idle fine to warm up then stays at 2000 after hard riding

[mason79]

i searched... but could not find

i really don't want to sync the bike, with all that gas spilling all over the place and struggling with the gas tank.

i didn't change anything really, just the battery.

the bike will warm up and idle perfect at around 800-1000

only after i ride it hard or maybe not so hard, it goes to 2000 and stays put, does not climb, any insight? TIA

[prometheus578]

Quit being such an "idler".

Idle seems a bit low... I happen to like around 1100 rpm.
Now then...
To idle higher once the engine warms means that you're not properly burning the fuel when cold.
You'll note that when using the choke to start:
You pull the choke out all the way and the bike idles at a certain RPM. As the engine warms, the idle suddenly rises, so you go to half-choke and it drops down again. Engine warms further and the idle starts to creep up again, and you turn the choke off.
I don't think that you're running on all cylinders at idle/start-up.
Just for a quick test, start the bike cold and spray the headers with water as the engine is warming up. You may have a cylinder not firing, or firing intermittently. The lack of "sizzling water" will identify which is the troublesome cylinder.
If this is correct, you also may have set your idle speed based on idling with only three cylinders... and when the fourth one kicks in, so does the higher RPM.
Vacuum leak is another consideration.

[DiverRay]

Mason,

i really don't want to sync the bike, with all that gas spilling all over the place and struggling with the gas tank.

I think you WILL need to sync the carbs. It should NOT be that big a deal. I usually wait until I have about 80 miles on the tank, and then do it. I would also check for vacuum leaks. Fist thing to look at is the plugs on the intake manifolds. If they are stock, REPLACE THEM!!

[Ivan]

when I work on the carbs, I just take the seat off, and flip the tank around and hook it back up to the fuel lines. Not that big a deal.

The sync will be worth it.

[mason79]

Prom, i thought when i replaced the petcock vacume line ( leak; it had a split, twice... bad part maybe not meant for motorsports, the other side is a manual petcock from mikes xs, so no prob there) that i took care of the high idle

i routinely feel the pipes when starting to gauge cylinder activity during start up, up until it gets too hot to play with, ( it goes from cold to warm to warmer blah blah hot to hotter to sizzle, you get what i mean)

so my guess until i go out there again to verify, is that all 4 clylinders are firing from the get go.

Ray, i have replaced those manifold port plugs with mike xs products when i got the bike so they appear not to be the culprit at this time.

yeah i think it's time to sync, but damn it any volunteers? local?

i made the homemade one and have just one gauge a real piss poor juggling act at best.


could it be the individual air fuel mixture screws?

[cywelchjr]

Ray, i have replaced those manifold port plugs with mike xs products when i got the bike so they appear not to be the culprit at this time.

yeah i think it's time to sync, but damn it any volunteers? local?

i made the homemade one and have just one gauge a real piss poor juggling act at best.


could it be the individual air fuel mixture screws?

I don't have enough experience with the 1100's yet, but with the 400's which in 1980 at least use the same carbs high hanging idle after hard running is lean idle mixture. I haven't touched my mixture screws yet because it seems to be pretty dialed in on my 1100 but on my 400 it took a lot of adjusting to get it right.

[TADracer]

Mason, kind of sounds to me like you need to re-sync your carbs (providing you have no vacuum leaks or sticking carb linkage). If just one is out of sync a touch too much from the others the out of sync carb can actually tend to have that cylinder drag the others along to an extent, usually raising the RPM to a slightly higher level at idle.

Adjust your idle mixture screws first then sync your carbs (I know you dont wanna) then adjust your idle speed to around 1100 then test ride.

[tarzan]

I dont even have to disconnect my fuel lines to sync.I got rid of the octy a while back ,then took a suggestion from channel eleven and routed the lines from left petcock to right side carbs and vice-versa.Also found I could leave enough extra line this way to be able to just remove the seat then lift the back of the tank and insert a block of wood under it to gain enough clearance to adjust pilot screws and sync.I can adjust and resync and have it all back together in about half hour.

[bikerphil]

sync

I use one of these screwdrivers to sync. Don't even have to unbolt the tank. Just hook up the vac. lines and adjust.

[mason79]

I use one of these screwdrivers to sync. Don't even have to unbolt the tank. Just hook up the vac. lines and adjust.

where do you get one of those screwdrivers? jc whitney? dennis kirk?

[bikerphil]

The one I have, I got from JCW for about $25. Having it is invaluable tuning these in line 4's.

[mason79]

i did it the last time, it was close but not spot on, i've been reading here, i'm gonna be using the single vacume gauge homemade unit
sync 4 to 3 and 1 to2 then those 2 banks to each other or is there another sequence,

like the bread wire method?

[GARTHXS]

sync

I use a homade sync tool , made from a yardstick. Some 1/8 clear tubing and some wire ties filled with 20/50 it takes a little time. And you have to put in some pilot jets into the ends of the tubes , but it works well enough for me

[thewiz]

In Synch ...

Not the boy band BUT I will synch your carbs .... I have a Morgan Carbtune and the angled screwdriver ... piece of cake. Now as far as the 'rising idle rpm' is concerned, could be that the remaining vac petcock is leaking back through diaphram then down the vac hose and finally into the cylinder itself ... 'specially you mentioned recently replacing a vac hose with multiple cracks. Vacuum hose in general doesn't hold up to gasoline too well at all, if ya' catch my drift. PM me or get my number from Richard and we'll set up a time ... I'm in Vista pretty close to the 15.

[mason79]

yes the newish mikes xs port caps had cracks in it, 2 years old, why?


the throttle cable seemed gummed up, i w d'd it, yet to ride but i think it was vacume leaks, the long tool is coming from ebay so....
thanks again for the support!!