From the Boutique:

Top End Noise After Conversion

Dale A.

Okay, after seeing a lot of top end noise Posts after a conversion I'd like to give some suggestions / answers that may help some in the future when doing a conversion. For the Lister I'm quoting above, this is not saying this is your problem or an answer to your problem. The below is general stuff.

#1. If you install anything more aggressive than stock cams in the 2000 & up models, YOU WILL hear & notice more valve train noise. In most cases, this is natural, the profile of the more aggressive cams & the shape of the cam lobe tend to cause a clicking noise as the cam passes thru it's highest lobe portion. This noise is transmitted thru the engine from the cam lobe all the way to the top end. You'll swear it's coming from the rocker box top where the rockers impact on the valve stem, but it's emanating from the cam lobe. Also aftermarket cams, even with close ratio gear teeth, tend to make more noise than HD stock cams as they ride on the pinion gear.

This is more noticeable in 2000 & up models including 2004 & up as these models use a smaller bore tappet or lifter than 91-99 models use.(I have the actual measurements wrote down somewhere at home) They tend to not like more aggressive cams or hold up as well due their smaller cross section that performs the hydraulic function within the tappet to keep it centered.

If I was installing N4's or any cam with more lift than N4's in a 2000 & up model I would use the better aftermarket hydraulic lifters available. What happens with the stock lifters is they lose a lot of pressure under high lift conditions around the top cap of the lifter. Oil bleeds right by as I found when putting together the 1000 cc race engine on the Mystery EVO back in 2000. One fix is to use shim stock & shim up the top cap of the lifter to plug these leaks, but that involves a total lifter disassembly which is not addressed in any HD maintenance manual. It's actually not that hard once you take one apart & do it.

INSPECTION: Everyone should do this if doing a conversion on a bike that has 30,000 plus miles. Remove the lifters, doing one at a time. Place it on a flat surface with the roller down, work bench, whatever & wrap it up in a clean rag while holding it firmly in one hand. Take the pushrod & press down hard into the lifter. The top cap plunger with the oil hole in it, of the lifter should not budge at all, that is it should not have any downward movement under normal hand & arm pressure. It takes a lot of force under engine operating conditions to budge this. If it does move downward, suspect a failed lifter OR ensure the lifter is full of oil. The above procedure should be done only on a lifter filled with oil. You can check the oil by taking a common oil squirt can & squeezing oil into the lifter thru the supply hole in it's side until it comes out the top oil hole in the plunger cap. This will be a messy operation, but it can be done & should be done.

If you are doing a conversion & the engine is apart a long time, week or longer with the lifters just sitting in their bores, they will lose oil. This is why we hear a lot after a conversion, the engine was very noisy or clacking on first start up. It takes a little while for oil to get back in that lifter...sometimes it can take a 10 mile ride to get them fully back up. It is important, especially if one is going to use adjustable pushrods to ensure the lifters are filled prior to setting the zero backlash of the adjustable pushrod. I've just made it a habit now, especially with 2000 & up rides to fill the smaller bore lifters with oil after installing the cylinders & heads & prior to installing the top rocker box & pushrods & covers.

#2 For those models that use the "W" grind cams, (Sport models & 2004 & up 1200's) when switching to other type cams, more noise will be heard than if it had the stock "D" cams of the standard models as the profile on this cam is very smooth & it's the quietest cam out their for Sportsters. You just need to know & understand this is going to be the case.

#3 If one installs a stock exhaust pushrod in the place of an intake pushrod, the exhaust pushrod is slightly longer than an intake pushrod, it will cause some weird noise if this happens as the longer pushrod is un-centering the hyd lifter & the lifter is not able to support that length, IE, the lifter is getting bottomed out, hence the noise.

Here is a source to get aftermarket lifters like Crane's & Fuelings at a cheaper price than Jim's Power Lifters:

http://www.head-quarters.com/html/hydraulic_lifters.html

For about 90 bux a set, these better lifters should be included in a conversion on 2000 & up bikes using more aggressive cams.