drilled out my baffles

paulson_shawn · Posted: July 28, 2007, 12:55 am Post subject: drilled out my baffles

i had one 1/2" hole in each baffle and got my carbs tuned pretty well with 2 up on the mains and 1 up on the pilot (pod filters also), but it seemed rich on the low end and died at idle a lot. i drilled 2 more holes in each muffler (3 per side now) and it made a big improvement on idle and mid range, ran great in town. today i went for a ride through the hills at highway speeds (60 - 70 MPH) and after a while it seemed to be running hotter and didn't pull as hard when i speed up on the staight aways. should i try one more up on the main jet or could a needle adjustment help? 78se cv38's. oh yaeh, i already raised the needles 1 notch. p.s. i know too rich of a MJ causes breakup but what is breakup ?

xsjohn · Posted: July 28, 2007, 2:30 am Post subject: Re: drilled out my baffles

Couple of things to look at.......Exact main needle position......If main jet is to large there is a tendency to not have the main needle high enough and it can get hot at moderate throttle.. Sometimes the sweet spot is in between the needle notches...experimentation for sure....Timing only advanced enough to make it run good ...I start retarding it until it runs weak and start going up.....any extra will cause heat........I used to reccomend the exhaust valves be set at 5......I was a dummy....This caused mine to run 8 degrees hotter and really gained nothing....A moderate 6 cold on the exhaust valves......Top end cooler will remove 15 or more degrees from the head but unless mixtures are right on with the main needle and even a tad rich to keep the cylinder heat from growing.......If it runs perfect before it is warmed up the main needle might be a tad low...Brinkmanship for sure with these air cooled engines....Easy to get the mixtukre screw to rich and the main needle to lean trying to set these.....A combination of things helps with the heat......I hate noise so I leave the exhaust as quiet as possible........Catch 22 for sure......May need a hotter plug for richer mixtures......Autolite 63 and bit hotter 64 are fun to play with......I quit tuning to plugs.....I tune to what I think is right then find the right heat range plug......

John hope this helps

INXS650 · 650Rider Supporter Joined: Mar 22, 2007 Posts: 645

Got 5 holes in mine now, and runs better than ever. It's also a lot cooler running as the exhaust can get out a little more effectively. Not too loud either, but approching a cafe racer sound instead of Harley. As far as the heat goes, you should try Johns top end cooler. More gas won't do you any good, time for some more cooling.

xsjohn · Posted: July 28, 2007, 11:01 am Post subject: Re: drilled out my baffles

I still have my stock pipes and am afraid to play with them....hard to replace the stockers .....With the stock crossover both pipes are working per thump.......Got my cylinder temps at 230 degrees at 50mph and 240 at 65 express..85-90 ambient.....Down 25 degrees from last year..totally different bike......Lots of work......50-52 mpg......Head never gets hot....

Found the tin top needles are almost impossible to get right without slightly changing the slope........10 degrees right there.......

John

xs1961 · Posted: July 28, 2007, 6:58 pm Post subject: Re: drilled out my baffles

...Best thing you can do for a performance improvement is to junk the stock silencers(mufflers) & downpipes(headers) they strangle the s*** out of your XS... The nips only put 'em on to meet/pass your stringent (U.S) emission controls...Drilling holes just gives you an impression of extra performace cos of the noise!...Get an after-market free-low baffle-less set-up...The best $200+ youll ever spend !

paulson_shawn · Posted: July 28, 2007, 10:28 pm Post subject: Re: drilled out my baffles

i put in the 142 1/2 MJ's. runs great took the same ride again and it didn't over heat and ran strong from idle (stays running at 1100) to 6000. less engine noise and smoother too. didn't check my milage yet.

paulson_shawn · Posted: July 28, 2007, 10:29 pm Post subject: Re: drilled out my baffles

free-low baffless ? you mean just head pipes?

grizld1 · Posted: July 28, 2007, 10:39 pm Post subject: Re: drilled out my baffles

Shawn, you should be able to run along at say 3800 rpm in 3rd, quickly roll (not snap) the throttle wide open, and have the engine respond without hesitation. If it does hesitate, pull the plugs and have a look. If they're sooty, you're too rich. Otherwise you're lean. Step up the mains till you get response.

Then you need to run a throttle chop on the main circuit. Put a fresh pair of plugs in your pocket, ride out of town, and put the fresh plugs in. Put 5 miles or so on the plugs at highway speed then open the throttle as close to wide open as you safely can on a long upgrade for a mile or more if you can find a spot to do that. Hit the kill switch and declutch at the same time and coast to a stop. Put the old plugs back in and take the test plugs home where you can examine them under a good light with magnification--a 10X loupe is good for that.

On the way back, open the throttle full then roll off quickly--a roll, not a snap--to 7/8 throttle. If the engine misses a bit--"breaks up"--the mains may be a bit rich. If the rolloffs are clean, run to full throttle again, and again roll off to 3/4 throttle. If the engine surges (gains power), your mains may be too lean.

