Shims basically just act like a preload adjustment or, rather, they could act as preload, right? This is so long as you don't have binding issues. So has anyone ever shimmed up on 954 OEM springs? Could you? Or does it not add enough seat pressure to make it worth it?

I peaked down the valve intakes on the head with my motor assembled. With the flashlight, I could see how close the piston was coming to the valves when they were opening. Holy good god, do they come close. I assume it's doubly bad for guys like mobbins, mika, and myself with aftermarket cams and 13.5:1 pistons. I'm starting to get slightly worried about it.

 

Yes. That's what the shims do. You can shim the oem springs little according webcams site but the oem valve springs of the 954 are progressive so you will be having problems whit coils binding very soon and you will have have to have extra of .045" of clearence so if i got it right whit the oem springs the free travel of the valve spring should be valve lift + .105". These measurements are from webcams site.
I think that the highcomp. piston normally have deeper pocket for the valves so there is least the same amount of room for valves to lift as oem pistons. So only thing reducing the clearence is bigger lift of cams.
Did you check how close the exhaust valves come whit the pistons?
You will get more room for the intake valves by retarding the cams to where they should be but that will reduce the clearence of exhaust valves.

 

Ahhh - progressive springs, I didn't think of that. Good point. So, basically, there is just not enough room to get substantially more seat pressure then. Where are you finding this info on webcams? I can't find any of it! I didn't measure or anything - my father-in-law and I were just curious, so we spun the motor. He's been building all kinds of motors (diesels, gas v8's, and countless bike motors) for over 40 years. His first words were "Oh ****, we're gonna hit" talking about the piston and valve. But in actuality, it was just very close. We double and triple checked our timing to make sure we were right on the money - which we were.

 

Conrice:
Why do you need stiffer valve springs? Your cams are bolt-on. You can shim the oem springs so much that it will count. They just can't handle my cams even shimmed so i needed stiffer ones. It wouldn't been even safe to use them shimmed whit these cams and oem limiter and my limiter will be set aprox 13500 so spring need will raise dramatically whit the revs. When we where planning using oem limiter we thought about shimming the springs. Then i got the calculation from professional based on the head flow characteristics, cams and compression that the peak hp will be way beyond the oem limiter.

The mark off the additional clearence when shimming springs are in the vehicle notes when you open the list what they have for the 954. The other measurements are from the installation .pdf:s from the bottom of the same page. You should probably check did i understand the clearences right.

What are your cam lobes at the moment? Do you use oem cam sprockets or adjustable ones? You can get little more room for the intake by retarding the cams.

 

this has gotten pretty good, i would not recommend shimming the oem springs if you are using higher lift cams. we had mine tested and they wouldnt have came clossssse to what i needed. i have my cams rertarded alittle past 107 ( it is almost alittle to much). When its trying to start on a hot day after already warming up it takes alittle throttle to get it started. my power band is right around 5 k but i get alittle hesitation between 6-7 then it takes off like a f'in rocket. so far ive based the hesitation in the fact that the e valve does create alittle back pressure in that rpm range. so im hoping a serpent exhaust will pop up soon so i can grab it. aparently they help this.

How did the kibble whites work out? im excited to see if they cause any problems. or not.

Also for valve clearance. We had the cames all over the place and we never hit a piston. Which, in all honesty, i was realllll scared considering im using a milled head.... for what ever damn reason... i cannot find my dyno sheet. im working on getting a new one from the shop.

Ive been actually burning a bit of oil lately. Im not sure why either. everything was fine when the valves got done.

 

when i was still looking for springs i called kible white and spoke with an engineer. for him to make them directly for the 954 it would have costed in the 5 digit category

 

its in the top end category. just a heads up for anyone else who may end up looking for them.

 

i think i would actually consider putting a turbo on if i wouldnt detonate the engine in the first five seconds it runs haha.

 

Ferrea Competition Valves for 2001 Honda CBR 929R | eBay

 

Hahaha 13.5:1 - Yeah, it might go boom... I've thought about a turbo before - but low comp pistons are hard to come by - plus it's a LOT of money to do a successful turbo build that is reliable.