Changing out different sized front sprockets on 250r atc

[sunnyday]

So I recently got this 1985- 250r......cosmetically it was in sad shape...but the motor and tranny seemed to be fine { kickstart does slip periodically}

it had a 14 tooth front sprocket and stock 20" tall rear tires....{ also has been bored out to 40 over, and has racing pipe/ KN air filter} ...

Id say the bike had a top speed of 85 + mph....which is way to much for my local area of riding { we have alot of woods, trails, stream, etc here} ..

So I went ahead and took the front sprocket down to a 11 tooth , and bought 21" tall tires for the rear.

im assuming this should really trim down its top speed, and give me a bit more torque and control for trail riding ?

any idea how many mph this will trim off the top end speed ? I dont need to go any faster then 65 mph. ...but I do need the ability to stay in 1st gear for tight turns/ trail riding..

[Mosh]

I am going to offer some advice after reading your posts over the last few days. You can take it or leave it.

You got a 250R. You want to run in muddy trails and climb logs and go into mudbogs. You have the wrong bike for what you want to do with the type of riding you want. Yes you can make a 250R do that stuff, but IMO you would be better off selling that bike and/or trading it for a Big red, or 250SX. You never want to spend any money, and you want to fix everything on the cheap which is fine. So why ride a 2 stroke that you have to run premium fuel in and 2 stroke oil when you can get a 4 stroke that will work better for you and the riding you want to use it for.
From what I see in your posts, you want to use a Porsche to the job of a 4x4 Chevy truck. It isnt very practical for you IMO.

I dont think you understand what you have got here. A good 250R engine alone, is worth 500-800 bucks. I would hate to see you throw a chain on a log and crush the discontinued cases, or suck a bunch of mud and water into the engine and ruin internal parts that are getting harder to come by and most of the internals are discontinued by the factory. You will have to pay out the nose to fix anything on this bike when it breaks because the parts are getting harder to get everyday. And for someone that wants to do everything cheap as possible, I personally dont feel this machine is up your alley of riding style and repair and maintenance costs.

You have threads on here asking to use rocks for silencer packing that only costs like 8 bucks. I have a hard time believing that you will want to spend 8 bucks everytime you fill a 5 gallon tank of gas on 2 stroke oil, and have to use premium to add to that cost. So what I see happening, is you just grabbing the cheapest weedeater oil you can find and blowing this motor up and having a bike that dont run.
I am not trying to be rude, just trying to help out, and save a trike, and you money in the long run.

[sunnyday]

I am going to offer some advice after reading your posts over the last few days. You can take it or leave it.

You got a 250R. You want to run in muddy trails and climb logs and go into mudbogs. You have the wrong bike for what you want to do with the type of riding you want. Yes you can make a 250R do that stuff, but IMO you would be better off selling that bike and/or trading it for a Big red, or 250SX. You never want to spend any money, and you want to fix everything on the cheap which is fine. So why ride a 2 stroke that you have to run premium fuel in and 2 stroke oil when you can get a 4 stroke that will work better for you and the riding you want to use it for.
From what I see in your posts, you want to use a Porsche to the job of a 4x4 Chevy truck. It isnt very practical for you IMO.

I dont think you understand what you have got here. A good 250R engine alone, is worth 500-800 bucks. I would hate to see you throw a chain on a log and crush the discontinued cases, or suck a bunch of mud and water into the engine and ruin internal parts that are getting harder to come by and most of the internals are discontinued by the factory. You will have to pay out the nose to fix anything on this bike when it breaks because the parts are getting harder to get everyday. And for someone that wants to do everything cheap as possible, I personally dont feel this machine is up your alley of riding style and repair and maintenance costs.

You have threads on here asking to use rocks for silencer packing that only costs like 8 bucks. I have a hard time believing that you will want to spend 8 bucks everytime you fill a 5 gallon tank of gas on 2 stroke oil, and have to use premium to add to that cost. So what I see happening, is you just grabbing the cheapest weedeater oil you can find and blowing this motor up and having a bike that dont run.
I am not trying to be rude, just trying to help out, and save a trike, and you money in the long run.

you seem to have a attitude, and make MANY wrong assumptions about me.

