Did any of you know that Yamaha 4T dirt bikes blow a plastic plug out of the head?

[merv]

There's me cool as a cucumber thinking at about 9pm last night I'll just fire my WR up and check it over before the CCA with the plan to fill it with fuel today and load a bag etc.

Blow me days its sitting outside my garage idling away and next thing there is smoke coming off the header pipe. Blip the throttle and it kind of blows it in puffs. Bit dark outside so I roll it back in the garage and find a plastic incased cap type plug has come out of the right front side of the cylinder head letting oil come out onto the header pipe.

All I can say is the gods were smiling because I'm lucky it didn't blow out when I was deep into the trail tomorrow and got lost leaving the engine pissing oil out of the head. What if I hadn't noticed it riding until the engine was dry, perish the thought?

I sealed it back in last night with black silicone gasket sealer but thought if it came out and went back in that easy I won't trust it to stay there. So home early from work tonight I made up a right angled piece of aluminium that I could bolt onto the side of the head that wraps around and holds the plug in place.

Until last night i didn't know it even had a plug there because its kind of out of view behind the radiator. Its not mentioned in the workshop manual at all either. I've talked to TSS and to Motorad and oh yeah they do that they say and my home made mod is quite common as is these http://cgi.ebay.com/ebaymotors/YAMAH...-/370343806498

That being the case why haven't Yamaha issued a maintenance alert or something or done a recall.

Sorry no pics at the moment but if you have a YZ or WR and this hasn't happened yet I'd say safeguard it now.

So that was a bit of a panic from a bike that has never given me any hassles before and then when I least needed it before the CCA, but I still had time for a shower and got to the briefing on time. Hope it all hangs together tomorrow.

[merv]

OK so no-one answered this question. My little home fix did the trick for today and the bike went well with no oil leaks all day. Sweet as.

[Ixion]

I can't comment on dirt bikes but the SRX250 which had what was originally a dirt bike engine though of an earlier era had a very similar arrangement. The plug blew out on me on the road spewing oil everywhere . Including the rear tyre. I did a similar bodge to you to ensure against repetition.

[Pixie]

It's not the valve adjustment access is it?

[Ixion]

No definately not. More like a frost plug sort of thing appeared to be to blank off a casting passage. Not intended ever to be removed. Until it blew I never even realized it was there.

[Motu]

plastic incased cap type plug]

Plastic - gone hard and brittle,lost it's ability to stay in place.We've been talking about plastic Japanese shitboxes since they were invented....has anybody listened? No,plastic shit keeps crapping out.Beyond it's service life - it's a dirt bike,it has no service life...and of no concern to Yamaha.

[merv]

Thanks for your replies guys and Ixion is on right on the button about the same problem. You'll see that ebay ad refers to it as a decompressor hole, but the WR I have doesn't have a decompressor - maybe some of them do.

I was hoping someone would pop up and say yeah its happened a lot and here's where you buy those plugs in NZ. Ref the NZ bike shop thread I'd want give them a chance and not buy on ebay yet huh!!

I was also thinking if I'm the first to post about this the other guys that own one could read it and go fix their bikes long before they crap out in the woods. That's what learning from experience is about.

Yesterday's ride report thread here http://www.kiwibiker.co.nz/forums/sh...ory-and-photos?

[The Pink Panther]

wr would be bucket and shim , so valve adjustment access would mean removing cam not like a rfs motor.

[Crasherfromwayback]

Good of you to bring it to other Yamaha owners attention Merv!

[merv]

.... and a rasberry to the industry again, I never ever did get a reply from TSS after ringing and emailing twice with the parts guy assuring me he'd check it out - even if it is a cheap item, courtesy should have it that you get a reply. Things like this are driving us to ebay.