Low RPM struggle

[audijunky]

From idle to 3000 rpm sucks! Cant figure it out. Compression good, Carbs clean, just cleaned idle mixture screw and ports. Running pod filters and open header. 145 mains and 45 pilots. I have got a 1 1/2 inch piece of tape wrapped around pods to limit air in, really no difference. What or where should I be looking? Back pressure? Plugs look good/maybe a little lean. I haven't synced carbs yet. I also get back firing during startup and warmup, but goes away when warm. Any Ideas? I have recently pulled carbs and sprayed out Idle circuit bowl straw, and idle mix screw and port. HELP I NEED MORE POWER I got a buudy w/ a sportster coming down this weekend and I want to show him whats what!

[petejw]

mine was doing the exact thing,
it becomes really annoying taking off at lights, when
cruising i dnt run it under 3000, if the pilots jets
are standard at 45 go one step bigger, mine only does
it when its warm, runs fine when its cold on choke, going up a size or running the idle circuit richer fixed my problem.
Im also running uni filter pods. hope this helps


peter

[audijunky]

Appreciate it, 45 is one size larger pilots. Any other ideas?

[randy]

audijunky;

Have you re-used your original jets or did you buy new jets? You do know about the K&L jet problem? If you put K&L jets in, revert back to your originals.

[audijunky]

thanks Randy, I did rejet but they are from MIKESXS. I was told that is the place to get em.

[trbig]

Ever get this figured out? Mine backfires on startup/ warmup also... but fine when it's warm. Thanks.

Tod

[audijunky]

Not yet, but I did have some broke off idle mixture screws, not sure if that was the problem, havent fixed yet. But it may also be cause I have no back pressure(open header) after I fix the screw problem gonna try to add some back pressure with the bolt and welded washer trick. Ill keep ya posted.

[strom]

Hmmm...
My 78E is really crap in low range. I can spin the rear wheel almost from idle on the 80.
I found out my vacuum pick up coil advance is really jerky on 78, but very smooth on the 80.

LP

[trbig]

My new main jets came in today, so at lunch, I ran home and jerked the carbs, cleaned the idler circuit out good, and installed the new mains.. then stuck the carbs back in the bike.
The bike has pod filters with original mains still, and was popping a bit on decel, so I went just one size up on the mains. I tried 3 sizes up a while back because I thought it may have been a little lean, then added the pods... WAY too much! So we shall see.

Tod

[mro]

Mikuni carburetor web site says that it may be difficult and sometimes impossible to properly tune their carbs on bikes with "straight pipes" (no restriction for back pressure).

THAT SAID, check out Knewsom and his 79' Maroon Baboon, he's got pod filters and a set of hardley muf's w/o baffles and seems to have got it tuned.

Personally think XS's run better with a baffle and would be much easier to tune. The washer mod should make little difference in sound but will impart some back pressure.

MAXIMAN's XJ with all those mods is running a full size muf with baffle, my hot rod XS is a little more XStream than MAXIMAN's XJ and I run it with baffle.


mro

[trbig]

I was working on the bike all night trying to get it ready for the Talimina rally, so I didn't get a chance to ride last night, but this morning, it feels like a whole new machine with just one size bigger main jet. Off the subject a touch.... I have inline filters, but what is that red crap that is settling in my bowls?? I think I had one idler jet stopped up.. cleaned them all up good. This morning it actually idled by itself on startup... NEVER did that before... but still popping and sputtering until it gets warm. And pulling from a stop sign... feels 200% better. I guess I just needed to get that idler circuit cleaned up. With that one size bigger jet, it just feels like a whole new machine. I wish I could have synched the carbs again after that... I'm sure it's off now that the idler jets are working better... ah well. I will do that after the rally!!

Tod

[Ken Talbot]

Originally posted by trbig
I wish I could have synched the carbs again after that... I'm sure it's off now that the idler jets are working better... ah well. I will do that after the rally!!

Tod

Whaddya mean after the rally?

[trbig]

Unfortunately, we aren't meeting at anyone's house. We'll be in a little town by the hills.... otherwise I would save it all up for you to do!!

Your version actually looks pretty fun though... all the guys.. a few beers... mechanical parts... All we'd really need is half naked pygmie girls like the ones in Pro's back yard!

Tod