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Good/bad idea: putting vacuum on Shovel case?

9K views 40 replies 14 participants last post by  TigerAlex 
#1 ·
I am getting get bad plug fouling in my 75 Super Glide. Both before and after rebuild. She runs/starts OK more or less despite the fouling, mostly thanks to the Daytona Twin Tech 1005 ignition (which I am very happy with).

She always fouled plugs before the rebuild, regardless of my riding habits. Post-rebuild (went from very worn 86" stroker crank and jugs to stock late-shovel 80" setup) she did not foul plugs so much. Then I moved houses (got a garage, finally!) and started a longer commute which involved higher speeds, i.e. using the HOV lanes. I thought high-speed runs would get her hot and help burn out fouling, but it seems like the opposite.

I have been told the fouling is typical in shovels, and it's because of the loose tolerances letting oil by, better to have too much than too little. I compensated in years past by using straight 70W in the summer months. It seems to seep by less. I am about to buy some more. I was using 20W-50 since the rebuild. (OK, I was being lazy and getting my oil two blocks away at Advance Auto, who carry 20W-50 and 10W-40 now in most stores.)

I've made good progress on reducing leaks on the ground, dealing with the usual leaks prone to shovels, and trying to do what I can. The breather hose puffs and chuffs, and drops oil, but that's not unusual, though I wish it didn't.

The issue of HP, leaks and fouling have all been on my mind for a while. I ride a Shovelhead after all...

After reading some of the ideas in KCgran's thread on Horsepower ideas, http://www.jockeyjournal.com/forum/showthread.php?t=178234 I wonder, has anyone noticed less fouling after putting vacuum in the bottom end? More HP is nice, but I've got enough to get to work. But helping rid fouling, that would be nice. And it seems easier than trying to set up a water vapor rig, which I've also been led to believe will help.
See comment in this thread from servi53 http://www.jockeyjournal.com/forum/showthread.php?t=127657&highlight=vacuum&page=2

At this time, she eats over a quart of oil a month. I had already stopped up the chain oiler mind you, and use PJ1 on the chain. Nearly all this consumption is internal. I'd like to stop that.

If vacuum on the lower end will help with oil in the combustion chamber, I'm game to try it. However, it occurs to me that the leaks could be from the top end, in which case I doubt vacuum would help.

I'm interested in opinions. It'll be a while before I undertake this even if it promises to work, mostly because of summer work to do and other repairs around the house. (This never happened when I didn't have a garage...)

Alternatively, I could spring for a spark plug cleaner attachment for my air compressor, some extra sets of plugs, and just make replacement a monthly maintenance check. But that is treating the symptoms...

Thanks for your feedback in advance.

Alex
 
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#2 ·
I rode a Shovel for years and never fouled a plug. Sounds like you need a rebore/hone and new pistons and rings and probably valve guides. Or if that was part of your recent rebuild, might have been honed out too loose.

Fitting a vacuum set up to reduce oil burning may be treating the symptom, not the problem.
 
#3 ·
not enough info for an informed guess

if you have an 86 inch - 3 1/2 bore / 4 5/8 stroke - it requires a mod to the barrels to lower the oil return holes from the heads to the engine block -- if this is not done the oil returning to the lower unit from the heads, ends up spilling directly into the middle between the second compression ring and the bottom oil ring // it needs to be below the oil ring not into it

no amount of rebuilding can fix that mistake - i just re did one exactly like that a couple months ago it was smoking for years now it does not

not looking at your engine this is my guess
 
#4 ·
Try changing your oil to straight 60 wt. its all I will ever run in my old bikes. Valvoline racing 60 wt or equivalent. Even plumb wore out, they have never fouled as bad as you say.

Ive had problems with multi viscosity oils in older bikes....fouling was the minor.

That said, what John is getting at is true.

You said its not 86" but 80" now? I don't know if the same would hold true with the less stroke. Interesting though. Sure sounds like ring seal, but I would think there would be more oil loss. Both plugs?
 
#5 ·
Without being overly critical of your post ; shovels are not known for fouling plugs. Start with checking compression and see where the oil is getting in combustion chamber[ rings -guides]. Note : want to sell the old stroker wheels? You are talking throwing band aids at what needs a top end job. Another note : multi-grade will ruin your roller bearings in a shovel.
 
#19 ·
Another note : multi-grade will ruin your roller bearings in a shovel.
I find this interesting. While I too am a straight weight aficionado, someone please correct me if I'm wrong. Evos are bearinged just like Shovels no? & while I personally run 50wt in my shit, there are a million Evos out there with 20w-50 in their veins. TK.
 
#9 ·
Thanks for the responses gents. I'll try to clarify some points.

She started life as a 74" obviously, and is now in late 70's / early 80's trim at 80", new crank and rods and pistons. Was 86" stroked when I got her.

