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TYS 125/175 Modifications - Further Thoughts


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#1 archie

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Posted 19 December 2011 - 07:31 PM

OK ausy300pro, I took my lightened flywheel to the Post Office this afternoon to get it weighed. Result 1.53kg

I know Nigel Birkett says the standard flywheel weighs 2.1kg, but I seem to remember mine (it came off a TTR125, paid £20 off fleebay) was 1.9kg.

Anyway, all I am saying is don't go less than 1.53kg! I found that the hesitaion was more pronounced with the lightened flywheel (obvious really), but when I lightened mine, I hadn't got the carburation sorted to the extent that I have now. The reason I didn't want to sell mine was, now that my carburation is sorted I quite fancy having another go with it.

The throttle response and acceleration off the bottom was quite something with the lightened flywheel. You are not talking about a small difference. I was very surprised at just how much difference it made. How you get on depends on your riding style I guess.

I would be interested to know how you get on :)

Edited by Archie, 19 December 2011 - 07:55 PM.



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#2 ausy300pro

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Posted 19 December 2011 - 10:50 PM

Well, made initial enquiries tonight about a flywheel, only ones I can find so far though are from XT125R,s I think they are suitable but not 100% sure so not bought one, will look another day or two for TTR flywheel, would agree with your comment about it being a noticeable mod as I have taken about half of the weight from the flywheel on my Majesty and that picks up much quicker (have done other stuff to that as well though)

#3 craig10

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Posted 20 December 2011 - 03:18 AM

Well, made initial enquiries tonight about a flywheel, only ones I can find so far though are from XT125R,s I think they are suitable but not 100% sure so not bought one, will look another day or two for TTR flywheel, would agree with your comment about it being a noticeable mod as I have taken about half of the weight from the flywheel on my Majesty and that picks up much quicker (have done other stuff to that as well though)


It's the same engine as the Yam YBR125, not sure but the flywheel may well be the same. Might be worth checking the part nos. online.

#4 archie

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Posted 25 December 2011 - 01:24 PM

Whilst we are waiting for ausy300pro to find a flywheel, here's a pic to keep the thread alive. This is my 2007 TYS175, it's a full racing spec 163cc bike with the following mods:

Exhaust box - all baffles removed
Carb - Re-jet and set-up
Cylinder head - ports polished, valve seats blended in and step removed from inlet manifold to inlet port
Clutch - Actuating rod profile softened
Throttle - Slow/super fast throttle
Chain tensioner - Birkett H/D
Gearing - 11/57 (have tried 10/57 & 10/54)
Flywheel - Currently standard although have tried lightened flywheel

Posted Image

Happy Christmas one and all :madnoel:

Edit: Sorry, don't know how to make the link live, you'll have to copy and paste!

Edited by Archie, 27 December 2011 - 04:42 PM.


#5 ausy300pro

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Posted 25 December 2011 - 02:57 PM

That's a coincidence Archie ! in between my dinner and pudding (got to rest !) I have just bought and paid for a flywheel rotor from a 2008 XT125R cos I could not find a TTR one, hopefully it is right for job, will have to weigh them both when it arrives and then gonna go halfway to birketts recommendation and see how it goes, ps I bought a set of red stickers (and yellow ones) from birkett while they still have stocks so interesting to see yours with red stickers, looks good might put my red ones on when I get mods finsihed.

#6 archie

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Posted 27 December 2011 - 04:40 PM

ausy300pro

Glad to hear youv'e found a flywheel. I put my lightened flywheel back on again this afternoon as I was interested to see just how much effect having the carburation sorted has had on things.

I will run it up a few sections tomorrow, but I have had a quick spin on it, and I was very pleasantly suprised to find that I couldn't get it to hesitate at all. I had it in 3rd going uphill only a really light throttle, and then whacked the trottle fully open - NO hesitaion!

I had also fogotten just how quickly the engine accelerates with the lightened flywheel fitted. SOOOO much more responsive :) Can't wait to give it a propper go tommorow.

Just out of interest, before I re-fitted my lightened flywhell, I took this pic of my original (standard) flywheel next to my lightened flywheel (donor bike TTR125).

