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Discussion Starter · #1 ·
I am going to start thread of my 225 build. But it will Go quiet for a while - I can't imagine myself getting to it sooner that next winter.
Keep in mind I'm building this out of my TW125 en EU.
Hehe, in the end I should have 225ccm bike, which weighs with me on it 225 kgs :D maybe some Day even 22.5 hp?
Most of the parts arrived. I will go with xts long range trans, xt225(01-07) crank and timing chain and valve gear - I want the supposedly stronger "silent chain". I ordered new but cheap replacement cylinder head from ebay for yfm250 complete with valves, cam and everything except covers. It's not yamaha genuine, but it has ball Bearings on both ends of cam - 6005 and 6202.
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One upgrade I want to make. To. The head is put rocker arm springs in place - just as the xt225 has. Some Guy on FB pointed that out. It should be quieter with those springs - #10 in pic.
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Actually two upgrades - I want to do some slight porting .

Next thing we'll see what about timing chain sliders/guides, since they're different for the DID SCR-0404 SV 104LE timing chain.

Piston and cylinder I purchased very cheaply from china - set for ttr225(70mm bore) . First I wanted to. Go with yfm250 set (71mm bore),but then I found out the yfm has lower compression ratio - 8.7:1 as opposed to tw and xt - 9.5:1

As for carb I want to try XTNG carburetor - truly a lectron clone for arounf half the price.
Maybe I'll try it first with tw125 oe 24mm carb, but I don't expect it to work very well, atleast not in the upper rpms.
And last a question. I think I have read the OE 34mm carb from xt/ttr doesn't fit. Does anyone know why? Frame clearance?
 
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what's the green day song?

wake me up, when september ends... best of luck with your build :)
 

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Hopefully that will work out. It looks like you are doing your research. Hopefully this will work out. I would like to see a performace mod or build with success. There have been many come on the site with great dreams of a souped up T-dub and then vanish into the mist. So far I think that Elime has the most successful build.
 

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Discussion Starter · #4 ·
Hopefully that will work out. It looks like you are doing your research. Hopefully this will work out. I would like to see a performace mod or build with success. There have been many come on the site with great dreams of a souped up T-dub and then vanish into the mist. So far I think that Elime has the most successful build.
I have been browsing all the tw forums I know - this, french, german and russian for like 3 years now? In the evenings when my toddler is asleep.. I keep noting pretty much everything interesting I see, I've managed to add up quite a LOT of info :D TW is my only bike, and don't ever plan to sell it, so as long my mind is alive, I want to keep posting.
 

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Discussion Starter · #6 ·
"And last a question. I think I have read the OE 34mm carb from xt/ttr doesn't fit. Does anyone know why? Frame clearance?"

Yes, frame clearance and no easy carb to airbox boot solution.
Ah yeah, the size of the boot.. makes sense. Thanks
 

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I will go with xts long range trans, xt225(01-07) crank and timing chain and valve gear - I want the supposedly stronger "silent chain". I ordered new but cheap replacement cylinder head from ebay for yfm250 complete with valves, cam and everything except covers. It's not yamaha genuine, but it has ball Bearings on both ends of cam - 6005 and 6202.

One upgrade I want to make. To. The head is put rocker arm springs in place - just as the xt225 has. Some Guy on FB pointed that out. It should be quieter with those springs - #10 in pic.

Next thing we'll see what about timing chain sliders/guides, since they're different for the DID SCR-0404 SV 104LE timing chain.

Piston and cylinder I purchased very cheaply from china - set for ttr225(70mm bore) .

As for carb I want to try XTNG carburetor - truly a lectron clone for arounf half the price.
I have questions about things you mention in your post;
1. You mention an xts transmission/xt225 (01-07) as 'long range'. Are you meaning a wide gear ratio? I am not aware that the XT225 or TTR225 transmissions of any year have different ratios. I do know the later version the TTR230 has a narrower ratio. Can you elaborate?
2. What is the supposedly stronger 'silent' timing chain?
3. Are you saying the YFM250 head will fit the XT or TTR225 motor directly, no mods? Also, that it will even fit in the TW200 frame if it does mate to the cylinder right with the right compression and all that?
4. The rocker arm springs will fit in without any further mods? It looks like it was an upgrade for 2001 and beyond. At least the parts diagram for a 1999 TTR225 valve assembly part numbers all match a 2001 XT225 other than that spring.
5. You mention the timing chain slider/guides for the different chain. I presume that is the part number for the 'silient' chain you have posted? DID SCR-0404 SV 104LE
6. I've seen those cylinder/piston sets on eBay for around $70 or so US. Is that what you are referring to as the cheap china sets?
7. What is the XTNG carb?
And finally, can you provide links to all the parts you have mentioned and in future posts also provide the links or sources you are using for your parts. It helps to review that info to see what you are using and where you are sourcing them.

