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Quick gearing Q for under powered engine

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lykan

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Ok, I have the trx .15 pro (good running), with the 22tooth CB Last time I had it out the mounts came loose, and I lost the cb (stripped it out) I belive I have a 72tooth spur gear. It's a hardened steel that takes the pegs.

It seemed to have ok power, but bogs a bit in second, and sometimes struggles a littlle on take off.

The thing Is I have two new CB's one is a 18 tooth, and the other is the same 22tooth. The last time I put the 18tooth on the 2nd gear shifting was off a bit (revved to high) I think that led to overheating, and loosing my old motor.

So it seems to me the 22 is too high of a gear makes it bog, causing it to overheat.

The 18 tooth I am afraid is going to be too low, and cause over revving-overheating.

So for the TRX .15 pro is 18/72 to low of a gear? Or is it going to be ok if I get the second gear shift setup right?

Is the 22 tooth too high of a gear for the poor over worked .15 causing it to overheat when I do a lot of takeoffs?

I'm putting it together now, and hoping to get a run in afore dark.. any help would be greatly appreciated. I'm not looking to go 50mph, I have limited space, so I want to be able to reach top speed a little faster. I just don't want to overworkt his engine, I want it to last..

tanks :D
 
instead of changing the cb, change the spur, get like a 74t spur, and you wil have a little faster accel times. it will work well. and fi it revs too high, just richen it so it doesn't overheat. itl last, i promise.
good luck!
 
So changin the spur gear a tooth or two makes subtle changes to the gear ratio while changin the CB makes a huge difference?

I might try a high toothed Spur on pay day. Unfortunetaly right now All I have is a 18 or a 22 tooth to decide from.

I'm wavering between going low gear, and shifting early, or using a high gear, and shifting in the higer revs.

For now I guess I will go with the 18 toother, and have the tranny shift before it revs too high. UNless of course any one see a bunch of red flags?
 
dude, just settle down, just go with the 18, and it wonthavemuch of a problem if it revs too high if YOU RiCHEN IT!! so dont worry about it overheating, and stick with the 18, dont be so worried!
 
I understand how to keep the temps down by mixture. I was just trying to figure out the best gear ratio for the trx. 15 for what I am doing.
 
Will - Lol dude, He doesn't need to "settle down". He's not some kid rambling in an ADD tantrim. He's a dude trying to find some answers.


Lykan - What CB gear did I send that with again. With that CB on the engine and a 72Spur I was getting perfect 2nd shifts right where I wanted them and was happy with the powerband. It's not a 2.5 but it's a hellava lot more reliable. You probably need to adjust your tranny shift point. As for gearing in general, I always experiment with various engines and don't always go by the "textbook" thinking when it comes to gearing.

BTW....for really powerfull engines like a 2.5, Sirio .18 or bigger I always run all twelve clutch pegs but I was happy just running 6 with that engine.
 
Hey ya NB, I stuffed 12 pegs into the stee l spur, its a 72 toother. You sent a 22t clutch bell, and your rightit hit second just perfect. I just wasn't impressed with the low end gurunt for what I do.

I tossed in the 18t bell, and its a rocket now. (I don't need 35+mph)

You are absoluetely right tho I need to adjust the shift point. Does anyone know whioch direction makes it shift later? I also forget which hex to use on that screw.

I am loving this engine with the 18t No more boggin on the start. Enough power to get up to speed before I run out of room.. just loven it now;)
 
Right on. right now I am thinking it stays in 1st gear a little too long for my liking, making it rev a bit too much.

**thinks out loud**
22 is too high, 18 seems to really rev it out (ran it today with the 18) maybe Ill try a 20 tooth next and see if that's a good combo.
 
I had the same thing when I put in an OS 15 cv-r in my maxx.

It didn't matter though. Regardless what I did, I was hitting temps around 270 all the time. Ended up doing a 21 conversion. Now I just have a hard time keeping the maxx in one piece.
 
Ok I was messing around with the shioft point, and turned it in too far. I touwldn't shift out of first. I had three kids over my shoulder, so I did 2 turns out, it was then stuck in second lol.

So I go to find the screw hole, and when i turn the shaft (opposite end of the spur) the shaft truns, but not the thing that has the screw in it. I can turn the plastic gear with the spur. But the metal inside that gear doesn't move so I can line up the holes for adjustment.

Did I just loosen the tranny so much that something fell out? Do I need to pull the tranny to fix this.. If so major bummer. I just had the maxx apart for a week messing wihth the pipes and CB's
 
dude, pulling the tranny doesn't take much work, and also you probably loosened it too much. ya gotta be careful with that screw. the tranny is pretty simple. dont worry, youl find what happened

also, if i say anythin offensive, just ignore it. my gf just dumped me... THIS SUCKS
 
Originally posted by Willthethrill


also, if i say anythin offensive, just ignore it. my gf just dumped me... THIS SUCKS
Click to expand...

That's understandable but no worries bro. THeir's a million fish in the c and @ your age you've got lots of time to search. Hey bro, I'd say this in PM but your box is full. How bout some feedback for the engine mount bro. Thanks.

Lykan - You definitley shouldn't have to pull the tranny but even if you do it's relatively easy and a good lesson. Just make sure your adjusting no more then 18/th of a turn @ a time.
 
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I took the tranny apart no screws are out of place. Everything looks as it should be.

Why when I have the spur gear in the proper place (the hole in the plastic showing so I can get at the adjustment).

I go to spin the shaft on the opposite end, and the metal inside part doesn't spin. I can't get the meta inside part to turn so I can adjust the screw. grrrph.
 
try stuffing something in there to hold the plastic gear in position, the metal will (should) rotate while the gear stays in place. If I am stupid and remember incorrectly, then just try turning the spur gear till the holes line up correctly. Either way will make the correct screw appear
 

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