer's are a hellava good book for about $35 from a dealer, a little less online.You'll see that ya don't have ' points'. Do all the maintenance & check/replace your intake reeds.Don't forget frontend maintenance,fork oil.Good Luck !

Answer 5

Check and make sure the exhaust port is not clogged up with carbon.....make sure spark arrestor is not clogged up as well.....check timing...the points should be cleaned and should "break" contact at the fire mark on the flywheel