TY 250 Improvements

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Stanm
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Re: TY 250 Improvements

Postby Stanm » Wed Feb 13, 2008 9:46 pm

Hello again
I picked up my new TY a few weeks ago and after cleaning the carby, fuel tap and tank it started second kick. The bike is an E model. I was a bit surprised to see the kick starter welded to the swing arm. My A is welded to the frame and I dont believe it was modified. Also it has some threaded holes in the cross tube under the rear of the motor that I am curious about. The forks are in great condition which is a plus.
OK the main problem I have is the swing arm bolt is seized. I have taken out the grease nipple and blown out the gease and have been drip feeding lub oil for a week now and have started to use a heat gun to supply heat. It still feels as solid as hell. I have read that you need to cut them off and buy a kit. Anyone had any experience with this?

David what is you opinion of the E model? Also I have a manual for an A&B so would fork oil specs etc be the same?

Cheers

Stan



David Lahey
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Re: TY 250 Improvements

Postby David Lahey » Wed Feb 13, 2008 11:34 pm

Yes it is common for the swingarm axle to freeze inside the bearing tube. There is lots of contact area between the two and both are steel.
Usual advice is to turn the bike upside down and cut the swingarm bolt through with a hacksaw. The bearing tube and bolt will come out of the plastic swingarm bushes easily once the frame is out of the way.
Kits to get it back in one piece are available from the enterprising John Cane in the UK. Yamaha no longer make the bearing tube but you can get the other bits from Yamaha if you really want and turn up and grind a new bearing tube.
I reckon the kit from John Cane saves a lot of mucking around. If you have a look on eBay including UK sellers you will pick up his website.

There is nothing special about the TY250E. As far as I know it is the same mechanically as the C and D models. The stand is on the swingarm on all models after the A. The threaded ends in the cross frame tube are to attach the accessory footpeg kit sold by Yamaha for trail riding. Along with the footpegs came a longer brake pedal to suit the footpeg location and a big seat. They were available for B model onwards.

Have a close look at the swingarm design. You should notice the E model (and C and D) has more elaborate gusseting between the bearing tube and the arms than the A model.

No the C and D model forks are a bit different and Yamaha reckon the oil volume is different to the A and B. I don't measure the volume anyway (I use 5" from the top with no springs) so don't remember what it is. I can look it up if you want for the C and D model forks assuming they are the same as the E.


relax, nothing is under control

Stu
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Re: TY 250 Improvements

Postby Stu » Sat Feb 16, 2008 11:28 pm

David,
I had extended the clutch arm on my TY250a years ago. I had a Serpa T 250 before the TY and I lightened the clutch on that also. The arm on the TY is a tight fit under the motor, but with a bit of fiddling it can be done quite easily. Since I did the mod, i don't suffer from arm cramps, so i've done something good then.


Feet up, as always!

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Re: TY 250 Improvements

Postby David Lahey » Sat Feb 16, 2008 11:34 pm

Stu wrote:David,
I had extended the clutch arm on my TY250a years ago. I had a Serpa T 250 before the TY and I lightened the clutch on that also. The arm on the TY is a tight fit under the motor, but with a bit of fiddling it can be done quite easily. Since I did the mod, i don't suffer from arm cramps, so i've done something good then.


Stu can you take a photo next time you have the bashplate off?


relax, nothing is under control

Stu
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Re: TY 250 Improvements

Postby Stu » Sat Feb 16, 2008 11:52 pm

Sure, I'll be cleaning the TY soon anyway. Maybe a respray of the tank, frame,etc....


Feet up, as always!

Stanm
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Re: TY 250 Improvements

Postby Stanm » Sat Mar 08, 2008 4:45 pm

David
I stuffed the swing arm bold on the E trying to get it out but did succeed getting a seized shaft out of an an old wrecking TY that I just bought for spares. Its a long story and I will post it soon but may have a method thats worth a try if you own an oxy and a welder.
For now I am trying to get the oil pump of the E . The shaft with the worm gear is stuck in the casing. On the A it pulls out easy. Should I keep pulling or do I need to remove the side cover

regards

Stan



David Lahey
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Re: TY 250 Improvements

Postby David Lahey » Sat Mar 08, 2008 6:47 pm

I don't remember what happened with my A when I took the oil pump off. It was 13 years ago after all! It doesn't surprise me that it is different to the later models.

I did just go and have a look inside a B model clutch cover that still has the oil pump in situ and there is a circlip holding the plastic gear on the worm shaft and the plastic gear is about 25mm diameter so yes I reckon the clutch cover will need to come off to get the worm shaft out.
Regards
David


relax, nothing is under control

Stanm
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Re: TY 250 Improvements

Postby Stanm » Tue Mar 11, 2008 10:37 pm

David
Thanks for the info on the oil pump.

Another question. Do you think it is worth it to relocate the side stand on the swing arm to reduce sprung weight? I had decided to do this until I looked at my sons Gas Gas and saw the side stand on the swing arm.

OK now for the story of the seized swing arm bolts.
In addition to the TY250 E I bought a wreck TY250 A last week and it
was a real rust bucket and also had a seized swing arm. This gave me the
opportunity to experiment with another method to free up the swing arm. As
many of you would be aware with seized shafts it is good practice to rotate
the shaft to free them up before pushing out. How to do this with the TY??
So with the TY you have the big inner bush that seizes to the bolt that
runs all the way between the swing arm. The smaller bushings at each end
are plastic and are generally free and you should be able to prove this by rotating the
swing arm bolt. Now if you take out the grease nipple and look inside when
you turn the bolt you will see the inner bush rotating. OK to free the
bolt from the inner bush you need to lock the swing arm to the inner bush.
I did this by drilling a 10mm hole through the center of the swing arm to
expose the inner bush, Next heat the bush through the swing arm with an oxy
to red hot. Next get your welder and weld through the 10mm hole to weld
the center bush to the swing arm. Now if you turn the swing arm bolt back and forth it may free up. I was surprised, especially with the old rust bucket, how easy this was and how clean the bolt was. Parts cleaned up well and could be reused.

Sadly I had already used a big hammer and had bent the bolt on the E.

All this aside, I agree for most the easiest option is to buy a kit and replace the parts. But if you are desperate the above may work but not guaranteed. I was just stubborn as I had read that it was not possible.

Cheers



David Lahey
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Re: TY 250 Improvements

Postby David Lahey » Wed Mar 12, 2008 6:36 pm

You do seem to like a challenge. I reckon you need to restore a Spanish bike that has been worked on by kids to get that well and truly out of your system.

What's that about moving the stand? The reason sensible bike makers have the stand on the swingarm is to prevent it getting broken off. Nothing to do with sprung or unsprung weight. Stands mounted to the main frame loop on a trials bike usually have a very short and brutal life as they stick out like buggy lamps whenever the suspension is away from the fullly extended position (which is 99.9% of the time you are riding).

Standard TY250 stands are pretty poor for keeping the bike upright due to the point where they touch the ground being too far to the rear of the bike, and because they are too short if you use 340mm shockies and modern high profile tyres. If you are going to use a stand mounted on the swingarm, make it a bit longer and put an S bend at the bottom to get the foot further forward. I'll post a photo if you want to see one done like that.


relax, nothing is under control

Beech
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Re: TY 250 Improvements

Postby Beech » Wed Mar 12, 2008 6:58 pm

Stan, you need less time in the shed and more time on the bike, don't worry about unsprung weight, just have another crownie at Glenmaggie and use that as ballast.
I'II have my TY at Glenmaggie so you/me Friday practise on our twinshocks followed by refreshments, ok?




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