@tbthegr81 change it mate it's not going to do any harm. Obviously allow it to breathe a bit better with a performance exhaust. Next step maybe go up one on the main jet and a performance air filter but not necessary. The 89 model has a restriction in the exhaust in the form of a small washer/collar in the header fixed with 2 spot welds though after all these years and I presume many owners it's probably been removed by now. I highly recommend the dep exhaust. You need to be doing some serious tuning/porting work to justify a bigger carb.
@yammieguy I don't have experience with arrow exhaust systems. But I do have a Gianelli which was great for peak power. And a Athena which has more low rpm power, less peak power
Now I have a custom one and sounds perfect. And great power all the way 👌
I have a Dep full system on my red Dt, and it's still like new. I am anal in maintaining it though, mainly because I knew it was flaky finish to start with. Not a cheap replacement so you would think they could at least build in some resilience to the finish. Does liven up the engine though.
Checked stroke of oil pump and found set at 0.22mm, OK for 3db1 model (0.20 to 0.25mm ), removed shim and Max stroke 0.17mm now, manual says 3rn1 onwards model 0.15 to 0.20. Bike late 89. Didn't seem smoky at all anyway, think running in below 6k for 400 miles left it a bit oily
@Bananper Without seeing a dyno it's hard to actually gauge.
Two stroke exhaust pipes work off resonance, fitting a pipe designed for another engine is incredibly unlikely to work as intended.
If it does work, then what is likely to be experienced is a shift in power. The WR200 exhaust is designed to produce a particular sound wave at a particular RPM for a particular engine.
When that translates to the DTR, it's likely that it's making less power down low, then picks up to an acceptable level. The change from where it makes less power, to more, (I.E. powerband) is likely to be exaggerated, such that the user thinks it's faster. But without a dyno, it really is hard to tell.
In other words, stick to an exhaust designed for the engine. As it has been designed to provide optimal results.