Titanium valves....less spring pressure?

[Pulido221]

I guess everybody went to sleep early on a Friday night huh Just drinking again and was wondering......By doing this light weight titanium valve train, will your bike run kinda like a two stroke? Your crank is obviously going to rotate more effortlessly due to the weaker springs when lobes make contact with the caps pushing the lighter valves down and to top that off the higher rev with the dyna, it sounds like it's gona spin the paddles more in the bottom and scream up top like a banshee? Just wondering if the light weight valve train is going to change the power band to favor the top end more? If so I would like to do the titanium thing myself if it will pull stronger up top, I think that's where the Z kinda fails pulling hard up top to compete with 450's like the yfz and trx(HRC cammed of course) Correct me if I'm wrong or if I've been drinking too much
BTW, I'm stalking this thread like crazy

[kfxguy]

Well I wouldn't really compare it to a two stroke. I'm not expecting slot of difference either. But what I am expecting is maybe a little bit more over rev or a slightly higher Rpm pull and possibly a higher safety margin on valve float. Honestly if I were you, I'd spend $500 somewhere else. I don't see a good carb listed in your sig....and I you don't have one....you really need one. Also if you need more topend you could retard your exhaust valve a couple degrees. That may help. What valve springs are you running with your oshc's?

[Pulido221]

Geez! 500$ is alot for ti set up! Ya, no fcr right now, got one off camaro real good price but no matter what I did and I do mean everything I did to the carb, I couldn't get the bog off idle to 2nd. I think it was due to my compression being weak(a guess)so I traded it for my current bbk I have now. I know everything inside and out to a fcr, not by choice, so if I see one I'll snatch it up and try it again now that I have fresh great compression. As of now I am running DRZ springs with KW valves and DID cam chain. I would like to go bigger on my cams for harder pull up top but I'm scared it will take my bottom away. Income tax is my bike money so I'll be looking for paddles, carb, and possibly webs. I hope you get a good improvement that you can feel off the TI set up

[kfxguy]

Well I'm not going to know honestly. I ported the head pretty big for this engine. I rebuilt the carrier with new bearings and seals. I removed the junk grease out of the new bearings and put magnalube in them. New chain. Aluminum sprocket. New pads. The bearings were so bad, you couldn't turn the axle by hand when the wheels were off the ground. I'm putting a dial a jet in too. Also cutting stuff off I don't need to lighten it up more. So I doubt I'll know what difference it'll make. Plus the exhaust valve was bent...which will slow me down. The valve springs were shot (I'm suspecting) il find out today. I'm gonna check them. I thought my research on the springs was over. Weatez just let me know the springs I was going to use is only good up to .400 lift. Well my cam is .410 lift. I know .010 isn't much, but I'm gonna call cv4 to find out if I just raise the installed height by .010 if I'll be ok. If not, I may just use the drz springs at a higher installed height. I'll have to mill the spring pocket a little deeper. This seems like a lot of work for not much return.

You really need a bigger carb. Even if it's not an fcr. Get the 42mm 450r carb. The one with the yellow choke arm. It will make a huuuuge difference over what you have now.

The funny thing is I just put a 41mm fcr on a stock bore stock compression bike and I tuned the bog out. You need to adjust the squirt to where it just misses the slide when you crack the throttle. Then you need a noss machine tapered adapter. Get the needle height correct. And you should be good.

[kfxguy]

Update. I checked the spring pressure. My prediction was correct. Here's what I found

Exhaust spring #1
62lbs @1.220 on the seat

Exhaust spring #2
64lbs @1.220 on seat

Intake spring #1
65lbs @1.220

Intake spring #2
64lbs @1.220

New spring out the package.
76lbs @1.220

The test was repeated 3 times for each spring. Just in case there was error. All numbers were repeated with 1lb of initial reading. I'll check open pressure later.

[CFM-Z440]

All those seat pressures are higher than what I'm running. Mine are about 60 on the intake side, and 50 on the exhaust side.

[kfxguy]

I'm not going to tell you the scale I used was accurate either. I just needed a comparison.

[kfxguy]

You gonna laugh but I'll tell you how I checked it. Keep in mind it was mainly for comparison sake. I went bought a regular ole bathroom scale. Put the valve in the head with a r/c car shock spring. Then measured my seat height as best I could and then cut a piece of rod the same length. Then I set the scale on my drill press. Of course I used the locator and the retainer when checking. I lowered the drill chuck down until the retainer was even with the rod. I did not look at the scale until the retainer was the right height. I figured I might fudge it (lol) because I really wanted the old springs to be weaker. Well by doing it that way, I got a true non fudged reading. I repeated the test on each one and it pretty much came out the same each time. I know this is a silly way to do it, but no one had a spring tester in town and I was impatient. So I figured it's probably not 100% accurate....but it would give me a accurate comparison. And that's all I needed to know. So I confirmed the springs were in fact weak.

[z455]

Haha nice! what ever works, works, right?

Sorry to get off topic but two questions:

Would you be willing to share your port measurements, i.e port throat, choke point, initial entrance, linear or non linear taper?

And are you using a 539,539+6 webs? I can't seem to find where you posted your cam card.

thanks

[kfxguy]

Cam card:


I'll try to measure as best I can. I tapered the intake inlet pretty generous. A smooth long taper. I made the intake a little bigger, streamlined the guides and rounded the bottom side of the port. I made the seat throat a tad bigger. I opened the exhaust up a bunch. It's way more choked than the intake. Also smoothing the combustion chamber is a must. The bad thing is, the parts I opened up I really won't be able to measure. They are too hard to get to. I'll see what I can do tho.

[CFM-Z440]

Originally Posted by kfxguy

You gonna laugh but I'll tell you how I checked it. Keep in mind it was mainly for comparison sake. I went bought a regular ole bathroom scale. Put the valve in the head with a r/c car shock spring. Then measured my seat height as best I could and then cut a piece of rod the same length. Then I set the scale on my drill press. Of course I used the locator and the retainer when checking. I lowered the drill chuck down until the retainer was even with the rod. I did not look at the scale until the retainer was the right height. I figured I might fudge it (lol) because I really wanted the old springs to be weaker. Well by doing it that way, I got a true non fudged reading. I repeated the test on each one and it pretty much came out the same each time. I know this is a silly way to do it, but no one had a spring tester in town and I was impatient. So I figured it's probably not 100% accurate....but it would give me a accurate comparison. And that's all I needed to know. So I confirmed the springs were in fact weak.

Quite the procedure you've got there. I took mine to a buddy that does SBC cylinder heads for stock cars. Finding the installed height was a real beyoch. I had to measure it with the DRZ inner spring. Used the end of the caliper to find the over all height, then subtract the retainer. It felt a little like guess work.

[kfxguy]

Yea. I was in a little hurry with it because we had stuff to do yesterday. So my installed height measurement probably wasn't 100% correct. But I did get it in the ball park. When I put it together, it will be correct tho. I just needed a comparison. And if you think about it, it's pretty accurate as long as the scale is accurate. And it cost me $8. Lol

[z455]

so I just measured my spring seat pressure at 1.220" and got

44lb 04oz Intake #1

45lb 01oz Intake #2

39lb 12oz Exhaust #1

40lb 05oz Exhaust #2



Dont have a new spring to compare but these were done right! (no offense ) On a Bridgeport with a refridgerant scale. Hmmmmm

[kfxguy]

I got mine set up with .005 on the height. The springs I have are for the ti valves. So I should be good to go

[cataway]

I'm pretty sure rawdawg will never use them again. he had one that snapped off an trashed the top end of his dvx400