Yikes !!! Siezed, chunks out of throttle plate

I have not opened the lid yet, but I looked in the back of my carb and can tell there is a chunk missing from the throttle plate.

Anyone siezed up like this? I have read a couple posts where the chunks go through without damage and Brandon said he found a piece inside of his. I have not read any posts that mention bieng siezed.

If anyone can give me some info on what to expect I would appreciate it. :)


Stands to reason that if you have a chunk of metal missing from the throttle plate that you may get a piece of metal where it shouldnt be and that could seize your engine. :)

Did you remove the throttle stop on your carb completely :D as I understood this was a likely outcome from not just grinding it down or repalcing with the YZ one ?

I'll check the throttle stop. I bought the bike used, I think it has had the stop modified. I have found signs that a HACK has worked on the bike in the past so it would not suprise me if the job had been botched. Thanks for the tip.

I would still like to here from anyone who has had an engine siezure :) as a result of a broken throttle plate.


Pop the engine's head off and check. A piece probably entered through an intake valve and wedged itself between piston and head. Check your valves, valve seats, piston top and head for damage...Your connecting rod may also be bent.

I'm gonna' skip popin' the top. I know it's not the safest route but what the .... :D

Here's the latest:

I pulled the carb and yes the bottom right side of the plate is gone. So I put a wrench on the fly wheel nut to check and see if it would turn backwards and :)

So I took it to the bottom and beat on the cylinder with a plastic mallet. It still wouldn't go past TDC so I turned it until the intake valves were open and blasted air through each valve (while using the hammer!), I also blew through the exhaust while pulling the decomp. Same with the plug hole. Yeehah, I could go past TDC.

So I kicked it through easy while listening closely and I saw something fly out of the plug hole. Couldn't find it on my (dirty) garage floor, so I kicked a little harder. I heard something small bounce off the wall :D a couple times while kicking it over more. I never felt any resistance while doing this.

:D I'm going to fix the carb and ride it!


I know a motorcycle repair shop where you'd fit right in...

You won't see my bike there though.

When you do ride it....I wouldn't ride it further than you can push it. :)

No problems. That slide plate is thin aluminum and the combustion chamber is way tougher.

Jimmy rides into the sunset.

Will you post a reply on how your ride went ??? I would like to know . Thanks Rob in Texas :)


I'll be sure and let everyone know how it goes.


I wonder if GrahamO and Rockieman ride with their teddy bears? :D

Jimmy :)

Nope, Just don't like the idea of foreign objects entering my motor. :)

My dad raced bikes and his dad raced boats (set world records). Both of them taught me to be gentle with an engine with phrases like: "Don't force it!"

I was just cracking up at: So I took it to the bottom and beat on the cylinder with a plastic mallet. It still wouldn't go past TDC so I turned it until the intake valves were open and blasted air through each valve (while using the hammer!)

I just love the thought of beating on my cylinder and kicking it over with metal chunks in the cylinder... LOVE IT!.

I do know a guy who rides with a teddy bear... rides very fast with a teddy bear.

The carb slider on my '99 just gave up the ghost about 3 weeks ago. Do a search for "carb slider" and you will see that they all seem to break the same way- the lower right part of the slide breaks off- just like yours did and just like mine did. (Wonder why that is?) I used a little fiber optic light to look into the intake valves and into the cylinder through the spark plug hole. I never did find the piece that broke off but then again my motor never seized. I agree with those who say the cylinder is much tougher than the little carb slider piece. If it shot out I'd say you'll be fine. If it didn't and my motor had seized, I would have taken off the cylinder head to find the piece that broke off.

I got the new carb slider installed and now it runs better than ever. I think the slide had been developing the crack for a while and it had been throwing off the jetting and causing it to run a bit rough. It also looks like Yamaha re-engineered that piece to make it stronger (machined vs. pressed.)


She runs great!

I've got 50+ miles since, and all is well. I found that I do not have a throttle stop, I think that was probably the root cause.

I've read a lot about the length of the stop, does anyone know the thread pitch/dia?

All is well that ends well.

Jimmy :D

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now