Top end query;

[XSokieSPECIAL]

Heh heh......... OK.......we've ascertained it's a chicken holding on to the BUCKHORN bars that seems to be low in the horsepower department.

So.......whatdya think? The thing runs like a champ until then.

Timing...valve adjustment....carbs?

I don't think it's a fuel problem, however, I thought I did hear a slight popping or pre ignition sound when it topped out.

Kinda like an under jetted engine. I am running 79 carbs with the main rods raised 1 notch though.

Hard to tell at that speed though.

[psycoreefer]

Heh heh......... OK.......we've ascertained it's a chicken holding on to the BUCKHORN bars that seems to be low in the horsepower department.

eieio.......

I'll bet if you left the buck and the horse at home you'd have no problem going faster, I mean that is a lot of weight, just ditch the barnyard animals and try again.....

[XSokieSPECIAL]

eieio.......

I'll bet if you left the buck and the horse at home you'd have no problem going faster, I mean that is a lot of weight, just ditch the barnyard animals and try again.....

ROTFLOL.........Damned farm animals from facebook have invaded this site now.






Anyone seen my little lost hog?

[crazy steve]

...It was a common problem (or is) on the mid 90's to 2002 Camaros that top speed could NOT be achieved in high gear. Because of a combination of things, you needed to be down 1 gear to reach the top speed the car could attain...

There's a prime example; too high a gear, and the motor is out of it's power curve and just doesn't have enough horsepower to overcome the mechanical disadvantage. So when you gear for reduced highway rpm/fuel economy, that won't increase your top speed and can actually reduce it. In this case, I think he's down on power and the FD change is just making it a bit more obvious.

'78E original owner

[XJOK2PLAY]

Greg,
Since doing my FD swap... I have -O- problems easily achieving 90 mph in 4th... and that's w/ my Vetter 4!

There's definitely something going on w/ yours.

So... you're saying you can twist her back wide open, on a long straightaway, and
98's all she's got? That ain't right at all.

With mine, now that I've swapped the FD, I've only had one brief opportunity to run it on up... and I hit 125 before I knew it... and it felt like I had loads to spare... more than before the swap for sure. I'm guessin' if I have the guts... I oughta see 135 or so... but probably won't do it... I've heard some say a Vetter 4 can become a parachute after the 120 mark...

Of course, the other thing that would limit the top IS HP...and I'm bettin' it'll start gasping for air somewhere around 130. 83 hp isn't 'all that' with the taller gearing. But I'm amazed how easily it'll get there now.

Something's gotta be holding yours back.

But you should be feeling it... if it were advance... or carbs... or a mechanical issue... even if it were an exhaust issue... I'd think you'd feel it being held back... but you say it seems to run great? Weird.
Maybe this weekend we can get together and go run them out... see the difference, if ya want. Let me know.

Steve's probably right... you're down on power, & the FD's making it show more. Question is... what's causing the power loss.
Bob

[TopCatGr58]

Hey Greg,

The XS max's it's cent. adv. at just under 5K rpm at 26 degrees, plus add the 10 degrees static, and that's 36 total for POWER curve. The vacuum adv. adds timing adv. under LOW THROTTLE cruising situations, but under strong throttle..it would actually be very little added. So you can check your Cent. Adv. with a timing light revving it to 5K rpm, with vac. capped off.

You haven't stated what your MAIN jets are? Running out of steam at top end sounds like your mains may be too small? Remember, you need to jet the 79 carbs according to the carbs, not the year of engine, and then adjustments with mods, adding sizes for freer flowing intake and exhausts.

Another thing could be restricted fuel flowing from the tank, so that after an extended high rpm run, the bowls could be emptying faster than they can be filled, resulting in lower fuel levels, and leaner running!?

Ivan and gang should have it figured out and tuned up in no time.
T.C.

[XSokieSPECIAL]

Yea TC, I'm gonna check the total advance when I screw up the anbitiion to pull the ignition cover AGAIN. I thought it was pickup coil wires to begin with.

Because of the preignition sound I think I heard I'm kinda thinkin' its runnin' out of gas.

I'm still running the octy and I may not be getting the fuel flow I need.

Not lookin' forward to takin' all that crap off just to check.

Maybe 98 is fast enough..................

[TopCatGr58]

A quick check will be to just put the petcocks on PRIME, bypassing the OCTY completely, and then take a run up and see what happens. IF it runs better, then you may have found the flow problem. IS the vacuum line to the octy in good condition...no cracks or such??
T.C.

[XSokieSPECIAL]

Never thought of that TC thanks.

I'll try that.

[jmnjrpa]

Hmmmmm Greg,

Check points should be: compression, shape of final drive (and mod), shape of middle drive, possible fuel restrictions, plug conditions, coils, valve clearances, wheel bearings, possible brake drag and maybe not last but not least atmospheric heat (heat alone can rob 10% of available HP).

Also +1 on your advance.

Scratch all that. I ain't no GURU.

[MindWebs]

when i figure it out i'll let you know, but if you get it fixed first PLEASE let me know!!!

i've got the exact same issue.
but mine stops at 105.

it don't have any barnyard animal problems... on the straights.
(except in corners, then you'll see my feathers)

i run 250's 2 stroke and four.. RPM is the ONLY way to get top speed.

i've tested my advance and it seems to stop shy of full stroke at 6cu. in vac..
(i think that's the right scale on the mighty vac) it fully engages at 9.

but yeah it seems more fual related....
i'm planning on jerking the octy for testing.
Prime still doesn't act quite right on my bike....??
pulling octy is a better test.

i'm installing green coils when they arrive.

keep me posted and i'll do the same.

[jmnjrpa]

Did you

check the air in the tires? He He He LOL Couldn't help it!

Seriously, stick a couple Roman Candles up the pipes and I bet your problem is solved! OK, OK, I'll sign off.

[DGXSER]

Wow...first its farm animals....now its shoving roman candles up his....pipes...yeah ...pipes. Well, this is Oklahoma now isn't it.

[petejw]

As TC stated, what size main jet are you running?
a to big or small main jet will cause what your describing,
and if the weathers hot like u stated earlier, could be a good
chance your running rich.

[MindWebs]

Agravation, irritation

Mine is running factory jetting.

i ran sporty pipes, same problem
i now have HD touring pipes, same problem
i installed adjustable inline exhaust restrictors, got rid of low rpm "dead spot"
still have same problem

it acts this way at all temps, i rode last fall down to 37F and this summer up to 88F and always acts the same.

all plugs show good light brown cardboard color.

have not "throttle chop" tested.

i have a colortune kit coming, should be here in a few days.
i have a spare TCI i'm going to try.
i have green coils coming, again.. in a few days.
i'll remove the octy to eliminate the posibility of a flow restriction issue.
the carbs ARE cleaned properly and floats are set properly

the octy, petcocks and carbs have all been rebuilt.

the pick-up fix is done.
the fuse block has been replaced (ATC)
all connections cleaned and die-electric greased.
spark plag caps are new.
spark plugs are new and in good shape.
timing light was used and vac advance unhooked.

pick-up tolerence has not been adjusted yet.
all 4 seem to fire evenly at low and mid throttle.

my idea's..

Bad TCI, messes up at high rpm under load.
Bad/weak coils.
Octy somehow restricting fuel flow...

Anyone have any other idea's please let us know.