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Discussion Starter #1
Aloha T dubbas

I just swapped sprockets from stock 14/50 to 15/49. It’s a great feel and draws out the shift points on the bike and allows me to cruise the highway comfortably without worrying about blowing up the freshly rebuilt motor.

However it definitely feels like it lost a small amount of get up so I am looking into a dg exhaust and bigger main jet to give a little umpff. I recall watching a video of MotoMax riding his tw with freshly upgraded exhaust and jet and saying he noticed an improvement.

From my research it sounds like the 128 is a good up jet from the stock 125 or maybe even 130? I live at a few hundred feet and ride mostly sealevel with occasional climbs to 6k plus

Still not sure which of the slip on pipes will give the Most performance increase and waiting to hear back from DG to get there opinion.

Any suggestions you all have are greatly appreciated.


Love modding this thing and stoked there are others out there who feel the same about riding and wrenching these little bikes
 

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After dealing with a tiny gearing change (47 rearsproket) that I'll say "I'm happy with" just to justify, losing 10lbs of weight (on me, not the bike) would give it more get-up-and-go.
If you want to go full-bore street or full-bore dirt you'll feel the difference. Something in the middle... they pretty much come stock that way.
Adding up most of the bolt-on accessories I've done most are for comfort. For better performance I bought a 250. Tweak-away.
 

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What year is your TW? Have you done any work on the carb at all? There is a lot of info about carb tuning here at the forum, and it does make a big difference.
 

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Punch a few holes in the airbox cover, slip on muffler (there's no appreciable difference, pick whichever one you can get a better deal on or like the look of), and a larger main/shim the needle. It's popular to enlarge the air hole in the CV slide as well to make the throttle response a bit snappier. I'd probably go with a 130 main.

It's not going to suddenly transform this into a 450 MXer, but you will notice an improvement across the board. 1 tooth in the rear is a very minor change.
 

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To restore "pep" go back to the stock 14/50 sprockets. Choose either "quick" or "fast" but no simple modification will make the TW go both quicker and faster. The 9% change made in overall gearing to reduce rpm at any given speed is of course going to be at the expense of acceleration. Basic physics.
 

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I went with the DG "O" series muffler on mine with a Dynojet jet kit. It was a noticeable improvement over stock. I also swapped to a 45 rear sprocket at the same time. The Dynojet kit was a breeze to install and I went with the 130 jet per the kit instructions. The kit also has a new slide needle and shim kit for that and the instructions were very clear and easy to follow.
Like has been said, it's not a huge improvement as far as gained horsepower, but rather how the power is delivered. I could feel how much smother and harder the bike pulled in the seat of my pants so to say. The other benefit that often gets overlooked on TW rejetting is the bike runs cooler. The excessively lean state of carburetor tune in the "As delivered" stock set up runs hotter. I'm not a scientist, but I can tell you that a cooler running engine will last longer.
I bought my Dynojet kit at denniskirk.com
 

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To restore "pep" go back to the stock 14/50 sprockets. Choose either "quick" or "fast" but no simple modification will make the TW go both quicker and faster. The 9% change made in overall gearing to reduce rpm at any given speed is of course going to be at the expense of acceleration. Basic physics.
I don't agree with that. I think the torque and power curves of the TW engine is better suited to a 15 front and 50 rear. Every gear winds out to a higher speed and my TW accelerates better with the 15 tooth front. Of course proper carb tuning is necessary to achieve those results.
 

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Discussion Starter #8
Definitely noticed the difference in gearing on the road today. Btw its equal to a 3-4 tooth change as up one in front equals down 2-3 in rear plus the one down in rear. Riding comfortably at highway speed and can make a turn without having to shift through 3 gears! I think the retune and pipe will feel good as it’s more response I am looking for. Also the trails we ride can have 6-10 foot guinea grass which makes it impossible to see if someone is around the corner or going the wrong way. A louder pipe means others can hear you coming and get out the way🤣


My TW is an 07 and carb is stock as far as I know.

I can’t lose much more weight at 140 and narey much body fat. Can’t break the bolts on right side footpeg or I’d take those off. But since they are stuck i have found they make nice foot rests for cruising on the highway and help to keep good back arch

So it sounds like might be worth doing a tuning kit over just a main jet swap
 

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Guys, one important thing to remember...
If you replace the pipe, change the jets, put holes in the airbox, change the gearing, etc. you won't really know what you got or what did what.
Maybe a different combination of things or even fewer changes might even work better. Or worse.
The only way to know for sure is do one thing at a time.
If it's better, go to next step.
If it's worse, go back a step and try something else.

If it's louder it usually seems faster.
And after all the work and money you expect it to go faster, and sometimes it seems that way. When it's really not.
Nobody wants to admit they 'effed up and your imagination can trick you.

But...it's really not all that random, either.
You need to have at least a basic understanding of what you're doing...cause & effect.
Read, ask around, but don't believe everything you read & hear, either!

Have patience. Try not to get "inventive"...I promise you, somebody has tried that before.
Gearing & carb tuning are complicated...get one right, then go on to the next. You learn from that.
Do them at the same time and if the result is faster, slower, the same...what have you really learned...why is it like that?

Your best & worst info sources are right here on the forum!
But who do you want to put your confidence in...the guy with 3 posts and an unknown background, telling you what you want to hear...or the old boot with 1500 posts and obviously worlds of experience, telling you something you don't want to hear.

Take your time, listen, read, understand or ask questions until you do.
"Pay your dues".