Posted Image

#7 rodt

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Posted 01 January 2012 - 07:13 PM

Posted Image

A more robust bash plate is worthwhile. On the downside it does get a bit muddy Posted Image

#8 ausy300pro

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Posted 02 January 2012 - 01:20 PM

Mine has a modified bash plate, only on clutch side though ?? I got the flywheel from an xt125r, checked it for weight, bang on at 1.6 kg so no need to skim any off, fitted it to bike and only then did I find that it is about 5mm bigger in od and was catching on casing, never noticed when on the bench, so don't get a flywheel from an xt125r, have now removed it and am waiting to get some turned off my original flywheel unless a ttr125 flywheel comes up on fleabay today or tomorrow.

#9 archie

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Posted 25 January 2012 - 07:54 PM

RodT, Nice bash plate, did you make it yourself, and what did you use to paint your exhaust? Has it stayed on!?

ausie300pro, have you tried out your lightened flywheel yet? What do you think?

#10 rodt

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Posted 25 January 2012 - 11:17 PM

RodT, Nice bash plate, did you make it yourself, and what did you use to paint your exhaust? Has it stayed on!?

ausie300pro, have you tried out your lightened flywheel yet? What do you think?


Hello Archie. Thank you for the comments.It is the standard bash plate with extension pieces added on. I bought a sheet of 5 mm thick 6082-T6 alloy plate from Ebay. The Exhaust is painted with Plastikote BBQ paint(also available from Ebay).It stays on very well. I recommend it. Your bike looks very nice :)

Edited by RodT, 25 January 2012 - 11:32 PM.



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#11 archie

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Posted 26 January 2012 - 12:24 PM

Nice job on the bash plate RodT. It looks so good I thought it was some new (expensive) after market custom part!

Cheers for the tip on the Plastikote btw. BBQ paint lol, that makes sense, I'll give it a go :)

#12 rodt

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Posted 03 February 2012 - 05:54 PM

Nice job on the bash plate RodT. It looks so good I thought it was some new (expensive) after market custom part!

Cheers for the tip on the Plastikote btw. BBQ paint lol, that makes sense, I'll give it a go :)

.
Can't take much credit for the bash plate, Archie as I robbed the idea from the works bike :)
http://www.trialscen...-1077206344.jpg and also.....http://www.trialscentral.com/forums/uploads/post-10-1082578931.jpg and ........http://www.trialscentral.com/forums/uploads/post-10-1082579322.jpg

#13 ausy300pro

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Posted 04 February 2012 - 05:13 PM

Well eventually got bike back together and had a ride (only ten mins though nd not very good land so not the best test), my flywheel is now 1.8kg so not as light as Archies or the birkett mod, I also upped the pilot jet size to 20, did this because having given carb a complete strip and ultrasonic cleaning I sussed out that the accelerator pump draws fuel through the pilot jet so can see it being starved of fuel, bike now responds better off of bottom and the cough stall has completely gone, however it is very slightly rich right at bottom I am hoping next weekend to get out and have enough time to play with air screw and needle position to fine tune it, fingers crossed, bike is getting better every time out, great little bike.
has anyone sourced a new piston for the 163 engine, am thinking of the future when it could be the part of the engine that we cannot get, birks reckons they originally came from supplier in France but not available at moment (wish Scorp would go the big bore route with the new ty125), would like a new piston for stock or even a suitable piston two or three mm oversize, don't want to go to 200 kit as Christian rayer never replies to my queries and birks told me that the 200 kit does not rev out as good as the 163.

#14 guido

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Posted 21 May 2014 - 05:54 AM

Well eventually got bike back together and had a ride (only ten mins though nd not very good land so not the best test), my flywheel is now 1.8kg so not as light as Archies or the birkett mod, I also upped the pilot jet size to 20, did this because having given carb a complete strip and ultrasonic cleaning I sussed out that the accelerator pump draws fuel through the pilot jet so can see it being starved of fuel, bike now responds better off of bottom and the cough stall has completely gone, however it is very slightly rich right at bottom I am hoping next weekend to get out and have enough time to play with air screw and needle position to fine tune it, fingers crossed, bike is getting better every time out, great little bike.
 

I googled "TYS 125 skid plate" and ended up on this old thread. Very nice skid plate but what really caught my eye is this statement about an accelerator pump. What carburetor have you found that has an accelerator pump in a size small enough for this engine? I have that little throttle lag on my 125 and have been looking around for a carb with an accelerator pump that's small enough but no luck. 



#15 craig10

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Posted 04 August 2014 - 07:32 PM

Hi Guido, he is probably talking about the small chamber with the spring loaded diaphragm on the side of the carb, it acts as a basic sort of pump linked to the air pressure in the carb




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