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Discussion Starter · #1 ·
So last night I took the carbs out and decided to try my first attempt at rejetting
The previous owner had work done to it so he could start the bike without using the choke, I still have yet to determine what exactly was done to it but here's the info I have gathered so far
The carbs have been tinkered with
I can see several float bowl bolt heads that have almost been rounded off so I know someone has been in there, also the welch plugs have been removed.

The kit I got from carbjetkits. com came with
4 needle shims (washers)
3 main jets sizes 110, 115, 120
2 pilot jets size 42

according to the instructions I am to put the bigger jet in the rear since it burns at a higher temp

Right now I have the size 120 in the rear and 115 in the front
Both pilot jets are 42
And I have one needle shim installed on each carb

As far as exhaust I am running drag pipes with no baffles
Intake I am running velocity stacks

"stock" main jets are 108 and 110
"stock" pilot jets are 40
That's what I pulled from them
Are those the actual stock sizes?

Right now it idles fine
BUT the pilot screws have no effect, I have turned them fully in (gently) while the bike is on and warmed up and it does nothing
At WOT it bogs out unless I very gently hit the throttle and even then it jumps and sputters
I tried opening the pilot screws and it still bogs out

From what I am to understand I am running too rich?
Any help or links to threads would greatly help
Future apology for my ignorance I am very new to jetting, carbs and motorcycles in general so I'm just trying to gather as much info as possible
 

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Discussion Starter · #3 ·
Ace 750
I went down to a local motorcycle supply shop and picked up a couple more jets
Right now I have
#42 pilot jets
#124 rear main jet #122 front main jet
0 needle shims

Before I had #120 on the rear and #115 on the front, it would idle but would bog out at WOT, I also turned the mixture screws all the way when the engine was warmed up which had no effect on the engine (supposed to kill it right?)

Now I have #124 on the rear and #122 on the front
it had the same symptoms of stumbling and sputter at WOT, I opened the mixture screws up to 3.5 turns out which almost completely solved the issue

From what I am to understand the needle shim would richen up the mixtures through the whole power band?
Should I install the needle shims also?
It sounds like I need bigger main jets also so I can turn that mixture screw in a bit, does that make sense?
Like I said before I know little to nothing about re jetting but I believe I am headed down the right path.
 

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Discussion Starter · #5 · (Edited)
2002 vt750cdc (i believe that's the california model?)
I was able to get rid of TONS of crap after this mod!
Right now I still have the same jetting
I installed two needle shims on each carb and it seemed to smooth it out a bit
the pilot jet appears to be the correct size since it idles fine
But under heavy load (WOT) it sputters and spits like it wants more gas
I believe new pilot jets are in order
Also on a side note I ended up making my own pod filters if anyone is interested
my carbs measures just about 50mm OD
I took a exhaust coupling from autozone (2"OD)
cut it in half so each one was about 2.5" high
Took a wire sink screen from home depot (6$) and added it to the end of each coupling piece via EZ tape silicone tape
Wrapped the carb intakes in the same tape
The E Z tape gasket is a temp solution but it seems to work really well for now
They arent really acting like velocity stacks since they aren't smooth at all
but I wouldn't really call them a pod filter since the only air opening is from the top (might not be too bad for side winds now that I think about it)

The main goal was to clean up the side of my engine (ba da ba ba baaa I'm lovin it)
and also to get a smaller tank (that air box under the stock tank is gone!)
 

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Discussion Starter · #6 ·
So in case anyone was wondering I figured it out
I went down to a local parts store and picked up 2 size #142 main jets
Slapped em in (total of 30 mins to remove/rejet/install now that all those damn hoses and junk are gone)
And fired it up
It now has more power than when I originally got the bike, not a huge difference but I can feel something, but the main thing that gets me grinning is how much better it looks without the bean box!
I currently have the idle screws out at 1.5 turns with no backfires on decel
I figure i will try going down a size to see how it runs but for now Its a little champ.

I wish I had re jet when I first got the bike, I was told they run really lean from the factory, so even if your bike is stock you should try it out.
Besides the power increase and my bike looking better, the main thing I took away from this project was the learning experience, I feel like I know my carbs and my bike in general a lot better now, which is great for someone who loves to tinker with things like I do :D
 

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Pilot jets work at idle to about 1/4 throttle, needle from about 1/4 to 3/4 throttle, main jet from 3/4 to WOT. Get main jets set first, can you rev out 4th gear at WOT or does it break up? When it breaks up, if you let off the throttle a little bit (like 1/8th of a turn) does it speed up a bit or slow down? If it speeds up for a second, too rich. What do your plugs look like?
 

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most motorcycle shops have jets in a box, all sizes. you walk in and say "i need some size xxx jets for a kehin carb" they pull out a box and find number xxx. My shop they're $5 a pop.
 
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