Rev limits?

[Dammit!]

I was looking and couldn't find anything. I want to know what the stock rev limits are on the popular trikes. Anybody know where I can find them?

[tecat-z]

I'm just guessin, but i would say roughly 8-9 thou max on the avarage twofiddy performance 2stroke. Porting and clean jetting will determine max rpm. But higher max rpm reduces low output dramatically in both 2 and 4 stroke. Always a tradeoff unfortunately. Don't think our old trikes have a max rpm built in to the ignition like newer 4strokes. But again it is still governed by the engines ability to inhale, and exhaust fuel til the tipping point has been reached.

[maggiesboy]

I read on ATVriders.com that common rev "limits" are 10-11K

I'll see if I can find that article

[300rman]

a 2 stroke does not have a "rev limit" that is governed electronically or otherwise.
a 2 strokes max rpm is determined by the pipe and jetting, but mainly the pipe.

when the "sound" waves begin to overlap each other in the expansion chamber is when the engine stops climbing in RPM's. the image below will help make the "soundwave" thimg make more sense.
http://en.wikipedia.org/wiki/Image:Arbeitsweise_Zweitakt.gif

yes, other factors will determine the RPM, like integrity of the ignition system.
so unless i have been misinformed, this is how that works.

and if the motor is mecanically sound (crank or rod is not shot) a 2 stroke will rarely Grenade from extended high-rpm use. it will, however, accelerate the wear of the topend.

[Dammit!]

Ok lets re-define rev limit. Poor choice of words on my part.

A bone stock 250R will typically redline at what rpm?

I know mods effect this and even simple tuning and atmospheric conditions but in a typical scenario on a stock 85-86 R is what I'm looking for here.

Also, I'm sure the 350x has a more easily defined limit.

[Billy Golightly]

11-12k is my guess but the end of the usable power is much lower probably around 9k is my guess.

[300rman]

Ok lets re-define rev limit. Poor choice of words on my part.

A bone stock 250R will typically redline at what rpm?

It wouldnt be so much a "redline" as just when the motor peaks out.

[Dammit!]

It wouldnt be so much a "redline" as just when the motor peaks out.

:rolleyes:

Stop nit picking the terminology. Jesus Christ it's obvious what I was asking here.

[300rman]

i know what you mean. im not trying to be an ass, just making it clear for someone else just skimming the thread is all.

[Rustytinhorn]

This is not answer your question directly (sorry), but I know there was someone on here that installed a trail pro computer on their trike. A feature on the trail pro is it has a tachometer built in. I dont know who this person is, but if they happen to read this, please post your input with the tach, as I am currious to know as well.
Rusty

[Rustytinhorn]

Bump for Update...

I will hopefully soon be installing a tach on my R.
But using other methods... MY R (Repeat "MY 250R") will reach its rpm limit at approx 7200 rpm. I know it seems kinda low, I was a little suprised myself it wasnt higher, but every other R I've ridden with sounds like it tops out at about the same place, maybe slighty higher.
Edit-Thats at 5280 ft above sea level on a fairly hot day ( less dense air).

[tecat-z]

Sounds about right to me. Newer 250's reach max R's at around 7200-7600 rpm's. And with the relatively conservative porting on most 2 stroke trikes, lower numbers would be expected. Obviously max rpm can be raised with better ignition, porting, and exhaust, but not drastically.

[Dammit!]

Bump for Update...

I will hopefully soon be installing a tach on my R.
But using other methods... MY R (Repeat "MY 250R") will reach its rpm limit at approx 7200 rpm. I know it seems kinda low, I was a little suprised myself it wasnt higher, but every other R I've ridden with sounds like it tops out at about the same place, maybe slighty higher.
Edit-Thats at 5280 ft above sea level on a fairly hot day ( less dense air).

What surface were you riding it on at the time?

[The Goat]

yeah seems like sand would lower it...asphault would be a lot higher

[Rustytinhorn]

What surface were you riding it on at the time?

An Asphalt Road.
However according to a different source its saying that mine is 9200-9500 rpm....hhmmmm....
I will have to look into this a little more and let you guys know what I find out. I am really curious to know and its going to bug me until I find out.

