TY 250 Improvements

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Stanm
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TY 250 Improvements

Postby Stanm » Mon Jun 25, 2007 8:47 pm

Hi
I have a TY250A that I am running in the Vic troy series. It goes OK
but I am no expert in the suspension set up or what can be done to improve them.

At present I have standard fork springs with 17mm preload 7.5w oil 175cc and the forks are down in the clamps 6mm. Rear end has steel falcon shocks 340mm long. Footpegs have been lowered. Flywheel is weighted.

One problem I need to fix is the baffle in the main pipe is rattling about. (bike still runs ok). Any one know wat side it is supposed to be fixed to?

I would appreciate any advice on how to improve the handling power delivery, weight reduction etc



Stu
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Postby Stu » Mon Jun 25, 2007 11:05 pm

Can't help you out on the muffler problem. It sounds like you have the suspension sorted though. I'd like some ideas on how to lighten my TY as well. I've had mine for 20 years and i ride it anywhere and everwhere!


Feet up, as always!

David Lahey
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Re: TY 250 Improvements

Postby David Lahey » Tue Jun 26, 2007 6:06 am

Stanm wrote:Hi
I have a TY250A that I am running in the Vic troy series. It goes OK
but I am no expert in the suspension set up or what can be done to improve them.

At present I have standard fork springs with 17mm preload 7.5w oil 175cc and the forks are down in the clamps 6mm. Rear end has steel falcon shocks 340mm long. Footpegs have been lowered. Flywheel is weighted.

One problem I need to fix is the baffle in the main pipe is rattling about. (bike still runs ok). Any one know wat side it is supposed to be fixed to?

I would appreciate any advice on how to improve the handling power delivery, weight reduction etc


The main exhaust section on a TY250A does not have a baffle but is a double wall design. The inner wall is made of perforated steel and is spot welded to the outer wall. The noise may also be a mud-wasp nest or a lump of carbon.

Re your suspension: I've found that 15 or 20 WT oil works best for me (90kg) and I run standard springs and standard preload. Be careful adding extra preload to those springs as they will coil-bind, limiting travel. Setting oil level using depth measurement is more repeatable than measuring oil volume and those forks are sensitive to both over and underfilling. Too little oil - they snore and too much oil - travel is reduced. 125mm from the top with forks bottomed works well.

Rear I use 50lb/inch springs on 340mm Falcons with 10wt oil. Preload set to give 5mm sag unladen.



Stanm
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Re: TY 250 Improvements

Postby Stanm » Tue Jun 26, 2007 9:19 pm

David Lahey wrote:
Stanm wrote:Hi
I have a TY250A that I am running in the Vic troy series. It goes OK
but I am no expert in the suspension set up or what can be done to improve them.

At present I have standard fork springs with 17mm preload 7.5w oil 175cc and the forks are down in the clamps 6mm. Rear end has steel falcon shocks 340mm long. Footpegs have been lowered. Flywheel is weighted.

One problem I need to fix is the baffle in the main pipe is rattling about. (bike still runs ok). Any one know wat side it is supposed to be fixed to?

I would appreciate any advice on how to improve the handling power delivery, weight reduction etc


The main exhaust section on a TY250A does not have a baffle but is a double wall design. The inner wall is made of perforated steel and is spot welded to the outer wall. The noise may also be a mud-wasp nest or a lump of carbon.

Re your suspension: I've found that 15 or 20 WT oil works best for me (90kg) and I run standard springs and standard preload. Be careful adding extra preload to those springs as they will coil-bind, limiting travel. Setting oil level using depth measurement is more repeatable than measuring oil volume and those forks are sensitive to both over and underfilling. Too little oil - they snore and too much oil - travel is reduced. 125mm from the top with forks bottomed works well.

Rear I use 50lb/inch springs on 340mm Falcons with 10wt oil. Preload set to give 5mm sag unladen.


Guys
thanks for the feedback
Re the muffler the inner perforated wall must have come loose as I cut a hole in the muffler and you can see it moving about. I rivited a patch over the hole as i was not sure of what best to do.
So can I get any lightweight /performance replacement or is it best to stick wit the original?
My 175cc of fork oil( Lazy way to do it I know) is about 150mm oil level so i have less oil than you. So i will try some 20 W and higher level.


Stu
I have been listing some of my ideas for weight reduction but not sure whether the effort is justified except for item 6

1/ Drilling the rear sprocket
2/ Alloy side stand or remove it
3/ Alloy tank
4/ Lighter Seat ( Mine is already Fiberglass)
5/ Cut off Misc small brackets
6/ Rider to loose weight

Anyone know if boysen reed are available and worth considering?

