[Crf450Ash]

Hello,

Just joined, looking for some help!

Recently bought a crf450r 2018,
Before riding I checked my clearances to find they were out of spec! Thought it would be best to do a piston change at this point to ensure I started a fresh with maintenance!

Once the head was off I checked both intake valves and exhaust valves with fluid to check for leakage, exhaust side all ok! Intake side both valves are letting by slightly, was advised to change for new so I stuck with stock and bought titanium! After doing some reading I payed someone to cut new seats for my new valves only after getting it home I have checked with fluid once again and I’m still getting leakage!

What should I do?
Is this common?

I’m concerned about cutting the seats again as could get to a point where I am no longer able to shim within spec

Thanks Ash

[Aussiecrf230]

Hi Ash and welcome to the site.

If you payed someone to cut your seats and they still leak, in the first instance take that up with who did the work. Do they regularly do motorcycle heads?

Did you have springs intalled or valves just sitting in head.
This can make a difference when freshly cut, shouldn't but can.

You can use some prussian blue to confirm good contact and sealing before you take it back. Something I have always done to prove the contact face is OK and in right spot on valve.

I am sure Jim or Neil will put their wisdom on the subject, If they can stop riding for a moment.

[Crf450Ash]

I did ring him, went back to his shop and he went on to say that he has seen new cylinder heads with new valves which leak,,

Obviously we had a bit of an argument due to that fact I’m no better off than I was before! He went on to say that they may bed in!!

He didn’t want to grind any more off the seat due to options when shimming the valve clearances!

I mean it takes a around a minute to show leakage and it does make me wonder if it is really gunna be that much of an issue?

The only other thing I was thinking of doing is to buy a stainless valve and with lapping paste try to get a better seat myself!

I have not yet checked with any engineers blue, also the springs were fitted when testing with fluid

Thanks Ash

[JimDirt]

Welcome to the site !!

Yea , I agree with Ray on this , they should not leak if the seats were cut correctly , etc. and yes I was riding .. question , does this guy do bike valves mainly , or is this just some mechanic that works on cars that said he could do this ?? , these valves require special cuts and tools , although he is correct about the seat depth , if it is cut too deep then what happens is the stem sticks out farther , then what happens is you need smaller shims because the distance is less , then if it is cut too deep then you can't get a small enough shim to fill the gap , so then once the first valve adjustment comes around , then the head is toast because you can't adjust it without replacing the seats or possibly scrapping the head ...... unless you take it to someone who really knows these heads and they replace the seats , which is basically like starting from new ..... but no matter what , they should not be leaking , the entire point of the valve face matching perfectly with the seat is so it seals .... and DO NOT try to lap them ... bad juju ...it will kill the valve right away

My personal opinion ( I get nothing out of this , just know what kind of work he does) is to send the head to Ken , here , and have him go over it , he will give you a honest and fair evaluation of what it needs or if it needs anything , and what way is best to go ...

On a side note ...I am guessing you bought the bike used ... do you know how the original owner maintained the bike or how he rode it ??? , my guess is he was riding in real dusty conditions and possibly dirt was getting past the filter to the inside of the air boot ??? , as this is usually what takes out valves quickly , not sure how many hours you have on the bike or if you know (I put a hour meter on mine before I ever rode it) ... dirt is the killer of valves .... unless you are or he was bouncing off the limiter all the time like Justin Barcia ... you should get a couple seasons out of the valves

I have 64 hours on my 20 with no issues , I plan on going to 100 then doing a piston and popping the valves out and taking a look at the valve faces at that time for cupping/wear

But seriously , Ken does excellent work at fair prices and is honest as they come , you can even get a complete ready to go head from him if there are serious issues with yours ... you will not be disappointed with his work or prices .. That is my recommendation , so you know what you have and what "needs" to be done with it to make it right .. I sure would NOT take your head back to the guy that did it ....he should stand behind his work and try to make you happy regardless of why it is leaking , you did not pay him to get back a head in basically the same condition you sent it to him in

Contact Ken with a Private Message
https://www.crfsonly.com/forum/memberli ... rofile&u=3

[Crf450Ash]

I checked out the link you sent me!

It’s in America, unfortunately I am in the uk! Does anyone know where I can get a good service in the uk?

Regards Ash

[JimDirt]

I don't know personally , I do know Ken will ship there and take things from there , but with the ports being the way they are , it is going to be tough to get anything shipped unless you don't need it for at least a few months .... so with that said , I do not know of anyone directly over there

I am sure you have Moto forums over there , I would bet there is a Sticky post or a topic somewhere with repair or machine shop services that are close enough to you to help , that everyone recommends highly , or I bet even guys at the track that would know or recommend a place local or close enough to drive or locally ship , or buy a complete setup/swap , without having to wait months to ship things here , then back ... hopefully just not the guy you had do your stuff already ...