airmancams 78mph 350X

[MR ATC]

first my apologies to the moderators for reopening this subject but it is purly from a technical aspect and a legitamate subject. i asked a question and he responded now i want to clarify

i quote airmancam...

"I changed my gearing to 12/36. The only reason I said that my 350x could beat T_Mans tecate is he said it would go 72 and I said mine would go 78."

so lets look at this...

stock gearing is 13/40 or 3.08 ratio and tops out at 72mph. with stock 22" tires
your gearing is 12/36 or 3.00 ratio so i would say about 74mph. but you are running 18" tires so your most likley toping out at about 68 with a tailwind. and here is why. lets look at this again

13/40 (stock) is 3.08 = 72 mph
13/39 is 3.00 with stock tires =74 mph
13/38 is 2.92 with stock tires =76 mph
12/36 is 3.00 with stock tires = 74 mph

now if a stock 350X with 13/38 will only do 76mph with stock 22" tires. and you have 18" turf tammers. there is no way your doing 78mph. so drop off about 4mph for each 2" of tire size decrease and you have arox. 66mph. then i gave you 2mph for your mods which in reality provide little if anything to your top speed.

[smokinwrench]

then i gave you 2mph for your mods which in reality provide little if anything to your top speed.

Holy Smokes me and Mr ATC agree on something :shock: . I was trying to explain that the other night and I was called the stupid one. You have to have higher rpm's or higher gearing (sprockets,tires) to have a faster top speed. Like I said the mods will get you to your top speed faster.

I think 3 guys on this forum should feel like real idiots. LOL

Josh

[smokinwrench]

Not to be rude AMC but I think the only accurate way to check your speed is with a radar gun. While driving beside the pickup one of you could always trying to catch up with the other one and get a false reading of your true speed.

Josh

Or a GPS unit.

[Wickedfinger]

...well I can see I'll be busy for a while editing this one........Guys please stick to the subject.

[MR ATC]

I'm just saying what the speedometer said in the jeep and the ram. I'm not lieing about the speed. I guess the only reason to prove this shizit to you guys is too take a picture of the speedometer saying 78 and me right next too the truck is that the only way to prove it?

i was not trying to imply you were liying. i was just curious as to how you determined 78 mph especially after looking at you trike with 18" tires. but before assuming anything just by looking at the tires i asked the question. then after finding out your gear ratio and combining that with your tires and mods i was able to determine your top speed + or - 1.5 mph.

the "jeep" method is inacurate as auto speedo's are typically + or - 5 mph off, and does it still have stock size tires?

with your gear ratio and smaller tires it is impossible for you to go over 70mph. your gearing is no differant then just switching from a 40 tooth rear to a 39 tooth rear sprocket. that alone will only give you 2mph but you went down 4" in tire size which has a bigger negative effect on speed then one tooth on a rear sprocket has positive effect.

[NOS_350X]

...well I can see I'll be busy for a while editing this one........Guys please stick to the subject.

sorry for putting you through that work. i'm a moderator and shouldnt of done that. but sometimes people get mad

[AirManCam]

I'm just saying what the speedometer said in the jeep and the ram. I'm not lieing about the speed. I guess the only reason to prove this shizit to you guys is too take a picture of the speedometer saying 78 and me right next too the truck is that the only way to prove it?

i was not trying to imply you were liying. i was just curious as to how you determined 78 mph especially after looking at you trike with 18" tires. but before assuming anything just by looking at the tires i asked the question. then after finding out your gear ratio and combining that with your tires and mods i was able to determine your top speed + or - 1.5 mph.

the "jeep" method is inacurate as auto speedo's are typically + or - 5 mph off, and does it still have stock size tires?

with your gear ratio and smaller tires it is impossible for you to go over 70mph. your gearing is no differant then just switching from a 40 tooth rear to a 39 tooth rear sprocket. that alone will only give you 2mph but you went down 4" in tire size which has a bigger negative effect on speed then one tooth on a rear sprocket has positive effect.

So what gearing should I go too? Im just telling you what the spedometer said. I know that car spedometers are usually off but thats pretty much the only thing I have to check my speed with. I'm amazed I never bought a gps because im a die-hard hunter. Will any gps tell you how fast you are going? And yes the jeep still has the stock tires. But the dodge doesnt thats why im thinking that it was faster with the dodge.