[3Razors]

Most modern worked 250's rev over 11K rpm. 500's though are hanging there tongue out around 8k.

[SWIGIN]

a wise old racer told me years ago you just hold it wide open till you see god.......then shift


lol

[Dammit!]

a wise old racer told me years ago you just hold it wide open till you see god.......then shift


lol

Man I LOVE that quote. :lol:

[Ryan.]

a wise old racer told me years ago you just hold it wide open till you see god.......then shift

thats goin in my sig :beer shens

[SWIGIN]

lol....glad you guys liked it

he had it painted on his trailer after we all started useing it.

[HondaManr]

I know typical 2 strokes rev like crazy, somewhere in the 9 - 12 thousand range. Just my guess...

[brapp]

the 2 strokes alldepend on porttimign ignition timign bore / stroke ratio, carburation , somany variables i was messign aroudn with my drag bike and advanced the timign 7 degrees and gained abotu 3k on top but mad eit almost impossibel to start by kicking itand refused to idle. but i have even seen twin cylinder2 strokes rev as high as almosy 17-20 k range and as far as the 350x and similar 4 strokes they did not have a preset rev limiter liek moden thumpers but they woudl rev out tillthe vlaves started floating( i am knowm for it)

[81Rmachine]

I was thinkin the same thing because my R screams to bloody hell, although I know when to stop, but i rode both my friends slightly modified Rs and they didn't seem to rev near as high you could dang near hold em wide open and they wouldnt scream as loud as mine and mines still has a ways to go, for certain it would blow up if you wanted it too. My brothers 200s floats the valves all the time of course he rides it like theres no tomorrow.

[Gag_Halfront]

So, brapp brought it around to the real heart of the matter. The term "rev limit" and "red line" are from the four stroke world and they indicate the point where you need to stop reving before you start to damage the valve springs. The question that was being asked was more along the lines of "how high do they rev" not "what's the mechanical limit" so the answer for 2-strokes is hard to nail down. It's going to be different for various builds even of the same model trike. With the four strokes there's a hard limit, though and it's determined by the strength of the valve springs. I would love to know what that number actually is for a 350x so that I could look for some springs from some other application that could take the abuse of a higher rev. I think the 350 leaves a lot of power on the table but I don't want to destroy my valve springs to find out.

Sure wish they'd come with a tach.

[SWIGIN]

So, brapp brought it around to the real heart of the matter. The term "rev limit" and "red line" are from the four stroke world and they indicate the point where you need to stop reving before you start to damage the valve springs. The question that was being asked was more along the lines of "how high do they rev" not "what's the mechanical limit" so the answer for 2-strokes is hard to nail down. It's going to be different for various builds even of the same model trike. With the four strokes there's a hard limit, though and it's determined by the strength of the valve springs. I would love to know what that number actually is for a 350x so that I could look for some springs from some other application that could take the abuse of a higher rev. I think the 350 leaves a lot of power on the table but I don't want to destroy my valve springs to find out.

Sure wish they'd come with a tach.



all you need is some r&d aftermarket springs

my 350x has a a high rev cam with a old set of r&d springs and it will rev till the ignition gives out (not a rev limiter)

now, from way back in the day i seem to remeber that a 350x ignition is good till about 10,000 rpm

my 110 is the same way.....huge cam titanium retainers and r&d springs.....revs to the moon (or untill you see god.....lol)

if a 4 stroke is built right you can rev them past the power band or untill the ignition gives out

[brapp]

yes swiggin is right but with a stock motor it will float the valvs unless modified to resist the floating feelign until the ignition can not keep up. and with a 2 or 4 stroke trike they will rev until they can not support the amount fo fuel and air or they blow apart

[Rustytinhorn]

I know this is an old post, but I thought I should tie up a loose end here.
I don't have any specifics with me at the moment, but I know there is a math formula you can use to figure your rpm's.
For this you have to know the Primary Gear Ratio, Gear Ratios for each gear (which I can post later on if anybody would be interested), Front sprocket size, rear sprocket size, tire height...
If you know your maximum speed in a given gear, then you can calculate your RPM's based on your gear ratio's, tire height, etc...
Or if math isn't suitable, install a tachometer.

-Rustytinhorn