Two weeks ago my dual rate intake valve spring broke in two and the shim shattered causing some damaged to the outer area of the head. Not sure if my Cam is regrind-able as one lobeis scored, somewhat deformed.

What I have in there is an Ron Wood Axtell A1 and A2 cams. Is there is something out there that gives more of a mid punch or more bottom to mid. I don't ride often in the high RPM range. Since it's apart I figured I'd change a few things here and there.

Who offers shim under kits and installs them? Aside from certain aggressive cams what are the benefits of shim unders? I appreciate any info someone can chime in for me. Thanks.

 

Call up Eric, he will take care of ya. The Hpr HR2,s sounds like what you need. I am not sure if shim unders are required. Basically they hold your valve from falling if you float the valve. How it is, when you float the valve, the shim can come out, and the valve keepers can come out and the valve drops into the engine. Only the bigger cams are really necessary for the shim unders. If you are happy with the top end of your cams, you could just add some compression to give you better bottom end aswell.

 

Well hells bells man, I'm sorry to hear it, but happy to hear your optomism and drive in getting her going again!


the hp3's are always compared to the axtell grind, going to an hp2 will be a step down. I personally don't think there is a better cam set than the axtell for all around bottom to top and great mid, but that's just me.

shim under is nothing more than a safety measure to keep a lost shim from bouncing around in the top of the head and finding its way down the cam chain opening into the crankcase. in the event of spring breakage, the shim is still contained under the bucket along with the spring pieces. I run it and recommend it to anybody who removes their rev limiter along with cam changes.
buy it from Web Cam, and have a reputable builder install it.

as for spring breakage, it happens all the time, more often than you even hear about on the forums. some will say springs should last forever and if they don't then it was not setup right with the correct springs, but more builders than not will tell you that they change springs frequently and that we should on a regular basis too. the factory puts in the motor a set of springs and cams that they know will last a mega long time, then we come along and put in higher lifts and higher revs and there is just no way we can expect it to last forever. if adding power with higher lift and higher revs has no trade-off then the factory would be doing it from the getgo.

I inspect my springs regularly - the outside one always breaks first, then after running on it like that for a bit the inner one breaks. I caught mine with broken outers last year, still held together by the unbroken inners. so I was really lucky and took no damage from it. so now I decided to replace all valve springs on a regular basis, and the time I settled on is every other winter, based on the kind of riding and how many hours a year I put on her.

 

Tanks Vipe and HT. I will contact web cam in a day or two. Who can install it? I'm wondering if my cam is fine. I spoked to Ron from RWR and he said generally if the cam journal is fine the cam is salvageable. I think I will keep the Axtells and add more compression. I do like the top end when it's there. I don't hit it much.. but it's nice to pull pull pull.

Hightwower my inner valve spring is what broke. Outer is still fine.

 

Did the valve with the broken spring drop into the cylinder? is that what had the motor locked up? don't see how the retainer would come off and allow the valve to drop if only one of the two springs were broken?


any bike motor shop can do the install for you, and the shims can be adjusted accordingly without having the head installed, meaning all the shop needs is the head, valves, cams, cam bridges, and spring kit.
after you put your motor back together you would then wanna check clearances yourself to doublecheck their work.

in the case of mine, my RWR cams had a base circle slightly larger than the stock cams, and the Web kit had buckets with a top surface slightly thicker than the stock buckets, and these two things combined created a situation where the thinnest shim made were still .002" too thick. this led me to have to have shims custom ground since none were available off a shelf anywhere. this is just one of the things that can be ran into when doing mods like this, and is a good reason why you wanna have somebody farely reputable do your work, somebody that can deal with and overcome little quirks along the way.

 

I use to work on sprint cars. we would check the springs after every race. I think it was on average about every other race that we would have a broken spring.