Did some repairs...Down to 4 problems... I think

[renegade_xs11g]

I finally got the carbs back on, for the umpteenth time,
had a float sticking on the wall of the bowl, NOW NO LEAKS!!!

pull the choke, hit the button, fired right up!
Gotta love that! (used to have to use ether or hold hand over the mouth of carb)

Sync'd carbs (home made version), put the rest of the req'd parts back on,

Now to the issue,
on take off, it faulters a little, don't know how else to describe it, (maybe a miss??)
but then it seems to catch and your off.

then... at around 30 mph it wants to take off, the exhaust even sounds different, (btw, wide open pipes)

Runs pretty good at idle and WOT, just not as strong,
I can feel the power lurking in there somewhere, it's just not quite there

A little history... the monster was stored for a long time, I limped it home.
WOW WHAT A RIDE, FELT LIKE A VERY ANGRY BULL UNDER ME!!!!
Cleaned the carbs the first time, Later that year I dumped it, (no major damage, except that it's not fully dressed anymore) Looks a lot better w/o the fairing and hard bags.
Cleaned the carbs a second time, (was still having problems)
Now I've done a lot of things to the monster over this past winter, including openning up the pipes,
now straight pipe (1-7/8" 33" long from the collector's)
put big carb kit's in used the 110 mains, (I'll have to get a couple more 120's then put them in), and now have pod filters, new battery, other items that have no effect on the performance,

It's starting to look like the bike I have in my minds eye

I have yet to check and clean the electrical connections, but not to sure if I really NEED to.

any idea's???
I'm STUMPED!!

thanks in advance, John

P.S. it's a 1980 xs11 spec (SG model, I think)

[Dennyz]

My guess is the bike is lean. Open exhaust will really upset the carb tune.

The '80 carbs are a little trickier to tune for this, but doable. I don't think 120s will be big enough. I would start with 125s all the way across (forget about staggered jetting).

[renegade_xs11g]

staggered jetting...



just trying the pic...

but I will say that the kits came with 4 ea 110's and 2 ea 120's. I put the 110's all the way across, planned to get the other 120's.
you think 125's????

[Dennyz]

Staggered Jetting - 110s on the outside jugs and 120s on the inside.

Typically 120s all the way across would be something to do if you added a K&N filter or went to aftermarket 4:2 exhaust. Pod intake filters and straight pipes is a major change and will require major jetting. IF you are looking to unleash the real monster. My bet is 125s would still be on the lean side.

In my opinion, the only way you will get it dialed in completely is with a range of jets (main and pilot), a good sync tool, and a colour tune. Otherwise, you are stabbing in the dark. 125s should get you a significant improvement in power. From there, it is plug checking and a lot of test runs (unless you have access to a dyno).

Poor Mans method;

I found that my fuel economy would continue to climb as I stepped up in main jet sizes until I reached a point where the top end would continue to improve as fuel economy dropped off. I would step back one size and call it good for the mains.

With the mains set, then it is into the pilot jets. On the earlier carbs, the pilot circuit and the main circuit are separate, making for a little more flexibility in tuning. The second generation carbs feed the pilot jet from the main jet circuit. This complicates the low and midrange tuning a bit. I found the second generation carbs actually like to have the pilot reduced if the main jet gets to big.

The exact opposite for the first generation carbs. I discovered that I could jet for kick ass low end performance and 38+ MPG cruising by stepping back on the main and increasing the pilot.

With each change of mains and pilots, sync'ing and colour tuning are required.

For me, plug reading is helpful in the very beginning, when looking for a place to start and less helpful in looking for that perfect jet size.

All forms of road and plug testing are tricking because driving and weather condition mess with test result. This is where a dyno is king. Be patent and methodical. Keep records and plot the changes. True jetting can be yours, grasshopper (sorry could not resist).

A lot of how far you take jetting depends on how much you care. If you get to a point where you are satisfied with how it runs, go with it. If you find yourself wondering if there is just a little more you can do, YOUR SICK. I know, I have this illness.

[randy]

I think if you put some real mufflers on it, adding some back pressure, you'd see a definite improvement in the performance. It would be simpler to tune also.