I own SEVERAL atvs...including.

honda fourtrax, honda rancher , honda BIG RED..and honda 250r.

maybe its best you ignore me and my posts, since they seem to irritate you ?

oh...and I only use BEL RAY 2 stroke oil...so youve made yet another wrong assumption about me.

[sunnyday]

Oh..and my question about using pumice rocks for silencer packing, was because they would be heat resistant and not wear out quickly like normal fiberglass packing would. Its called " thinking outside the box " . Sorry it seems to make you upset. Like I said, maybe its best you dont read any of my posts from here on out ? I dont want to continue to cause you all this physcological trauma.

:}

[Mosh]

I dont have an attitude. Just a realistic observation. I made no assumptions. You have said many times that "i dont want to spend alot of money" from everything from seatcovers to brake pads to now silencer packing. That is not an assumption that you are frugal, it is an observation based on your posts. And it is no assumption you wont want to spend money on good 2 stroke oil either based on your previous postings. I have seen too many times where people operate in the same fashion, and they post on here or other forums trying to jet the carb because it dont run right, only to find out they are using a coffee can and pillowcase for an air filter, running 87 octane gas and Tradco outboard marine 2 stroke oil and wonder why the machine dont run correctly.
The only thing that would irritate me, is to see a 250R run into the ground by lack of maintenance or just plain abuse or just being too "frugal" to use the proper repair parts and maintenance items..
You say you are into music. What I read from you in this fashion would be the same as you stringing a gutiar with mechanics wire, or using plastic trash can lids for drum heads to save money.
It just doesnt make sense to me. But it is a free world and you can do whatever makes you happy. I dont think in all my years I have ever heard anyone suggest or even think of using rocks for silencer packing.

I digress and will ignore you from now..Good luck.

[sunnyday]

I dont have an attitude. Just a realistic observation. I made no assumptions. You have said many times that "i dont want to spend alot of money" from everything from seatcovers to brake pads to now silencer packing. That is not an assumption that you are frugal, it is an observation based on your posts. And it is no assumption you wont want to spend money on good 2 stroke oil either based on your previous postings. I have seen too many times where people operate in the same fashion, and they post on here or other forums trying to jet the carb because it dont run right, only to find out they are using a coffee can and pillowcase for an air filter, running 87 octane gas and Tradco outboard marine 2 stroke oil and wonder why the machine dont run correctly.
The only thing that would irritate me, is to see a 250R run into the ground by lack of maintenance or just plain abuse or just being too "frugal" to use the proper repair parts and maintenance items..
I digress and will ignore you from now..Good luck.

You say you are into music. What I read from you in this fashion would be the same as you stringing a gutiar with mechanics wire, or using plastic trash can lids for drum heads to save money.
It just doesnt make sense to me. But it is a free world and you can do whatever makes you happy. I dont think in all my years I have ever heard anyone suggest or even think of using rocks for silencer packing.

you made MANY wrong assumptions in your 1st reply..

1 of them was that I would only buy the cheapest 2 stroke weedeater oil ....WRONG..I only use bel ray..

you also assumed that I will be riding thru " mudbogs" .....Ive never even mentioned the word " mudbogs " or mudholes...in any post I have made on this site, since I joined up.

so how can you possibly claim that you are not making wrong assumptions ?

[sunnyday]

So can we try and get back to the original subject matter ? Seriously dude, its not a big deal for people to want to change sprocket sizes on a 2 stroke vehicle, to make them more favorable for trail riding , instead of all out balls to the walls racing or doing 90 mph top speed on straight aways.

I have 3 other atvs that are 4 strokes..but sometimes Id like to do trail riding with a 2 stroke .

[ezmoney1979]

What is the matter with you? A guy takes time to offer you sound advice and you get all pissy about it!? He didnt call you names, he just called it like he sees it and is an expert on the subject. And rocks for silencer packing is not "thinking outside the box" its more like "not thinking at all".

