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The TTR250 FAQ web pages -> TTR250 -> Repairs and maintenance -> Valve seat cutter choice and/or replacement of seats?
Post Info TOPIC: Valve seat cutter choice and/or replacement of seats?
sena


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Valve seat cutter choice and/or replacement of seats?
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    Hello everyone.

my bike restoration project seems becoming a "Winter project in a Tropical country" confuse

After cleaning and gently grinding in the valves, I found that exhaust ones are out of specification.

I will need to order a new set and cut the valve seats to fit the specs. Then it will be another story for shims....  but today my question is: I would like to order a Valve seat cutting tool. Not knowing different brands and qualities, I saw too many different sizes and brands available from too many makers, some cheap and some priced more than a whole engine.

- Which brand/ model/ Part N° will fit my needs?

- also, which model of "valve grinding tool" for a drill can I choose? I saw some but don't know the SIZE of the suitable suction pad for TTR small valves.  ( the tool that TTRFan uses, once attached to the drill it transforms Rotations to Oscillations). 

I tried grinding valves by hands, with a stick; also with a hose;  that's not a job for me.  And I don't want to risk attaching a hose to a drill: too easy to ruin valve guides and seats. no

 



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TTRfan


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valve seat cutter choice ?
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Hi Sena

I am guessing that no-one has tried re-cutting their own valve seats hence the lack of replies.

Selecting a valve seat grinder set that is the correct size etc. for the TTR and capable of dealing with the hardened valve seats is difficult. Most of those listed on eBay are for older engines that don't have the hardened valve seats which accompanied the introduction of unleaded petrol.

The only set that can be 100% trusted is the one specified by Yamaha in the "special tools" section of the workshop (valve seat cutter set YM-91043). My Yamaha parts supplier has quoted £739 for the genuine Yamaha set  cry  This would be a big outlay for a tool set that might only be used once. 

I have to confess that I am completely out of my comfort zone on this question and would really appreciate input from any other owner with direct experience.

I cannot find the valve lapping tool I use on eBay but one of the same design is available here.  

The valve shim sets are expensive and if you buy one for your project, rather than individual shims, you will end up with a lot of shims that you will never use. Here is an example of a kit. An alternative would be to buy 2 or 3 each of the most commonly used shims - 1.80 to 2.00 perhaps?

 

Brian



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sena


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crycry  sounds really expensive for a one-time. I try to get as most tools as I can afford to service my bike by myself.

In my country, only KTM shop mechanics have all the right tools and do a correct job. They refuse to work on other brands furious

All others don't even read manuals before hammering down and overtighten bolts and nuts, stripping threads and breaking parts. Usually a serviced bike produces more smoke and runs worse after than before disbelief

If I get it right, running with mating surfaces little out of specs doesn't totally kill the performance ? or grinding-in a new valve set somehow allows to avoid cutting seats ?

-sorry for dumb questions, right now I have only IP addresses and passwords in my head (solving entreprise local network issues, almost done)



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TTRfan


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RE: Valve seat cutter choice and/or replacement of seats?
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Has any owner had their valve seats replaced? 

If so, can you give us the details please biggrin

See here for some more information about the process.

Brian



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