Got to test out the 250r with 11 tooth sprocket in front

[sunnyday]

Finally got this 85 - 250r atc back together and running properly. Was having a terrible time with the carb overflowing and finally figured out the floats needed adjusting.

anyways...this had a 14 tooth front sprocket , and it really was to fast for my needs...with that 14 tooth sprocket the powerband was noticebale in every gear. When I nailed it in any gear you could feel the powerband kick in.,..

got the 11 tooth sprocket , and the changes are astronomical. As 1 poster said, it will feel like youve lost 6th gear , and thats about right. Also, the powerband is largely diminshed..its still slightly noticeable from 1`-3 rd gear..but from 4-6th gear, its basically gone.

Definitely notice a power increase ...but im not sure if 11 tooth upfront is where I will stay....looks like some people suggestions to go to a 12 tooth upfront woulda been the best of both worlds...so I may do that. I think the good thing about the power it now has, is it should allow it to climb pretty steep hills, without the need to hit those hills at a high rate of speed...1st and 2nd gear almost feel as though they have the power of a 4 stroker engine now.


On another note, im curious how many riders dont use the clutch on their 250r and shift without it ? It just seems natural on the 250r atc to not really need the hand clutch to often when shifting up thru the gears.

[sunnyday]

I wonder if there is any info available concerning these 250r atcs , as far as stock engine setup and top speed per different sized front sprocket.

in other words..

top speed for 11 tooth , 12 tooth, 13 tooth, 14 tooth, etc...with everything else being stock.

It feels as though I have lost about 20 mph off top end by going to the 11 tooth front sprocket...ecspecially since the powerband has diminished in the top 3 gears.

[atctim]

With having a smaller front sprocket (shorter gears) - your "powerband" should be more noticeable, not less. Not sure where you are coming from???????????????????????????

[HuffieVA]

http://www.ljsoftware.com/DS/GearSpeedCalculator.html

Here you go, keep in mind this doesn't account for any wheel spin, clutch slippage etc...

Like Tim said above, your observation doesn't quite make sense, are you short shifting and running in to high of a gear?

[sunnyday]

With having a smaller front sprocket (shorter gears) - your "powerband" should be more noticeable, not less. Not sure where you are coming from???????????????????????????

not what im experiencing...

dont get me wrong...the gears get up to speed quicker now, with a loss of total top end speed...but that actuall powerband that I felt with the 14 tooth sprocket has diminsihed greatly...

in other words..before with the 14 th sprocket...3 rd- 6th gear had a incredible punch when i nailed the throttle....and you can audibly hear it when it kicked in...now that punch is missing....

before it was like it had a 3rd gear and then a 3-1/2 gear { when you nailed the throttle} and it did this thru all gears... and you could feel it kick in...now 3-6 gears are just there....and that incredible speed band has gone on the last 3 gears. ......


which is fine..im not complaining, just giving my experiences.

[sunnyday]

http://www.ljsoftware.com/DS/GearSpeedCalculator.html

Here you go, keep in mind this doesn't account for any wheel spin, clutch slippage etc...

Like Tim said above, your observation doesn't quite make sense, are you short shifting and running in to high of a gear?

thanks for the chart...

There was another poster on here named tim, who told me it would perform as though it was only a 5 speed...and he nailed that correctly....

along with the incredible loss of the powerband.....

I guess the best way to explain it, would be to compare it to a 4 stroker that had powerstroke that wasnt working properly :}

with the 14 th sprocket...when i nailed it in all gears , the speed was so fast coming, that it felt like it wanted to do a wheelie thru all the gears...

now that is mostly gone...so i guess what happens is this...

the incredible speed that kicks in with the powerband, with the 14th sprocket may not be " power" but more of a intense and immediate boost of speed, that gives the imitation of power...

and now, the 11th sprocket has lost that imitation power boost that was noticed due to the immediate speed kicking in, and replaced that with more of a real power...but that power isnt great enough to make it feel like the front end wants to come up in all gears.

[Mosh]

.


On another note, im curious how many riders dont use the clutch on their 250r and shift without it ? It just seems natural on the 250r atc to not really need the hand clutch to often when shifting up thru the gears.

As I said last week. 85% of the 250R engine (including) transmission gears are DISCONTINUED.
Do a search on here about shifting without the clutch.
It does ruin the trans eventually.
I agree the 12 tooth would have been better..deja vu

[sunnyday]

As I said last week. 85% of the 250R engine (including) transmission gears are DISCONTINUED.
Do a search on here about shifting without the clutch.
It does ruin the trans eventually.
I agree the 12 tooth would have been better..deja vu

its no big deal to replace the sprocklet with a 12 toother...and they are only about $9....and I may do that ..

so shifitng without the hand clutch, does ruin the gears..even if the shifting is done at the proper moment ?

[sunnyday]

any of you guys running a 14 tooth or higher front sprocket ? ..or is 14 tooth the highest it should go on the front ?

[sunnyday]

actually, i just though of a great comparison..

this 85 with the 11 th sprocket, kinda feels like it runs/performs like a earlier air cooled 250r...in stock formatt

[ATC-Eric]

Yes, shifting without the clutch will eventually ruin something in the tranny. I had to learn the hard way.

[RIDE-RED 250r]

I was running 12/39 gearing on my stock cylinder with a better carb, reeds, exhaust and high compression setup and found that gearing to be quite good all round. I could have used a little more upper midrange-topend puch but the engine was setup more for low end/midrange anyway.

Yes, slam shifting it IS hard on your gears and shift forks. I recently found out they don't make shift forks anymore either. They were still available about a year ago, but now discontinued. Don't abuse your transmission.

What I do when I want to power shift (so to speak) is keep the throttle pinned while administering a quick pull of the clutch and a gear shift. You get a quick burst of RPM as you shift and instead of the gears and transmission taking the brunt of of the stress, the clutch does instead. Clutches are still readily available.

Tomorrow, I will be helping my cousin re-assemble his '87 TRX for about the 3rd time due to transmission troubles. That's how I know the shift forks are NLA....

[falloutboy]

I guess I don't get it. You want a nice, mild, low end, smooth power curve, and don't really want the bike to be fast.

You should have just bought a 4 stroke

[350XJEDI]

a slow 250r ? get a us90 WHY OH WHY

[TimSr]

On another note, im curious how many riders dont use the clutch on their 250r and shift without it ? It just seems natural on the 250r atc to not really need the hand clutch to often when shifting up thru the gears.

Whats a clutch? Is that the lever I only pull when coming to a coming to a complete stop, or starting from one? True, l only had my 86 TRX250R for like 4 years, but after 22 years of abuse on my longest used 85 TriZ gearbox, Im still waiting for that catastrophic gearbox failure. My 86 gearbox has only been abused for like 10 years though so it might come at any time. Maybe my secret is that Dollar General 10W40 oil I run in them!

I think the debate over powerband here revolves around a misuse of the term. Powerband is the RPM range at which your motor delivers maximum power, and has nothing to do with gearing. The only thing that will change with gearing is the speed you are going in a given gear when you reach that RPM level. If you change gearing to that extent and shift the entire gearbox range down by one gear, roughy speaking, gears 2, 3, 4, 5, and 6 should feel nearly indistinguishable from what gears 1, 2, 3, 4, and 5 used to be.