Ok Didn't want to bore the list but will post some of what I found out.
As many of you know I am having a rich running problem with my long rod.
I ran last week and one pass would be 129MPH and then the next was
126MPH. I would yank my plugs and I found out that I was fouling the
plugs pretty bad. I had been experiencing with the mains and I was
getting it to foul less but still fouling pretty bad. When I took it to
be dynoed it came in at 172Hp corrected and that is what my friends was
at so I knew it couldn't be right. The perf shop told me the dyno was
telling me my bike was running fine. This makes sense as I found out
that they Dyno doesn't correctly interpret the mixture on flatsides cuz
it only works at wide open throttle. My mains were ok at wide open
throttle BUT my plugs were fouled when I had the dyno done. therefore my
HP WAS around 172 but my bike was not running properly at the low end.
So when I'm at the track and I run down with a fresh set of plugs my hp
was higher than what it had been dynoed at.
I called PCW and they started the troubleshooting process with me. Why
were my plugs fouling ? I could go on about the mistakes I made in the
last week but there were too many so I will talk about the way these
things should be tuned. First an overview of what is tunable on these
carbs and some history.
I never realized where these carbs come from, They are the flatside
carbs from Keihin that PCW MODIFYS. I always thought that PCW just
acquired them from Keihin as is and did some minor mods to make them
work on their big bores. They are the inline carbs and PCW modifys(cuts
them into individual carbs) and then fits them to the motor and puts on
brackets etc...... First eye opener for me !
Tuning
The carbs I thought had three adjustments to them Idle mixture, needles
and mains. With the order of throttle being 0-1/4, 1/4 to 3/4 and WOT
(wide open throttle respectively). I have been trying to launch this
bike and in order to get my bike to run have been whacking the throttle
too much. I was doing this because the bike just wasn't running to well
from 0 -1/2 throttle. Well that is killing my 0-60ft times. I had better
times on my stock vmax 0-60 at this altitude. Well, there is also a slow
speed circuit which has two adjustments to it. The slow speed jet(SSJ)
and the slow speed air jet(SSAJ). The SSJ and the SSAJ are what controls
my 0-1/4 throttle. Let me give you some symptoms on my 0-1/2 throttle
problems.
Problems
When I started my bike when it was cold it would start right up.Then
after it was running normal temp and I shut it off the bike would barely
start......Analysis, RICH RUNNING low end.
When I launch my bike it would bog a little and then at 1/2 throttle it
would take off like a bat out of hell ......Analysis RICH RUNNING LOW
end.
My bike was quieter than my friends 1428 long rod
(noticably)....Analysis RICH RUNNING low end.
Finally When I turned my fuel mixture screws all the way in to max rich,
The bike would stay running just fine.....Analysis RICH RUNNING low end.
These are classic symptoms of the low end being way out of whack. I
talked for about an hour with a guy named Paul Morgan at Sudco
(distributor) and he detailed what to do to fix these classic symptoms
of the flatsides. One other note the Mechanical activation of these
carbs dictates to ROLL the throttle PERIOD. IF you whack the throttle a
bunch of fuel runs into your cylinders and doesn't burn properly. A
habit very hard to break with my background running stock carbs. Keep in
mind the stockers are vacuum advanced such that the fuel is regulated
with the engine speed.
Back to tuning.
The SSJ circuit is a jet by the velocity stack and the jets are changed
out with smaller ones for rich running circuits. You use a smaller jet
to run leaner as they work with the fuel.
The SSAJ circuit can be one of TWO types. Either a needle type OR a jet
type. He thinks that I probably have the needle type in my carbs and
that they are adjusted all the way in. The jet type regulates air flow
and you turn those all the way in. The needle type is adjusted 1 and 1/2
turns to get them set appropriately.
The needles are like stock carbs and are adjusted with clips closer to
the point makes them richer (pulls the needle in more) further out makes
them leaner and pulls the needle out more which gives more air to the
mixture.
The mains for wot are jets and smaller numbers give you less fuel and
bigger numbers give you more fuel.
I took my bike home tonite and I am convinced that my slow circuit is
all screwed up. On the way home I started really feeling the throttle
and its response. When I am at 0-1/2 throttle my bike is not pulling
very hard and it seems to like bog. When I get to 1/2 throttle and roll
the throttle to WOT it just frigging screams. I am going to dive deep
into this low speed circuit and get this worked out......
I can't wait. I hope this helps and will update the list with what else
I find out about this. Some of you guys probably knew this but it was
totally eye opening to me.
Take care Colo Phil
Dennis Clarke wrote:
>
> Phil,
>
> why not post for all to read ?
>
> Dennis
>
> I found out some interesting things about the flatside carburetors. For
> those of you that this is of note to give me an email and I'll fill you
> in on the tuning tips that I got from a company today. Absolutely Eye
> opening !!
>
> Take care Phil
>
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