Bumpy low speed driving

[Carl0s]

Any ideas what can i do, when cruising low speed on first or second gear, the ride is everything else exept smooth.

like, if you try to drive steady, second gear and ~2000rpm, the bike is constantly swooping, deaccelerating, and it sounds bit like its missing few sparks. So if you want to cruise ~walking speed, you cant drive whit torque, since you need to slip the clutch to keep ~2200rpm.

On third, the bike cruises nicely all the way from 1500rpm, but on the first and second its realy bumpy...

Ideas ?

 

[Oldgit]

Do you have the airbox breather reroute mod? It helps with low-speed bumpiness.

 

[07Bolt]

Do you have the airbox breather reroute mod? It helps with low-speed bumpiness.

at low speeds more oil seeps into the intake, without the breather reroute, vs higher speed when the oil is circulating better

 

[Carl0s]

Kinda, just did it yesterday. (the simplest breather mod one)



Just gotted my EMCSpy cable ready, any map-tuning that i could do to enhance the low rpm performance ?

 

[Sirius815]

It's really a shot in the dark if you don't have a wideband o2 sensor to know whether you're a little lean or a little rich - you can try decreasing a point or two from the fuel map between 900 and 1900 rpm at the two lowest throttle positions. If that makes it worse, definitely go back to the original map. Or of course you could try adding a point or two.

Also - double check your static timing (just for good measure).

 

[Lesley]

it is the nature of the beast.

[up] They are not smooth riding until 3rd gear or approx 30 mph

HD pushrod motors do not like city or parade speeds.

 

[07Bolt]

start with the easier ones first like a TPS reset; idle adjustment; spark plugs

 

[Iamarchangel]

Nature of the beast is best answer.

DO NOT TRY ANY ENGINE ADJUSTMENT FOR THIS.

2200 is too low for a big twin, really. Don't listen to anybody else.

First and second gear are like that, it's not a parade bike.

(Mechanically: you said it works fine in other gears, that tells you everything is fine. It's the gearing and physics.)

I just shut the bike off and straddle walk it if I'm stuck in a jam and I avoid parades.

 

[konarider94]

x2 to what 07Bolt said. those things are key to low speed smoothness. as well as primary tension that others have mentioned.

 

[Oldgit]

Thanks for expanding with an explanation 07Bolt

To be honest, since I did the breather reroute my bikes a LOT smoother in 1st/2nd.

 

[07Bolt]

if ur primary chain is loose/too tight it can wreak havoc on the trans/engine sprocket. like when u speed up the chain gets a better grip. and when u slow down its loose/floppy maybe.

then u would check the bolt tensioner bottom of primary cover. also check the slack of the primary chain in the inspection window hot & cold to accurate specs

 

[Carl0s]

Thanks, need to first do the tps reset, and check the plugs. Tho, the tps part need to wait a bit, bit shamed to admid that i managed to assebly the plug wrong way aroung (shamed since im electronics technician and worked ~2years as car electric specialist, now working on electronics and precicion mechanics)

dont know what i was smoking while asseblying the connector, now the wires come out on that end that were suppose to be plugged in the bike... well, i guess we all have our blond moments (oh wait, i am blond!)

For the plugs, OEM or Iridium? the prev owner had the plugs changed last winter, but he swore in the name of OEM, so the bike has genuine H-D plugs, good or bad ?

For the primary, need to check the tension, would it be any help if i buy the spring loaded drive belt tensioner from troijan-horse ? (i need more excuses to buy then just that it looks cool)


thanks

 

[Carl0s]

Update:

Checked the primary chain, was realy, realy loose. The freeplay was ~2chain from top to bottom.

Havent tested it yeat, the bike is on stand's while doing fork rebuild. Also, need to change the plugs to iridium, flash racemap, and make the airbox breath a litle better.

Also, unriveted my drummer. Just an hollow box, think il add an meshpipe that goes from the outlet half way to the pipe, and fill the rest of it whit steelwool...

 

[Oldgit]

My PChain was 18mm cold, should be max 12.7mm lol. Really sounded like a bag of bolts was thrashing around in there.

Iridium IX plugs.

 

[freak2180]

Also, unriveted my drummer. Just an hollow box, think il add an meshpipe that goes from the outlet half way to the pipe, and fill the rest of it whit steelwool...

If your drummer was hollow and didn't have the cage with packing then you got shafted when you bought it.

 

[Carl0s]

If your drummer was hollow and didn't have the cage with packing then you got shafted when you bought it.

There was cage, and some burn cushing between the cage and the shell. The catch is, im suppose to be on track whit the bike on wednesday, and the track has an 96dB noise limit.

 

[freak2180]

Not much to do other than repack the drummer the way it was designed to be packed. You try to engeneire your own core and you will quite possibly destroy any gains it gave you. Sounds like you need a stock muffler for your track days....

 

[ich]

like, if you try to drive steady, second gear and ~2000rpm, the bike is constantly swooping, deaccelerating, and it sounds bit like its missing few sparks.

http://www.ukbeg.com/forum/viewtopic.php?p=187712#p187712

 

[Carl0s]

Not much to do other than repack the drummer the way it was designed to be packed. You try to engeneire your own core and you will quite possibly destroy any gains it gave you. Sounds like you need a stock muffler for your track days....

The meshpipe that i plan to install inside the drummer aint suppose to be permanent solution, but more like db-killer for the track day.

tho, if i put the meshpipe straight from the inlet to the outlet, it would change the mufler from hollow type to flow trough, probly increasing the high rpm power, but decreasing low rpm. Also, the DB-killer should have opposite effect.

 

[freak2180]

It's ur pipe man so do as you wish. The drummer design is actually quieter than any straight through pipe. The more direct the flow the louder it will be. It dosent matter how much packing you place around the inner core if the exhaust dosent have a chance to slow down and allow the packing to do its job. I bet if you just repack it with somthing like FMF 4 stroke packing it will be more pleasing to the ear. Then you can concentrate on a DB killer that just slips in the outlet of the pipe. Tou may even contact Kevin and see if he will fab one up for your needs.