03 Yamaha WR250 - dropped valve

[Mudd Slinger]

I have an 03 that did not get ridden much over the last 2 years and mostly trail rides with maybe a few hot laps on it (higher revs). Everything is stock (except free mods) and the valve were checked 2 rides ago (last year but still in spec) but on the tight side. I started adding up the mileage (before hour meter added) and hours on the bike and was quite disturbed to guesstimate there was almost 100 hours on it. I should have rebuilt it and I would not be having this issue. I run 100 octane from the same pump/station to avoid junk and other gas issues (Exxon?).

I was having varnish problems in the carb on that day (would not idle well and had a bog when getting on the throttle too fast). I assumed I needed to soak the carb and clean it even though I rode it a month prior at home. On the previous ride it did the same thing but cleared up quickly with a ride up and down the road . Could this cause a lean condition and valve damage? See pictures.

The bike was only ridden twice on the trails this year due to a recent unemployment problem (corporations needs to quit hiring foreigners to replace american workers). I typically start and ride my bikes in the field next to my house approximately once a month to avoid issues with sitting too long.

The head popped of the valve stem and did some damage to the piston face and head but not too serious. Clyinder looks good. I will post some pics. I assuming both the head and piston are trashed. The broken valve head did some damage around the area of the valve seats. I do not think it can be cleaned up and still be reliabile (valve seats?). Do I need to worry about the connecting rod bearings and crank berarings too since I am tore down?

I am in the process of pricing parts and the OEM head is approximately $650 each (OUCH). I would like to go with the Black Diamond Kibbblewhite SS valves and some stage 1 hot cams. I am still researching my options from there.

What are my options? I don't race anymore but can occasionally get a little agressive on the trails but reliability is more important due to my long rides in remote mountains where pushing a broken bike to a road would be a problem.

Please help!!

 

[_JOE_]

Wow, that sucks! Is this grenaded 4 stroke week or what? Good thing I'm not riding mine! Those valves look pretty rusty? Have they been shimmed before? 700 bucks for an OE head, that's expensive, my CRF head is under 300.

 

[Mudd Slinger]

The valves were checked about a year ago (actually 2 rides ago). They were on the tight side of the spec but still in spec so they were not shimmed. I talked to williamsmotowerx about salvaging the head and they want to look at it. They said the rusty valves is not uncommon from sitting.

I am hunting for a better OEM head price. Williamsmotorwerx may be my best option with stage 1 hot cams. I need to research Williamsmotorwerx some more.

I now have a new excuse to ride. Sweety, I need to go riding this weekend so my valves don't get rusty and I pop a valve head again.

 

[YZ Teacher]

bike bandit will save you money. Also if you are an ama member you get 10 percent off. I can do an 06 yz250F topend with gaskets, springs, faction valves, for under $300.

 

[_JOE_]

Beware of poor quality valves. I've seen some disturbing pictures of a valve failure.....http://www.dirtrider.net/forums3/showthread.php?p=1314647#post1314647

 

[_JOE_]

bike bandit will save you money. Also if you are an ama member you get 10 percent off. I can do an 06 yz250F topend with gaskets, springs, faction valves, for under $300.

If you buy at wholesale maybe, but that spring kit alone is 250 bucks.......And who cut the seats for free?

 

[Mudd Slinger]

Joe, I read the link you suggested and seen it before but could not find it when I searched. Thanks for the link. I talked to Jesse Williams yesterday and listened to what he had to say and ask a lot of questions.

I was a reliability engineering technician (mainly electronics) in the military hardware world for years and have some limited knowledge on metallurgy based on the reliability issues I worked (typically pulled in more knowledgable people than me to solve the issue). I was very suspicious of the dimpled TI valve being a reliability issue and compromising valve reliability (not going there). I agree with the theory of the dimples being a possible long term reliability issues (would like to know how dimples were formed) and question flow enhancement characteristics (golf ball theory) inside a head. I was more curouis of the stainles steel valves vrs TI, the added weight to the valve train, cam wear, guide wear, seat wear, etc. (with the upgraded spring kit). Intutively I was thinking it could be more reliability but was worried about the added weight of the SS valve and the added spring tension for the heavier valves (head not designed for added weight and springs?). I am not a mechanical engineer but know enough that I don't trust intution, just hard data and good data analysis. I am hoping to hear some ideas from some of you more experienced engine builders (learn from your experiences and of course, mistakes - be honest). I will keep researching, learning, and processing data.

YZ Teacher, I have been doing price comparasions. I will compare bike bandit prices with the other price info I gathered. Thanks for the info.

I would also like to talk to Eric Gore yet but their list prices for completed performance heads seem a little high for me. Reliability, no job, and small bank account are my primary concerns right now but I would like to get a little performance boost if possible.

What are faction valves?

I was reading on some other posts that I may be able to go with a later year head and piston (if they both need replaced and head cannot be reworked) to get a little performance boost. Is this true in your experience?

Rich, any experienced input?

"I am an old woods racer that is slightly beat up and out of shape but still happy to be able to do some trail riding. I still love the power of a high performance bike, just too poor to have one, so I have to make it cost efficienctly."

 

[_JOE_]

I've heard nothing but great reviews on the Kibblewhite steel valves. Guys are getting hundreds of hours of use out of them. The Faction parts have many mixed reviews. Personally, if your luck is at all like mine, I would recommend sticking with the proven reliability of the Kibblewhites. If you plan to run Hotcams the reliability is usually even better, I hear they are easier on the valves. I priced having the valve seats machined in my head and it was just as much as a new head so my plan is to load Kibblewhites into a new, stock head. As for power increase, the cam will help and so would a higher compression piston and head porting.

 

[Mudd Slinger]

Thanks joe for you input. I appricate all the help. So the newer heads and pistons are a higher compression?

 

[Mudd Slinger]

Lapping valve seats with SS valves

Do you need to lap the valve/valve seat when using Kibblewhite SS valves on a new OEM head. That is what I am hearing.

 

[Rich Rohrich]

Mike at Engine Dynamics can fix that head. His work is fantastic and reliability will not be an issue, plus it's much cheaper than replacing the head.

http://www.enginedynamics.com/

Eric is a good choice for a replacement head that is ported and built to last a LONG time but it will likely be a more expensive option than fixing your damaged head.

http://www.ericgorr.com/4stroke.html


If you want to deal with Jesse Williams you're on your own. :rotfl: :rotfl:

For what it's worth, I wouldn't put Faction valves in any engine I put my name on, but that's just me. ;)

 

[YZ Teacher]

Nice to know your thoughts about the faction valves. Also, is it known that you should not use stock springs with SS valves, due to the weight difference?

 

[_JOE_]

Yes, you need to buy a spring kit to run SS valves. The factory springs for Ti valves are much too light to control the valve at 13k rpm. I'm not sure on the lapping of new valves in a new head.

 

[_JOE_]

And the "newer heads and pistons" aren't necessarily higher compression, though it is possible. Wiseco should offer a higher compression unit.

 

[YZ Teacher]

Mike's shop looks killer. I would love to see some of the projects he has improved/worked on.

 

[Mudd Slinger]

Thanks for all the free help guys!

I was a subscriber until I seen the writing on the wall, I did not renew several things and one was my Dirt Rider internet subscription (kept the mag subscript). I will try to get the bike running after the 1st of the year. Mike at engine dymanics looks like my best option.