Thanks



David Lahey
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Postby David Lahey » Tue Jun 26, 2007 9:55 pm

Generally the higher the item is on the bike and the closer to the front or back the more benefit it is to lose a given amount of weight. Same for the front end, weight lost from the wheel rim or handlebar ends will have a bigger effect than the same weight lost from the wheel hub.
In other words the weight of the bashplate or footpegs or motor flywheel is much less important than the fuel tank or exhaust.
Yes Boyesen reeds available for TY250 from B&J racing. I have some on order - yet to try.
Yes better (fully aluminium main section and end muffler) exhausts are available. Still uses steel header section. Brand is WES. Quite expensive but works well and much lighter than stock. B&J Racing sell WES as do many other places.
You can make a thin-wall stainless steel header section and save weight.
Yes remove the stand.
The standard TY250B,C,D aluminium tank is pretty light and fits TY250A.
Majesty replica aluminium tanks are even lighter at 1250grams but are very expensive.
The steering head stem can be replaced with an aluminium alloy item at great expense as can the bolt that screws into the top of the stem.
I'm assuming you have lightweight handlebars already.
Aluminium rear sprocket drilled to the max.
The aluminium bodied Falcons save weight.
Rider losing weight doesn't help the bikes handling. It is the bike that is improved by losing weight.
Suppliers:
B&J Racing (Tennessee) http://www.bjracing.com
Moto Majesty (UK) http://www.yamaha-majesty.com
France Trial Classic (France) http://www.francetrialclassic.com/fr
Trials and Trails (UK) http://www.tytrials.com



Stu
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Postby Stu » Thu Jun 28, 2007 1:41 pm

At this stage getting the rider's weight down would be the easiest to do! We'll see at mt Kembla this weekend.


Feet up, as always!

Stanm
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Postby Stanm » Thu Jun 28, 2007 10:02 pm

David
Thanks for the comments on the weight reduction. I figure every bit counts and it will either cost time, effort and or money. So I will chip away at it.

Do you have A WES exhaust? I am interested to know what the boyesen reed perform like.


Thanks for the web sites.Some great stuff on them.

Here is one I used that has a good article on setting up suspension

http://www.gasgas.com/Pages/Technical/t ... -tips.html.



David Lahey
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Postby David Lahey » Fri Jun 29, 2007 7:19 pm

Yes Stan. I chip away at my bikes too. That's why it has taken me 12 years from getting the first TY250 till I have finally bought my first set of Boyesen reeds for one.

Getting the suspension right, motor running perfectly, new tyres, strong brakes, nice controls and the bike running as reliably as possible are my primary goals.

Those things are more important to me than the weight savings from a WES exhaust so that mod hasn't happened yet but is definitely on the list.



Stanm
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Postby Stanm » Mon Jul 02, 2007 6:29 pm

David
I tried the 20W weight @175cc in the forks and it did no get so twitchy in rocky sections so I will stick with it for a while.
I also burnt out my exhaust on the weekend. Basically built a fire and threw the exhaust on and rotated ot now and then. Waiting till it stopped smoking and then steam cleaned it when it cooled down.I took off the patches made to look in the exhaust and steam cleaned through these which made it easier to rid of the gunk, I recon it weighed at least half a kilo lighter. Didn't seem to improve the performance but it is a bit quieter.
Somene told me that they soak the exhaut with petrol before burning. So what is the normal method of cleaning a two stroke exhaust?

Cheers



David Lahey
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Postby David Lahey » Mon Jul 02, 2007 7:03 pm

Good to hear the front suspension is working better.
If the exhaust is steel only ie no mineral fibre sound deadening sections, it can be burned out. What you did on the fire is pretty normal. Oxy acetylene welding gear works a treat and usually doesn't need any follow up cleaning.
If there was still gooey gunk inside after the burnout, you didn't burn it out for long enough. Do run the bike soon after the cleanout to prevent the pipe rusting on the inside.
Mineral fibre melts and makes a mess if you try and burn a pipe that has it inside (like a Sherpa T front muffler)
If you live in a city there may be anti-pollution laws that prevent you cleaning it out this way.
I've heard that motorbike shops have a special solvent for cleaning out the gunk without burning, which may be needed for bikes with aluminium exhausts or steel exhausts with special coatings which would otherwise be destroyed by the high temperature generated when burning out.
One time when I cleaned out a well-used TY175 pipe, it was about 650grams lighter than before and the bike ran better too (cheap weight loss hey?)
I wouldn't think it was very safe to soak the exhaust in petrol due to the risk of it exploding the pipe when lit up. I've never needed to add anything to get it to burn all the way through.



