Everyone should check this! Thanks, Frostbite!

During my last ride on my 98 WR400 my idle went high, and I couldn't get it to settle down. I figured my float was stuck, so I took the carb off and checked it. That wasn't the problem. I have very little knowledge about mechanics, so I didn't know what else to look for. I hopped on ThumperTalk, did a search for high idle, and found a thread by Frostbite with several pictures showing the slide plate in the carb when his broke. I used these pictures and the schematic to find it. Mine had not broken yet, but it had 2 large cracks in it. I spent $100 for the parts to fix it instead of paying $300-$400 for the dealer to do it. Without those pictures, I wouldn't have been able to fix it myself, and it could have done a lot of damage if it had broken off and went into the motor.

The next time you have your carburetor off your bike, check the slide plate for cracks. I was lucky and caught mine before it broke off and did expensive damage to the motor.

This is another example of how this website keeps the average rider on his bike. I have been able to do several repairs myself from the advice here. I would not be able to afford to ride if I had to take my bike to a mechanic every time something went wrong.

Thanks to Frostbite, and to all you gearheads that share your knowledge with the rest of us. :ride::cry::thumbsup:


congrats on being able to save a heap of $$

TT must be responsible for so many hi performance 4 stroke mechanics not being able to charge $50 an hour to replace a plug and tell you it was a whole lot more.

I reckon i've saved about a grand so far in tiny niggly little things let alone the things i've avoided through research here.

No one should own a hi - po 4 stroke without reading all they can here first.

long live collective intelligence.

p.s havent heard from frostbite for a while, snow must have melted and its too hot for him to go outside. reckon he'd dehydrate at over 10 celcius.

Kevin on your advice i have searched to find the slide plate number to get a quote and to replace mine when i do my job, but i am unable to determine what the part number is, due mainly to not being able to identify the part.

is it the square thing with the little wheels on the side and a big hole in the middle of it? and do you have a part number? my genuine lack of knowledge is now evident.

It is part #12 on the carburetor schematic at yamaha-motor.com. It's the square plate that slides up and down as you turn the throttle. The actual part number to order is 4FN-14546-01-00. You will also want to replace the seal ring while you're there. It is 4FN-14997-00-00. I bought mine at www.ronayers.com for $74.55 (plate) and $6.87 (seal).

thanks for that.

i notice its a part that has been altered /improved/updated.

getting quote now

thanks again

yup, the new part seems to have less of an indentation, which hopefully makes it a bit stronger...I'm going to be very unhappy if this thing cracks again once my bike is back together....in that case I would've rather put the $100 towards an Edelbrock...

The last throttle plate that I purchased from yamaha was said to be updated, and it looked the same as the one I bought 3 years prior. Don't be fooled by the new part number. I bought mine last January, so unless the number has changed since then don't expect much. My '98 WR 400 has eaten 2 plates since I bought it. I now run a stronger billet plate that I had machined and hard anodized. My new design does not have the indentations in the engine side of the plate. I have descovered no reason for them. My bike runs great with the new plate, even though it is a well used bike, and has eaten 2 plate chunks already. I have some extras if anyone is interested.

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