300 trx in an sx?

[King Trikester]

So from what I understand the 300 trx will fit in an sx, after changing the output shaft. I'm wondering how much I will gain in bottom end, I'm not a speed Demond I like torque. How are the 300's geared compared to the 250's? I have found a 300trx that has been rolled, runs great.

Any one have a imput on this, pros/cons?

[C.J]

you have to use the 2 wheel drive version.

swap in the cam from an 89 300 and its a reeaall torquey little monster.

the "first" gear is actually called SL, super low LOL
they go r-n-sl-1-2-3-4

[Dirtcrasher]

Trail rider or trailer rider did the swap and told everyone what had to be done.

Look him up!!

[King Trikester]

you have to use the 2 wheel drive version.

swap in the cam from an 89 300 and its a reeaall torquey little monster.

the "first" gear is actually called SL, super low LOL
they go r-n-sl-1-2-3-4

yes it is a 2 wheel drive model, im not sure what year im going to try and get ahold of him and get more info about. it seems like a great idea im going to go for it

[Name Brand]

SL gear in an 250SX is 3.615
SL gear in a TRX300 is 4.083

To add more torque you could swap out the rear diff unit. The 250SX came with a 4.969 ratio in the rear diff. I have heard you can swap out to a 250ES rear diff which would have a 5.684 ratio. I run the complete swing arm and rear axle from a TRX250 to accommodate 25" tires. I am having trouble finding that gear ratio, but it is torquey like the 250ES.

So lowest crawl ratio (SL x rear diff) on the SX is 17.963. TRX300 SL gear with a 250ES rear diff would give a crawl ratio of 23.208.

My SX with 25" tires works great at crawling over rocks and through swamps as well as with good speed in the flatlands. My crawl ratio should be around 20.548. When I had stock 22" tires with this ratio it was slow at top speeds and I had to stay full throttle to keep up with other riders. Not so enjoyable and lots of RPMs from the engine. It would crawl well and hill climb great though.

The SX and TRX300 do share a 0.848 gear ratio in 4th gear. So if you only change the engine your top speed won't be affected by gearing; only more power from the extra displacement. You will have more torque with just an engine change. Likely it will work well for slow speed crawling and just as good for faster travel in the top gear. Should be a good combo.

I don't think you would need to change the rear diff for more torque. I'd say ride it with the TRX300 engine and see how you like it. If you want it to have more torque (or to adjust for larger tires like I did) then you can simply change the rear diff later.