Talking myself into doing some upgrades & not sure how far I can take it without having to get into bottom end work.

I've been bouncing back & forth on just putting a bolt on cam (SE204) or doing more with it. Was thinking I would just do it all at once and go with the SE Pro Stage IV (92500005) on my 2014 in sig. That way compression, heads, cam, valves all done & work as they should together. (dont want to increase displacement).

I've been advised that it wouldn't be wise to do this w/out also getting into the bottom end and welding the crank etc. which is just not possible.

I guess I'm wondering if this is sound advise?

If it is, I have a couple options. 1) drop a bolt in cam and call it good. (most likely the 204/54H 2) find some other combo??? 57H? or woods 5-6

 

SE stage 4 is fine no need to pin and weld the crank. Although even stock it never a bad idea to do that.

 

Hi,

Got mates here in Aus who have the stage4 in their fatbobs and they ride them hard and for many kms with ease,

Like you rgr357 i wondering whether just cams will satisfy me or wait a bit, save the $ and go the stage4 kit straight up

Thanks
Mirrmu

 

find a builder have head work done, fitted to a cam that meets your needs
set up for correct compression . you will have a lot better setup and will cost you less money. and you will be very happy.

 

target64: I'd probably go that route but no local performance shops to speak of.

The SE Pro Stage IV takes the guess work out of it for matching heads, porting/valves, compression etc. for a otherwise stock 103. The real question I have is at what point do you need to pin & weld the crank? I get that it would be better in any case, but know there must be some general accepted understanding.

Yes I want more out of it, but want to stay withing the accepted norm for not sacrificing reliability with this type of top end work. Not trying to make a drag bike, just fun street bike.

Makes financial sense to do cam & other top end work all at once.

 

Buy the Feuling Crank run-out tool and measure your run-out, you will have to take the cam plate off but if you want to get into engine building then go for it. IMHO a crank run-out of about .006" or less for what you are talking about is fine, above .006" then go get your crank fixed. There are a ton of differing opinions on all this crank run-out stuff so read up, and good luck!

 

Well that's what I'm saying, I don't want to do it.

I do want to upgrade the top end, but want to stop before bottom end is more of a requirement. Does a 103 with a stage 4 push it to the point where you need to do the bottom end work.

I imagine it comes down to what kind of numbers the bottom will reasonably hold up to?

 

You want to know if your bottom end is good enough without checking the run-out? That is the best data you can have on what you can do. Even if all I was going to do was change cams, I would still want to check it. It will give you a major indication of the health of your bottom end and reference point if you have an issue or decide to upgrade the engine again.

Now a lot of people do big upgrades and never check, but you need to know that you are taking a risk - a risk that is relatively easy to avoid. The tool is about $100 and you could probably sell it for $80, so $20 plus some shipping $.

 

I think you are not understanding what alansummrs means.
I always suggest to have the run out checked before doing anything. It doesn't cost that much but may save you a lot of $$ in the long run.

I would rather be safe than sorry later on.

 

Understood, I have read about the tolerances required before going to a gear driven cam.

Haven't heard of it in terms of a general health check, but it stands to reason the further out the more susceptible you might be.

Not going to a gear driven cam, but Ill add it to my list of things to check, at least I will know for future work or reference. So are you saying, under a .006 would likely be ok? I thought the reason behind the bottom end work was to 1) fix the tolerances required for gear driven cams, 2) make it stronger so you dont twist or otherwise break things. which #2 is why I inquire.

Maybe I'm going about asking the question the wrong way. For those who have gone into the bottom end for the sake of pining and welding, what were the motivating factors?