Suzuki Central Forum banner

1 - 10 of 10 Posts

·
Registered
Joined
·
2 Posts
Discussion Starter #1
Hey guys, new here.
I purchased an '03 ltz 400 with a broken exhaust valve an the atv was in pieces. I replaced the exhaust valve with a shindy valve and discovered this quad has the cot cams #47, #48 with adjustable sprocket. So after reading half the the threads on here(thank you) I was able to get it in time but bent an intake valve. So then I replaced all the valves with kibblewhite's and new valve seals. Got the engine started!!! Pulled it out of the shop, called the wife and kids outside to witness the greatness, hit the starter button and shattered the starter clutch. Back to reading threads(thanks again).
While waiting on the starter clutch to come in the mail, my kibblewhite racing valve springs and retainers came so off with the head again. This is where I broke down and cried, my brand new kibblewhite stainless steel one piece valve was warped and slightly hanging out of the head, a keeper had came off one side, dropped the valve, and destroyed a valve guide. Now I have ordered new kibblewhite guides and a guide tool! The ONE intake valve that has been giving me problems(not both just one) has no valve lash. No valve lash WITHOUT SHIMS! just tappet, cam, and valve spring..... No shims and no lash not even .004

Have any of you guys seen this before?
Do I have a warped cam or possibly a bad valve seat?
 

·
Administrator
Joined
·
7,781 Posts
Did you have the seats cut for the new valves? The seats should be freshly machined for new valves. They will definitely need it for new guides. I recommend having a shop that's good with metric motorcycle heads do this work for you. It's a lot more intricate than changing parts.

My other recommendation is to get rid of the kibblewhite valves. They have earned a terrible reputation in these engines. The suzuki seats are too hard for the Kibblewhite valves, even if everything is prepared properly. Sometimes people get them to live in a mild build, but they never live in an aggressive build. All of their other parts have been ok, but the valves are just trash. Ferrea valves are the best, and still reasonably priced. I'd strongly recommend those.
 

·
::3 Pump Chump!::
Joined
·
3,008 Posts
My other recommendation is to get rid of the kibblewhite valves. They have earned a terrible reputation in these engines. The suzuki seats are too hard for the Kibblewhite valves, even if everything is prepared properly. Sometimes people get them to live in a mild build, but they never live in an aggressive build
I never had a problem in my z or ltr. 🤷‍♀️
 

·
Administrator
Joined
·
7,781 Posts
I never had a problem in my z or ltr. 🤷‍♀️

What I've seen is this. First, I rarely ever tear down something with Kibblewhite valves that doesn't at least have an intake that's distorted, if it isn't already something you could shave with. That's across all brands and engine platforms that come through my shop. That said, I had good luck with a set once too, way back when I was still running hotcams in a 440.

Where it gets really bad, is when you go with oversize valves from them, and put them with aggressive cams. I was doing an engine build, and I really wanted the KW +1 valves to work, because at the time, they were better on the flow bench. I prepared the seats exactly how I always do with Ferrea valves, which by the way, I've never had cup, in any build ever. I used the KW springs, the valves were set at the proper depth in the seats, everything was by the book. Within 1 hour of run time I was at zero lash. Changed shims, knowing it wouldn't work, 1 more hour and zero lash. They had not even seen any dust. I had already experienced this exact scenario a few years prior on my own machine, back when there was still talk of a bad batch. I figured they had corrected the issue, but apparently not.

I tore it back down, freshened up the seats, replaced with Ferrea, changing nothing else... 3 years later, that engine still had the same shims that I put in, when I built it.


I also, more recently, started building some 300EX's for a youth XC class. I know how lame that sounds, but I'm doubling the stock output and still have a good powerband for XC. Kibblewhite is the only choice for those. They've been getting 1 season on valves, and most look bad when they come out. I had Ferrea make me some customs, just trying to get these guys something more reliable.
 

