Hi,

I have a 94 FXSTC with 24K and I'm wondering if I have an issue brewing.

On a cold start I get a little smoke out of the rear cylinder, it looks white/brown in color but it is very little and does not linger in the air like oil smoke. It seems to only do it with the enricher pulled out but that may be due to the rpms being higher and the smoke more obvious, goes away after a minute or two. It also "pops" more or louder out of that cylinder, hold your hand over the exhast and you can feel it. It runs strong, oil temp never gets much above 180-5, does not use any oil that I can tell, the plugs look the same and good, mileage is good and the exhasts have a light brownish/black color. Is something going on or am I being ****?

The second issue is valve train noise and I've read countless threads here. Mine is pretty quiet when cold and gradually gets louder as it warms. It sounds like the front exhast is the loudest (screwdriver to ear), and the rear intake is quiet. The PO installed a crane cv3 cam and some sort of adjustable pushrods, I'd like to try adjusting them but have no idea what kind they are. I read about using a thread pitch guage but I'm wondering if I should just replace them and maybe the tappets while I'm in there since I would want to replace the O rings anyway. If I replace them, do I need special lifters for that cam and what kind of pushrods should I look at?

Thanks,
Doug

 

The clue you gave is the enrichener valve. No two clyinders will be perfectly matched and it's just a little excess fuel being burned off. The way this animal breathes through one manifold...could be the rear is getting a little more air/fuel than the front. If it stops after you close the valve and take off...not to worry.

If you are unsure about adjusting push rods, I'd just get me a set of stock ones and put back in there. The thread-pitch on the adjustable ones doesn't matter and only gives you a reference as to how far you are moving the length of the rod. A course thread will move the lock-nut farther than a fine thread, but each set comes with a pretty complete set of instructions. You do this by feel anyway. There is a detail procedure that tells you how they should feel (how hard they turn with your fingers, etc.). The thread pitch won't matter a hoot, unless you are reading instructions from one maker and have rods from another maker with a different pitch. Obviously, if the instructions tell you to turn the nut 2-rounds based on their pitch and you have rods of another pitch...it won't be right. In the end game, it's how they feel after they bleed down and if you have them too tight or too loose, you should be able to tell.

There are lots of good lifters out there if you plan to change yours, but you say the cam has been changed and there are "some sort" of adjustable rods in there. These may not be properly adjusted or need to be tweaked after run-in.

 

First you need to put some miles on that puppy!!! Second the smoke is more than likely the enrichner. Third most aftermarket cams are noisier than the stock ones. If you really feel a need to get in there and replace the lifters you can use the Harley "B" lifters, they have a "B" at the end of the part number showing that they have been revised. Adjusting the pushrods does depend on the thread, the object is to lengthen them about .100" as the lifters have about .200" of travel and you need to take about half of it out to get everything working right.
First you lenghten the pushrod (with the lifter on the heel of the cam) until there is no free play, then lengthen it between 2 1/2 to 4 turns (this is the most common range) depending on the thread pitch until the pushrods are about .100" longer. Then wait (about 15 mins) until you can spin the pushrods easily by hand. Do not turn the engine over with the starter until you can spin the pushrods or you will damage the engine. Hope this helps

 

I vote for adjusting the pushrods since it's quiet cold and noisy hot. And if possible, verify the oil pressure is sufficient when warmed up.

That design of pushtube cover has been used for nearly a hundred years... the old bikes needed the valves adjusted about every 500 miles, so they are designed to be opened up and put back without issues. As long as the o-rings and tubes are wiped clean before reassembly, it's almost never you have to replace those o-rings.

Yeah, do a good valve adjustment. You'll find eliminating the simple and inexpensive possibilities first, is generally the "best rule of thumb."

 

OK, forget the valve noise for now, I've got a new symptom.

Yesterday on my way home from work it started to miss, fully warm @ 30 mph in traffic. A quick look at the trip-o showed about 150 miles so I switched to reserve figuring I was low on fuel. It picked back up but continued to miss a little until I got to a place where I could crank it up. The reserve port on my pitcock does not have a screen so I figured I picked up some dirt, filled the tank. This morning it did the same thing, lunch the same and the trip home was real bad until it got hot. It seems to run OK-(not great)-after I've been running it for 5-10 minutes. I just pulled the plugs again, the rear one is really black, thick soot, the front has a white insulator and the metal ring at the end of the threads is black-(they both always looked like this).

I'll probably drop the bowl, clean it and the jets out but it seems to be centering around the rear cylinder. Even before it started to miss you could feel an irregularity in the exhast between the two. At cold idle the rear seemed to fire a few times and then kind of pop, when warm the rear was the one doing the popping on deceleration..

Something is "up" I'm sure. Would a leaky intake cause any of this?

Ideas??


Thanks,
Doug

 

A leaky intake can cause it to run crappy at low speed and seem to run better at higher engine speed.

 

Check your coil to make sure it is not cracked, it sounds like you are losing power off, on off, on, off, on. This could cause all the symtoms you have posted.

 

sounds like an intermittent spark problem on the rear cyclinder, not an air leak.

 

If you think it is an intake leak,spray some carb cleaner on the intake seals-that will tell you immediately if there is a problem-just my two cents.

 

Well, I don't think it's dirt in the carb, I put a set of old plugs in and it runs OK. It still has that popping or uneven fireing out of the rear cylinder and it's more obvious when cold.

Will it hurt it to run on one cylinder for awhile. I want to pull the rear plug, ground it and observe the spark.

If I can get my hands on a strobe I'm gonna check the timing and pull the coil to test it.

Also do the intake test for S&G's

Other than that I can't fathom why the rear would be so much richer than the front. It actually fouled the plug with carbon to the point it stopped working. Unless the plug was bad, what are the odds and I'm not normally that lucky...

Thanks
Doug

PS: Miacycles, I've only had it a couple of months and it needed a bunch of work but you made me think of something. I've mainly been riding it local to me which is country roads at good speeds. Last couple of weeks I started using it for my commute which is mainly city driving. Maybe those slower speeds made the issue more obvious by not burning off the carbon.