about valvesprings???

[phylzub02]

How do I know when to change valve springs???and which type to use????and is there a way to check them????how often should they be changed???how can I tell if they are heavy duty???I have the valve spring compressor???it is a rebuilt 1200.has about 30 races on it...asphalt racing 1/4 and 1/3rd mile..red box..frank

[VMS Motorsports]

If you're pulling it apart, spending the extra $80 for a set of new valve springs is a no-brainer in my opinion.
Are you having a driveability issue you're trying to fix, or looking at it as a maintenance issue?

[phylzub02]

no not having an  issue. I am just wanting to know how to check them, and which are better. I've heard of the APE . And the kibble White..there has to be specs on them...how do I check them.. what do the 1250's use

[VMS Motorsports]

The only way to accurately check them is to pull them out and rate/check them.

Personally, if you're not having a problem, I wouldn't worry about it.

I do not know what USLC uses in the 1250, Dennis, Brad, or Tim can probably answer that one.

I use the APE and am very happy with them. at $110, they are cheaper than a set of standard Yamaha springs. I have over 105 races on my current set of APE valve springs

http://www.vmsmotorsports.com/apps/webstore/products/show/1092795

[phylzub02]

well that is good to  know that  they go that far.. yes I will pull em out and random check them or whatever it takes, just wanting to know specs and how to do it...but just cannot see putting in new rings and all and not knowing about the springs..
how do I tell if they are A P E ???and or the others???or Yamaha ones???thanx

[racerrad8]

As Jim said they have to be removed to test them. You need to check free length and then you have to have a valve spring checker to check the actual rate. Every brand has a different advertised rate.

I personally sell and use RPM/KPM valve springs and can get you the specs, just shoot me an email.

I can only offer for identification purposes the Yamaha springs have paint on the upper portion of the spring. All other manufactures do not have distinctive marking that I can see.

Depending on the age of the engine the valve springs might just be what is replaced as the older the spring is the softer it gets due to heat & duty cycles.

Randy - RPM

[Gimpster]

Valve Spring :

Inner Spring:
Free length - Intake 39.65 mm (1.56 in)
                       -exhaust  39.65 mm (1.65 in)
Limit         in. and ex.  37.65 (1.48 in)
Set Length (valve closed) 32.8 mm (1.29 in) (this measurement can also tell if a valve face is sunk into the head too far) for both intake and exhaust
Tilt limit ( removed spring standing next to a 90 degree surface) 2.5 degrees/1.6mm (.063 in) for both in and ex springs

Outer Spring:
Free Length - 42.1 mm (1.62 in) for both intake and exhaust
Limit in. and ex. is 39.0 mm (1.53 in)
Set length is 34.8 mm for both in. and ex. or 1.37 inches
Tilt is also 2.5 degrees but the measurement is 1.7 mm for both or .067 inches

No spring poundage rate via a compressed measurement or seat pressure is presented in the service manual.

The reason I am choosy on aftermarket valve springs is for their resistance against the cams. I would opt for a lesser poundage (myself) of aftermarket springs when compared to each other. Personally, I would not install heavier springs with hollow camshafts.. that is looking for trouble...

~The Gimpster~