I was going to rebuild my motor, high compression piston (102mm) and cam. does anyone know how important it is to polish and port the head? also the manufacturer of the cam I am looking at tells me titanium valve springs are a waste of money, whats the word on valve springs do I need to replace them or not? thanks for any help

 

I posted a similar question recently. Raptor720 responded that the titanium valve springs will not hold up to continued use. You should replace the factory springs but I can't tell you with what. According to Raptor720, the stock ones don't have enough pressure and most aftermarket ones have too much pressure. Perhaps he will read this and give you the low down. There is a solution to your question but I don't know the full answer.

/NotuRaptor

 

go with the web cam. Not sure about the valve springs.

 

webcam is probably my choice for a cam, they are telling me I dont need new springs, they also have a couple of cams to choose from. I am hoping to get some feedback from 720raptor on the springs and polish and port question

 

I talked to webcam and they suggested staying with the stock springs, but definatly recommend the polish and port if you are replacing piston and cam

 

I got the same reply from webcam, right now I am not sure where to get heavier valve springs even if I want them, local Yam dealer is no help

 

try calling mickey dunlap at four stroke tech. 1-814-842-6159. 4-7 pm east coast times. he will have the answers you need. he has a flow bench and does all his own port and flow work.

 

Hi guys,

porting of the intake is very important as is shaping the exhaust. Beyond that, with the 102mm piston, major chamber work is where you will be rewarded. (With kits like those sold by CT Racing, using the stock 100mm bore piston, you cannot correct the chamber problems. The CT 100mm pistons will never perform like the 102 not because the 102 is larger but because the 102 allows the correct mods to the chamber.)

On the springs, I like WebCams. I know Dunlap uses MegaCycle but Mega will admit that they have not done any research on the Raptor and are simply handing out old cams that they designed years ago for the Yamaha XT.

On the springs, sure the stock springs will run BUT I would not run them. They will bounce and do other fun things. Stock springs have an installed height spring pressure of about 35 pounds. With that low pressure, you will have valve bounce. RD is known world wide for making a great product; however, their springs test out at well over 60 pounds at the installed height. Shoot for 50 pounds and you will be good. The RD springs come with Ti retainers that are strong and cut the valve train weight down -- just remember to use the stock split keepers with the Ti retainers.

Here is a hint on the springs. First, it is expensive to have the spring pockets cut to correct for too much spring pressure. It is also expensive, and a flow problem, to have the valves cut deeper in the seats to correct spring pressure. Trying to make or install a taller retainer to correct spring height is also a problem if you go taller than the RD retainers (you will hit the rocker arms). If you can't get springs to work, ask RD to sell you 5 intake springs. Install the springs to get as close to 50 pounds as possible (each head is different) then on the exhaust (that has a different spring length) add a shim of about .140" below the spring to correct spring pressure and height.

Now you will have correct seat and over the lobe spring pressures for any Web Cam currently offered.

Again, if this is getting beyond the scope of your abilities or beyond the limitations of your favorite shop, I suggest sending the head to Trinity Racing in Anaheim, CA or Bikeworx. Perhaps there are other shops that can perform the work with equal integrity but that decision is up to you.

 

Thanks 720raptor that is exactly the information I was looking for, one more question: do you have contact information for RD Springs? I have my cam on order along with a J&E 102mm piston (I find wiseco --substandard--). My local Yam shop thought I was nuts when I told them my raptor was sluggish, after dusting the shop owners raptor on the track. go fast or go home

 

Sure, I will post info on RD later today. I want to call ahead to make sure he will provide the spring combo.

ON the Piston thing --- ah, J&E is owned by Wiesco.

I use the J&E's and cannot complain. I would note that the valve relief angle for the intake valves is not correct -- but that will not cause you any problem if you are using any of the avaliable Web Cams.

Ross Pistons are also great. I understand that Ross actually worked at J&E and set up their program for the piston. Perhaps the Ross has the correct valve relief angle. 6 of one -- half dozen of the other.