Valve job time

Ok ive been reading some past posts on here and found some good info but still had a few questions. I think its time for a valve job and here is what ive been thinking 04 CRF 250R...

Ti vs SS im leaning Ti but not sure. I read about the SS causing more wear on the head and having to replace the head eventually that doesnt sound fun to me. Also i read about the Ti reving easier and less weight ect.

I plan to replace the springs, locks, reatiners, seals, valves, and have the seats cut. While im there thinking of putting a new piston, rings, and gaskets. OEM piston or something like a weisco? Is a high compression piston really worth it? I usually just do practice days at the track and some trail/dune riding. Is there anything else i should replace while im in there? cam chain etc? I have a friend that can help with the wrenching and i got a place to cut the seats but were are some good places to get parts besides the TT store?

After the valve job how long typically does it last untill i have to start shimming again? Ive read basically by the 3rd shim its not worth shimming anymore. Do the valve coatings only start to go once the clearance zeros out? After a valve job how often should i check the valve clearance? 10 hrs?

If I catch the valves before they go to zero and shim them does the 3 time shim guideline still hold?

Last question off subject anyone know a good starting point for the carb? It has a yosh pipe (there website didnt have any specs) other then that stock? Ride in michigan i think 600-1800 ft but could be wrong on that part.

First off, what kind of machine are you going to use to have the seats cut?

My buddy used to work at a machine shop that does top fuel heads and such. He said he still has a good friend there that can do it. He had it done on his YZF 250. Are there any special specs/techniques i should tell the guy?

I haven't heard of SS doing MORE damage then TI valves but probably could do equally the same if not taken care of. I've seen a couple of threads with TI valves making a 250r head look like a cheese shredder (pictures.) I just did a complete rebuild on my 07 250r head. Had the seats cut by the local honda shop and did the rest of the labor myself. Replaced my intake valves/springs/retainers with SS Faction mx. Ordered oem seals and new cam chain (reccomended due to wear/stretching) since it was apart. Exhaust valves haven't moved yet (They're SS stock.) Decided to put in a JE high comp piston since the bike had around 40 hours on the stock one- chose to do so after the high reviews and praise on here. Couldn't be happier with the performance compared to stock - bike is noticably stronger throught the power curve. Bottom line is I would reccomend using SS valves if your'e not a regular weekend racer - you won't notice the very slight weight of the SS vs TI and the durability of SS will suit your needs and wallet better than TI. And also highly reccomend the high comp piston because considering your bike is an 04 and not being sure what's all done to ti, it's probably in need of a rebuild. As far as valve clearance...I've put 14 hours on my bike since the new parts and the valves haven't moved yet. This basically depends on filter maintence and frequent oil changes that im sure you've read a lot about on here already.:thumbsup:

thanks for the info so far. im new to the 4 stroke thing. My exhaust valves moved .001 since my last shim but were still in spec so i left them. Since the valves started to move should i also replace them while im there? I dont completely understand the valve wear. Is it once you start to shim them you are just buying time till the next valve job? Is there a period when you first do a valve job that the valves stay at spec for a longer period of time?

Ive shimmed my bike twice since i got it used and the longest i went between shim jobs was maybe 5 rides (probably under 200 miles). The first time the clearance was at 0 the second time i caught it at ~.002. I guess my question is with a proper valve job how long should i be able to go with out having to shim again? I seem to be shimming mine more then i ride it and that doesnt seem right.

thanks for the info so far. im new to the 4 stroke thing. My exhaust valves moved .001 since my last shim but were still in spec so i left them. Since the valves started to move should i also replace them while im there? I dont completely understand the valve wear. Is it once you start to shim them you are just buying time till the next valve job? Is there a period when you first do a valve job that the valves stay at spec for a longer period of time?

Ive shimmed my bike twice since i got it used and the longest i went between shim jobs was maybe 5 rides (probably under 200 miles). The first time the clearance was at 0 the second time i caught it at ~.002. I guess my question is with a proper valve job how long should i be able to go with out having to shim again? I seem to be shimming mine more then i ride it and that doesnt seem right.

you really need to do a valve job now!!

Yes im having a valve job done just trying to figure out exactly what im going to have done and what i can expect from the results. From what i understand so far for valve job piston and related parts im looking ~$500-600 does that seem about right?

well i ordered all the new parts and they should be here in a couple days. I got all new valves, springs, retainers, locks, valve seals, piston kit, gaskets and timing chain. I got a shop that will recut the valves with a SERDI tool. Any special tips/tricks/special things to look for during the tear down/rebuild? Ive rebuilt a few 2 stroke snowmobiles but this is the first 4 stroke. I got a buddy that has done a few 4 strokes to help me but I would like to know if there is anything special i should be aware of/look for when i go in. Yes i did read the valve job and piston replacement posts in the tech forum and seems pretty straight forward. Just dont want to miss something stupid.

thanks guys appreciate the help so far.

Special tips/tricks. Hone the cylinder and do the dry rebuild method. It is well worth it. Here is how to do it:

Hone the cylinder (ball hone or brush hone) in soap/water. Clean out with break clean and paper towels until there is no black on the cylinder. I have a 3.5” ball hone in 180 grit.

Wash the piston/rings in soap/water, spray off with break clean and let air dry.

Install the rings on the piston. Use proper ring staggering - follow the manuals staggering method - Be really careful not to get any oil residue on the piston, rings, or cylinder. Keep your hands wahsed

Install one clip on the piston. - the right side one.

Install the piston on the rod, use a light coat of oil on the wrist pin only.

Install the other clip, be sure not to get any oil residue on piston/cylinder.

Install the piston in the cylinder. Compress the rings with your hands and very carefully install it. Be sure that the oil ring doesn't bend over.

With the motor together, and no crankcase oil rotate it 50 times. Then fill with oil and check all fluid levels

Do not start the bike until you intend to ride it. Start it up, let it warm up good, go ride it hard with engine breaking, this will ensure the ring seal.

And my impressions after I have done it on my thread here:

http://www.thumpertalk.com/forum/showthread.php?t=670880

Thanks yes i was going to hone the cylinder. 180 grit is ok? i thought that might be a bit rough. Ive always honed with 220+. I havent pulled the cylinder or head yet (hoping they are good... used bike) I have one of those after market manuals but there really isnt much good info in there. What specs should i check on the cylinder after i pull it besides bore? Also what are the specs supposed to be? Ive done pistons before on 2 strokes just the whole valve thing is going to be a new experience.

Thanks again

180 grit is ok. I have the 180 grit 3.5" ball hone. It works really nice to clean up the cylinder.

And you won't regret the dry method. Great ring seal and can't say enough of how much I like the motor on my bike now. Just be really careful to not get any oil residue on the piston/rings/cylinder. Keep your hands washed all of the time.

Yeah I used the same method when installing my new JE when I put my faction valves in a month or 2 ago...bike runs fenominal now:ride:

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