Author Topic: sprocket size opinions for low/mid ported motor? (Read 3636 times)

supernutt · « **on:** August 10, 2014, 11:15:26 AM »

Usually run a trx5 pipe on my 310 pro-x cylinder ported by Neil for midrange. Changed it to a CT midrange pipe. Power is much lower in the RPM range now. Seems that I have to shift a lot more to keep it accelerating. Doesn't FEEL nearly as fast due to not having as much top end. My question is, what do you guys run for gearing on a midrange ported motor? My gears seem pretty short since it doesn't rev nearly as high as the trx5 did. Currently have 13/37 on it with 20" rear tires. I don't know if I can squeeze a 14 tooth front sprocket in or not because my chain might not be long enough to run 14/38 to try so I would love some opinions. Thanks..

GO OVRIT · « **Reply #1 on:** August 10, 2014, 12:58:57 PM »

I would say how broad off a powerband you have is more important than where in the rpm range its ported to run. It sounds like that ct pipe shortened your usable power band. The taller gears let you stay in that powerband longer. He 310 I used to have with a trx5 pulled good with 14 37 gearing and 18" tires. Are you keeping the ct pipe or going back to the esr?

supernutt · « **Reply #2 on:** August 10, 2014, 01:04:14 PM »

I will be going back to the ESR when it comes back to my house but it may be a few months so I have to ride this thing like it is and have to make the best of it. I am swapping gears right now I'm going to try it out

Rupp250 · « **Reply #3 on:** August 10, 2014, 01:08:04 PM »

You could use a half link to gain a little length in the chain.
https://www.denniskirk.com/parts-unlimited/520-standard-chain-repair-kit.p113131.prd/113131.sku

But like already said, sounds like you lost a lot of usable power with that pipe change. I bet you didn't actually "gain" any bottom end but just lost all your mid-top. Me personally have 13-15t fronts and 36-40t rears and gear accordingly to where I am riding. I try to put a combo on that I can run usually 3rd mostly without constantly shifting.

supernutt · « **Reply #4 on:** August 10, 2014, 01:11:35 PM »

The machine always seems to be in the right gear I do not have to shift as much but it just runs out of revs up top

dlunn · « **Reply #5 on:** August 10, 2014, 01:53:59 PM »

I have the same midrange port by Neil and when I was asking him about pipes to run with his port job he suggested the TRX5 if i wanted more top end and the CT if you wanted a good grunt motor. You could play with gearing but I think the CT pipe will still hold you back as it won't allow the engine to rev like the TRX5.

supernutt · « **Reply #6 on:** August 10, 2014, 02:03:56 PM »

thats what I am noticing. Definitely a big difference between the 2 pipes. I have both pipes just don't have the trx5 here right now. Just trying to make the best of it for now..

supernutt · « **Reply #7 on:** August 10, 2014, 04:40:08 PM »

Well, swapped on a 14/38 combo and went for a spin. Definitely not any worse, in fact it feels a little better. Gonna have to be good enough for now.........but won't know for sure until I get it on a sandy trail....

Tbone07 · « **Reply #8 on:** August 11, 2014, 12:06:11 AM »

I used 13/38 on my pc2000 275 I believe. With 20" tires it seemed to be pretty well suited for XC

quadmad · « **Reply #9 on:** August 15, 2014, 09:14:26 PM »

I got the 310 with the CT pipe on 20" tyres and can't seem to get it to hookup with the 14-38 so I am thinking off going to a 15 to try and get traction.