Yamaha TRX850 Enthusiasts Forum

Hi.

Thought this forum might be the best to check this query:

Checked my TRX valve clearances: Meant to be 0.15 to 0.2 mm inlets
Are actually 0.27 to 0.29 mm inlets
Do you think that they need reshiming; 0.07 mm doesn’t sound a lot... or does it?

Regards,

Paul.

Norton850 wrote:Hi.

Thought this forum might be the best to check this query:

Checked my TRX valve clearances: Meant to be 0.15 to 0.2 mm inlets
Are actually 0.27 to 0.29 mm inlets
Do you think that they need reshiming; 0.07 mm doesn’t sound a lot... or does it?

Regards,

Paul.

You are in the region where you hear a distinct tick when the cam hits the bucket, you also miss out on lift.
All i can say, i would!

Tolerances exist for good reason, outside of tolerance? Replace the shims, simple as that.
As for why?
Think of a hammer and a well used cold chisel, note how the end of the chisel that get`s struck tends to deform and curl over?
Deformation can and does occur in components of a valve train if tolerances are ignored, plus your TRX will start to sound `unhealthy` too.
Go to page 21 of 306 on the repair pdf (downloads section) of the forum, you`ll note tolerances quoted for ALL the components that rotate or open / close and play their part in the combustion cycles inside your engine.

thanks for that will resim them then get a tune

Norton850 wrote:Hi.

Thought this forum might be the best to check this query:

Checked my TRX valve clearances: Meant to be 0.15 to 0.2 mm inlets
Are actually 0.27 to 0.29 mm inlets
Do you think that they need reshiming; 0.07 mm doesn’t sound a lot... or does it?

Regards,

Paul.

.07mm may not be much in terms of size but it's 35%

what you'll find is that you can probably move shims around to give you the tolerances you need which will limit the number of replacements you need. Yamaha used to do swaps as well