Hey guys, I need some help setting up the Trail Tech tachometer I just put on my 1991 KDX250. I want to set the shift lights, but I'm not sure what this thing revs up to. What does the bike redline at, and what's a good, safe maximum shift point. The computer has two shift lights. One for a regular gear change (yellow light) and a 'change-now-or-bike-will-blow-up!' gear change (red light). Thanks.
KDX250 Trail Tech
- Thread starter bajus22
- Start date
- Jul 20, 2009
- 417
- 0
Honestly, I don't think you really have to worry about over revving or redline on the KDXs. Put simply, when it stops pulling hard, time to change gear. It's not as if they blow up by over revving them. What they predominantly don't like is being held hard on the gas for sustained periods of time. It's a KDX, sometimes you short shift it sometimes long shift it, whatever suits the terrain. Do you road ride it or something?
- Thread starter
- #6
Yes, it will be road ridden. I just managed to get it safetied for the road. The Trail Tech was the last thing it needed. Will there be a problem road riding it? I put on a 16 tooth front sprocket to try and lower the revs. It still pops the front wheel (just not as bad). It will be easier riding it to the trails, rather than loading it up on a trailer. Probably no more than a quick 40km ride down the highway to get to decent trails from my place.
With the right tires it should be a blast on the roads.
If it were me, I'd watch the tach while I wind it out. Whenever it stops pulling, that's where I'd put the shift light. A 2 stroke doesn't have one of those "stop now or it will blow up" ranges. Those are for 4 strokes. The 2t will simply run as fast as it can and not any faster. That's why nobody ever bothered to put a rev limiter on one. You got no valve float to worry about, it's just piston port timing. One light should be fine. Even that is not necessary. The bike will tell you when to shift, and you can't really over-rev it.
If it were me, I'd watch the tach while I wind it out. Whenever it stops pulling, that's where I'd put the shift light. A 2 stroke doesn't have one of those "stop now or it will blow up" ranges. Those are for 4 strokes. The 2t will simply run as fast as it can and not any faster. That's why nobody ever bothered to put a rev limiter on one. You got no valve float to worry about, it's just piston port timing. One light should be fine. Even that is not necessary. The bike will tell you when to shift, and you can't really over-rev it.
dirt bike dave
Sponsoring Member
- May 3, 2000
- 5,349
- 3
FWIW, I put a 15t countershaft sprocket on my KDX250 for dual sport rides.
Tight trail performance is definitely reduced with a 15. It might even be hard to fit a 16 on there.
Honestly, I don't see a need for a tach, redline or shift light.
Overall, the 250 makes a decent dual sport two stroke. It has a big tank, which is nice. Both mine and my buddy's measured at 3.6 gallons actual.
One annoying thing is the bike does not like to hold a steady rpm on the road. At steady throttle, the powervalve will start to open, and the bike will speed up. So you roll off the throttle. Then increase the throttle when you slow down too much. Then hold the throttle when you get to the desired speed. Then the powervalve starts to open. Repeat this cycle over and over, anytime you are on the highway.
Tight trail performance is definitely reduced with a 15. It might even be hard to fit a 16 on there.
Honestly, I don't see a need for a tach, redline or shift light.
Overall, the 250 makes a decent dual sport two stroke. It has a big tank, which is nice. Both mine and my buddy's measured at 3.6 gallons actual.
One annoying thing is the bike does not like to hold a steady rpm on the road. At steady throttle, the powervalve will start to open, and the bike will speed up. So you roll off the throttle. Then increase the throttle when you slow down too much. Then hold the throttle when you get to the desired speed. Then the powervalve starts to open. Repeat this cycle over and over, anytime you are on the highway.
I really dont pay much attention to my tach at all. I can sense when to shift in different conditions, as most riders do. I bought the Trail Tech for my old YZ400F, which overheated in the tight woods. I was always concerned I was going to damage the engine, so I bought a Trail Tech, which has a temp display. I sold the YZ and moved it to the WR. IMO, the tach's only real purpose is for tuning.
