TY 250 Improvements

Need help finding information or parts for that old machine in your shed? Someone in here will know!

Moderator: Moderators

David Lahey
Champion
Champion
Posts: 3389
Joined: Thu Jun 05, 2003 7:01 pm
Bike: Many Twinshocks
Club: CQTC Inc, RTC Inc
Location: Gladstone, Queensland

Postby David Lahey » Thu Jul 19, 2007 9:26 pm

After a wet ride or after washing a bike it is helpful to loosen the magneto flywheel cover screws and leave the cover loose or remove it completely for a few days to let the electrics dry out fully.



User avatar
Tee-Why
Expert participant
Expert participant
Posts: 261
Joined: Fri Apr 16, 2004 12:05 am
Location: Central QLD

Postby Tee-Why » Fri Jul 20, 2007 11:48 pm

I have mixed feelings about my Falcon shocks. These are my first set and appear to be the quality article.

They weren't set hard hard enough from supply as per requested info to supplier, and needed to pre-load them more by lowering the clip - seems ok now. But compared to another bike ridden that had 10lb heavier springs that more or less equal to the front fork spring rate, that is faster in rebound. Mine are un-equal, I haven't changed my fork oil yet to try and balance the effect with heavier oil.

First thing that happens with inverted spring design to the original shocks is that the spring rubs against the chain (428), so I had to use a large size cable tie in the bottom spring retainer guide slot to pull the spring away from the chain.

Then riding the last trial, that bottom retainer on the RHS had dislodged and was nearly lost, even with the increase in spring pre-load.

This was a wet ride and the inner side of the springs were rubbing on the shock body and seems to have caused the chrome layer to go, and cause the spring to leave a rust mark on the shock body (alloy).

I know we are riding a competition dirt bike in arduous conditions and treatment, but I thought at 3 trials in 6 months low usage, they wouldnt be too much of a problem.

Pricing - mine were $450 local supply, a bit different to $380.


I would rather push my twinshock than ride a modern!

Stanm
A grade participant
A grade participant
Posts: 121
Joined: Wed Jan 14, 2004 10:17 am

Postby Stanm » Sat Jul 21, 2007 9:18 am

Yeh I know you should not force water near seals and that's the first thing you teach your kids to do when you make them steam clean your bike when you take the lazy way out.
I recently blew a source coil so are now starting to get into the habbit of opening up the flywheel case which as mentioned is a good habbit. If I find water I blow it out with air and then use a heat gun. Then give the points a clean. Used to have to take off the bash plat to take off the cover but have modified now so this is not necessay.
My 250A came without a bash plate so I made my own. Can someone supply a picture of the original type?

Good point about the falcons hitting the chain. Mine is 7mm away without the 6mm spacer to compensate for the non dished 520 sprocket (280mm dia). So looks like trouble if i put the spacer in??
Another thing i was not keen on with the falcons was that the end rubbers dont have a metal inner bush. Is this same with other brands??
Had 4 rides or so with the 20W oil as David suggested and i am really happy with is so will keep it for the TROY Trial this weekend.
My springs are 50 lb and i have them on the highest clip (almost no preload) never had a problem with the retainer. What spring clip position are you guys using?
regards Stan



David Lahey
Champion
Champion
Posts: 3389
Joined: Thu Jun 05, 2003 7:01 pm
Bike: Many Twinshocks
Club: CQTC Inc, RTC Inc
Location: Gladstone, Queensland

Postby David Lahey » Sat Jul 21, 2007 9:49 am

Stanm
Falcon eye rubbers work fine without a steel bush.
On a TY175 or TY250 twinshock with standard sprocket diameter and offset, Falcon shockies need to be spaced across to the left approx 4mm to prevent the chain rubbing on the spring. I had to do a similar thing with Falcons on my KT250.
New Falcon springs tend to take a while to settle down. On TY250 twinshocks, I find that new 50 pound/inch springs work well for me on the second groove and by the time they have settled down, they are on the fourth or fifth groove. I weigh about 88kg and use 10WT oil in the Falcons.
The recommendation on the Falcon website is for 40 pound/inch springs on the TY250 but I found that was too soft even with lots of preload. The spring rate is engraved on the end of the springs.
I haven't had a problem with the spring retainers. Maybe they are different on the aluminium bodied model. All mine are the basic steel bodied type.
I can send you a photo of an original TY250A bashplate if you want. It is pretty much the same shape as for the TY250B,C,D,E except the A model bashplate is made of fibreglass! I'll take a photo over the weekend and post it on this thread.
Good luck for the trial.
Subanator
Are you sure that one of your Falcons doesn't have a bent shaft? I only say that because it took me two trials to work out why I couldn't get much lift on obstacles before I realised one of mine had been bent and had a sticky spot. The other thought I had about yours was do they both have the same gas pressure inside?



User avatar
Tee-Why
Expert participant
Expert participant
Posts: 261
Joined: Fri Apr 16, 2004 12:05 am
Location: Central QLD

Postby Tee-Why » Mon Jul 23, 2007 12:11 am

Hi David, RE the Falcon shocks, I didnt think they were bent, after washing the bike they looked fine. I will pull the shocks off later and remove the springs to feel the gas dampening, as I dont know how to accurately measure the pressure without loosing gas with a test gauge. I may even insert a plastic guide to stop the spring rubbing if possible. I did space my shock, but not as far as 4mm, as the rubber looked to hang over the pin.
I must admit the bike took a heavy fall on that side, and may have dislodged the retainer? I will keep an eye on this.

