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The TTR250 FAQ web pages -> TTR250 -> Repairs and maintenance -> Cam buckets or "Valve Lifters" query
Post Info TOPIC: Cam buckets or "Valve Lifters" query
TTRfan


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Cam buckets or "Valve Lifters" query
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Hi folks

I need some advice please.

A customer asked for a quote for 4 valve lifters - as Yamaha calls them. I looked up the fiche and it showed two different parts - a blue and a red confuse

cam followers.jpg

Anyone know the difference please?

Brian



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TT-R250M


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One is for OS valves the other is for standard. Don't quote me on it but I am pretty sure blue is standard and red is OS.

Jarrah



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TTRfan


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Hi Jarrah

What are OS valves please? I can only see the standard valves listed on the fiche confuse

Brian



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TT-R250M


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Oversize. The oversize valves will not be listed as they are not standard parts.

Jarrah



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Cubber


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How does an OS (over size) valve head make it necessary to have a different sized valve lifter (cam bucket)? confuse

Are the valve stem diameters different between OS and standard? confuse

If so, are the valve guide bore sizes affected? confuse

Do RED and BLUE in the remarks column of the lifters mean different sizes?

The prefix UR in the remarks column means "Use specified parts number" according to page A5 of the catalogue.

Martyn



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TT-R250M


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Cubber wrote:

How does an OS (over size) valve head make it necessary to have a different sized valve lifter (cam bucket)? confuse

Are the valve stem diameters different between OS and standard? confuse

If so, are the valve guide bore sizes affected? confuse

Do RED and BLUE in the remarks column of the lifters mean different sizes?

The prefix UR in the remarks column means "Use specified parts number" according to page A5 of the catalogue.

Martyn

 N1. You need to fit oversize springs to go with the oversize valves.

N2. Yes.

N3. Yes, you have to fit oversize valve guides.

N4. I can't be 100% on this but I'd say the RED are the OS and Blue are standard.

Jarrah

 



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Well I never would have imagined that.

It seems as if I live up to my signature - yet again. biggrinhmmno

Martyn



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Andy_C


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Hi Brian
Do the "old" ones have a coloured dot on them,if so you could get like for like,assuming everything is standard.

Do they need to be different for exhaust and inlet valve? to allow for valve temperature difference?

Just putting those thoughts out there.

 

just had a quick goggle and found this,may shed some light on it,interesting reading anyway.

http://www.thumpertalk.com/topic/865418-yamaha-yz250f-question/



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Andy_C wrote:

Hi Brian
Do the "old" ones have a coloured dot on them,if so you could get like for like,assuming everything is standard.

Do they need to be different for exhaust and inlet valve? to allow for valve temperature difference?

 

 No, they do not have blue or red dots on them. If they did they would wear off anyway.

No, the intake and exhaust are both the same part number.

Jarrah

 



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