Morning all

Ive just purchased a newly rebuilt ty250r mono 1985 

Guess what she's pinking..ie irregular knock top end at low to medium revs..... it wasn't when I went for test ride, just hunting a bit,  but guys at shop said it needed to run ritcher so raised the needle .. to the top..by lowering the circlip to the bottom notch, messed with the mixture screw and tick over..and it seemed to run ok, more responsive

Took it for a spin once home and found it knocking (not all the time)

Ive since popped the needle back a notch and it kinda improved it .. I wish to put the needle back to centre notch as original and start again... but would like to confirm what the mixture screw should be set at

Key points 

its had first bore and sleeved, ported barrel professionally worked, new custom inlet manifold and reeds, new oko carb, exhaust felted, custom air box resonator, high powered electric ignition converstion new air filter

im running it on 50;1 

In short I think I need to set the carb to factory seetings and maybe start again,, 

Thanks for reading any help welcomed 

Best

CSP

 

 

 Well at least you have more jetting options with the OKO. I would go way up on the pilot. I know your fuel is way different. Someone might come along with some better help, like which slide would work.

Factory settings would seem unlikely to be correct for a bike with so many mods to the motor and a completely different carb. You may have some experimentation ahead of you...............

Thanks for your thoughts

 

Hi Csp you say its had a rebore and piston do you know what piston was used?? The reason I ask is I have just rebuilt mine last year along with two of my mates bikes ALL with wossnor pistons and they knock like a diesel engine..

My mate actually took his barrel & piston off his pinky to experiment  (genuine standard Yam piston) and guess what no knocking.

I have had to put two base gaskets on as the port timing was all wrong with the wossnor  piston, As for jetting it's all trial and error.

 

12 hours ago, 2stroke4stroke said:

Factory settings would seem unlikely to be correct for a bike with so many mods to the motor and a completely different carb. You may have some experimentation ahead of you...............

This.

+1.

With ALL THE MODS you listed, i can guarantee you it aint gonna run on stock base settings.

23 hours ago, lineaway said:

 Well at least you have more jetting options with the OKO. I would go way up on the pilot. I know your fuel is way different. Someone might come along with some better help, like which slide would work.

The question I would ask is why have you (or someone else) put a cheap copy of a Keihin carb on especially seeing as you have spent so much time and effort modifying this bike? Surely it would make sense to pay the extra for the Keihin and then see if you can set the carb up.

 

Try adding some octane booster to the fuel, if is detonation you are hearing this should sort it, you could also retard the ignition timing a little, maybe run an extra head gasket or two base gaskets?

I'm more of a fan of a thicker head gasket, adding a base gasket will change the '' port timing '' but it's a simple way to find if high comp is your problem. 

On 2/25/2020 at 4:38 AM, bumpy_ltd said:

The question I would ask is why have you (or someone else) put a cheap copy of a Keihin carb on especially seeing as you have spent so much time and effort modifying this bike? Surely it would make sense to pay the extra for the Keihin and then see if you can set the carb up.

 

As long it's a genuine Oko & not a chinese knock off it's as good as a keihin, my experience with the 1 on my sherco is that they aren't as sensitive to weather changes