[Dennyz]

I agree wih randy, back pressure makes things easier.

A cross over also helps if you are runnning 4:2.

[renegade_xs11g]

thanks for replies

I understand the back pressure,

It is a whole lotta loud, Really too loud.

A friend just bought an '07 Softtail, He's gonna put aftermarket exhaust on,
I might get those mufflers from him.

I do need to quiet it down, some way or another, haven't decided how yet

Thanks, John

[79XS11F]

The real best way to discover what is going on is a little time consuming but worth the effort. Head out for a few runs with a pocket full of plugs ... NEW PLUGS ... that are pre gapped, a plug wrench, a pen and some parer. Run the bike in each RPM range.
You don't really need to be speeding to do this if you choose the right gears for the runs but the engine MUST be working (pulling) before the shut down. So ... do a low RPM run and pull the clutch in at the same time as you kill the engine with the kill switch. Come to a stop .. of course ... and Pull the plugs and check them for the burning condition. Repeat for the mid range RPM and the high end too. Once this is done you will have a good idea where your jetting issues are and your issue sounds like a jetting issue. Even if it proves to not be a jetting issue at least your jetting will be correct for you pipes etc.
Rob

[81xsproject]

I would also add to the list pulling out whatever jets came in your 'kit' and putting mikuni parts back in.

[Dennyz]

Correction!

It has been brought to my attention that I made a major mixup in my description of the two generations of Carbs.

The 1st generation carbs fuel their pilot jets through the the main jet. The 2nd generation carbs fuel their pilots directly from the fuel bowl.

I was trying to make the point that the 1st generation carbs are a bit easier to tune (IMHO), but I screwed it up.

And to think they trust me with teaching their children!

[skids]

Re: Correction!

Denny, your descriptions of the differences between models, where the pilot jets seemed to go in different "directions" to optimise efficiency, is really important. You might have saved me a lot of time there! (Who would have guessed that a pilot jet would need to be decreased because the mains were increased??? I would have fought that realizm with my preconceived ideas and I therefore would never come up with that unless it was a complete accident!
Thanks

Originally posted by Dennyz
It has been brought to my attention that I made a major mixup in my description of the two generations of Carbs.

[renegade_xs11g]

First, having grown up in a junk yard, I have tinkered with everything on wheels, never met an engine I couldn't get running,

Second, I know cars NOT bikes

Third, I may have been a little vague in describing the problem.

The biggest thing is that the exhaust, while loud, sounds off, (for lack of a better description) more like I have a set of coils not firing all the time, or maybe a broken spring on the centrifical advance. BOTH sides of the exhaust, too. That kinda leans me in the direction of 2 cylinders maybe on the same coil...........

While I understand all of your XSively wise replies, I just have a GUT FEELING it some other problem

Originally posted by 81xsproject
I would also add to the list pulling out whatever jets came in your 'kit' and putting mikuni parts back in.

81xsproject, I assume that you mean my old 110 jets, It was apparent to me that these carbs had been rebuilt in the past, I do have the 'old' ones, same size. I can't imagine that helping?????

As far as the comment by RANDY, I know what you mean, and SWMBO also says 'THIS D@MN THING IS TOO F-ING LOUD' She can't hear her I-POD while riding

Dennyz: I, too, am afflicted with the "just not quite done yet" illness, in fact, I think I may be the poster child

Just got home from a long week (3384 miles, 5 days), I think I'll go on my first solo ride of the season , just 'cause she's not home right now.

still stumped, John

[pggg]

CV carbs, pod filters. Not the perfect combination actually. The airbox system works with CV carbs better. Slide operation can be 'out of whack' with the pod filter setup. Motor feeling somewhat 'flat'? You can tweak for improvement. Drill the slide vac holes to 3mm diameter, and snip 1/2 to 3/4 inch off the slide springs to shorten.

[randy]

Oh, and i should have added, wide open exhaust can cause very lean running and burnt exhaust valves

[Dennyz]

If you think it is a coil, it could be a pickup coil wire. They can be real sneaky.

You could also have a weak coil or bad ignition wire.