I've had the top end done more than once, and always fouled afterwards to some degree. Local shops, the first one VERY good, second maybe not good, but performance (fouling) not much different.

Always turn off petcock, yes. Yes, I have a compression gauge. I will see about checking that, thanks for the reminder.

Carb is S&S Super E, stock out of the box as-shipped jetting, don't recall the numbers.

I wonder it might be running rich, a tiny bit, since the jets are the same as when she was 86". It's mostly oil fouling though, black and gritty.

Both plugs foul, but rear a little more than fore'ard.

DaveB: re the Crank, PM sent.

I will go ahead and order some 70W based on this discussion, and we'll see what we get. I'm still wondering if playing w vacuum would be fun. Right now I've got a dead regulator, so I have to deal with that and pray the alternator stator is still OK.

Any other thoughts anyone?

Have a great weekend all,
Alex
 
#10 ·
what spark plugs are you using and what is the heat range as the 86 inch would have had more compression then the 74 or 80 inch motor and they would require a hotter plug

but if the shop that is was helping should have asked that question as well

tin valve seals are always in question what oil control is the issue as some shops use odd sizing of valve to valve guide distance and then a tin seal - we have seen this issue many times as sometimes its in the parts that were used and how it was assembled
 
#13 · (Edited)
I rode my 76 FLH as a 74"er for 10 years then switched it to a 93" S&S shovel repop 11 years ago. Neither engine has fouled plugs on a regular basis.

If you're sure it's oil fouling get a light and a mirror, look into the carb and exhaust ports on the heads and see if oil is running down the valve stems.

I have a Hayden crank vent on my case breather. I don't know if I should credit that or better machining by S&S and me using Cometic gaskets but my mill is not a leaker. Allegedly that's a benefit of holding a vacuum on the lower end. Snake oil? Not sure what the crank vent does for one internally.

As far as carbs go about all I remember about my two Es were they were decent carbs but I felt they are too rich out of the box, easily remedied. For me a 40mm CV was the best carb I ever stuck on a shovel. Running a 44mm CV now on the 93 mostly because I wanted to try it. Besides, I dream of going to 106". Runs great just has to get good and warmed up to hold a nice idle.

Mark
 
#14 ·
Back some years ago when I was way more into old hot rods and horsey power, I added an exhaust scavenging system to an EVO. I used the vents in the heads and ran it to the then new exhaust called a Thunder Header.

Its an old trick used in automotive world that was cutting edge at the time in that area for bikes. It was the first for that spot on the globe.

Whats funny is the bikes owner swore it was much faster. I couldnt tell the difference. All I know is it was way faster than my bike. I had a 38 knuck chopper. Lol.
 
#16 ·
Lots of great additional replies. Thanks men. I appreciate it.

I did a compression check and she was 75psi front and 125psi rear. Obviously something isn't right.

As I said, this bike has ALWAYS fouled plugs to some degree, always oil fouling. I have had the heads done and redone more than once over the years. I cannot recall now if they were re-done this most recent rebuild. I can try to email the mechanic who led the work on my bike, he is a good mech and left that shop not long after my build due to not being happy with overall quality of work and being encouraged to cut corners. I just wish his new shop was a lot closer! I will email him and ask about the heads. He had them cleaned, but I don't think valves were replaced or relapped or anything else.

I do wonder now if the main jet is too large and washing out the ring seal. That might do it. Yes I usually shut off the petcock every time. I could also try to lean out the accelerator pump a bit. I haven't checked that in a while.

Based on past performance though at this point I suspect my valve guides, they are my usual suspects. I've had them replaced more than once. Finding a garage that can do it right has been a challenge.

As to the question of plugs; I have long reach heads and usually run 5RLs, they foul less than 5R6As and the bike is definitely happier on them. I am currently running the Drag Specialties replacement plug for 5R6A because I had run out of clean plugs and needed some unfouled plugs fast and that's what I could lay my hands on. (Side note: I finally ordered the spark plug cleaner attachment for my air compressor, so I can clean my own by this weekend.)

Following the compression check I made a mental note to readjust the pushrods on the front, but haven't gotten to it yet. I was just finishing the compression check when a lady friend announced she was feeling frisky, so I put the new plugs in, left the tools laying out, buttoned up the bike then started unbuttoning other things. Gotta make hay while the sun shines.

I changed over to 70W last night. I might get to rods tonight, but I promised a friend we'd catch up on drinking and wenching.

I will check the new plugs soon, and also check cylinders and valves with my digital inspection camera next time I get an hour in the garage. (That was the best birthday present ever, thanks me! You're welcome!)

It is close to 100F afternoons lately, so getting into the garage to hump a hot bike has been hard to get psyched up for.

