Wr450f 2004 Thumpertalk Saves The Day

Hi Bryan and all at Thumpertalk

Thank you very much for saving a Fantastic days Trail Riding in the Lake District of Northern England. I had arranged for a guide and was Really looking forward to riding on the legal trails around the Lake District.

Prepped my WR450F 2004 model on the Saturday, new brake pads, chain & sprockets etc and took a quick test ride around 5pm to make sure all was OK. All wasn't OK, my bike was spitting oil out over my exhaust from a gaping hole in the head? I checked the manual and couldn't even find a picture of what was missing from this hole. I thought I had done some serious damage to the engine and being 5pm all the Yamaha Dealers were closed so I couldn't ask them.

I remembered reading about a "PLUG" for the Yamahas on your website, but I had no clue what this plug was for. So I logged on to Thumpertalk and found the Thumpertalk Decompression Plug which even had photos of the hole, the new plug and the mess that the oil makes over the exhaust and radiator.

Thanks to your site I found the problem and realised that I hadn't blown my bike up. Printed the photos and phoned a friend that does some wood turning who turned a copy of the Thumpertalk Plug out of Beech Wood and we cut a gasket out of an old piece of thick Inner Tube.

The temporary wooden plug worked and a got a Fantastic day riding on the Sunday in the picturesque Lake District.

I have since ordered my Thumpertalk Decompression Plug which is on its way to me after an initial hic-cup on me inputting my card details wrong.

It may be worth putting the photo of the Oily Mess that loosing the genuine plug leaves next to the photo of your Thumpertalk Decompression Plug so that members understand what happens when the genuine plug blows out?

Thank you very much for saving a fantastic days riding.

Alex Robinson - England

I have now recieved my Thumpertalk Plug and will be installing it for this weekend, Cheers, Alex

A plug turned out of wood ! :naughty: what a cool story! :naughty:


The product description doesn't mention current engines:

When using an 03 exhaust cam in a 98-02 engine, the manual decompression lever, cable and actuation arm/shaft can be removed. Yamaha sells a rubber plug that replaces the hole this leaves however, the plug doesn’t fit well and can be blown out by normal crankcase pressure! Even if you ride an 03 to 04 machine, Yamaha didn’t recast the head, so the same, inferior rubber plug comes stock.

Apparently it happened to alexrobinson's '04. Is this something to consider as preventative maintenance for an '05?

I just got the NEW after market plug from TT also.

I was on the ice when mine blew and I literally thought I blew my bike up.....

I almost cried like a little baby.

nice to see the 05 bikes have that hole capped off for real.

Hi Alex,

I've just bought an 04 Wr450 and I'm now concerned that may happen on mine. Where should i be looking for this plug?

By the way, I'm over in Northumberland...let me know if your heading over this way and maybe arrange a rideout.


Hi 636Sean in Northumberland. Check out the HOME PAGE of Thumpertalk they advertise the Thumpertalk Decompression Plug, click on this link for more details and click on "view more pictures" it has pictures of where this plug is on your bike and the mess it makes if or when it pops out. I ordered mine online from Thumpertalk and cost about £20.00 with the exchange rate and postage etc and it took about 1 week to come.

I am a member of Teesside TRF Group and am leading a group on the TRF Coast to Coast, so have been doing lots of riding to finalise our route from Scarborough to Hawes 1st day with lots of Lanes over the North York Moors and the Yorkshire Dales to Hawes and 2nd Day The Lake District over to Coniston then down to Morecambe.

Usually get up Northumberland a couple of times a year starting from Hexham with Dennis from your local TRF group. Is it right that there have been a lot of Lanes closed TRO'd up in Northumberland?? Also want to get back up to the Cheviots, I have only been fortunate enough to ride up there twice, but some of our group will be making a trip up their this year for sure.

Order your Thumpertalk Decompression Plug before the Yamaha Original pops out, also check that your TPS Throttle Position Sensor is unplugged (little electrical connector that joins to the TPS on your carburettor) unplug it and tape up the ends. If you leave the TPS connected you will never get rid of the Stutter at constant Mid Revs that you can only feel when riding on the road between Trails and it drives you nuts.(Lots of Details on Thumpertalk about the TPS Sensor).

Also I found that changing the 14 tooth Front Sprocket to a 13 tooth Front Sprocket and keeping the standard 50 Tooth rear is best for Trail Riding.

Hope this helps, Cheers Alex Robinson (Teesside Trail Riders Fellowship)

Hi Alex,

thanks for the info. I only picked the bike up last weekend and when i took it up the road for a spin i thought the bike didn't feel very happy cruising at a steady throttle, seemed to be stuttering. So I've rushed into the garage to un-plug that TPS connector, hope i've un-plugged the right thing ( electrical connector zip-tied to the frame on left side of carb).

I'll see if it makes a difference tomorrow.

Im totally new to green laning, so dont know about any lane closures.

Hoping to contact my local TRF soon to arrange some rideouts.

The coast to coast sounds like a real adventure....maybe need a few miles under me before attempting something like that!!

I'll let you know how i get on when i get up into the cheviots



Hi 636 Sean,

Yes it sounds like you disconnected the right plug, I am sure you will feel the difference.

Yes contact your local Trail Riders Fellowship Group to get on one of their club runs. Our Teesside TRF Group meets every 3rd Tuesday of the month at the Ranch House near Stokesley (which is tomorrow night), it's a long treck for you but the Teesside Group has Club Runs that you may be able to mix with the Northumberland TRF Runs until you get to know where you are riding.

Don't forget to check that Decompression Plug.

Cheers, Alex

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