Yamaha TRX850 Enthusiasts Forum

As usual I've been tinkering with the bike today & thought I should change my spark plugs while the fairing was off. I was shocked at the general condition of them both (very rusty, probably not been changed for years) but my main concern was the fact that the right hand plug looks to be running a wee bit rich. Then I remembered reading on here that 1 side does run richer than the other so I just want to know... . . WHY ???
I have searched.

One cylinder runs hotter due to water jacket

Cheers for that. A design flaw then ?

Hi G Beale!

As most recently (two hours ago) posted in the German forum by "Brummer" a reason for a richer running cylinder can also be a defektive vacuum membrane of the fuel tap leaking additional fuel in the (in Brummer's case) right cylinder.

Transferring greetings from Munich!

Ive got the same problem. RH side plug has carbon fouled on me a couple of times latley.Will have to delve into it.

phuk72 wrote:One cylinder runs hotter due to water jacket

What is it about the water jacket that affects the cooling phuk?

Carbon fouled plug RHS. Found the RHS cylinder vacuum hose connected to fuel pump, disconnected smelt of fuel but dry. Manual says no spare parts for pump eg. diaphram only sold as complete unit. Has anyone run into this problem before?

Thanks for the info lads. Fitted new plugs now so will keep an eye on their state over the next few hundred miles. If it's too bad I will look into it but I'm a bit reluctant regards taking stuff to pieces unless it's so broke the bike wont run.
I thought maybe leaning off the right hand carb might even things out a bit ?

Leaning the mixture (by the screw) will only affect the very low speed and idle running.