any input before i dig in again?

[beechfront]

recently rebuilt the carbs as they were leaking. put on individual air filters, used 42.5 pilot (45's were on backorder) and 147.5 mains (per recommendation). I set the float height (dry only) and finally balanced the carbs.

On the drive -- idles great, runs good up to around 4800 - 5000 though it seems to be lacking power, then at the 5k point, I have the throttle wide open it cuts out about then and will only creep up past 5 if I let off the gas a little bit. Couldn't get it past 90 mph.

My plan is to put the 45 pilots on - hoping that will help with the power on the low end - I'm also wondering if my problem on the high end is that the 147.5's are too much. I plan on putting in the 145's.



any thoughts?



this thing is LOUD now with those individual filters.

[schpiff]

hi beech..I aint an expert but if its cutting out at mid/higher rpm under a load it sounds to me like its not gettin the fuel it needs. Some ignition issues come to mind (a lean mixture is harder to light) but..I myself would double check fuel levels and make sure it isnt "starving for fuel". Make sure you got good flow of fuel from the tank as well...

[MartyA]

You said you set the floats dry. I think you have to invert the carbs to set the floats, so they would have to be dry. They may be set too low.


Here is some theory:
http://www.factorypro.com/tech/carbt...m_engines.html

and here:
http://oldmanhonda.com/MC/Rcarbs.html

Blaine's site:
http://www.sonic.net/~blaineh/Carbal1.html

and of course don't miss this:
http://www.xs11.com/tips/maintenance/index.shtml

[Jerry]

Check the fuel lines themselves. If not fairly new, put on new stuff. Had an experience where old lines swelled from the inside, strangling fuel flow. (Not a bad idea to replace vacuum lines as well.) While you are at it, adding in-line fuel filters are recommended by many poeple on this list.

[RiskyBusiness]

Look into those individual air filters. Many of the designs have an internal flange that works like a choke at high revs. Search through the discussions as there is previous discussion concerning this.

I have two sets of indy filters. One from Cycle-Recycle and one set from partsNmore (the oval ones). Both seem to have a smaller internal diameter just past the mounting flange. I am concerned about that blocking some of the airflow or possibly the air to the air jet intakes. I plan on playing with these this weekend. I just got K&N rebuild kits from Cycle-recycle. I am very happy (so far) with the kits. They seem to replace more "squishy" parts than other kits. Especially that little o-ring on the idle mixture screw.

[beechfront]

I set the floats per directions in the clymer manual. carbs upside down, and using a caliper to measure the distance to the base of the bowl - but being the first time i've done that I could easily have screwed something up there. Before I tear anything apart I'm going to go see how it acts cold - according to one of the three great links MartyA provided- if it is a jetting problem like I originally suspected it should perform better when cold. "If the bike pulls harder at high rpm when cold and less hard when fully warmed up, the main jet is too large". For the time being - i removed the octopus (since it wasn't doing anything anyway) and put in filters. I'll check my fuel lines as I very well may have done something to restrict fuel flow. Risky - your suggestion would also explain it's behaviour. seems like when under full throttle when it hits a certain RPM it just stops and will not accelerate any further unless you back off the throttle a bit which will get me just a few more (500 or so) RPMs. The filters I got were from cycle-recycle - were you experiencing problems with both? I tried searching for information but had no luck.

thanks for all of your help.

Cory

[CA.XSer]

Cory

What do your spark plugs look like?
Was the bike running before you made changes?

The main jets work some at idle but really start to come in around 4500-5000 rpm range, I think you are to big on main jets.


On my 79 Special I have a Jardine 4-2 exhaust and K & N filter, running 142.5 mains, which is a little rich.