[sunnyday]

What is the matter with you? A guy takes time to offer you sound advice and you get all pissy about it!? He didnt call you names, he just called it like he sees it and is an expert on the subject. And rocks for silencer packing is not "thinking outside the box" its more like "not thinking at all".

Its not his advice that bothered me, its his wrong assumptions about me that needed to be addressed.

He must not be to much of a expert on the subject, if he makes several claims about me and my actions, which are untrue.

think about it.

In fact, he didnt even really address the main subject matter of my post that started this thread...he went off ranting about me using " cheap 2stroke weed whacker oil, and riding in " mudbogs"....none of which I do !

[Mr. Clean]

So I recently got this 1985- 250r......cosmetically it was in sad shape...but the motor and tranny seemed to be fine { kickstart does slip periodically}

it had a 14 tooth front sprocket and stock 20" tall rear tires....{ also has been bored out to 40 over, and has racing pipe/ KN air filter} ...

Id say the bike had a top speed of 85 + mph....which is way to much for my local area of riding { we have alot of woods, trails, stream, etc here} ..

So I went ahead and took the front sprocket down to a 11 tooth , and bought 21" tall tires for the rear.

im assuming this should really trim down its top speed, and give me a bit more torque and control for trail riding ?

any idea how many mph this will trim off the top end speed ? I dont need to go any faster then 65 mph. ...but I do need the ability to stay in 1st gear for tight turns/ trail riding..

BS, now way that 250r top speed is 85 mph......Since you already have the 11 tooth sprocket, why not go ride and report back your increased torque and control for trail riding and how much mph you trim off that reported top speed.

In this thread you started another member posted some excellent info on sprockets, did you read it?

http://www.3wheelerworld.com/showthr...42#post1103842

[sunnyday]

BS, now way that 250r top speed is 85 mph......Since you already have the 11 tooth sprocket, why not go ride and report back your increased torque and control for trail riding and how much mph you trim off that reported top speed.

In this thread you started another member posted some excellent info on sprockets, did you read it?

http://www.3wheelerworld.com/showthr...42#post1103842

Then please tell us, what do you think the top speed was that I encountered on it ? Full throttle 6th gear...

KN air filter / with air cover off


40 over bored out

racing pipe

carb rejetted

and my bodyweight of 169 lbs.

You act as though 85 mph top end speed , in these conditions is absoloutley unheard of..

[Mosh]

Posted in order of dates and times.

the 22 " tall tires a bit to low profile for riding in my area { woods , trails, with streams, logs to ride over, etc...}

so I was looking to get a bit more ground clearance for local riding. I dont race this 250r and I dont have the money to purchase another atv that is a 4 stroke with tall tires.

Could you give me a link to a set of tires that are 25 " tall, that would fit my 1985 rear / front rims ?

you seem to have a attitude, and make MANY wrong assumptions about me.

I own SEVERAL atvs...including.

honda fourtrax, honda rancher , honda BIG RED..and honda 250r.

maybe its best you ignore me and my posts, since they seem to irritate you ?

oh...and I only use BEL RAY 2 stroke oil...so youve made yet another wrong assumption about me.

you made MANY wrong assumptions in your 1st reply..

1 of them was that I would only buy the cheapest 2 stroke weedeater oil ....WRONG..I only use bel ray..

you also assumed that I will be riding thru " mudbogs" .....Ive never even mentioned the word " mudbogs " or mudholes...in any post I have made on this site, since I joined up.

so how can you possibly claim that you are not making wrong assumptions ?

