TY 250 Improvements

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Stanm
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Re: TY 250 Improvements

Postby Stanm » Fri Jun 27, 2008 8:51 pm

Hi again
I have been riding the TY250E in this years comp and the bike feels great. Handling is also much better however I cannot spot any difference in the frame. Is there any difference? The motor is far superior than the A. And I thought my A motor would be stuffed.
I have pulled the barrel off the A and considering I have ridden it for 5 years the bore and the piston look pretty good. I checked the bore and piston and they seem ok.( Measured them however ring gap was way out) Any hints on best way to check if rings only are required? Funny T shaped top ring in the A and what is the concept?

Your comments would be atppreciated
\Regards

Stan



David Lahey
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Re: TY 250 Improvements

Postby David Lahey » Fri Jun 27, 2008 9:23 pm

If you are thinking of buying new rings for the A model piston, have a try getting some before you worry too much about how to proceed. I would be very surprised if you can get new Yamaha rings for your piston.
Most people just buy the next size up aftermarket piston kit and rebore the cylinder. For the cost of the piston kit vs the cost of a piston kit and a rebore, it doesn't make much sense to fit a new same-size piston.
If it has an L top ring, that was a popular idea a while ago for helping the combustion chamber pressure to push the rings against the bore. I have never pulled my A model apart to see what it has but I've worked on plenty of Bultacos with Mahle pistons that used that idea.
The frame geometry of the A and later model TY250s are the same. The fork springs are slightly different on the C model and later models and the A model lacks the fork brace under the mudguard seen on B and later models. I can't think of anything else that would differentiate the handling between the A and E models.
I know what you mean though because my A model feels quite different to my B and D models to ride and I have always attributed the difference to the very different way the A model motor responds.


relax, nothing is under control

AussieE
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Re: TY 250 Improvements

Postby AussieE » Thu Jul 10, 2008 1:58 pm

G'Day Guys
I'm a newbie here and I have just bought myself a TY250B after a bit of serching for a decent one, The one I have is pritty much complete with speedo, lights ect.The switch for the lights has the knob broken off and some one has had the switch apart and lost the detent out if it, I have moved the slider along in the switch and the lights do work,so does the brake light.I do intend to get it regoed eventually as I will be useing it at my sons Minicyle club where they do motorcross, Trials, Minikhana,and Enduro's,I'am the club trials captain this year and this is what the bike will mainly be used for, setting up the kids trials zones ect as My CRF450 is not realy the right bike for this job.
So the first question I have is the the rear shocks have some rust on the springs and don't seem to perform at all under my hefty weight I have found a set of Betor rearshocks on the UK TY trails site and was wondering if anyone knows anything of the Betor shocks in the 50lb spring and 13.4" lenght.Are they any good or a waist of money?
My intention is to keep the bike as original as possible so I may get the original shocks restored at a later date and kept for when shes just kept for show.
Thanks for any info guys.
AussieE



David Lahey
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Re: TY 250 Improvements

Postby David Lahey » Thu Jul 10, 2008 7:13 pm

E
There are a couple of types of Betors shocks for sale for the TY250.
The modern design Betors would be fine for your TY250 and if you are less than about 100kg, 50 lb/in springs will also be fine.
There are also lower price Betors that look like what came on 1970s Bultacos and work about as well as they did in the 1970s (not very well in comparison)
There are also shockies available that would be better if you were going to ride sections but at a higher cost.

Before you get your original TY shockies rebuilt, find out how much new Yamaha Ty250 shockies cost as that may be a cheaper option.

Here is a link to a picture of the Betor shockies I think you are talking about

http://cgi.ebay.com.au/NEW-YAMAHA-TY125 ... m153.l1262

Regards
David


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AussieE
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Re: TY 250 Improvements

Postby AussieE » Fri Jul 11, 2008 10:27 pm

Thanks David
I did try the local Yamaha dealer about new shocks but they just said they were no longer available thats why I went looking else where.OK,Yes those are the shock I was looking at and boy do I wish I only weighed 100kg, so I guess I'am looking for something a bit better then these ones then.It was just these where the only ones I came across and I didn't even see them on E-bay guess I need to do a little more research I generally get Ian Whiteman at Pro Moto Suspenion (Singleton) to do all my suspenion work on my other bikes I might have to have a word to him about it.
where do you guys get the Good shockies?
and dose the heavier rate shocks put much more strain on the mounting points on the TY or can they handle it no worries?
Cheers
"E"



David Lahey
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Re: TY 250 Improvements

Postby David Lahey » Sat Jul 12, 2008 10:05 am

You probably don't need "better" shockies, but you do need to use the right springs for your weight. For trials bikes, the usual sag with rider is 50% travel and sag with no rider is about 5mm. The Betors would be fine for any weight rider but for spring choice, try springs that will give approx 50% sag. Here's a guide for trials bikes with the same shockie leverage ratio as the TY250:
80kg rider - 40lb/in
100kg rider - 50lb/in
120kg rider - 60lb/in
140kg rider - 70lb/in
160kg rider - 80lb/in
The TY shockie mounts will be fine provided the springs are stiff enough to prevent heavy bottoming. That is what bends shockie mounts, not a heavy rider.
You may have trouble getting springs stiffer than 50 lb/in with your Betors but higher rate springs are available from other sources. I reckon Ian will probably know where to get springs. If you get stuck you can always buy Falcon brand springs that will fit the Betors. Falcon shockies are form the UK. They make a trials shockie that looks very much the same as the Betors and is called "Falcon Trial Classic" but have a damping action that is better for trials competition and they cost more than the Betors. The springs are available separately. Don Newell Motorcycles in Brisbane is the Australian importer for Falcon.
Regards
David


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AussieE
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Re: TY 250 Improvements

Postby AussieE » Sat Jul 12, 2008 8:14 pm

Thanks David
Your wealth of knowledge is greatly appreciated =D> =D> =D>
"E"



Stanm
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Re: TY 250 Improvements

Postby Stanm » Tue Sep 01, 2009 10:02 pm

Hi David Lahey
Nice to meet you at Pacific Park Last weekend.
So I have a question for you or others to comment on!! If I want to relocate my TY 250 foot pegs what is the general consensus as to what is the best position.
I found one post on Trials central suggesting 1 3/8 inch down and the same back (35mm)

Regards

Stanm



Westy
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Re: TY 250 Improvements

Postby Westy » Wed Sep 02, 2009 9:04 am

I bought a TY! Don't worry, I am not setting the RL aside any time soon.
I need a few more parts to get the TY going.

Here is a photo of my TY. There's a lot missing. It's in great nick!
Image


Is it time to ride yet?

brownie
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Re: TY 250 Improvements

Postby brownie » Fri Sep 04, 2009 10:44 am

Stanm,
I did my pegs recently 25mm down x 20mm back, thats the back of the old pegs compared to the back of the new pegs probably could gone back a bit further, although they feel pretty good, a lot more comfortable than the old position even though ones a bit lower than the other :oops: any way I'll get round to making another set one day and take a bit more time.
To get the footpeg position right next time I'll get a piece of 1/4 " plate about 3" square , mount to the frame, then tack the peg mounts to it in the position that looks about right, put the pegs on then go for a ride see what its like. when the position feels right weld the mounts and shape the the plate to suit. If you leave the old mounts on it makes it easy to get the angle right as its parralel to the new one and to me I don't notice its there when riding.
Looking at the pegs I have, 35mm down would be at or lower than the bashplate so you might want to consider the actual peg dimensions too.
Having not had Trials bike for nearly 30 years until recently I'm no expert but I hope this helps a bit.
Ross




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