[beechfront]

Will check plugs when it cools down. the bike was running perfectly before i made any changes. only problem was leaky carbs. I lowered the floats just under 2 mm this morning. Seemed to help just a bit on the top end, but taking off from idle is much worse now. I am going to put the 145's in and see what happens. if that doesn't help on the high end i guess i'll have to order the 142.5's. Still waiting on the bigger pilots which I am hoping will help off of idle.



also - GAS WAS ON THE FLOOR AGAIN THIS MORNING - if the fuel level is too high in the carbs will that cause gas to leak? I thought that if the floats were working properly it should never get high enough to leak out. assuming that i'm wrong - i hope that the lower fuel level will take care of this but i don't have my hopes up.

thanks again.

[beechfront]

CA.XSer --by the way - did you change your pilot jets? you have the same setup as me except i'm running 4-2 stock exhaust and cheap-o air filters.

[CA.XSer]

I lowered the floats just under 2 mm this morning. Seemed to help just a bit on the top end, but taking off from idle is much worse now. I am going to put the 145's in and see what happens. if that doesn't help on the high end i guess i'll have to order the 142.5's.

With the carbs upside down on the bench is the 2mm closer to the carb body or further away? If closer you are making the fuel level higher in the carbs which makes the fuel mixture richer.

What mains did you remove from the carbs when it was running ok? I would start with one size larger from what was removed if the only mod done was indy filters and work from there.


Do you have a set of 140 mains? I would use those.
The 79 Special was stock with 137.5 mains.

[CA.XSer]

CA.XSer --by the way - did you change your pilot jets? you have the same setup as me except i'm running 4-2 stock exhaust and cheap-o air filters.

I did not change pilot jets, they are stock size.

[beechfront]

I was going off of these JETTING RECOMMENDATIONS and then on another post somebody said that they might want to go one more on the individual filters. Firstly I think I misread it which put me at 145. then per the advice on another thread put me at 147.5 -- so I'll try the 145's and hope the advice was right. This is what confused me-

first it said:

"Add up all the jet size increases and subtract one. (Remember they go in steps of 2.5 for each jet size)"

then immediately after said:

"Under a mismatch condition, like individual filters and stock exhaust or 4 into 1 header with stock filter and air box, subtract an additional 1 jet size."

I was reading both lines as being together - meaning if you were using a combination of more than one of the things listed - you were to subtract one jet size from the total. So I went up three when I think I should have went up two..



Also --with the carbs upside down i moved the floats further away from the carb body.

Cory

[CA.XSer]

I was going off of these JETTING RECOMMENDATIONS and then on another post somebody said that they might want to go one more on the individual filters.

The way I understand the Jet Recom. you should be up 1 jet size at 140 mains.

I am heading out of town but will be back Sunday eve. Will get on line then and see how you are doing. Hang in there you will get it right!!

Good Luck

[beechfront]

well it says: 3 jet sizes for individual filters which should put me at 145. i am confused about whether or not i should subtract one size or not.

anyway, my 145's were a significant improvement from 147.5's. I was able to get 110 mph out of it. still bogging at full throttle though. So I went and bought a set of 142.5's at the local shop. They said if they aren't right they would trade them. After I get this right it's on to the pilot jets.


Thanks so much for your help. hopefully i'll have it working good before you get back.

Cory

[beechfront]

I AM AN IDIOT.

When I synchronized the carbs for the first time - i removed the octopus since it was not working anyway. Well, when I did that I failed to plug the vacuum tube coming off of #2. Here's where I'm at now - I have put on 142.5 mains, and still running stock 142.5 pilots. out on the drive - low end problems are pretty much gone however there is still a slight flutter around 3000 rpm. Out on my "private highway" top end was better - but now I seems to be losing power around 6k. A much more gradual loss now which makes me think it's not getting enough fuel. So first I will try the 145's again and see how it acts. if it gets worse I think I'll use the 142.5's and raise the fuel level a bit.

I have two questions:

FIRST: will the pilot jets make any difference at higher RPMs?

SECOND: by raising/lowering fuel level in the carbs, does that cause it to run rich/lean or just change the amount of fuel available? If it does cause it to run rich/lean - why even bother with jetting?


I'll eventually figure this out on my own but if somebody could help me out it would speed things up a bit.


THANKS!