I am really confused.
(1) I assume in your area there will be no mudholes in a creek or river. Most rivers and creeks I have been across or through do indeed have some sort of mud content.
(2) You own a bunch of machines but cant afford to buy a 4 stroke with larger tires to use, even though you already have one.
(3) You never stated what oil you will run, until I mentioned it may be cheap stuff, then 8 minutes later you edit your post to describe what oil you do run.
But I will address you original question with a question.
What does it matter what you will knock off your top speed if you are primarily concerned with trail riding? Most trails wont allow a bike to get much faster than 45-55mph. And most avid 2 stroke trail riders dont care how fast the top end speed is once they set their trail gearing. So why does it make a hill of beans being concerned with a bike that does 70 mph stock, to dropping down to 65 mph by going to an 11 tooth sprocket?

Run your 11 tooth front sprocket. I am sure it wont dig the chain down on your front chain slider too hard and cause it wear out prematurely. But that is just an assumption.

I am really not an expert at anything. I just read and make observations.

However, a good running 250R does not need clutched to death with 21's and a 13 tooth sprocket at slow speeds. Everything you are trying to do to your 250r for trail riding is overkill on set-up. You dont need 11 tooth sprockets and 22-25 inch tires. They do fine with stockish gearing in the trails and a 21 inch tire max. I wouldnt even consider anything less than a 12 tooth and that is only if I would be riding in the tightest of trails that require such low gearing.
I ride mine in some of the toughest trails you can imagine and so does my wife. And we do it on 18's.

[dcreel]

You act as though 85 mph top end speed , in these conditions is absoloutley unheard of..

Not unheard of.. 9 times out of 10 it's wrong.. There's always someone on Craigslist with a 90 mph 250R.

[sunnyday]

Posted in order of dates and times.









I am really confused.
(1) I assume in your area there will be no mudholes in a creek or river. Most rivers and creeks I have been across or through do indeed have some sort of mud content.
(2) You own a bunch of machines but cant afford to buy a 4 stroke with larger tires to use, even though you already have one.
(3) You never stated what oil you will run, until I mentioned it may be cheap stuff, then 8 minutes later you edit your post to describe what oil you do run.
But I will address you original question with a question.
What does it matter what you will knock off your top speed if you are primarily concerned with trail riding? Most trails wont allow a bike to get much faster than 45-55mph. And most avid 2 stroke trail riders dont care how fast the top end speed is once they set their trail gearing. So why does it make a hill of beans being concerned with a bike that does 70 mph stock, to dropping down to 65 mph by going to an 11 tooth sprocket?

Run your 11 tooth front sprocket. I am sure it wont dig the chain down on your front chain slider too hard and cause it wear out prematurely. But that is just an assumption.

I am really not an expert at anything. I just read and make observations.

However, a good running 250R does not need clutched to death with 21's and a 13 tooth sprocket at slow speeds. Everything you are trying to do to your 250r for trail riding is overkill on set-up. You dont need 11 tooth sprockets and 22-25 inch tires. They do fine with stockish gearing in the trails and a 21 inch tire max. I wouldnt even consider anything less than a 12 tooth and that is only if I would be riding in the tightest of trails that require such low gearing.
I ride mine in some of the toughest trails you can imagine and so does my wife. And we do it on 18's.

I will clear up your confusions..or try..


No, most of the trails around my area, are not filled with " mudbogs" ....There are some fallen trees { nothing to large] , shallow streams - 8" or less . I would never purposely take a 250r 2 stroke thru a " mudbog"

Yes, I have 4 atvs all together , 2 of them are currently tore down , getting repairs , but I wanted to make this 250r more adequate for trail riding..

Ive been using bel ray 2 stroke oil for almost 20 years...I dont use wal mart weed whacker 2 stroke oil..

Your post above contains alot more useable info, then your first reply, that was loaded with wrong assumptions about me.


If you are a " expert" , then good for you . I like expert advice, without the insults and wrong assumptions...

So, back to the original question..

going down from a 14 tooth front sprocket, to a 11 tooth, should take how many mph off top end speed ?

[dcreel]

going down from a 14 tooth front sprocket, to a 11 tooth, should take how many mph off top end speed ?

The only person who can honestly answer that question is you. With a GPS, 11 tooth and 14 tooth sprockets and a run using both. Anything else would be a well informed guess..

There was a gearing calculator on the internet but it seems to have been removed.