Red lining 87 KDX

[Some_chump_Dad]

Our KDX ripper is psycho !
Hello we are new to the site and excited to be apart of the community!
We recently got a 87 KDX that need some luvn. We took care of the typical issues it had from sitting and she fired like a champ. Recently it's been acting crazy like balls to the wall throttle. She doesn't like to be kicked cold very easy but always cranks. Since putting holes in my sandlels, and redwings we normally pop start it. Well when she kicks the throttle screams to the top and is literally a green streak. Now we have opened the throttle cover and found a kink in the cable. We straightend it out lubed it well and this time cranked it making sure to close the throttle. Same thing ! She shoots straight to redline. My neighbor are gona kill me if the KDX doesn't first.

We have a new cable on order. As we **** with the cable under those extreme revs the cable seems to be snapping back but ... Holy freak we don't let her rev more than a few secs. Carb is clean, existing cable has no kinks, and routed properly. Hopefully the new cable will solve the problem. What else could make it rev like that.....? Has to be throttle related right ?
Any help would be greatly appreciated !!!

[6 Riders]

Probably need a top end and reeds. A kinked throttle cable is NOT ok, don't run the bike until you get that fixed. Imagine riding down a trail about 1/2 throttle, you give it a little "blip" of the throttle and the bike locks full throttle, with you on it Don't do it, ever. Also check for dirt, grime and water in the needle, slide and seat. Oh hell, take the carb off, give it a good cleaning, check the reeds since you are in there and look into the cylinder and see if you can see scratches, or "blow by" on the piston.

[canamfan]

Crank seal on the ignition side, sucking air?

[pkenney]

I second Canamfan's diagnosis.
Does it bog when you open the throttle and rev when you close it?
Also are you sure the slide is in the right way and closing all the way?

[Tedh98]

What everyone else said plus I would also check for air leaks around where the carb boot/reeds bolt to the cylinder. And on a bike that old, there certainly could be some cracks in the carb/reed boot letting in air.

[Some_chump_Dad]

I guess the reed valves will looked toastied up or roasted if bad ? Not sure what Ill be looking at but, going to tear into her before the cable comes. Right after dinner if fact. Looking for air leaks well

[Some_chump_Dad]

Pkenney - she goes straight to whiskey 110% no mess'n around soon as fired

[KDXGarage]

air leak or timing off, had a beat up '87 that did it

[Some_chump_Dad]

Thank you for the leads. I will be sure to keep the thread updated