Author Topic: Is re-jetting necessary? (Read 8081 times)

kiley · « **on:** June 08, 2005, 09:54:39 PM »

Hi gang!! I just bought a Yoshi RS-1 slip on and mid pipe off ebay for my Bandit. The previous owner mentioned he had rejetted. Is this necessary? And if so, how expensive and difficult is it? Thanks in advance!!

Kiley

WEINERDOGBONE · « **Reply #1 on:** June 08, 2005, 11:11:04 PM »

I rode my B12 for quite a while with a Yosh bike and standard jetting. You probably will want to drill the plugs out and open up your pilot screws a bit more to compensate for the increased exhaust flow. If you don't, you may find that your Bandit runs more lean than normal.

Re-jetting is not difficult but I found that it is time consuming when I finally installed my Holeshot stage 1 kit. The hardest part is getting the carbs off the bike. The Holeshot kit goes for $100.00 to $125.00 if I remember correctly. Others have had good success with IVAN'S jet kit.

Wait for Paul to chime in here. He is the resident mechanical guru. You should like that pipe. I'm really pleased with mine. I have the TRS Zyclone.

Red01 · « **Reply #2 on:** June 09, 2005, 02:43:56 AM »

No, you don't have to. It will run much better if you do though. Instead of just making a sweeter noise, you'll cut loose 15-20 ponies with a jet kit.
Ivan's or Holeshot are the most popular.

DaveG · « **Reply #3 on:** June 09, 2005, 12:55:10 PM »

my b12 with scorpion seem just fine after i drilled out the plugs and opened the a/f screws a bit. feels like a huge difference in power.

starts up quicker and needs less warmup now. can't feel any flatspots and a few plug checks shows things just a tad on the rich side. a quarter turn either way seems to make quite a difference.

the yosh may be more free flowing and require rejetting, but see how it goes after you get the a/f screws right. then raise the needles a notch or two and try that. then rejet if need be.

kiley · « **Reply #4 on:** June 09, 2005, 01:13:46 PM »

Thanks everyone. Now, next question. How exactly do I "drill out the plugs and adjust the a/f screws"? Where are they? Used to working on v8's under hoods...
Kiley

Red01 · « **Reply #5 on:** June 09, 2005, 07:58:11 PM »

Kiley, click here then scroll down to Step 26.

Bazza · « **Reply #6 on:** June 26, 2005, 06:30:36 AM »

Hi Kiley:

To start off, I am in no way trying to bash either Dale or Ivan as they have probably forgot more than I will ever know about b-12's.

I helped install Dale's stage 1 kit on a friends Bandit and after much struggling to get it to run right (Never could get a proper idle) we removed the timing advancer, put the stock mains & pilots back in, and closed up the airbox hole. (We did leave the needle shims in).

I have to tell you in all honesty, his bike runs all around much better with this set-up. (We set the air/fuel screws out to 3 3/4") Seems much crisper at low RPM & the shims seemed to get rid of the mid range bog typical on most B-12's around 3500 rpm.

In all fairness, it is probably our drastic changes in temp & humidity that caused the change back to stock. Could get the bike to run decent one day, and it would run like hell the next day after a weather change.

I had better sucess on my B-12 with Ivan's kit, (however I had a lot more time to tinker with mine). And again, our climate here made Ivan's suggested settings not the optimum ones.

In all fairness, Ivan gave great support to the jet kit I purchased, and Dale gave great support in helping my friend with suggestions.

From what I personally have seen, on my next B-12 I would probably just shim the stock needle valves, drill out the a/f screw caps and set the screws out more than the stock setting. From what I have seen with my friends experiment today, it left the bike with better all around performance . Granted a B-12 with a jet kit may do better in the quarter mile, but not much from what I can tell in our climate.

Just my observations.

Bazza

slo coach · « **Reply #7 on:** June 26, 2005, 10:51:15 PM »

Bazza, I would after having fun playing with the carbs,agree that what you have written is accurate,and is in keeping with loads of other posts on this site were it appears that unless you've got some dyno or a\f annalysers its hard to dial in the modified jetting and get a consistant result through a range of conditions.i settled on one clip up on needles.bigger mains,more air and scorpion.
i'm real happy.but cold temperature does effect the way it runs,plus it doesn't need to suck truckloads of air when commuting anyway.so getting that personal balance on how you want the bike to run ain't that eassy

slo coach

Bazza · « **Reply #8 on:** June 27, 2005, 05:19:15 AM »

Hey slo:

Just sharing my missery!

I am guessing there is no one faster on this site at removing carbs, replacing jets and syncing. (all in about an hour)

Another observation is that airbox mods seem to affect low down fun
(0-30 mph) .

I have no doubts that mine will out run a stock Bandit at top end & 30 mph roll on's but I went from 45 mpg to 36 mpg (worse if I ride like a child) This is something else to consider if you do much touring. I have rolled into a couple of small towns on fumes.

DaveG · « **Reply #9 on:** June 27, 2005, 10:08:16 AM »

added the scorpion and adjusted the a/f to 4 1/2 turns and went from 220km. to reserve to 300km. a 15% improvement in mileage (kilometerage??) btw with the increase in acceleration that i seem to be "testing" more than before i expected a decrease in mileage.

just turned the screws out 1/4 at a time until the popping went away.
at 4 1/4 it only popped very sightly but seemed a little weaker in the 3500 to 4000 range. still better that before but not as good as 4 1/2

shimming the needles would probably allow leaning out the a/f a bit.

but for now i like it alot.

Red01 · « **Reply #10 on:** June 27, 2005, 09:50:17 PM »

Quote from: "DaveG"

a 15% improvement in mileage (kilometerage??)

You're asking us if kilometerage is a word? Shouldn't any good Canadian know?

snofrog · « **Reply #11 on:** June 27, 2005, 10:41:02 PM »

Quote from: "Red01"

Quote from: "DaveG"
a 15% improvement in mileage (kilometerage??)

You're asking us if kilometerage is a word? Shouldn't any good Canadian know?

i dont think asking a Canadian aboot spelling is advisable

Red01 · « **Reply #12 on:** June 28, 2005, 02:26:02 AM »

We obviously don't care about spelling around here...

I was questioning vocabulary.

Boosted-Bandit · « **Reply #13 on:** June 30, 2005, 12:59:24 AM »

I have to add my bike runs much better with a jet kit, dynojet stage 1.
Didn't get rid of a lopy idle like I thought it would but it pulls much stronger. (This engine cammed up or what?)
Upon opening the air box hole with a die grinder I lost all composure.
I had to reconstruct the thing back to what it once appeared to be or face the task of changing jets and playing the shim the needle game.
Now I won't even touch the little rubber thing that smooths out the incoming air.

Red01 · « **Reply #14 on:** June 30, 2005, 01:05:29 AM »

Quote from: "Boosted-Bandit"

(This engine cammed up or what?)

Not really. Cams are pretty mild... unless someone has slipped GSXR cams in it.
(A common mod for those who gotta have more.)