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Discussion Starter #1
I have been thinking about this for months now. There are kits for the blaster 200 but no mention of a TW kit. Is it possible that the blaster kit may work for our bikes? This may be a dumb question but it is one I feel the need to ask.
 

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The Blaster is a 2-stroke. Different critter altogether..



Kits for the TW probably wouldn't sell very well because the case mouths won't accept much of an overbore. Oversized pistons exist and any reputable shop can bore your cylinder, it just won't yield much bang for the buck. Standard bore is only 67mm yielding 196cc. A 1mm overbore only yields 202cc and a 2mm overbore is 208. Lots of munny and effort for a 10% gain.



Opening the case mouths takes things out of the realm of the simple "bolt-on" big bore as it requires splitting and machining cases, but it allows you to move up to the 225 cylinders which have a 70mm standard bore.



A 70mm bore with the TW's 55.7mm stroke yields 214cc. 227cc if the 225 cylinder is overbored to 72mm.



Add the 225's longer stroke 58mm crank and you get 223cc with the 70mm bore and 236cc with a 72mm overbore.



Those are about the max displacements using pistons which are readily available.
 

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Discussion Starter #3
Hmmm... sounds like I need to make nice with someone that owns a machine shop.
 

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There is also a 73mm (233,1ccm with 55,7mm stroke/242,8ccm with 58mm stroke) piston from Wössner available



It's also possible to upgrade to 250ccm -> 74mm piston (is a std. piston, available from Yamaha, Wiseco and JE Piston).

But you will need for this a 225 crankshaft, a new con rod and a special new big pin bearing.



Yery important:

You have to upgrade your clutch, if you're going over 225ccm.

I have 229,6ccm and the Dyno result is 22hp (Akrapovic Racing exhaust and Webcam stage 3 camshaft).

I am using friction plates from EBC and the stiffer springs from EBC (CSK052), but this isn't enough. The clutch is slipping in higher RPM.

So, I recommend friction plates from Barnett and some other stiffer springs from EBC (CSK002). This should handle the power.





Sebastian

TW-Parts.com
 

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Discussion Starter #5
If i'm not mistaken, while looking at tw-parts.com it states that you can use a 69-73mm piston with the oem head, different liner and modify the airbox to reach higher cc's?



Would there be any noticeable difference from the oem piston to a same size high compression piston?
 

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Check with Sebastian. I believe the bigger liner still requires opening up the case mouth.



The 73mm piston is low compression. I'm not sure how performance will stack up against the smaller bore and higher compression offerings.
 

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Discussion Starter #7
Has anyone installed a high compression piston that can attest to the difference between the stock piston?
 

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Discussion Starter #10
I have considered an engine swap but mine still has over 3 years left on the warranty. Just looking for a little more bottom end grunt for riding trails. If I need more speed I will get a different bike. The TWs top speed keeps me out of trouble and off the highway.
 

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I have no dog in this fight cuz I'm building a much bigger motor, but we haven't heard much feedback on the Webcam 40a cam on an otherwise stock TW. At least one XT225 guy has said the gains were similar from either the cam OR a 2mm overbore on those motors.



Ultimately the two mods are fairly similar in cost, but the cam requires no downtime and is less work. Might be an option worth looking into if you're looking for a small boost.
 

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I have considered an engine swap but mine still has over 3 years left on the warranty. Just looking for a little more bottom end grunt for riding trails.
I thought the TW was popular for its lower end grunt for trail riding? I am not trying to contradict you. I was just surprised to see this statement. That was one of the reasons I was looking for a TW; to have fun off-road on trails at lower than MX speeds.
 

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Discussion Starter #13
Don't get me wrong, I am looking for better throttle response similar to that of a mx bike. I like to ride trails at around 20mph. I would like to be able to lift the front end up to get a little air when going over bumps. And I do mean a little. I know the limitations of our suspensions.
 

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Discussion Starter #14
I have no dog in this fight cuz I'm building a much bigger motor, but we haven't heard much feedback on the Webcam 40a cam on an otherwise stock TW. At least one XT225 guy has said the gains were similar from either the cam OR a 2mm overbore on those motors.



Ultimately the two mods are fairly similar in cost, but the cam requires no downtime and is less work. Might be an option worth looking into if you're looking for a small boost.


I was watching your webcam thread and was turned away when some thing came up about sending in your cam before ordering. I believe that was the issue, it has been a while. I did find it strange that nobody commented about it after install. I assume that a few people ended up ordering them.
 

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I suppose now that I've cooled off the story can be told. lol.



The problem with the group buy was that I arranged it, announced it and laid the deal out to you guys, then they kept changing the rules with each successive phone call. When it all shook out, they finally admitted that they only had one core in stock at any given time and they demanded that I provide them with enough of my own cores to get the ball rolling, be financially responsible for the condition of all your cores, handle all the munny, shipping, etc. etc. Worst outfit I've ever tried to deal with in that respect. I like you guys but I wasn't gunna tear several perfectly good motors apart because they didn't want to invest in the cores.



Frankly, I told them to kiss my posterior and the group buy went byebye.



That said, they're the only game in town other than Engines Only who offer an of-the-rack cam, and for all I know EO buys theirs from Webcam, as well. Most do. I may have an axe to grind with them, but I can't say that I've ever heard that the product itself wasn't a good one. Under normal circumstances you'd just pay the core charge up front and it would be refunded once they receive your regrindable core. Ergo, no down time.
 

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I went ahead and paid the core charge and got my 40A pretty quick. I just need to send back my cam for a refund. It's a PITA; but it's all we got. I'm waiting on carb parts before I can give an assessment of the cam upgrade. An oil cooler and extended swingarm are next; but I'll give a report before I do those two mods. Besides; I can't find an extended arm yet.
 

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I ended up with two spare stock cams (found one on ebay for $40 and one came with the head I bought when my valves got bent).



Sent both to webcam for the 40a grind and have installed one so far (the other is for a friend).



So here's the deal on the 40a: there is no change to the top-end. My top speed has not changed at all. Also, there is no change to the bottom end - no sudden wheelie monster!



Where I have noticed the change: Mid-range power. There is now more pull through 4000 (ish) RPM. Also, strangely I get better mileage now?!? Before, I got 200kms per tank (12 litres), now I get 230kms per tank! Weird.



So on power alone, It's hard to justify. But add the 15% better mileage? Hell ya!
 

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There is also a 73mm (233,1ccm with 55,7mm stroke/242,8ccm with 58mm stroke) piston from Wössner available



It's also possible to upgrade to 250ccm -> 74mm piston (is a std. piston, available from Yamaha, Wiseco and JE Piston).

But you will need for this a 225 crankshaft, a new con rod and a special new big pin bearing.



Yery important:

You have to upgrade your clutch, if you're going over 225ccm.

I have 229,6ccm and the Dyno result is 22hp (Akrapovic Racing exhaust and Webcam stage 3 camshaft).

I am using friction plates from EBC and the stiffer springs from EBC (CSK052), but this isn't enough. The clutch is slipping in higher RPM.

So, I recommend friction plates from Barnett and some other stiffer springs from EBC (CSK002). This should handle the power.





Sebastian

TW-Parts.com
Hi! Which cam did you go for on the webcam website? I've been looking at the Tw 200 options and they don't seem to have the stage 3 option? I was also curious as to what carb/jetting you are running? Thanks!
 
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