[MR ATC]

So what gearing should I go too?

well if it's top speed your after get rid of the 12 tooth sprocket going smaller on the front give you more power not speed. i personally carry a 12 tooth in my fanny pack this way if i ever find a killer hillclimb i wanna attempt i switch it right in the field and i know i can pull 3rd up most hills. ( i run a 38 in the rear) put a 13 back on then put on a least 20" tires and you'll be around 74mph if you really want 78mph then go with 22" tires. if your stuck on having 18" tires you'll need to go to a 13/30 gearing to get 76mph. small tires are not good for top speed

[ejc042]

I was wondering if you have the formula to determine max top speed on a 350X, based on gearing and tire size. I am building a 350X and want to get good top speed, without sacrificing too much power.
johnnyrebracin@hotmail.com

[MR ATC]

i had the formunla for a long time but with my doemestic problems i lost a ton of my information and resources. however since i've been seting up 350X's for well over 15yrs i can get pretty close just by experiance.
if you want to gain anything more then a few mph's without sacraficing low end you will need to do some motor mods to increase H.P. this way you can run taller gearing and still have low end.

you may be able to contact sidewindersprockets.com they are the ones i got the original formula from. they don't have it on their website but someone there may be able to get it for you.

[ejc042]

I will be running 22" tires. What kind of mods would I need if I wanted to break 80 mph without losing low end. Or how about 85mph.

[NOS_350X]

I used to run a 15 tooth front sproket and a 38 rear (i might have had the stock 40 on tho) with 22's and i was hittin 85+ but i woudnt open it up on the road, it would start bouncing. rember gearing that high will kill clutch plates!!! first is still low enough to climb things.

[ATC crazy]

I will be running 22" tires. What kind of mods would I need if I wanted to break 80 mph without losing low end. Or how about 85mph.

A good bore job would be the best idea for that. My brother's 350X motor was bored to 372 stroker with new rod, piston, cam, and other engine mods. It was geared down for the woods with 22" tires, but would still reach 70MPH. If you do those mods and run a +1 or +2 C/S sprocket, or -2 or so rear sprocket from stock, you would reach 80+MPH easily. The 372 stroker kit will ensure that you have enough power.

[TimSr]

rember gearing that high will kill clutch plates!!!

Heck yeah, youve got slip your clutch until you hit 25mph! Gearing low serves a lot more function than just having enough power to climb. You can ride trails comfortable without constantly slipping and frying clutches. On two strokes, you can keep the RPMs up at low speeds, and ride all day without fouling a plug. (Its not riding "fast" that keeps them cleaned out)

I guess everybody needs to do their own thing, but Ill never understand why a guy will struggle with slipping a clutch all day, to hit speeds that I cant even conceive for an offroad vehicle. Even with competitive drag racing on standard track lengths, most drivers run out of track before they run out of top speed. I would die to see these off road riding areas in which 70mph doesnt offer a high enough top speed! The big (so called) MX track at Haspin is the first MX track Ive ever even hit 6th gear on with my R, using 11/43 gearing on 18" Turf Tamers. My Z with 11/43 driving 22" All Traks hits high gear on Haspin's drag strip, but never tops out before running out of strip. Do you guys race on a 3 mile drag strip or something? Indy 500? Im just really curious as to where or what type of riding you do in which gearing for speeds beyond 70mph offers any advantages at all, other than to be able to say "it will do 95mph". If it'll do 95, what good is it, if you cant use it?

Top speed has little to do with even normal drag racing, unless your running and endless track, and I think its given far more creedance than it deserves, but Im open, if someone can convince me otherwise.

[MR ATC]

A good bore job would be the best idea for that. My brother's 350X motor was bored to 372 stroker with new rod, piston, cam, and other engine mods. It was geared down for the woods with 22" tires, but would still reach 70MPH. If you do those mods and run a +1 or +2 C/S sprocket, or -2 or so rear sprocket from stock, you would reach 80+MPH easily. The 372 stroker kit will ensure that you have enough power.

a +1 front or 14/40 will give you a 2.85 ratio or = to a 13/37 which is good for 77mph

a + 2 front or 15/40 will give you 2.67 or = to 13/35 which is good for 79 mph

nos_350X with a 15/38 combo you have a 2.57 ratio = to a 13/33 which is good for about 81 so 85+ is streching it. and you will lose a lot of low end

if you want to hit 85 you will need a 2.31 ratio or close to it. to get that ratio you would need either a 12/28, 13/30, 14/32, or a 15/35 set up. to mange this and have low end you will need at least 10 more H.P.

to get 10 H.P. your talking pipe,carb,big piston,cam,porting,