Post derestriction jetting change on a 1998 Dtr de03
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I just bought a 98 Dtr that was already derestricted with open powervalve etc. it sometimes likes to bog down at any throttle when cold and id like to know if anyone knows what the issue could be. My thought process is that its either a clogged or too small main jet and i just wanted to confirm my theory with people who have experience with this exact motorcycle. Thanks in advance and cheers!
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I just bought a 98 Dtr that was already derestricted with open powervalve etc. it sometimes likes to bog down at any throttle when cold and id like to know if anyone knows what the issue could be. My thought process is that its either a clogged or too small main jet and i just wanted to confirm my theory with people who have experience with this exact motorcycle. Thanks in advance and cheers!
@Dougster Most two-strokes are a bit boggy when cold and this is also when most engine damage occurs so warm it up carefully keeping the revs low for the first couple of miles.
If you mean the powervalve is pinned open, that is probably the source of your problem. Pinning the powervalve makes the DTR very difficult to ride as it robs it of low-end power without gaining any top-end.
As far as I'm aware the DE03 model ran the 5-wire servo; these are easier to find and cheaper than earlier 3-wire versions so if you don't have one on the bike ATM it might be easier than you think to sort this by having a look around eBay, Facebook DTR pages etc.
If the jets in the carb at the moment are what your manual says they should be, don't stray from this setup until you've got a servo fitted and working, it's a massive improvement to the DTR riding/ownership experience (particularly off-road) as you don't have to thrash the bike everywhere to make it do anything.
Look around eBay for a pulley/housing as well, these are the same as on most other YPVS-equipped Yamahas including the RD350YPVS, TZR/TDR250 and TZR125 (the "29L" on the inside of the pulley housing is the RD350YPVS model designation). Buy genuine powervalve cables from Fowlers (Yambits pattern ones are the wrong length) or make your own here, it's no more complicated than replacing gear cables on a mountain bike: https://dt125r.co.uk/post/28693
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As @HOTSHOT-III has stated, if you're not running a powervalve then this will hinder performance. If your model has restrictions on it still, then this may have been why the powervalve was pinned. Certain CDIs close the powervalve after certain RPMs, limiting the top end potential.
All of which can be worked around these days with no real dramas.
