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DieselsRcool

Free compression release plug security!!!

18 posts in this topic

I'm sorry, I'm just too cheap to pay $20+ for a little piece of turned aluminum to replace the plug in the compression release hole in my 04' WR. So, I bent a small piece of brass plate to do the trick. Any material would do I would think. Now, if there's still enough crankcase pressure to blow the plug out, I've got bigger problems.

WR_plugsaver.jpg

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Mine blew out last weekend and I red loctited it back in. 28 months and the stock plug finally blew out when I started it cold back at the Chadwick campground. :)

I ordered the decomp plug for a back up. You can really tell when it pops out the engine runs poorly and spits oil. :D

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I made a similar 'security' plate for my WR about a year ago, out of aluminium. It was only gonna be temporary, until I got the TT plug, but it's in there and works fine. Oh, and i'm probably a bit cheap too..... :)

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If you had enough pressure to blow that plug out, you better start looking for the kink in your vent hose. If it's not kinked, you got a problem.

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Hey Larry, bike is looking kinda dirty :D:D Hey, I was just thinking of that last weekend while i was riding in th Gifford. I envisioned oil on my cherry red header and a rip snorting fire. :) Hey, can I use a starter contact :):worthy:

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Hey Rick

Sorry, LOL, I just picked my bike up the other day from Big Jim (Blireef on TT) who hauled it back up from Baja for me. I havn't had a chance to clean it up yet. Yea I was thinking about fire too and figured I'd nip that problem in the bud. I also just checked the valves, changed the oil and filter and am now ready for spring riding. :D:) OK, OK I'll wash it too.

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If you had enough pressure to blow that plug out, you better start looking for the kink in your vent hose. If it's not kinked, you got a problem.

The stock plug pushed back in with absolutely no resistance! :) I suspect the dimensional stability of the seal is not good long term. The material shrinks as it dries out over time. My breather is clear and working fine. :D

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Hey Rick... I also just checked the valves, changed the oil and filter and am now ready for spring riding. :D:) OK, OK I'll wash it too.

Larry, out of curiosity, was any valves out? I only have 230 miles on my bike now. How many does yours have? I'm hoping I have no reason to go in there yet. Now get to scrubbing! :)

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I made an aluminium plug to the dimension of the decomp shaft, but I left the decomp shaft in when I installed the yz autocedomp cam. Next time I check the valve I'll put the blank plug in. I'm cheao and lazy :)

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Nothing wrong with being cheap. :)

Rick, I have 1000+km on mine and the valves were fine. No adjustment needed.

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So, I bent a small piece of brass plate to do the trick. Any material would do I would think. QUOTE]

Did you still use the small copper washer? Did you use the original metal screw? From looking at the picture, I can't really tell.

I made up an aluminium bracket, but I reckon that if I use the original screw, it won't be long enough.

regards,

Nigel

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i just knocked this up on my little lathe today. Looks like shit but will never fall out. Uses the original shaft seal. Hopfully will have my head back this week, should be roosting by the weekend :) She is going to be a torque monster! Got the chamber, and had the floor of the inlet port built up, probably reduced port volume by about 25% and still had flow gains :D

decomp%20plug.jpg

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i just knocked this up on my little lathe today. Looks like shit but will never fall out. Uses the original shaft seal. Hopfully will have my head back this week, should be roosting by the weekend :D She is going to be a torque monster! Got the chamber, and had the floor of the inlet port built up, probably reduced port volume by about 25% and still had flow gains :)

decomp%20plug.jpg

That looks a lot like the one I made for my 426/450 cam conversion. Only problem I had was a small leak from the original seal for the decompress arm. When I went down to the dealer to get a new one, I was going to have to order it and it was a couple dollars more than the 450 plug they had in stock. Since I'm a cheap bastard that hates wiating for ordered stuff, I just bought the plug. I put a thin bit of sealer around it and popped it in and have never had any issues, along with all the other '03 and later bikes I see where I ride that run the stock plug.

My point with the vent tube is that, if it's not kinked and clear, there should not be enough pressure in your engine to blow out that plug, no matter how whimpy it installs, unless there is something adding to the pressure that a normal engine would have. My expierience is automotive in this regard, and if there is enough engine pressure to create problems, it's usually bad rings or cracked blocks and/or heads. Since a four stroke is a four stroke, I could see where this would be the same for our bikes. I could be wrong and perhaps our bikes at times build up a ton of pressure, but I have yet to see the results of that problem on my bike. :)

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IMO you are wrong about the plug issues that many WR450 owners have had. I just had my engine completey rebuilt and the plugs pop off with no effort that it is a sign that the rubber plug shrinks and the fit becomes loose. :)

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what's the deal with the plug on the 04 WR450. I got 800 miles on mine and haven't had any problems with that plug thingy

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I did not know 04's had a plug as well. I thought they recast the heads in 04? :)

'04s have the plug. Yam did not modify their castings until '05.

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Did you still use the small copper washer? Did you use the original metal screw? From looking at the picture, I can't really tell.

I made up an aluminium bracket, but I reckon that if I use the original screw, it won't be long enough.

I left off the copper washer and used some gasket sealer on the screw threads. The brass sheet I used is only slightly thicker that the washer was. I also put a little gasket sealer around the seal before re-installing it. My plug never popped out, I pulled it to get the dimensions to turn my own plug but couldn't get into the hole to measure it correctly so decided to go this route.

Remember this is a single cyl engine. Unlike auto engines that have one piston moving up at the same time another piston moving down to balance the crankcase pressure, this engine has to displace 450cc of air out the vent tube and then back in every revolution. Since the air inertia is too much to really vent out the vent tube at anything above idle the crankcase pressure just fluctuates positive to negative every revolution. Once the plug gets old it doesn't take much to vibrate it out. I have a friend with two WRF450 quads and both spit out the plug after only a couple hours from new. It makes a big oily mess and ends your riding day early. :)

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