Best 250sx Performance Mods For You!

[Dirtcrasher]

Anyone who has an SX would like to add a few ponies, but there just isn't that much out there. Last week I finished one of my 85 250SX in stock form with an 87 rear end. I haden't rode it since I got my 87 250SX running. What a difference! My 87 (same motor) absolutely smokes the doors off of my 85. Much better mid and top end performance. Go and get yourself a COBRA exhaust, take off your airbox lid and toss a 350X 138 main jet in there. It will be a tad louder and you may have to mess with your air screw a bit (mine went out a full turn before it stopped backfiring) but it is the best bang for your buck, under 150$ or less for used stuff. I have not yet tried the whole 350X carb but it does bolt right on. I was afraid I'd get the "cold starting problem" which was corrected when Honda had installed the Keihen 08 model carb in 86 and 87. The 350X carb does have a larger throttle valve ( carb slide itself ) and with proper jetting may give me just a little more somewhere I'm lacking. Jet size will vary upon altitude, engine wear and other individual aspects of your trike. Of course if you can afford a larger piston or if a better cam is out there - grab it!! but top ends don't come cheap, this does!!

[3WheelsForever]

Hey Dirtcrasher keep your eyes peeled for me if you can. I am in need of a 250sx rear end bad. Let me know if you have an 87 rear end or if you know some one who does. Thanks.

[200xer]

we are comtemplating parting out our 250sx because the swingarm bearings went and we're sick of pumping money into it. We had the pumpkin rebuilt about 2 years ago ($350 ouch). Is that what you need? It's off an 85, only difference is that more of the swingarm came apart in the 86 and 87s.

[Dirtcrasher]

Good luck finding a good diff. I've sold 2 in the last couple of months for good money and all my trikes have mint diffs. It is very hard to find a good diff, even removing the oil cap isn't a clear indicator of it's condition. If you do bid on EBAY ask ALOT of questions. On top of all this they are neither cheap or easy to rebuild.

[3WheelsForever]

Hey 200xer how much are you asking?

[Dirtcrasher]

we are comtemplating parting out our 250sx because the swingarm bearings went and we're sick of pumping money into it. We had the pumpkin rebuilt about 2 years ago ($350 ouch). Is that what you need? It's off an 85, only difference is that more of the swingarm came apart in the 86 and 87s.


Mine got 350$ plus on EBAY. I'll bet the 87 rear I have (my spare) could grab 500$ :-D

[3WheelsForever]

Hey Dirtcrasher, what would you do in my case? I ride in dusty conditions almost all of the time. Very seldom unless it rains, it gets muddy around here. Would you go without an air box lid? I may get a filter cover for it. Im not sure. Give me your 2 cents.

[Dirtcrasher]

Hey Dirtcrasher, what would you do in my case? I ride in dusty conditions almost all of the time. Very seldom unless it rains, it gets muddy around here. Would you go without an air box lid? I may get a filter cover for it. Im not sure. Give me your 2 cents.


You'd just have to try it - that box lid is under the seat so I don't seem to get a huge amount of myd in there - but I'm not a big mud guy either. You can always use a forstner bit and cut 1" diameter holes in it and attatch some screen or something. As long as your letting in more air it will be fine.