Obviously, I'm writing this with the newer cats in mind, the ones who can benefit the most.
But don't have 100% confidence in the old/experienced guys either. Everyone can be wrong, or mistaken...or just plain don't know. Or their ego gets in their way. Or maybe they're pissing on your pants leg and telling you it's raining! I've seen it all on every forum I've ever been on, and I include myself.
I've been doing this stuff for a long time but I still ask lots of questions and usually learn something when I do.

If this comes across as preachy or know-it-all...I have not done a good job, that's not the way I meant it..
And I apologize.
One last thing...have fun! If you don't YOU are doing it wrong! :D
 

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https://www.denniskirk.com/dynojet/stage-1-jet-kit-4191.p174040.prd/174040.sku

This is the kit you want from denniskirk.com
I recommend this kit over the procycle kit for two reasons
1 It comes with instructions. The procycle kit does not.
2 This kit was already dyno tested and the results are provided in the kit. The procycle kit is just a bunch of jets in a box and you have to figure it out on your own. Dynojet already did all the testing for you and support their results with a printed performance curve so you can see the improvements over the stock tuning.

And no, I do not work for denniskirk or Dynojet. I have however used their kits in many motorcycles from Harleys to Yamahas. They are always spot on and the results speak for themselves.
 

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This thread was begun over concern of loss of acceleration after a ~9% reduction in overall drive ratios due to sprocket changes. Original poster expressed interest in whether simple jet exchange and a muffler would help compensate for loss of acceleration due to a somewhat significant gearing change.
It would be interesting to see the printed "performance curve" from Denniskrk on their Dynojet kit compared to stock to see quantitatively if and where in the rpm range there is increases in either torque and horsepower to address OP's concerns over loss of pep (acceleration) due to 9% change in all his gear's drive ratios.
 

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Discussion Starter #15
https://www.denniskirk.com/dynojet/stage-1-jet-kit-4191.p174040.prd/174040.sku

This is the kit you want from denniskirk.com
I recommend this kit over the procycle kit for two reasons
1 It comes with instructions. The procycle kit does not.
2 This kit was already dyno tested and the results are provided in the kit. The procycle kit is just a bunch of jets in a box and you have to figure it out on your own. Dynojet already did all the testing for you and support their results with a printed performance curve so you can see the improvements over the stock tuning.

And no, I do not work for denniskirk or Dynojet. I have however used their kits in many motorcycles from Harleys to Yamahas. They are always spot on and the results speak for themselves.

I like that they include instructions but honestly a little nervous about drilling out a perfectly good carb haha! Also.... the graph they have in the pdf manual is well to say the least impossible to read lol!

I would love a full rebuild kit that allows for some upjetting to handle the new pipe
 

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I like that they include instructions but honestly a little nervous about drilling out a perfectly good carb haha! Also.... the graph they have in the pdf manual is well to say the least impossible to read lol!

I would love a full rebuild kit that allows for some upjetting to handle the new pipe
Did you find a PDF without a password, or did they give you the password after you ordered? The manual on their site is password protected. I regularly look at a products manual before deciding to buy or not, and was rather disappointed when I saw that.
 

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If the graph was legible, and from a credible dynamometer source ( don't forget they are putting their best foot forward in an attempt to sell their product) then the Original Poster's concerns could be addressed. In order to "restore pep"for the OP's bike the torque and horsepower curves for the Dynajet would have to equal or exceed the output from the stock configuration at RPMs ~9% less than the stock bike. Anything less and bike will still accelerate slower than the unmodified stock geared with a stock carburetor bike. Basic physics.
Butt Dyno impressions may satisfy us but hard numbers tell the real truth.
 

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Myself and a few other members have used the kit and felt the difference in the bike. Proof is in the pudding. You can bench race all day, but actually driving a bike with this kit installed beats bench racing every time. To wholesale dismiss something with no experience with it makes sense in someones world I guess. I brought forth my life experience with the product. My mistake on this forum.
 

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Discussion Starter #19
I appreciate both points of view. I am honestly not trying to get the numbers back to where they were or necessarily even go beyond that point. I adjusted the gearing knowing full well the bike would loose low end. I am 100% happy with the way it’s operating but have wanted to do the carb and pipe anyway. If it increases the performance noticeably and preferably in a reference-able way that’s great. 2-3% increase of 9 is something and from what i have heard the carb stock tuning can be improved upon even with leaving exhaust stock.

Now two or three people have mentioned that this tuning and exhaust has shown improvement. MotoMax in a video even expressed that he was able to wheelie the bike in higher gears than before both adjustments. That’s pretty good 1st hand IMHO He also spoke about the better throttle response.

The reasons I am considering doing the exhaust and tuning are for some performance improvement but also as stated earlier frequent riding on back trails and overgrown jungle tracks the louder your pipe the easier an oncoming rider, truck, or person can hear you and prevent a dangerous collision.

It would be cool to see actual scientifc evidence i.e. dyno results after the changes as well as my own personal first hand experience.

Thanks to everyone who has posted in here your views and inputs are all appreciated, you all rock!

Still not sure what kit would be ideal, pretty nervous about drilling out a carb that runs around 300 to replace maybe someone can verify it is easy and worth doing. Otherwise I will probably simply go to 130 on the main and order a 128 as well to have room to adjust.

Results pending ;) awaiting rain to end after 4 days so I can get back to work haha!
 

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Discussion Starter #20
Did you find a PDF without a password, or did they give you the password after you ordered? The manual on their site is password protected. I regularly look at a products manual before deciding to buy or not, and was rather disappointed when I saw that.
I’m pretty sure it was just linked on the site it was a pretty terrible graph if I can find it I will post for the laughs
 
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