I haven't ever put together the bits needed to do a leakdown test, but yes it does sound like a good next step. I am hoping that readjusting the pushrods and going to straight weight will help the valves seal up better in front. I will try that first before assembling the parts for leakdown.

I have thought about going down one main jet size in the S&S E since the rebuild but haven't gotten the gumption up. The reason I've thought of doing it is because I get the identical gas mileage on the rebuild at 80" that I got on the 86" stroker. Seems to me that I should get a little better fuel economy for highway riding. I asked the mech but he said "I only count fun per gallon, not miles per gallon", which I can't completely argue with, but still I think I should get better than 33mpg.

And yes, I'm sure it's oil fouling. I have been using a quart a month and it doesn't leak on the ground noticeably (caveat: except from the leaking trans main seal, but that's def the trans oil there under her).

I'll update as I get to the items listed above, one at a time likely. I thank you again for the ideas and advice, and welcome more ideas.

Alex
 
#18 ·
Leaking guides wont affect compression. Thicker oil will help slow down the fouling, but wont cure the low compression.

The fouling and low compression are symptoms of the real problem. Consequently the lack of compression is not helping the plugs burn off. Oil is getting in somehow and compression is escaping. A leak down test will tell you much more.

After adjusting the valves do another compression test, if you don't have a leak down tester. If you do have one by now, test before and after adjustment too verify effective direction.

Im gonna go with rings.
 
#22 ·
using the speed of the exhaust is the common way most racers have done it by connecting a one way 60s emissions valve to a sipper pipe in the exhaust header @ a 45 degree angle - this creates the negative in a V8 when connected to a sealed motor at both valve covers for the oil pan - the idea comes from piston ring flutter and this is a way to control that

they also use an negative air pump directly connected to the engine so the amount can be determined with dyno runs just how much at what engine speed works for the most power =
 
#21 ·
DaveB, I usually switch to 50W in late September and come late November I sweeten it with about 20% by volume of synthetic 20W-50 to help with cold starts. That was when I parked outside. Now she's garaged so cold kicking isn't as big a concern.

JAWS, I also wonder about rings, or maybe I managed to glaze the cylinder. I don't think it's glazed, since the fouling wasn't so bad for the first 6 months.

Armand, you're quite right, this thread has wandered, but I don't mind.

Alex
 
#23 · (Edited)
For the bikes I use steel threaded PCV valve. Does exactly what the emissions check valve does but is smaller. Some fittings and braided line.....

On another similar project I was messing with position. After some tries I got the angle and the length of tube it siphons from down. I actually built a manometer, so I could calibrate it. Worked slick as snot.

Each application will be different.
 
#25 ·
The problem with using engine vacuum to vent the cases is it introduces a new variable into the fuel/air mixture. The longer an engine runs, the more wear and more blowby, pulling that into the intake track and into the combustion chambers takes up some of the "room" for actual fuel/air, potentially robbing the engine of HP.

Less emissions yes...

If plumbed into the air filter before the carb, then you will get oily mist that collects dust and will gum up the front of the carb.

If plumbed into the intake track after the carb, the fuel/air mix will act as a solvent and keep it cleaner, but a Vac leak will then be present and needed tuning after the fact.
 
#26 ·
if you have oil squirt can shoot a small dose in the spark plug hole and re check comp. if its washed out that will bring it way up, but might bring it way up for every other cause you've stated. still ridin shovels every day thatnever foul plugs, 80 in 29.5 intermediate and 70 main jet,if you have a compression gauge your half way to leak down tester, if you have the type with a disconnect hose,match your air line to that,turn your regulator down and give it a dose of compressed, with valves closed, listen and watch for the escape
 
#29 ·
with total seal rings they will suck the intake gasket in if its not torqued correctly / but the cork or paper gaskets are usually first to be pulled in, smokes so bad you end up with tech in the pits

we have played with the amounts and it depends on what combo but 6 to 10 inches is kind of the normal for us - others have had good luck with less and some with more
 
#31 ·
John,
I had forgotten Dad talking about drilling small holes in the tops of pistons down to the ring grooves. I had thought it was to force the rings out to seal better but, the flutter makes more sense.
 
#33 ·
that is still in use and that method is called Gas Porting the piston tops, mostly NOS and ALKY injected big power 2500 3000 HP motors today but

the Big Block modified open wheel cars were the first too see this mod with 427 motors with compression of 14 to 1 - it came as a result of stopping the engine from smoking just before the turns and blinding the guy behind you

Gas ported -- thats a different thing but it does the same thing under different circumstances, both systems are employed in most drag Pro cars today but they use a dry sump pan, and and an engine driven evac pump on the motor with a blow off valve like a turbo would have - the one 2 shift in a glide of stick car the engine speed change is so sudden its in the mix co correct the pressures - lots and lots of very small tricks that the old timers have passed along learned in a dirt floor garage back in the day
 
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