Confirm the function checks by looking at the test plugs. The first thing to look at is the smoke ring at the very base of the insulator. If the mix is good there should be a thin dark grey ring at the insulator base. If it's not there, you're too lean. If it's 1/8" or more thick, you're on the rich side. The next thing to look for is grey aluminum flecks on the insulator nose. If there are any there, that's stuff that belongs on your pistons; retard the timing by the width of the stator mark to inhibit detonation and go again. Look at the ceramic on the insulator. If it has a course, grainy look to it compared to a fresh plug, go to a colder heat range.

Keep the clip in the middle 3 notches of the needle. Going outside that gets you out of the most effective metering range of the needle. Over the years I've run the BS38 carbs with a number of exhaust and filter combinations (Mac and Kerker 2-1's, Mac glasspack 2-2's, big ole TT pipes), and I've gotten the best results by tuning from the pilots and mains and leaving the clip in the middle notch.

A word to the wise--if you get into the throttle chop run and start hearing detonation, terminate it and try again when you've retarded the timing a little.

grizld1 · Posted: July 28, 2007, 10:51 pm Post subject: Re: drilled out my baffles

Oops! We were writing at the same time, Shawn--guess you don't have to wonder whether the main mix was rich or lean now, eh? Let us know what happens on the chops. You've discovered an important thing about these carbs--everything affects everything else--the change to your mains helped your pilot circuit.

xs1961 · Posted: July 29, 2007, 7:05 am Post subject: Re: drilled out my baffles

Shawn,I meant free-flow (baffle-less) silencers or mufflers as theyre called in the US,such as the Triumph T120 items I have on my XS

INXS650 · 650Rider Supporter Joined: Mar 22, 2007 Posts: 645

After drilling, went from 38 MPG to 41 MPG. I think I'm on to something!

xsjohn · Posted: July 29, 2007, 4:02 pm Post subject: Re: drilled out my baffles

You still have 10 more MPG to go......Would have to be some pretty big holes to deal with that gap.....Maybe the lucky 7........Hard to close them off though......Don't care what anyone says the sockers are great.......The only hole I'm gonna drill is in my head...........Stockers may keep if from turning 7000......Don't know for sure never tried it.......But that's why there is more gears........

John

INXS650 · 650Rider Supporter Joined: Mar 22, 2007 Posts: 645

My stockers are still on, just slightly modified. They are on their last legs, so I figured I would give it a try. My cross over pipe it about rusted in two, and the rest of the pipes are pitted. Almost time for new ones, but have to save my pennies for that.

xsjohn · Posted: July 29, 2007, 5:56 pm Post subject: Re: drilled out my baffles

When mine take a "S"...Although they are suprisingly in good shape.....Think I would go for some harley sporster mufflers of sort...Even if I have to build an short extension off the original headers and cover it with a small muffler guard.......From what I have heard these are pretty well made mufflers and might last a while.......

John

paulson_shawn · Posted: July 31, 2007, 1:04 am Post subject: Re: drilled out my baffles

went on a 75 mile trip through the hills, ran really good . my milage was 52 mpg, less than before but it ran so much better. tried the bosch platinum +4 plugs and they looked good afterwards , they made me have to drop my idle but now it doesn't hesitate coming back down when i rev it and still stays idleing at 1100 rpm. i didn't change my needle, it's still at the fourth notch down. i didn't take it over 6000 rpm but it pulled good from about 3000 to 6000 at full throtle still not much for top end speed, i guess it's just the way this bike runs. i did take the interstate home from sturgis at 70 for about 30 miles and it ran smooth and didn't over heat. maybe i'll try an 18 tooth front sprocket. i want to try the sportster mufflers too but i have the special exhaust so i have to get headpipes first, but it does seem too work well now so maybe i shouldn't change it. my cross over was rusted thru so i jb welded cast iron pipe plugs into the holes

xsjohn · Posted: July 31, 2007, 8:58 am Post subject: Re: drilled out my baffles

52 mpg is what I'm getting with my epa carbs.....Richened it like you did.....At 50 mph mine runs cool as a cucumber bump it to 65 and the cylinder temps go up 20 degrees..85 ambient..Still not real hot but it buggs the heck out of me.....I hate to fool with the stock pipes cause if it doesn't help I am just stuck with the extra noise......230 cylinder temps at 50 mph 250 degrees max at 65 mph 85 degrees ambient.......I am geared 18/29 so I put it in 4th which is about stock gearing and rode it 10 miles at 65 to see of the gearing was heating it up....Not the gears...same temps.......Must be the back pressure....??

Never had my stock 80 mufflers off the head pipe.....I'm sure they come off....Could use a muffler spacer to mate with the harley muffler and use the double walled stock header pipe.......A thirty dollar infrared thermometer sure is handy....at least we could get over the terms....running cooler....not runnig hot ...not heating up.....overheating...........ect

2007 harley guys are complaining about 235 oil temps..Heard some say 300+ head temps...Larger cylinder fins isn't helping the super lean mixtures demanded on them.....can you imagine...EPA has them hosed into a corner.....At least we can play.....my spin on runs 150 max ...... top end cooler runs 135-140 max...head runs 235 max...Lower end runs 180 max....If I can solve the 250 max cylinder temps at higher speeds I would be happy...If not everything is cool...Maybe better mufflers.....??????

John

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