Great thread, looking forward to following you.
Cheers!
 

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Discussion Starter · #8 · (Edited)
I have questions about things you mention in your post;
1. You mention an xts transmission/xt225 (01-07) as 'long range'. Are you meaning a wide gear ratio? I am not aware that the XT225 or TTR225 transmissions of any year have different ratios. I do know the later version the TTR230 has a narrower ratio. Can you elaborate?
2. What is the supposedly stronger 'silent' timing chain?
3. Are you saying the YFM250 head will fit the XT or TTR225 motor directly, no mods? Also, that it will even fit in the TW200 frame if it does mate to the cylinder right with the right compression and all that?
4. The rocker arm springs will fit in without any further mods? It looks like it was an upgrade for 2001 and beyond. At least the parts diagram for a 1999 TTR225 valve assembly part numbers all match a 2001 XT225 other than that spring.
5. You mention the timing chain slider/guides for the different chain. I presume that is the part number for the 'silient' chain you have posted? DID SCR-0404 SV 104LE
6. I've seen those cylinder/piston sets on eBay for around $70 or so US. Is that what you are referring to as the cheap china sets?
7. What is the XTNG carb?
And finally, can you provide links to all the parts you have mentioned and in future posts also provide the links or sources you are using for your parts. It helps to review that info to see what you are using and where you are sourcing them.

Great thread, looking forward to following you.
Cheers!
pretty much everything I know is on the internet, you just have to search. most of the info is from sebastian's thread : List with parts you will need to upgrade your TW to 214...
1. - WIDE RATIO - that is the word combination I´ve been looking for! :D and no the (01-07) wasn't meant for the trans, hence why it's written by the crank. thanks for clarification of the trans - It didn't occur to me that TTR225 would have wide ration too. TBH I nearly forgot the TTR225.. I had in mind XT225 as wide ratio and TTR230 as close ratio.
2. DID SCR-0404 SV 104LE is the name and type of the chain
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not exactly the one in pic, but this type. XT225 01-07 had this chain and nikasil plated cylinder instead of steel insert( these cylindershave OD of 78,5mm unlike the steel ones - 76mm. the same goes for crankcase opening for the cylinder.) I bought XT225 04 crank exclusively for this. and consequently the cam gear, which is easily bought here in czech rep. sebastian mentioned the weakness of our engines is the timing chain, it stretches easily once you add spring rate on valves.

3. yes. sebastian lightly mensions it in the thread I posted above. I think he mentioned the same heads more in other thread. YFM/YFB 250 are just 230ccm, just marketing I guess. only differences between yfm and xt/ttr are compression and bore. I'd say the compressin difference is due to different pistons. anything from top end fits right away. I faintly remember 4wheelers had different timing of the cam lobes, but I am not sure about that - service manual say the same lift of cam for yfm and xt ( even for TW125!). 4wheel cams are said to be more low end, and xt/ttr more top end. but that I am really not sure about.
Cylinder Head & Valve Assembly Fits Yamaha Bear Tracker 250 YFM250 1999-2004 | eBay this is the one I bought

4. yes I think it won't require any modification, just disassemble and reassemble. we'll see.

5. you can see in the pic above the chain has completely flat backside that's not the case for the DID 25 SH/104 chain TW and all 225,230 and "250" use.
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^ these guides are for the basic chain, look at the profile. ( now I am noticing for the first time, the profile is only on one of them)
for the silent chain the guides have "U" profile, see below. couldn't find better pic.
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I will compare and post the differences between those two types once my friend( who is also upgrading from 125 to 225) receives them. shouldnt take long, the package is in import process already in our country.


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YOU KIDDING ME EBAY?!AFTER I BOUGHT EVERYTHING I NEEDED? sad
6. yes, not exactly 70usd for me, because of shipping and VAT and CLO, this one was cheaper for me. CYLINDER PISTON RINGS TOP END KIT SET Fits Yamaha TTR225 TTR230 XT225 92-16 S8 | eBay

7. oh wow, they have website - didn't know that, I found them randomly on internet, and at that time they were only on FB. XTNG MOTO SPORTS
I know almost nothing other than that it is similar to lectron and smartcarb and that it is cheaper.
this guy is pretty much the only one (for now) who is not sponsored by xtng
 

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Discussion Starter · #9 · (Edited)
I found out XTNG has 36 and 38mm carbs only. I emailed them asking if they plan on making smaller ones.
and one sad news. my cylinder head arrived slightly damaged, mostly aesthetics, but still...
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packaging is highly inadequate,but for travelling half the globe not bad.I guess I got what I paid for? :D

EDIT: I got what I didn't pay for ! the seller gave me full refund, what a generous man. So for 70 USD (shipping and other charges) I got complete head. Can't say that is a bad deal..
 

