Twin cam base gasket leak Harley Engine Discuss Twin cam base gasket leak in the Harley Tech & Harley How-to forums; Frisco, Hope you weathered the holiday well. I still haven't gotten that 78 in (the bargin I thought I was getting on jets from ebay turned out to be for ...

[weig0047]

Frisco,

Hope you weathered the holiday well. I still haven't gotten that 78 in (the bargin I thought I was getting on jets from ebay turned out to be for another carb, im not entirely sure what they're labeled as S&S jets but don't specify so maybe a B?). Aside from that now that the family has all left the rain decided to set in for the night so no go on the testing.

I did get a chance to tear open the primary tonight when I was changing fluids. There are definitely no timing marks on the twin cam. Just the compensating nut/hub and some writing stating no sharp tools or something along those lines.

Off to the local shop tomorrow to pick up some jets and continue with the carb tuning...

On a side note there seems to be a little more knock on start up, present until she is fully warm. Only happens when the rpm's are slightly below the 1050 idle mark, as happens when she is too warm for the enrichener and too cold to be fully warmed up. Any thoughts on this?

[frisco-rigid]

Hi Buddy

Yes, we got through the 4th fine,, thanks..

Ok, first of all, the jets for the B, E, and G are the exact same,, no diff what-so-ever..
Perhaps you simply got ripped by the seller..

The timing marks you want to look for are behind the timing hole plug on the flywheels..
I started timing the way I described in that post waaay before EFI & twinkys came out so I'm not sure if it will work on your sickle..
Read it again and you will see that you must remove the timing hole plug and find the full advance mark and TDC mark on the flywheels and transfer them over to the Rotor and the inner primary surface.. That all depends on if there are the neccessary timing marks on the flywheels..
Whew---- too much explain on that one..

Knock on start-up is often caused by tooo much advance at start up..
Kinda tatamount to "kick-back" with a kick start motor..
When a Kicker kicks back it simply kicks back ---- But when a starter is pushing it through and it cannot "Kick-back" it can cause a wee knock of detonation..
I'm only going by what you're describing to me,, although it sure sounds like what you've got..

Now,,, one thing you might try, whether or not you are able to adjust any timing, is to adjust the Idle A/F mix slightly to the rich side,, in my experience, S&S's like a wee rich idle mix..

It's not going to be long now..
After determining if the 78 get's you up to 5500,,, you may want to try a 32 or 33 Inter jet to see if it runs better in the lower ranges..
If it does and you settle for a richer Inter you may want to plug test the 78 jet high R's again---- why you ask--- because the jets stack on each other and if a richer inter is better it may make the 78 and high R's a wee too rich, maybe not though..
Usually I start from the Inter and go up to the main but not this time,, I guess I got caught up in getting it up to that 5500 in 5th.. I'm getting your excitement vicariously..!!!
Like I said,, not long,, you're doing great..
This is how you get it right, stick with it..

[weig0047]

Frisco,

I went out to test the 78 tonight but...
It turned out what I thought was plenty of fuel wasn't near enough. I hit the reserve about a mile into WOT. As it was about 20 miles to the nearest station with high octane fuel, and would have been prime deer hours by the time I got back to the sweet little road I've been runnin' on I decided to let it wait a little longer.

I did get a chance to push her a little bit, but I'm not sure I saw any improvement with the step up. I didn't push her real hard for real long but seemed to top at 102-3 sub 5000. Is it possible to loose some power/top end if you go to fat?

Got a whole weekend in front of me and a little bag of jets to play with so things are lookin good.

[frisco-rigid]

Hi Bud

Yes.. Being toooo rich will lose power too but this is how you find out..
That's also why I sugg'd you may want to test again after you settle on the best Inter jet---- to make sure it doesn't Over-load the main..
You're waaay in the ballpark now..

WOT is great and it's fun to see if you have what it takes to get the Full Tilt Boogie,, but most of your runnin is around what RPM----- 3500 to 4500????????
Soo, that's where you want to do the test as I described and get that snap-shot of the Mix at that RPM..
One of the probs with S&S's is that, jetted for normal runnin you might be a bit lean for WOT power, that's why someone invented the Thunder-Jet..
It's like a 2nd Main jet for waay R's.. It also shows a very basic deficiency in the S&S's----- you need a whole other "add-on" fuel system to keep from burning your motor up at WOT..
That's why I alway jetted a wee fat in the main when I ran S&S's..

There are other tricks too like increasing the size of the Main-jet air-bleed..
If you have a newer E, it'll have that capacity..
Years ago we would drill out the B's Main air-bleed, tap it for a main jet and change the timing of when the Main "came-in"..
Now, the newer S&S's are already drilled & tapped..
I alway ended up with the stock size hole though cuz it just worked for me..

I still have even more tricks..

That sweet LiL road sounds soooo fun, ah,, I need to do some testing..............

[weig0047]

Well I finally got her dialed in... and then I went and switched the cams.

I ended up with a 32 int. and the 76 in the main. Which put me right where I wanted to be. Maybe a hair rich but runnin real nice.

I suppose now that I have the new cams in I'll have to fine tune again, but I kind of enjoyed playing with my options and experimenting so that's ok.

Thanks for all of your help and input, I learned alot about my bike and carburetors in the last couple of weeks.