Kientech extended fuel screw failure (seized) & jetting question.

Hello all,

I was rejetting my bike for the TRC Ti that I recently installed. Everything went smooth up to the point when I tried to adjust my fuel mixture screw. The screw was stuck in one position and wouldn't turn at all (using finger force). So I decided to attack it with WD40 from the bottom and through the tiny passage in the throttle body. I let it sit for some time and finally the screw let go and I was able to back it out for about half a turn. Then it got stuck again and I said to myself "jeez it can't be good". At this point after good amount of "finagling" I decided to remove it using pliers. So I slowly removed it. Lo and behold the thread closest to the tip of the screw had been bent and filled with aluminum thread from the carb body. I tried removing it from the screw thread and put the screw back in but it wouldn't go. Nonetheless, I was able to install the stock fuel screw with no problems at all and it looks like I am stuck using it for now.

Here is some points that I want to make before anyone says anything:

1. The Kientech screw was installed about 2 years ago.

2. The Kientech screw was installed properly (no cross threading).

3. It was finger tightened and then backed out.

Did anyone ever come across a similar problem with Kientech screw? I will be contacting manufacturer for sure to see what they have to say..

Now to the jetting question: the tip of the stock fuel screw and of the Kientech screw look very much the same. Should I follow the same jetting instructions for the stock screw as for the Kientech extended? If not can anyone provide correct settings equal to Kientech 2.5 turns out and 2.75 turns out?

They are identical. 2.5 is 2.5 turns

Not sure why yours seized. Possible a little corrosion. You bike sat all winter in an unheated space?

They are identical. 2.5 is 2.5 turns

Not sure why yours seized. Possible a little corrosion. You bike sat all winter in an unheated space?

Thank you William. Yes, it is stored in a detached garage all winter...

use a little anti seize on the threads.

Now to the jetting question: the tip of the stock fuel screw and of the Kientech screw look very much the same. Should I follow the same jetting instructions for the stock screw as for the Kientech extended? If not can anyone provide correct settings equal to Kientech 2.5 turns out and 2.75 turns out?

They look similar but they are different..

22.5 pilot jet with extended screw or 25 pilot jet with stock screw

2.75 turns

For open pipe/3x3/sea level

im using 25 pilot, 155 main, 2.5 turns, 3x3, stock pipe at sea level

My new Kientech appears to be stainless. I would guess the carb body is cast in some blend of aluminum.....potential for dissimilar metal corrosion. Kientech warns of debris-caused binding in the threads during installation.

My new Kientech appears to be stainless. I would guess the carb body is cast in some blend of aluminum.....potential for dissimilar metal corrosion. Kientech warns of debris-caused binding in the threads during installation.

You know, it's been working just fine after the installation. I've been able to adjust it for as long as I needed after the installation therefore I highly doubt any kind of debris got in there. I am waiting for a response from Jesse Kientz from Kientech. I guess I will find out what's popping and whether there is a warranty and if the screw seizure is covered under it... Not sure if I want to install it again though. I honestly don't feel like replacing the carburetor due to stripped thread...

Not sure this is a manufacturing failure. And maybe there was no debris. I was wondering about the corrosion factor. Your carb is likely repairable, the Kientech is likely re-usable, even with reduced threads.

Not sure this is a manufacturing failure. And maybe there was no debris. I was wondering about the corrosion factor. Your carb is likely repairable, the Kientech is likely re-usable, even with reduced threads.

I'm not sure either. I'm by no means a metallurgy specialist but maybe there is some sort of chemical reaction between the screw and the carburetor which caused the seizure... I guess Suzuki decided to use brass for some reason.

Also I agree with you about being able to reuse Kientech screw.. Only two of the topmost threads would have to be ground down and I guess this would enable me to reinstall it.

I guess most of the people install the screw and don't adjust it after long periods of time so even if there are more seizures like mine it is likely that they won't be discovered anytime soon....

Also thanks for your input :smirk:

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