Hey Everyone! Vote for the Site Favourite BOTM winner for the year of 2022 HERE!

Assembling a modified TW125 engine

7429 Views 14 Replies 7 Participants Last post by TWrider, Jan 29, 2011

btdc

Discussion Starter · Jan 24, 2011

Dear forum,

Assembling the engine finally once againg. Had to dissamble it when the TW200 crank connecting rod bearing went bad. Got off ebay a used XT225 crank and a balancer to go with it. Had the crank rebuilt and now assembling it back together. The case is originally a TW125 and to fit the balancer i had to replace the left bearing with another one with same outer diameter but bigger inner diameter. The crank fits without modification. Cylinder opening have been machined up to allow 225 sized cylinders previously.

Kick assembly and 6 disc clutch is off a TT225 1986.

Waiting for a new clutch lock washer before i can proceed...

See less See more

2

1 - 15 of 15 Posts

christddel

· #2 · Jan 24, 2011

Hello,

Nice work ..!

Warning, if you put the clutch 225 (6 Discs)

The mechanism is much larger

He must then place the clutch case of the 225

If you do not change the clutch is destroyed

See less See more

2

btdc

Discussion Starter · #3 · Jan 24, 2011

christddel said:
Hello,

Nice work ..!

Warning, if you put the clutch 225 (6 Discs)

The mechanism is much larger

He must then place the clutch case of the 225

If you do not change the clutch is destroyed

I got an almost complete TT225 engine of ebay so I also have the clutch cover. Have already used the clutch and works good.

Does anyone know what the idea is with part 18 and 19 in the picture below. It's the part diagram for TT225 1986. I use 6 normal clutch disks and it works just fine.

See less See more

Mame Shiba

· #4 · Jan 25, 2011

Hi

I think that as long as these parts are mounted on your genuine Yamaha clutch it would be safer to put the same when you replace it.

It's obvious that an engine can work without some minor parts but it generally doesn't last, therefore don't take the risk

Cheers

See less See more

sinophilia

· #5 · Jan 25, 2011

Interesting work! I'm sorry I don't know much about engine stuff, but I like to read about it and learn. Thank you!

christddel

· #6 · Jan 25, 2011

Hello,

These parts serve just to space the clutch disks.

There is no problem you can put 6 normal clutch discs, it works perfectly.

I made this montage with 6 normal clutch discs on 3 or 4 engine, and its works perfectly

See less See more

rtbuckingham

· #7 · Jan 25, 2011

I'm with Sinophilia on this one. It is very interesting seeing how all this stuff works, but I am not quite ready to start pulling my engine apart!! Great pics.

Mame Shiba

· #8 · Jan 25, 2011

Basically it's more a spring that allows all the discs to be in contact smoothly than a spacer, better go to your usual Yamaha dealer and put the same part

cheers

See less See more

christddel

· #9 · Jan 25, 2011

More pictures

A view of The Whole ...

There is no risk, it works very well with 6 normal clutch disks

See less See more

2

TWrider

· #10 · Jan 27, 2011

btdc said:
Dear forum,

Assembling the engine finally once againg. Had to dissamble it when the TW200 crank connecting rod bearing went bad. Got off ebay a used XT225 crank and a balancer to go with it. Had the crank rebuilt and now assembling it back together. The case is originally a TW125 and to fit the balancer i had to replace the left bearing with another one with same outer diameter but bigger inner diameter. The crank fits without modification. Cylinder opening have been machined up to allow 225 sized cylinders previously.

Windage house prevents oil splash from being directly sucked out vent on 125/200cc

Waiting for a new clutch lock washer before i can proceed...

Please keep crankcase ventilation issues in mind when converting to a 6 disk clutch on either 125cc, or 200cc cases. Study your factory manual so you are fully intimate with how the ventilation gasses differ in routing, you could end up with an engine that under pressurizes and runs poorly....If in doubt about the case modifications that need to be performed in order to make a 6 disk clutch work properly on 125 or 200 cases, then run the 200cc balancer, and the 5 disk clutch and cover...there is not enough payoff in the six disk clutch if you are not prepared to do it properly...The best way by far, to run the 6 disk clutch, is to use factory 225cc cases with the TW125/200cc transmission and shift segment installed.

christddel

· #11 · Jan 27, 2011

Yes, the ventilation is different on the 125 and 225 TT TW (XT).

But this did not influence the pressure in the crankcase.

The ventilation of the 125 is sufficient

I placed the clutch housing 225 on the 125 engine, no problem!

See less See more

TWrider

· #12 · Jan 28, 2011

christddel said:
Yes, the ventilation is different on the 125 and 225 TT TW (XT).

But this did not influence the pressure in the crankcase.

The ventilation of the 125 is sufficient

I placed the clutch housing 225 on the 125 engine, no problem!

http://img257.images...erembrtwttr.jpg

Not on mine, mine's closed

I know it will run, but they made an alternate design, to deal with the oil splash when using that 6 disk cover

Early 225cc cases (1983 and 1984 trikes and quads) did NOT have a 225 vent house, they vented the same as the 125/200cc mc cases....they also used the Yamaha15A XT200cc engine balancer instead of the later 1KH 225 balancer.

See less See more

3

christddel

· #13 · Jan 29, 2011

TWrider said:
Not on mine, mine's closed

I know it will run, but they made an alternate design, to deal with the oil splash when using that 6 disk cover

Early 225cc cases (1983 and 1984 trikes and quads) did NOT have a 225 vent house, they vented the same as the 125/200cc mc cases....they also used the Yamaha15A XT200cc engine balancer instead of the later 1KH 225 balancer.

OK, thanks for such technical data

On my engines crankcases of TW125 only, there was this little hole ...

See less See more

qwerty

· #14 · Jan 29, 2011

christddel said:
OK, thanks for such technical data

On my engines crankcases of TW125 only, there was this little hole ...

When I clicked on your thumbnail for a better look my anti-malware defenses went beserk.

TWrider

· #15 · Jan 29, 2011

christddel said:
OK, thanks for such technical data

On my engines crankcases of TW125 only, there was this little hole ...

yes that's a later model, you can tell the Yamaha engineers had ventilation on their mind, they designed 3 different covers in the first 3 years of production, 2JX=1987, 2YG =1988, 3AW= 1989-2000, 5FY = 2001-2002, 5EK=2003-2011.

So that's 5 different covers, not including the 15A cover which was used on early xt125 and xt200, which will also work.

After 30 years of taking apart motors, I always take a close look at Ventilation, and Lubrication paths because so many problems can take place by not paying close to something that is easily overlooked by many hobby mechanics. IMO it's just as important to understand how things work and why the engineers did this or that, as it is to know what goes where and what position was it in before it was removed, and why did it wear out?

1 - 15 of 15 Posts

This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.