abnormal wear

[ifixtheyride]

I know the valve thing is pretty well covered on the web but I still need to ask. I have an 03kfx400 that I replaced all 4 valves in March08. I bought new cam chain at the time. My quad started running a little poorly and starting hard lately so i checked the gap and sure enough the intakes were basically no gap. I dropped from .280/.285 shims to .255/.260 and it runs fine now but I also found the cam chain tensioner on the last click so its stretched. Doesn't that seam a bit fast only a couple months to stretch. I did not remove the head and inspect the valves the shop that did it seam to think its proboble the seats more then the valves and I thought I could postpone until winter. The valves were Kibblewhite blackdiamonds. I do have the 430 Athena big bore kit and a full Sparks racing exhaust along with an 39mm FCR carb. Will I cause more damage by shimming the valves instead of fixing the real problem? The shop said and showed me a CRF450 there that basically has same issue they adjust the valves about once a month. Soft seats?

Thanks in advance

[ceofuller]

You didn't replace the seats when you put the new stems in?

[ifixtheyride]

I'm not sure of terminology here but the guides were replaced along with valves. Are the seats not where the valve face is? Isn't that part of the head or are they replaceable? I took the head to a machine shop to do that work because I thought a professional would replace the right parts.

Thanks again,
Bill

[ceofuller]

It sounds like we are talking about the same parts. The seats or guides as you call them are replaceable. When you damage your valves you consequently damage the seats too.

I am getting ready to rebuild my head, you may have seen another thead right above yours "head rebuild" that is me asking the same question.

And to answer both of us, from all the reading I have done the past 48 hrs the seats HAVE to be replaced when you fit new valves otherwise your new valve will conform to the damage of the old seats/valves.

In my case, the valve stems are "cupping" essentially the stem is slowly pushing its way up into the head, in turn closing the gaps on my cams. Now, if the stem is pushing up into the head, that kinda tells you I have damage were ever the stem is pushing up.

It sounds like you have done the same thing. STOP riding NOW. You may have caught it soon enough to were you havent damaged the new stems and can still use them. I just ordered the same stems you have so I know you paid dearly for them;)

[ifixtheyride]

Your right about the seats they are replaceable and I do not know if they were changed I was talking about the oil seals not guides sorry I need to call the guy and ask but I only think he replaced valves and seals. I thought the seat was part of the head and machined. When I went to the machine shop that did it to get new shims he told me he only once had to send a head out for remachineing of the seat so maybe I need to find another machinist. I thought I did the right thing buy going to the extreme racing shop in my area and getting their recommendation of a machine shop they use looks like I was wrong. My original valves were cupped as you say. the actual valve once removed you could see on the sealing surface it was cut in to the surface. I just assumed when he replaced the valves the mating parts were done as well. If he did change the seats it still doesn't explain why the quick failure of the cam chain and most certain at least the seat. I'm thinking of going to the DRZ upgrade just not sure what all that involves and what are benifits. I've spent quite a bit of money on a 2003 quad and not all was worth it in my mind so the DRZ thing has me hesitent. The biggest improvement so far has been the carb.

[ceofuller]

If those seats were not changed then I would say that is the prob. But as for the timeing chain, that one would have me scratching my head too. If it is stretching I would wonder if it is getting too hot.

[airmobile101]

The Z400 eats cam chains, period!!!! You need to install a manual cam chain tensioner(MCCT). I had installed a new DID cam chain in Feb. of this year. Six races on it and a few joy rides later, and I was down to two clicks.
Put a new cam chain(DID) in and install a MCCT. That will eliminate the chain from stretching so quick.

As for the seats ,hell I have no idea. I didnt even pay attention if they are removeable or not when I Installed my valves. I will say this, my hands where sore as hell from lapping. Thats with 0% leakage.

The DRZ is a cheap mod. If your gonna have the head off, you might as well slap that DRZ gasket in. The springs from a DRZ are more aftermarket cdi friendly. Its suppose to bump the compression up. Im not sure of the compression ratio. 12 something? I moreless did it for reliability issues.

[ifixtheyride]

I just pulled out my receipt from the shop and it was for 2 intakes and 2 exhaust and 4 seals ouch no seats! I know I read in hear and it was between you airmobile and cataway about lapping valves I'm not going there I dont know how the guy sealed mine up it did run really good until now and I shimmed the vaves for now and it is ok for now. Thanks about the DRZ info I figured like you said why not upgrade at least the springs are heavier on Kibblewhites website they claim weak springs can cause cupping as well from allowing valve to slam into the seats. Is that manual cam chain tightener the manufacturer name and where did you get it and what makes it better? Does it extend further and do you have to adjust it as it wears?

Thanks guys

[airmobile101]

Yea, I guess your suppose to have new seats or have the old ones cut? I don't know. I got my crap to seal and its been just about a year now. So Im happy. The MCCT doesnt apply as much pressure to the cam chain as a Automatic(stocker). That auto seems to apply too much pressure .

[airmobile101]

Here yea go!!

http://shop.thumpertalk.com/Manual_Cam_Chain_Tensioner_p/eng_tt_mcct1.htm

[ceofuller]

If you do the mcct mod how do you know when it needs adjusting?

[ifixtheyride]

Thanks for the info I ordered a MCCT from thumper talk although its on back order I think I'll go with the DRZe upgrade for the valve springs and better cam chain. I don't plan to do it until the winter here in Pennsylvania.

[airmobile101]

Originally posted by ceofuller
If you do the mcct mod how do you know when it needs adjusting?
Well, they say to hand tighten it until its tight. Then back it off about a quarter or half turn.
What it did was start the bike up(youll hear the chain slapping around). While the bike was idling,I slowly hand tighten the adjuster until I didnt hear the chain slapping around anymore. Then I tightened it an additional 1/4 turn. I then proceeded to slowly rev the bike up to make sure there was no slack in that chain. If there was slack,your gonna hear it. Make sense?

[ceofuller]

Makes perfect sence, thanks for the help

[RATPACK Z400]

anybody have pic of cam chain tension adjuster and how to tighten have no manual to see how.