Ty 175 Knock On Decel?

[shipdamite]

Glad you have improved the running of your bike. How do you get on with the forks mounted high in the yokes, looks like the tubes are nearly flush with the yokes. I used have problems with the front washing out on a tight turn with them mounted high. Recommend drop in yokes is 20mm. Thought I would just mention it...sorry if you knew

Hi Andy - thanks! I read on the ty trials site that the longer rear shocks (as on my bike) needed the front forks to be flush with the top of the yokes. The bike came with that set up, but i did the drop then read about them being flush! I will see how it goes on sunday.... might do one lap 'as is' then drop at lunch time ........ need to make some risers I think (being over 6ft the bike is a bit small)........ cheers - Andrew

[andy.t]

Yes mate your right it does say that, and I have the longer rear shocks fitted also. Mine is still dropped down 20mm. The problem I found is that with the fork tubes up high they tend to flex even more than normal and the rake on the forks makes it handle more like a chopper. Like you said give a try lower and you should notice less wash out of the front wheel. As for the risers there was a bit on here..somewhere. I chopped of the original clamps and drilled through to accept some clamps and risers off a husquvana motocross bike (£10 off eBAY), I did fit a bit of plate under the yoke where the casting is thinner so to bolt down on. It works treat and gets rid of that tiller effect that the pull back existing clamps have.

Good luck with trial on sunday, you will have to get down to Suffolk and do some of our twinshock trials

[shipdamite]

Hi Andy - I will defo try the forks through the yokes again. I have just used a set of ty clamps to raise my bars .... basically filed the top to take the slight camber out, turned them over and used them below the top clamp to raise them a bit ..... the turned bars slightly forward; seems easier to turn tight corners now! like the sound of what you have done though, will hav eto get another top yoke of eblag and have a play.

thanks for the good luck! suffolk sounds good! still have to get to corton for a play.

[Tillerman6]

Shippy,

  I would have to assume that your changing of the pilot jet size did fix the problem with the dong-dong noise?, and I have that same noise on my TY250 A -  when on a deceleration of more than say 30 feet with the throttle closed, especially if the engine is fully warmed up.  But now I am thinking that I simply should not be using the engine for deceleration at all!   The idea is that the rings will scrape the cylinder wall dry in just a few strokes with the throttle closed and the cylinder and piston and head are possibly still hot from the last uphill run. If there is any glowing  carbon stuck to the piston crown or the exhaust port or anywhere that fuel and air can get to,  and that starts glowing hot enough to ignite the tiny bit of residual fuel that gets sucked under the carb slide when the vacum is high and your have a sort of unwanted pulse of power which may or may not co-inside with the spark plug timing.  (or a tight downhill section that you need to keep your speed down to an absolute minimum) 

What I am getting is almost a diesel type of ignition or pre-ignition.   It also will push the bike sharply for one piston stroke and yank on the gears and chain because the chain was putting  slack on top of the chain loop but all of a sudden the engine fires once and takes all the slack out of the system!  But then immediately the engine stops firing again and the slack moves back to the top of the loop!  So what could possibly go wrong with this scenario?

 

The engine will not ever make that noise unless the throttle is closed while on a down hill, so I have to think that what I was doing was abuse. I would also get 30 seconds of piston slap noise along with the dong! dong! so I don't think if was doing the engine any good. 

But all that being said, if you could stop this dong - dong stuff entirely by changing the pilot jet size then at least you are not yanking on the gears and chain every 10 feet.

I don't understand how increasing the pilot jet size would help this situation because you would think that if there was any residual weeping of the carb with the throttle closed, that it would weep more fuel with the larger jet size but I must be missing something?

I guess it all boils down to my stupidity for wearing out my engine and gears rather than some brake shoe material.

 

By the way- I am a newbie on here and I appreciate all the help you guys are dishing out!

Please let me know if anything has changed in the way your bike is performing or your riding style since this old thread was created?

Thanks for your input!