·
Registered
Joined
·
2 Posts
Discussion Starter #5
I finally got the bike to start and idle perfect but off idle it like bogs and sometimes shoots flames. After trying everything under the sun from double checking my work to trying different jets, to trying reverse rev eliminator. Nothing worked so I sucked it up and dropped it off at a shop yesterday.
I have a honey do project coming up so I had to clear some things off my list.
Can't wait to here what the shop has to say and how much it's gonna cost me!
 

·
::3 Pump Chump!::
Joined
·
3,008 Posts
What I've seen is this. First, I rarely ever tear down something with Kibblewhite valves that doesn't at least have an intake that's distorted, if it isn't already something you could shave with. That's across all brands and engine platforms that come through my shop. That said, I had good luck with a set once too, way back when I was still running hotcams in a 440.

Where it gets really bad, is when you go with oversize valves from them, and put them with aggressive cams. I was doing an engine build, and I really wanted the KW +1 valves to work, because at the time, they were better on the flow bench. I prepared the seats exactly how I always do with Ferrea valves, which by the way, I've never had cup, in any build ever. I used the KW springs, the valves were set at the proper depth in the seats, everything was by the book. Within 1 hour of run time I was at zero lash. Changed shims, knowing it wouldn't work, 1 more hour and zero lash. They had not even seen any dust. I had already experienced this exact scenario a few years prior on my own machine, back when there was still talk of a bad batch. I figured they had corrected the issue, but apparently not.

I tore it back down, freshened up the seats, replaced with Ferrea, changing nothing else... 3 years later, that engine still had the same shims that I put in, when I built it.


I also, more recently, started building some 300EX's for a youth XC class. I know how lame that sounds, but I'm doubling the stock output and still have a good powerband for XC. Kibblewhite is the only choice for those. They've been getting 1 season on valves, and most look bad when they come out. I had Ferrea make me some customs, just trying to get these guys something more reliable.
Interesting your the guy that looks at them more than I do. I know in the LTR I put the dual springs and KW in and I havent adjusted the valves yet and that was back when I xc raced and bounced it off the rev limiter more than I should have.

all in all it sounds like they are good just not for high HP applications.
 

·
Administrator
Joined
·
7,781 Posts
Interesting your the guy that looks at them more than I do. I know in the LTR I put the dual springs and KW in and I havent adjusted the valves yet and that was back when I xc raced and bounced it off the rev limiter more than I should have.

all in all it sounds like they are good just not for high HP applications.

I think it's a valve bounce issue, more so than anything else. Valve bounce is a really interesting phenomenon. It's definitely worse with more aggressive valvetrain parts, hard seats, banging off the limiter, and the problems with the Kibblewhites in a Z400 seem to match that theory. One model to the next could be completely different as to if or when it happens. The extra half mm of stem in the LTR might make just enough difference to keep it from happening.

All that said, Ferrea are only a few bucks more, and in my experience, rarely ever even need reshimmed in a builds that Kibblewhites wont even survive in. I have to think that they will tolerate a less than perfect situation at the seat also, like when guys don't get the seats machined and so on. That's where I was coming from initially.
 

·
::3 Pump Chump!::
Joined
·
3,008 Posts
Valve bounce is a really interesting phenomenon.
What is this witchcraft your talking about? I know of valve float tell use more!
 

·
Administrator
Joined
·
7,781 Posts
What is this witchcraft your talking about? I know of valve float tell use more!

Valve bounce is when the valve closes, but due to the speed and intensity, will actually bounce off the seat like a cue ball on a cement floor. There are many causes, or at least many things that play into it. Not enough spring pressure, flex in the components, camshaft intensity, ect. It can come on at certain rpm's where the harmonics are just right.

Check out this video. It's improperly titled valve float, but it's actually showing valve bounce. This will make it a little more clear, although spring choice is behind the problem they are showing, it does show just how imperfect and chaotic this all can be, as well as just how much flex and distortion happens in a running engine, at high rpm.

 

·
Administrator
Joined
·
7,781 Posts
Here's another that's pretty cool. Watch the springs spin when it gets wound up.

 
1 - 10 of 10 Posts
Top