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Discussion Starter #1
I just picked up a complete TTR225 and after a little searching found someone mentioned extending the front sprocket shaft so it would line up with the chain and mount into a TW200 side cover, he didn't get a response so I had to ask, has anyone tried this? is there something else that would prevent installation? I'll be glad to take the covers off and document any findings I just wanted to know if there were any known issues.
 

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Check that the TTR case has the oil passage to the outer countershaft bearing in the TW cover. That is the problem. In Japan is is fairly common to put all the TTR/XT parts including the more robust clutch and 6-speed trans in a TW case set. The TW countershaft can be machined to accept the 6-speed trans.
 

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http://tw200forum.co...7/ShowPost.aspx



http://tw200forum.co...94-engine-swap/



http://tw200forum.co...5/ShowPost.aspx



Some tidbits from past threads







From Steves10

The various options for the countershaft were discussed at length on a thread on another forum (I can't seem to find it again), and included making a shaft extension with internal boached splines (considered the best idea, but VERY expensive), havind a whole new shaft made (also very expensive, and al kinds of heat-treat/hardening issues), and some other stuff, which I can't remember.



I really think the best approach is using the TW countershaft in an XT250, and providing oiling either internally, or through an external oil line/drain. But until someone has both bikes (or engines) side-by-side, all this is barely informed guessing.





From TWrider

The main problem I have with the swap route is that all the Yamaha motors that are the best candidates are rare birds. Power to weight , still keeping it streetable, electric start, air cooled, keeping frame geometry, are all factors, In my opinion the absolute best swap would be the TTR 250 engine. In the states, these are rare engines. Yamaha was insane not to offer a TW 250

or XT with that motor, they finally discontinued the TTR250 for the US because they weren't selling enough, go figure? What do they expect if they don't make a street legal version available? The TTR 250 is something like 28-30 HP stock, an instant 10 hp increase for only an extra 20 pounds weight penalty, It's physical dimensions and power are similar to the old XT 350 engine, but with electric start up under the carb. I'm pretty sure US buyers would plunk down an extra $1000- $1500 for a larger, more powerful TW.
 

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Discussion Starter #4
Good call on the outer bearing getting oil, maybe I could convert it to a greaseable bearing? Just for the heck of it searched sprocket extension on google and came up with extensions for Harleys but they seem to have 10 splines on the inside and what looks to be 1 inch outside diameter 6 spline, I was hoping to make this an outside the case mod if I were to go ahead with it. Has anyone come across some kind of tube that would slide onto the sprocket splines? or should I try to mount to the existing sprocket kinda like the double sprocket technique? with a dowel going to the outer bearing of course.

I found this thing:

http://oceanindustryhz.en.made-in-china.com/product/WbumgEfCOBcA/China-Sprocket-With-Spline-Shaft.html

but does anyone know of something like this available to buy? would be a good start.
 

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I just picked up a complete TTR225 and after a little searching found someone mentioned extending the front sprocket shaft so it would line up with the chain and mount into a TW200 side cover, he didn't get a response so I had to ask, has anyone tried this? is there something else that would prevent installation? I'll be glad to take the covers off and document any findings I just wanted to know if there were any known issues.


I am working on the 6 speed trans from the TTR into the TW. I think the TW sprocket shaft will fit into the TTR with the mod I am working on also. I do not know at this time if I will use the TTR cases or the TW cases.



Ronnydog
 

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[quote name='Rich' date='22 February 2011 - 01:03 PM' timestamp='1298397803' post='13183']

http://tw200forum.co...7/ShowPost.aspx



http://tw200forum.co...94-engine-swap/



http://tw200forum.co...5/ShowPost.aspx



Some tidbits from past threads











I really think the best approach is using the TW countershaft in an XT250, and providing oiling either internally, or through an external oil line/drain. But until someone has both bikes (or engines) side-by-side, all this is barely informed guessing.



-----------------



another option may be to use a sealed high speed bearing....for instance some machine tools use non pressure lubed bearings that can exceed 20000 rpm. They do cost more though.
 

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Discussion Starter #8
What about ordering a custom made made offset sprocket? I found this guy: http://cgi.ebay.com/ebaymotors/UNIQUE-OFFSET-FRONT-SPROCKET-YAMAHA-MADE-ORDER-_W0QQcmdZViewItemQQhashZitem35af962b72QQitemZ230579121010QQptZMotorcyclesQ5fPartsQ5fAccessories



So if I had an offset sprocket made and then fabricated something to make it to the outer bearing, I see some dragbike offset sprockets that have what they call a "snout" coming out the other side, I assume for an outer bearing.



I guess I would go with a 520 chain but any suggestions for how many teeth?



And finally can anyone tell me how the oil makes it out to the outer bearing? where is it pumped from? or does it just leak in and out?
 

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With a new axis manufactured.

No problems for 6 speed...

6 speed TTR or XT, in Motor TW...







Christddel, what you call a new "Axis", we call it the drive axle, drive shaft, driven shaft/axle, or output shaft.

Do you make a completely new "axis"?, or do you weld up, regrind, and modify a 5 speed TW125 "axis"?
 

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Christddel, what you call a new "Axis", we call it the drive axle, drive shaft, driven shaft/axle, or output shaft.

Do you make a completely new "axis"?, or do you weld up, regrind, and modify a 5 speed TW125 "axis"?


Yes, I'm making a new axis.

To the length of the TW 5 speed, and with the measures for the XT225 6 speed

It's simple ...But costs 700 Euro,
Just for the axis

I ordered 2 new axis, for my 2 other motors



 

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Yes, I'm making a new axis.

