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View Full Version : Might sound crazy, but would it work?



midnight_rider7
03-09-2007, 06:35 AM
Ok ladies and gentlemen how is everyone doing? I have a quick question and was curious as to if anyone has thought about this. Would there ever be anyway to machine a larger gear say 5th gear for the 250ex inside gear box? I have no idea if that would ever work but I think it would be awesome. Before anyone replies please don't even say get a 300ex or a 400ex I just simply wonder if this though has been took into consideration by anyone that enjoys their 250ex and would love to have a little more top-speed out of the shaft driven beast.

ryanh250ex
03-09-2007, 10:26 AM
I'd imagine it would be possible. I'd personally like all the gears to be slightly taller. Realistically, though, i could settle for a revised 5th gear.

are you serious about doing such a thing or are you just pipe dreamin'?

I guess in order to make the gear taller, you would have to make the gear be physically bigger/more teeth.

I'm gonna be splittin the cases anyways to throw in a vesrah rod, It would be an ideal time to throw in a different gear at that time...

Rev box= poor mans re-gear.

midnight_rider7
03-09-2007, 11:18 AM
Ok to begin I would like to start by saying I would love to know if this idea would work. I honestly have no reason to believe it wouldn't. I have personaly never adventured and took the rear drivetrain apart on a 250ex. I would imagine much like anything else there would be a series of gears. The gear I would like to put thought into would be in re-designing the 5th gear which would allow for more top speed if and only if the bike was built and powerful enough to get it going which with as many aftermarket part available I feel that wouldn't be a problem. Depending on the setup of the gears and how the design is determines wether we can successfuly pull this re-design off. If by a miracle the gearing was fairly simple and there was enough room to allow for the re-designed gear to fit which I am sure there should be because of oil around the stock gear, then we could remove the gear and allow a machine shop to fab a tad bit larger gear. Let me know what you think of the idea also keep me updated on the look of the rear drivetrain when you have it apart and see for yourself if this idea even holds water.

PS: Rev-box. I have a few things I would like to share with you. I owned a 2003 250ex with a DG full exhaust about 3years ago. I traded my 1999 300ex for the bike because the guy really wanted a clutch and was willing to trade title for title so I was like ok sure thing bud. Upon my trading the boy ask if we could open them up down the road in front of my home and see just how far ahead the 300ex got ahead of the 250. I said yeah that is fine. So we took off down the road for about a 2mile straight. The 300ex stayed exactly about 8 fourwheeler length ahead of me on the 250ex. When I sold the bike I know for certain the exact speed of my ol 300ex. It ran 59MPH flat no faster no slower that was it. So honeslty I dont think I was running much slower than him trailing behind on the 250ex. To add to all of this I have a few more things I would like to say. My younger brother has a recon in which my dad bought for him. I at the time had the 250ex. I know there is a huge debate over speed and what not on this site everyone feels different. But here is my experience take it for what you want. I rode both the recon and the 250ex all the time. The gearing between the to machines was night and day different. I could easily so easily hit the rev limiter on the recon in what seemed like a 300yrd span. But on the other hand I never hardly hit the rev limiter it seemed like there was still so much more to go with the higher geared rear end in the 250ex and yes that is a fact the recon and 250ex both have different gearing. In conclusion I would have loved to have invested in more work and a rev-box if only they had such back then I would have surely bought it for the bike and I still want so bad to know what difference it make son the 250ex's.

Here is a write up I found in an article read this and you will seem they feel very similar to my experiences:

The 250EX sports a 229cc OHV air-cooled engine and like all Honda shaft-drive quads, it's longitudinally mounted in the double cradle steel frame. This configuration allows direct drive-shaft alignment to the rear wheels with less moving parts for more efficient power transfer. An efficient oil-cooler supplements the 2-quart capacity wet sump providing lower operating temperatures for increased engine life. A 20mm carburetor with a unique buffer plate in the float chamber helps maintain a consistent fuel flow regardless of terrain variance. A solid-state CD ignition has an 8750-RPM rev-limiter and the electric start engine has a 123-watt capacity alternator. Surprisingly, there is no backup recoil starting system. Access to the air filter is accomplished by sliding off four clips from the intake airbox lid. Although the engine has been pilfered off the Recon, a few performance features have been incorporated to deliver on the sporty side of the 250EX. A new two-valve cylinder head design features performance-optimized valve timing. A 31.5-mm diameter intake valve (1-mm larger than the Recon's) and a 27-mm diameter exhaust valve produce a broader usable powerband. Also new is the 55-degree intake valve angle as compared to the Recon's parallel intake valves. The 1-mm larger intake valve and more efficient angle give the 250EX 10% more power than the Recon. The new cylinder head gives it a slightly higher 9.2:1 compression ratio as compared to the Recon's 9.0:1 The power increase is matched to a new set of higher gear ratios that give the 250EX a more "sporty" feel than the utility-oriented Recon. The semi-automatic (no hand clutching) gear shifts are easy, crisp and precise.


For comparison testing of the 250EX's engine power, Honda had brought along a few Recons and a few 300EX's. Switching back and forth between machines made it obvious that the new 250 was much quicker than the Recon. This wasn't too surprising as the Recon is 42-pounds heavier with 10% less power. What was surprising was the small margin of difference in speed between the 250EX and 300EX.

http://www.atvconnection.com/Features/ATV_Reviews/2000-Honda-250ex-review.cfm

<---source

midnight_rider7
03-09-2007, 11:25 AM
Oh I almost forgot...lol hard to believe I could forget something with all that crap up there aint lol.. But just think with the redesigned gear and the TURBO ( WOW! might I add) your 250ex would be smokin past the competition and then maybe just then we could set back and say what? where? 300ex? lol just kidding 300ex riders but I enjoy greatly being the underdog because it just pisses everyone off when you beat them. By the way I would love to see a video when you finally get the turbo complete on the 250. GL and get back with me!

BlasterEaten250
03-09-2007, 02:06 PM
I believe honda changed the internal gears on a rincon to compete in the Baja 1000 a few years ago. You could technically do it but it would be very hard and very expensive.

ryanh250ex
03-09-2007, 02:32 PM
OK no offense but it doesn't seem like you know very much about drivetrains/transmissions. Either that or i'm totally misunderstanding you.

In the 250ex the transmission (where all the gears are) is contained in the bottom end with the crank/connecting rod, etc etc

This rear drive gear you speak of is the final gear case which affects the ratio of ALL gears, not any one in particular. In a car like a camaro or mustang which might have say a 3.27 final gear ratio or 3.55, for better acceleration you might upgrade to a 4.10 or 4.56 gear ratio while sacrificing top speed. in this case we want a smaller number.

The biggest thing about changing gears is setting them with proper backlash, etc.

450rJam
03-11-2007, 07:44 AM
get taller tires, it will make all the gears a little higher.

little less low end power and a little more top speed.

the 250ex is more of a trail atv than a highway cruiser.