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As for 70mm piston get a Wiseco 4312M07000. With the longer stroke 225 crankshaft it yields 10.25:1 compression. With the shorter stroke TW200 crankshaft its 9.9:1 They are more expensive and they are forged and worth it.

Are you going to convert a TW 125 engine into a 225 engine using Bear 250 parts? Research your parts compatibility really well. I seem to recall the Bear was different than all the other small Yamaha engines.
 

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Discussion Starter · #11 ·
As for 70mm piston get a Wiseco 4312M07000. With the longer stroke 225 crankshaft it yields 10.25:1 compression. With the shorter stroke TW200 crankshaft its 9.9:1 They are more expensive and they are forged and worth it.

Are you going to convert a TW 125 engine into a 225 engine using Bear 250 parts? Research your parts compatibility really well. I seem to recall the Bear was different than all the other small Yamaha engines.
well now that I'll get back 130 USD I may consider the wiseco.. initially I didn't want to spend that much altogether. I think I will cheap out and use the piston provided in the piston and cylinder set, and after that one is shot, I'll get wiseco.
only the cylinder head is from a 4wheeler, the rest is XT225.
 
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As for 70mm piston get a Wiseco 4312M07000. With the longer stroke 225 crankshaft it yields 10.25:1 compression. With the shorter stroke TW200 crankshaft its 9.9:1 They are more expensive and they are forged and worth it.

Are you going to convert a TW 125 engine into a 225 engine using Bear 250 parts? Research your parts compatibility really well. I seem to recall the Bear was different than all the other small Yamaha engines.
I have no experience mixing/matching 4-stroke pistons to cylinder, but with 2-stroke I have. I always had to mic out the barrel and spec an A, B, or C piston for correct fitment. With 4 strokes is there any such discretion in selection/match?
 

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I have no experience mixing/matching 4-stroke pistons to cylinder, but with 2-stroke I have. I always had to mic out the barrel and spec an A, B, or C piston for correct fitment. With 4 strokes is there any such discretion in selection/match?
I just took Sebastian recommendation and used said piston. The wrist pin and the deck height were the correct size and I honed the bore until the diameter was correct and the rest is history.

So far I think that Elime has the most successful build.
There are many with much better builds than mine. TWBrian and JoeBand are two examples that have left me in the dust figuratively but not yet literally as we have yet to race!
 

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I just took Sebastian recommendation and used said piston. The wrist pin and the deck height were the correct size and I honed the bore until the diameter was correct and the rest is history.


There are many with much better builds than mine. TWBrian and JoeBand are two examples that have left me in the dust figuratively but not yet literally as we have yet to race!
We need that, a big TW race and some skills competitions. That would be some fun.
 

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Discussion Starter · #16 ·
XTNG replied and said they make 34mm carbs too. Anyone has measurements of mikuni BST34 carb? The one from xt/ttr225/230?
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Discussion Starter · #17 ·
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Possible bigger boot? Bolt holes are off by 4mm, I'm thinking some hand filing could get the holes where we want them. Then it would be question ifhe angle was correct, so carb woild point where it should point
 

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XTNG replied and said they make 34mm carbs too. Anyone has measurements of mikuni BST34 carb? The one from xt/ttr225/230?
Did you measure the diameter of the intake port on the head? It doesn't do any good and probably will do harm if the carb is bigger than the intake port. IIRC, the intake port on the TW head is about 30mm.

When it comes to carburetors it is better to error on the side of small. On the head measured below it was 29mm.
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Since no one answered ski on the gear ratios. Ttr 225 and xt225 are the same ratio (widest) the ttr230 has the narrower but still wider than TW.
The only way to get the true wider ratio in the dub is to use Placerlodes shaft extension because 1st gear is part of the counter shaft.
 
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Since no one answered ski on the gear ratios. Ttr 225 and xt225 are the same ratio (widest) the ttr230 has the narrower but still wider than TW.
The only way to get the true wider ratio in the dub is to use Placerlodes shaft extension because 1st gear is part of the counter shaft.
Thanks!
I did do the research but didn't report back the same findings you reported here. Now the rest of the story is documented and known by all.
 
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