CRF 250R 04 steel valves question !

[Kolias89]

Hi guys!
I wanted to ask...if i add steel valves on my CRF without changing the springs or anything else and keep the OEM's?... what could really happend on my Bike?
I mean a friend gave me 2 brand new intake kibblewhite valves and i wonder what could be the damage if i just put them instead of the titanioum ones!

Thanks in advance for your time!

 

[_JOE_]

You can ruin the head. Your stock valve springs can't control the extra weight of the steel valve which leads to "float" and burnt seats.

 

[whenfoxforks-ruled]

As long as the valves are new, re-cut the head seats, and get the springs, buckets and keepers for the KW's. It should last a good while. Check your piston and crank while you are at it. Vintage Bob

 

[Kolias89]

thanks for the replys guys!

Here is another question that a friend asked me about kibblewhite valves!

He bought the kibblewhite kit(steel valves, springs washers retainers), after he installed the kit he run the bike and everything seems to be ok!
After 5 hours of use he start hearing a noise from his top end...
When he opend the top end and took out the camshaft he realised that the camshaft (left lobe height) was destroyed and the left bucket too! When i am saying "destroyed" i mean that the left cam lobe height went from 36mm to 35mm and the bucket got a "hole" 0.3mm!

Why do you think that this happend??
He didn't do anything wrong and the bike was run great as he told me until this engine noise!!
Thanks in advence!

 

[mideastrider]

assuming he did everything right (almost) and all parts where good/new, the oiler or squirter for that lobe&bucket is clogged or for some reason not putting the oil where it should go Check the oil passage all the way back to the oil pump..

 

[Kolias89]

All the parts was brand new!
I asked him and told me that he checked the oil pump and everything seems to be fine!
I also take a look at his bike and there is no way that the oil there, isn't enough because when he opened the cap you could clearly see that everything was flooded of oil!!

With some research i've made i noticed that kibblewhite sells different buckets designed for the kibblewhite valve kit!
Though, he didn't change the buckets and left the OEM's, do you think that the camshaft first damage the buckets because of the harder springs and then damage the camshaft because of the hole on the bucket??
I can't think anything else!
Also just to let you know the oil he used this time was Motul 15w-50 4stroke!
I know that on crf models you should use 10W-40!

 

[IndyMX]

I changed my stock valves out last year with Kibblewhites. I did not change the buckets, and they are still just fine.

 

[Ol'89r]

My guess is he didn't re-check his valve clearance soon enough. When installing new valves, they normally seat in very quickly. When they seat-in, they lose their clearance and if all of the clearance goes away, there will not be enough room for oil to get in between the cam and cup. If you continue to run the bike, it will quickly wear out the cam and cup. Like Indy said, the stock cups work fine with the KW valves.

Did he re-grind/re-cut the seats?

Did he lap the valves into the seats? (SS & steel valves only)

Failure to do this can result in the valve seating itself during the first hour of operation and the loss of clearance between the cam and cup. If he continued to run the bike for five hours without checking the clearance, that could be his problem.

IMO, the valve clearance should be checked right away after installing new valves.

 

[Kolias89]

Ok just called him...

He didn't re-cut the seats...
He installed the valves and gave the correct clearance...
After that he run the bike for about 15 minutes at 3000-4000 rpm and then he re-checked the clearance and told me that the clearance was as at the first place!
So he left it as it was BUT he mentioned that until he find out the problem the compression was perfect with no problems and the bike was cold start with 3-4 kicks!
If the clearance was zero then he couldn't have this compression right!??

Thanks again!!!

 

[Ol'89r]

If the clearance was zero then he couldn't have this compression right!??!

On a cold engine he could have compression with minimal clearance. But, when the engine warms up, everything expands with the heat and the clearance will go away. If the bike requires .010 thousands clearance, usually the valves will tighten up with the heat expansion leaving only .001" or .002" clearance under normal operating temp. If the valves only have .007" clearance when cold, you will have a negative .001" or 002" clearance when the engine is hot resulting in burnt seats and damage to the cam and cup.