To the length of the TW 5 speed, and with the measures for the XT225 6 speed

It's simple ...But costs 700 Euro,
Just for the axis

I ordered 2 new axis, for my 2 other motors





yes, I looked into having a new shaft made....It was $700 US just for the tooling, and that was almost a decade ago. I ask because the Japanese are running modified 200/225 TW shafts, I believe they are ground, new clip grooves and lube holes machined, and maybe some welding. They claim it works fine. But your route is definitely the most correct and expen$$$ive route.



I wanted a pure shaft extension (or offset sprocket) as a viable option. mainly because (and this is especially attractive for North Americans) complete 225 engines are fairly cheap and plentiful due to the ttr225 being such a crap bike, but 1000's were sold. So, If you can get the offset without having to rip into the engine cases, then it it becomes very attractive solution indeed. The problem is, a high speed bearing without forced lubrication is probably needed.
 

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Skullhag, the oil passes thru the center of the shaft and it is pretty much the end of the line. After the outboard bearing, the oil is just dumped back into the case via that 'webbed' section. At this point (bearing) the oil is under VERY little pressure as it would not keep my warning light from going off when the engine warmed up, and my sensor was set at 2psi. GErry
 

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Skullhag, the oil passes thru the center of the shaft and it is pretty much the end of the line. After the outboard bearing, the oil is just dumped back into the case via that 'webbed' section. At this point (bearing) the oil is under VERY little pressure as it would not keep my warning light from going off when the engine warmed up, and my sensor was set at 2psi. GErry


Gerry , I think a lot of the confusion comes from the TW service manual, It seems the lube diagram they included shows the short shaft 125/200/225 diagram, and shows it does not pass through the center shaft to the outboard bearing. I believe this is just laziness on Yamaha's part, and you are correct.
 

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The reason for the outboard bearing on the TW is that the shaft would exert too much pressure on the cases and/or significant bendong of the countershaft without the outboard bearing. Using an extended shaft or offset sprocket without the bearing will result in cracked engine cases and/or a bent/broken countershaft, especially in engines modifies for more output. Yamaha would not have gone through the expense of adding the bearing if it wasn't necessary.
 

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The reason for the outboard bearing on the TW is that the shaft would exert too much pressure on the cases and/or significant bendong of the countershaft without the outboard bearing. Using an extended shaft or offset sprocket without the bearing will result in cracked engine cases and/or a bent/broken countershaft, especially in engines modifies for more output. Yamaha would not have gone through the expense of adding the bearing if it wasn't necessary.
I should have a TW 6 speed shaft to share next week. I cut a new grove and made a spacer. This I think is the cheapest way to do this.



Ronnydog
 

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I should have a TW 6 speed shaft to share next week. I cut a new grove and made a spacer. This I think is the cheapest way to do this.



Ronnydog




Are you reworking a TW shaft as the Tdubers from Japan have shown us? If so, save your CAD--you'll likely have many requests for the modification.
 

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I am modifying the stock TW shaft.
I've noticed the splines on the clutch side are different for the 5-speed and 6-speed shafts that I have seen. I haven't studied closely, but doesn't look like it will be an issue.



Which gears are you using, TT-R or XT? If memory serves, the XT has a slightly lower ratio in 1st and 2nd, but 3rd through 6th are the same for both models. The XT has a 3.091:1 1st and the TT-R has a 2.923:1 first.



Total spread on the XT is 3.091 to 0.793 (3.90), on the TT-R is 2.923 to 0.793 (3.69), on the TW is 2.833 to 0.821 (3.45).



rpm drop in %

........1......2......3......4......5......6

XT......54.6....40.....27....21.5....16.8

TT-R....54.7....32.2...27....21.5....16.8

TW......58.4....35.7...26.7..26.7



I don't complicate the numbers with different primary drive ratios because whatever the ratio with which you end up, the overall final drive ratio is easily adjusted with choice of countershaft and wheel sprocket ratio.



My biggest beef with the TW ratios is the 4-5 gap is too wide. The 5-6 gap of the 6-speed is much more livable, if not a little too close. I've also been a little uncomfortable with the TW's 1-2 and 3-4 gaps, the 1-2 gap because 1st is too low on the street and 2nd is too high, and the 3-4 is just too wide. I'm questioning if the 40% rpm drop on the 2-3 shift of the XT's gears might be a bit much.



Assigning 100 dots equivalent to 1:1 ratio (1st 30 dots removed), here's a graph comparing the maximum rpm shift points:

TW

.....

..........................

..............................................

..................................................................

...................................................................................

XT

..

....................

........................................

...........................................................

..............................................................................

................................................................................................

TT-R

....

.......................

........................................

...........................................................

..............................................................................

................................................................................................



Will you do one for me when the time comes? If so, how much?



Added:

Comparative total reduction ratios if sprockets chosen for same top ratio of engine rpm to rear wheel rpm:

.............1...........2..........3...........4...........5...........6

XT.......3.898.....2.522....1.802...1.418....1.168....1

TT-R....3.686....2.382.....1.802...1.418....1.168....1

TW......3.451....2.179.....1.605....1.267....1



It seems a lot of the dualsport riding I do finds 4th to low and 5th to high. Geared for the same top end, 5th with the 6 speed will be about right.
 

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After I finish I will post pics and you can see what I did. I will need to test it in my bike before I make any more shafts. If It works ......I can make more.



Ronnydog


Excellent! My access to my brother-in-law's machine shop is non-existent--he's running 24/7 right now.
 
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