A forum for owners of Yamaha TTR250 trail and enduro bikes!

barra8 · Guru

What to replace when replacing valves

barra8 · Guru

Ironhorsend wrote:
Hey Jarrah,
Any thoughts on the Kibblewhite valves for the TTR250?
I see they are available.
Looks like they also have a spring and titanium retainer kit as well.
Yes they are spendy.
Any benefit going with these or is it overkill/waste of dollars?

The TTR is not a high reving engine so these won;t be needed.

It also has a restrictor built into the CDI so valve bouncing is'nt a problem.

If i was to de-restrict it then i would upgrade the valves.

The benifiet being that they last longer with the downfall of paying more.

Up to you but it's definately not needed in a TTR250.

..................

Jarrah.

-- Edited by barra8 on Thursday 20th of December 2012 01:28:39 AM

Ironhorsend · Member

Thanks Jarrah!
Looks like my post got moved.
I must have subconsciously tried to jack your thread!
All apologies,
Darin

Ironhorsend · Member

Hey Jarrah,
Any thoughts on the Kibblewhite valves for the TTR250?
I see they are available.
Looks like they also have a spring and titanium retainer kit as well.
Yes they are spendy.
Any benefit going with these or is it overkill/waste of dollars?

barra8 · Guru

mingle wrote:
You only need to replace valves if they are bent as in hitting the
Piston, its very rare they wear out. Valve seats and valves guides,
And valve seals wear out first. A machine shop will be able to
"regrind" your seats and Valves. This saves money in
not replacing parts that don't need replacement

Some of what you say is true & some is not...

The valve stem seals are the first to wear out.

Next is the exhaust valves (as they burn)

Then the intake valves.

Then valve springs.

Very rarely do you ever have to replace the valve guides unless the valve has been broken & damaged the guide (or you have a burnt valve)
.........................

Springs & valves are cheap & for a mechanic to have to clean & re-face old valves would cost more than new valves.

Fitting new valve guides on the other hand will become expensive $$$$

Also if you have to fit new valve guides new valves will be needed anyway.

.....................

I'm not sure how expensive a mechanic is over there but here they are AU $60-$80 an hour. For them to clean,re-face four valves then reseat & re-shim them would be an hour. I got mine done in half an hour with the new valves...They ''basically'' payed for themselves.

I also had porting done which was an extra $40 (some of which i did myself) but that's another story. smile

...............................................

So you understand................

This tread was removed from my rebuild thread so it didn;t clog it up so it may not read right from the top.

I started this thread for Darin as he is ''ifiing & butting'' about wanting to re-build the top end.

ps. Still pissed about your homemade ''dodgy'' brake bracket i take it -don't worry maybe someday you will get your sweet revenge wink

................

Jarrah.

-- Edited by barra8 on Thursday 20th of December 2012 08:22:23 AM

mingle · Veteran Member

You only need to replace valves if they are bent as in hitting the
Piston, its very rare they wear out. Valve seats and valves guides,
And valve seals wear out first. A machine shop will be able to
"regrind" your seats and Valves. This saves money in
not replacing parts that don't need replacement

barra8 · Guru

To mingle.... $80 is (roughly) how much the valves cost me so you did'nt save much at all.

Of course you can re-face them but why bother when they are $19.00 each??

If you have to get a mechanic to re-face them it will cost roughly $40

If he has to clean them it will be an extra $30 (as they don't like doing this much ).

Then re-seating them will take longer than new valves so there is an extra $20

So you may save $20 or so on fitting old valves (not much) if most of the work is done yourself.

I don't work for less than $20 an hour so if i had to do the work i'd have to take that into account aswell.

The valves are the most important part as if these go ''all goes''

I'll stick to buying them new & having peace of mind

Each to their own.

...................

The days of re-grinding old valves are nearly over. New valves are becoming cheaper & not alot of mechanics these days like to re-grind unless the new valves are expensive. Re-grinding will become a thing of the past given time. I know i would rather pay $20 more to have the new valves (but i'm fussy).

Jarrah.

-- Edited by barra8 on Friday 21st of December 2012 01:01:25 AM

barra8 · Guru

To do it properly ...