I would recommend he take the head to someone that has the proper tools and knowledge to do the job right.

 

[Kolias89]

Thank you very much for your interest!!!
Though, it's too late he changed averything back to OEM's valves, springs,retainers, new camshaft!
He told me that now everything seems to be ok!
For what he did now with brand new OEM parts what is the right break-in procedure?
And after the break-in what is the right thing to do?
About checking his valve clearance and stuff!

 

[Ol'89r]

Assuming he cut the seats before installing the valves, he should check them after the first hour of operation. Then, check them after each ride to insure they stay the same. After checking them 2-3 times they should be ok as long as they didn't move much in the beginning. He may also want to use the proper oil. A 10W-30 or 40 is thinner than a 15W-50. The modern day fourstroke has very small orifices to transmit the oil. If you use too heavy of an oil, parts can be starved for oil during start up.

 

[Kolias89]

I don't think he re-cut his seats but i will tell him to check his clearance very often for a few times just to be sure!

And one question for me now!!
How can you understand if your seats need cut?
Is there only one way or multiple!?

 

[Ol'89r]

They almost always need to be cut. After a while, the seats get pounded down into the head. Since there is not the same support around the whole seat, they will become uneven after a while. If you take some machinists dye and coat the seat and the valve and then lap the valve into the seat, you can see where the seat is not sealing. If you don't grind the seat, you will quickly burn your new valves.

 

[whenfoxforks-ruled]

They almost always need to be cut. After a while, the seats get pounded down into the head. Since there is not the same support around the whole seat, they will become uneven after a while. If you take some machinists dye and coat the seat and the valve and then lap the valve into the seat, you can see where the seat is not sealing. If you don't grind the seat, you will quickly burn your new valves.

+2!

 

[Ol'89r]

Is there only one way or multiple!?

There are several ways to cut the seats. They all require special tools. They range from a SERDI machine that costs several thousands of dollars to hand cutters that cost a few hundred. There are also valve seat grinders.

This thread is a perfect example of what happens when you don't spend a little extra money to get the job done right. Your friend has already done the job twice and if he didn't re-cut his seats, he will most likely have to do it a third time. :yikes:

For what he paid to replace his camshaft and the rest of the damaged parts he could have bought a new head.

If you don't have the proper tools and the knowledge to operate those tools, IMO, it's better to take your head to someone that does. The heads on these new thumpers are not the same as the one's on your granpa's XR.

 

[Patman]

The heads on these new thumpers are not the same as the one's on your granpa's XR.

And even though I have an xould XR's I send my stuff out to be properly done. Cheap insurance for long service.

 

[Kolias89]

Yeah you got right!!
He got some knowledge but not as many as he had to....!!

I am starting to think that the choice of buying a 4 stroke was a bad idea...
With a 2 stroke you don't have that kind of problems!
and i don't race just for trail riding!!
OMG....

 

[IndyMX]

There's nothing wrong with modern four stroke race bikes. You just have to use some common sense. And like Terry said above, take it to someone who knows what they are doing when you don't..

 

[whenfoxforks-ruled]

I honestly feel the 2 stroke has more areas that fools with tools can screw up.

 

[helio lucas]

I honestly feel the 2 stroke has more areas that fools with tools can screw up.

naah... only the piston or the cylinder ;)

 

[Kolias89]

Hi guys another question!

What could happend if i use a 15w-50 oil instead of 10w-40 on my CRF250R 04'?

I had an argument with my friend that uses 15w-50 and i thought to ask you guys!

Thanks!

 

[_JOE_]

In warm temps it might actually be a better choice, given equal oils.

 

[Kolias89]

I am talking about Motul 5100 oil and about 10-15 celious degrees!

And in cold temperatures what could happend?
There is a reason i am asking and i want your opinions!
Thanks!

 

[Patman]

Those are not the warmer temps he was referring to, try at least 85F. There is a reason Honda has a specific oil requirement.