My springs are 40lb as I am 75kg on the TY175, they seem to have bedded down ok and have left them at the second groove so far. Shocks are well worth the effort and make a huge difference. Dont know how these compare to Icon's, maybe someone could give their comment.


I would rather push my twinshock than ride a modern!

David Lahey
Champion
Champion
Posts: 3389
Joined: Thu Jun 05, 2003 7:01 pm
Bike: Many Twinshocks
Club: CQTC Inc, RTC Inc
Location: Gladstone, Queensland

Postby David Lahey » Mon Jul 23, 2007 9:17 am

The plastic sleeve sounds like a good idea to protect those aluminium bodies. There looks to be lots of room to fit a sleeve in there. The rubbing doesn't seem to worry the steel bodies.
The bend in mine was about halfway along the shaft so was easy to repair. The local motorbike shop straightened it in their hydraulic press and charged me $10. Another rider from here had his Falcon shockie shaft bend too but his bend was right near the piston end so he ended up buying a new shaft.
I know that you are supposed to use Nitrogen or Argon in shockies to reduce the deterioration rate of the oil but I have always just used air and change the oil every 6 months and have never had a problem. This way I can check and adjust the pressure anytime I like without having to go to the bike shop. I just use a standard tyre filling pressure guage and have no problems getting the pressure somewhere between 60 and 80psi which works well. I don't remember pressure what Falcon recommend but they do seem to need above about 30psi to make the seals work well. There is no diaphragm or floating piston to separate the oil and gas in Falcon shocks so make sure the valve is at the top when you let the gas out (or you'll get sprayed with oil!)
Yes when you space the shockie over the mounting pin no longer goes all the way across the shockie eye but nothing seems to come of it in use. The KT is the same as my TYs in this regard.
I think I can comment about IKONs as I have a set of late model (1996)KONIs which are the same as the ones that IKON make now. They are reliable and well made but have a few features that limit them for trials use.
Unless they have started making a new range of springs, the range available for these shocks (they are a larger diameter body to the KONIs made in the 1970s) are all too stiff for even me so I reckon they would be for you too at 75kg. The softest springs and are not bad for trail riding, but for good performance in trials, the shockies need to move through their full travel.
Another issue is travel. The KONIs have only about 3.25 inches shaft travel while the Falcons are 4 inches. It doesn't sound much but it makes a big difference in competition.
The main problem is that the damping is not set up for trials use. I suspect the KONI valving is set up for road riding where firmer is often better but this isn't the case in trials where you need very little damping. I've tried the lightest oil but there is still too much damping for my taste.



David Lahey
Champion
Champion
Posts: 3389
Joined: Thu Jun 05, 2003 7:01 pm
Bike: Many Twinshocks
Club: CQTC Inc, RTC Inc
Location: Gladstone, Queensland

Postby David Lahey » Mon Jul 23, 2007 9:38 am

Stanm wrote:My 250A came without a bash plate so I made my own. Can someone supply a picture of the original type?
regards Stan

The BCDE model aluminium plates appear to be exactly the same shape as the A model fibrelass plate. I have an A model with an aluminium Yamaha plate and it fits fine.
Attachments
TY250 bashplates 002.JPG
Original A model plate under B model aluminium plate on bike
TY250 bashplates 001.JPG
Original A model plate is white one. Black one is replica also fibreglass.



Stanm
A grade participant
A grade participant
Posts: 121
Joined: Wed Jan 14, 2004 10:17 am

Postby Stanm » Tue Jul 24, 2007 6:05 pm

Thanks for the bash plate pictures. I would be a bit worried using the same bash plate on an A as a B. As you know the A has much wider casings so my bashplate is wider at the front to protect those precious casings.
I had a bit of ignition failure at the weekend. Still found water in the case. Do you guys still have a case breather??
Sounds like something I would do with the air in the shocks. If ite works well why not. Thanks for the tips.

Cheers



David Lahey
Champion
Champion
Posts: 3389
Joined: Thu Jun 05, 2003 7:01 pm
Bike: Many Twinshocks
Club: CQTC Inc, RTC Inc
Location: Gladstone, Queensland

Postby David Lahey » Tue Jul 24, 2007 6:44 pm

Yes I use the standard case breather on my Yamahas and I don't use a gasket or any sealant. Never had a problem with water in the points. There is sometimes a little puddle in the bottom when I take the cover off after a wet trial.
On one bike for an experiment I cut a groove in the bottom edge of the casing joint (to let water out) and never had any problems with that bike from normal wet trial use but obviously if I had parked the bike with the cases under water level it would have eventually filled up! It worked well in that I never found any little puddle in the bottom of that one after wet events.



Stanm
A grade participant
A grade participant
Posts: 121
Joined: Wed Jan 14, 2004 10:17 am

Postby Stanm » Tue Jul 31, 2007 6:02 pm

Hi Again
I had a big off on my Sunday Practice. I had just started the TY and decided to putt up a steep incline as slow as I could go. It jumped out of gear and I rolled back over a 3ft rock ledge. Dinting my pride and the tank again. Any way my TY tends to jump out of gear sometimes and i suspect more so when cold. But I dont see any logic in why it would do it more when cold. Any comments??
I found my previously mentioned problem was water / dirt in the carby not and not an ignition problem. Do you guys run an inline filter?




Return to “Twinshock & Classic Trials”

Who is online

Users browsing this forum: No registered users and 7 guests