Okay first thing they to do is clean them $30

Then they regrind /re-face them $40.....They grind the ''old'' valves back to the right angle (re-face.)

Then they have to cut new seats into the head. (usually only needed for old valves or damaged head) (re-seat)

They then re-seat/lap them into the head $40 (or $20 for new valves)...... using the grinding paste. (re-seat/lap)

.......................................

The way your doing it works but i bet it takes a bit of grinding with the paste wink (try this on cars & you'll have fun :)

They don't do that because it would take too long & cost more.

................

Jarrah.

-- Edited by barra8 on Friday 21st of December 2012 03:14:09 AM

mingle · Veteran Member

You can save a lot of money If you know how to readjust valves with a feeler gauge and perform a little math.
And porting and polishing isn't exactly rocket science. Being a auto mechanic has its perks, I have a buddy who owns amachine shop
And he refaced my valves for $40US. I assembled it measured them.
A trick is : use a 12mm socket on the end of the valve retainer. Support the valve face. Then tap the socket with a hammer and the valve keepers pop out. But make sure to keep track of them!!. And jarrah my dodgy brake set up has been performing flawlessly. I've gotten multiple complements on it. And its still waaay better than stock when it comes to stopping distance and braking effort

TTRfan · Super Guru

Maybe I have been lucky with valves.

My original project bike engine was pretty knackered and the valves were well coked up showing that at one stage the bike had run hot and lean and then started burning a lot of oil.

A "before" shot of the valves.

Engine build 020.jpg

I expect any mechanic reading this will cringe at how I clean the valves but I haven't had a problem yet using this technique! I stick the valves in the electric drill and then get most of the coke off with a metal scraper blade and then follow up with 2 or 3 different grades of emery paper.

Engine build 021.jpg

Engine build 025.jpg

I was surprised at how thick the crud was on the exhaust valves so weighed them before and after. There was about 2 grammes difference after cleaning! The valves now look fine and are definitely re-usable. The seats will grind in nicely.

Engine build 023.jpg

The grinding in process takes a while but I haven't yet come across a straight valve that I haven't been able to re-use. You just have to use the "rough" valve grinding paste occasionally biggrin biggrin biggrin

Brian

TTRfan · Super Guru

I may be confused here confuse

What do you mean by "re-grinding" Jarrah?

Is it the same as lapping? See vid below:

barra8 · Guru

I forgot to say to Mingle.... I know you can tap the valve retainers with a hammer to loosen the keepers. After that all you need to do is push down & they come out. Showed someone a vid awhile back on how to do this.

I have done valve re-grinds on cars so i don't need to be told how to do it.

I don't have a problem with you buddy but please stop trying to pick apart anything i say.

....................

Jarrah.

barra8 · Guru

Because this thread has now got clogged up...

So if you want to do the valves i suggest you buy...

New valves (unless you don't mind doing the work)

New valve stem seals (all the same)

New springs (if needed)

............................................................

Other than that it's not likely that you will have to replace anything else other than the shims.

Here is the thread for the youtube vid for removing valves that i was talking about in the post above ...... here

.............................

Jarrah.

-- Edited by barra8 on Friday 21st of December 2012 10:03:48 AM

Ironhorsend · Member

Thanks for all your input, gentlemen.
Each post is useful and has it's merit.

I fixed my leaking decompresser plug last evening. It's great not to have any leaking oil.
It's beginning to look like the seafoam job I did on my valves is working.
It doesn't smoke at all now and runs very nicely.

I might give it one more shot of seafoam, burn it off again, change oil to remove any crap the seafoam dissolves, and try a compression test.

I did have a minor score thought the other day. I found a site that had the complete Kibblewhite valve springs, titanium retainers and clips for a really good price. The Kibblewhite spring kit retailed for around $160 USD. This site had the complete kit, new, for $20 shipped. I figured that's even cheaper than the stock springs/retainers etc, so I better snap it up for a rainy day.

Happy Holidays to you all over there.

Best wishes to you and all your loved ones,

Darin

TTRfan · Super Guru

I have deleted the last couple of messages that didn't really add anything to the thread. Please keep to the plot folks.

Brian