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Some More Questions

Postby Stanm » Wed Jul 04, 2007 5:21 pm

So does anyone know how the pros used to set uo the TY250's. For example mine has a flywheel weight ring which I believe is not standard but was a mod that was quite common.
I just use normal Unleaded. Does premium fuel make much of a difference.
Mine is set to standard timing, Can this be improved?
What are the best performing brake pads?
What about the aftermarket BJRacing fork springs? Anyone got these to comment on?
I put 520 chain and sprockets on but did not put on a spacer to compensate for the original dished rear. Had some trouble with the chain coming off. Can anyone tell me what the offset spacer thickness should be.

thanks
Stan



David Lahey
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Re: Some More Questions

Postby David Lahey » Wed Jul 04, 2007 6:10 pm

Stanm wrote:So does anyone know how the pros used to set uo the TY250's. For example mine has a flywheel weight ring which I believe is not standard but was a mod that was quite common.
Standard TY flywheels have a weight ring. The A model has a narrow ring and the B,C,D models have a wider ring. If you want a photo I will send one. I prefer riding competition with the ring removed for dry events and with the ring on for mud.

I just use normal Unleaded. Does premium fuel make much of a difference.
If your bike runs well, why change? Premium may make the bike run a bit smoother if you are having problems due to poor jetting or carbon buildup.

Mine is set to standard timing, Can this be improved?
Timing is adjustable to suit what you want. Standard timing works fine. Advance it a bit for more top end or * it a bit from standard for better throttle response at very low RPM. A hint here is if you set the timing using a static method, make sure you set the plug gap to recommended gap as a wide gap will affect the timing.

What are the best performing brake pads?
Ones that fit the shape of the drum properly. EBC pads have metal particles in the material which provide a stronger braking effect for the same cable pull than Yamaha TY shoes.

What about the aftermarket BJRacing fork springs? Anyone got these to comment on?
I bought two sets of B&J fork springs and rode with them for a couple of years in my TY250B and in my TY175 with TY250 forks and eventually took them out again as the spring rate was a bit high for my weight. They are well made and are high quality. If you are heavy and love big obstacles or trail riding, they are great.

I put 520 chain and sprockets on but did not put on a spacer to compensate for the original dished rear. Had some trouble with the chain coming off. Can anyone tell me what the offset spacer thickness should be.

6mm offset.

David Lahey

thanks
Stan



Stanm
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Postby Stanm » Thu Jul 05, 2007 6:16 pm

David
That's really good info and gives me a few things to tinker with and the excuse to test ride each weekend.
Yeh i saw a the TY 250 B has a flywheel weight that is much thicker. My A has nuts that stick out that are handy to hold with a screwdriver to take off the flywheel Nut. Do you have a special set up to take the weight off easily??
I hover between 85 to 90kg so I will take the BJ springs off my wish list. I used to hit the big obsticles but found I was chewing up tyres and injuring myself. So now cut back on this and concentrating on the slower technical stuff.
Is there another way to set the timing other than static? Can you use a Strob timing light? I have always just use a bit if chip packet foil to sense the points opening. I will check the spark plug gap.
Easy i will wip up a spacer from a bit of 6mm alum.

Thanks



David Lahey
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Postby David Lahey » Thu Jul 05, 2007 7:43 pm

Stanm wrote:David
That's really good info and gives me a few things to tinker with and the excuse to test ride each weekend.
Yeh i saw a the TY 250 B has a flywheel weight that is much thicker. My A has nuts that stick out that are handy to hold with a screwdriver to take off the flywheel Nut. Do you have a special set up to take the weight off easily??
I use two different flywheels. One with band and one without. I've heard that the ring can be taken off without cutting it but each time I have tried to get a ring off in one piece there has been some pretty fierce glue holding it on as well as the screws so I have given up and made a cut with a hacksaw to get it off without risking damage to the flywheel.

I hover between 85 to 90kg so I will take the BJ springs off my wish list. I used to hit the big obsticles but found I was chewing up tyres and injuring myself. So now cut back on this and concentrating on the slower technical stuff.
Is there another way to set the timing other than static? Can you use a Strob timing light? I have always just use a bit if chip packet foil to sense the points opening.
Yes set the timing close to the right spot static then check the timing with a strobe light. The strobe sensor is triggered by the HT lead and a 12V lawnmower battery powers it. My favourite timing is 22mm BTDC measured around the circumference of the flywheel rim.

I will check the spark plug gap.

Easy i will wip up a spacer from a bit of 6mm alum.
You will probably need to use countersunk head screws or machine the heads of the standard screws thinner to give clearance to the swingarm once you space the sprocket over to the left.

David

Thanks



Stanm
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Postby Stanm » Sat Jul 07, 2007 7:03 pm

David
I will give the dynamic timing a go tomorrow. I previously made some timing marks in the flywheel and case and standard timing looks about another 6mm BTDC than your 22mm. My points gap is on the low side. Points seem OK so I believe it must be a worn cam to have this effect?
It will be interesting to see where the timing really is compared to wher i think i set it. And to play wit the settings.
Have you Lowered you pegs? I made up some adapters and have the pegs in the lower cross tube. Also extended my pegs. Last trial I had some issues with clearance in tight rocks ( both of the things I did dont help) so want to optomise the size and position. Any ideas on this?
Cheers




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