Carb Question

[lastleg]

Before anyone starts yelling at me... I HAVE read carbs 101 (I have a heavily thumbed, greasy and splotched hard copy of it on my bench) and I still have a few questions.

1. 91 Katana 600 with the Mikuni carbs.
2. Existing main jets: unknown. PO really butchered the carbs replacing the jets (guessing he re-jetted it to accommodate the V&H supersport setup)
3. Existing Pilot Jets: replaced the jets with 35's (orig equipment is 32.5) to combat poor take-off power.

Here's the issue: I knew that I'd be ditching the V&H pipe, so I didn't try to play with the jetting too much. Finally did my rebuild of the bike and kept the V&H 4 into 1 header but installed a Yosh RS-1 exhaust (meant for a GSXR600) to quiet the bike down.

The new can sounds great-- very quiet and produces a nice exhaust note. At this point, however, the bike is just sort of wishy-washy. My first instinct is to return to dead-stock jetting and then play around with it from there.

Problems:

1. Bike simply fails to idle correctly. Playing with the idle adjustment either leaves me idling at 2000 rpm, or barely running at 300 rpm.

2. Once off the pilot jets, acceleration is nice through 4-5K, then seems to bog out.... If I keep rolling on slowly, power returns at approximately 6-7K.

3. I smell gas all the time.

4. I get crappy fuel economy.

5. While decelerating the bike backfires quite a bit.

I'll be ordering new jets as soon as I get a general opinion from the group:

Go back to bone stock 112.5 jets or not? I know the the V&H pipe was wide open. Very little back-pressure. Yosh is much more restrictive. Thoughts?

As an FYI- I also think that the E-10 gas here in NJ is gumming everything up. Adding 1.5 ounces of Seafoam made a huge difference, but the bike definitely needs the carbs worked over.

Thanks,

Andy

[Maverick.Marq]

I have the V&H full exhaust so I can comment on a few of these things...

Problems:

1. Bike simply fails to idle correctly. Playing with the idle adjustment either leaves me idling at 2000 rpm, or barely running at 300 rpm.

if you figure this one out, let me know...

2. Once off the pilot jets, acceleration is nice through 4-5K, then seems to bog out.... If I keep rolling on slowly, power returns at approximately 6-7K.

if you have adjustable needles, I find the kat pulls stronger on the second clip ie. one down from middle (richer)

3. I smell gas all the time.

this is to be expected (for the most part)

4. I get crappy fuel economy.

I get about 35 mpg

5. While decelerating the bike backfires quite a bit.

This is most likely an after fire caused by lean conditions.

Tuning for the V&H exhaust system has proven to be a huge pain in the butt for me. and I'm still not done.

It's important to start with well cleaned and properly synced carbs before experimenting and making sure you don't have some other sorts of issues affecting your riding. or you'll be kicking yourself for longer than you'd care to admit (for example, electrical issues, dragging clutch stuff like that)

[Kreylyn]

Which V&H system? To confirm the CC size the V&H system was made for, where does the collector on the header terminate at in relation to the bike. At or even with the oil drain plug, or well past it a few inches?


What kind of jet kit are you using? That's pretty important to know before we can specific jet size and needle positions. If you don't know the jetkit, describe the jet needles in detail including how many e-clip slots and we can probably help you out. A clear close up pic would be better.


Have the carbs been fully disassembled and deep cleaned? Have the carbs been synced on the bike? Did you check the valve clearances before doing the carb sync?


Krey

[e30bradley]

ill take the exhaust off your hands if you want to sell it or trade, I have tons of stuff I could trade you.

[lastleg]

The Old V&H pipe? Ha... you can HAVE it... beat to hell.

[lastleg]

reply

Which V&H system? To confirm the CC size the V&H system was made for, where does the collector on the header terminate at in relation to the bike. At or even with the oil drain plug, or well past it a few inches?

What kind of jet kit are you using? That's pretty important to know before we can specific jet size and needle positions. If you don't know the jetkit, describe the jet needles in detail including how many e-clip slots and we can probably help you out. A clear close up pic would be better.

Have the carbs been fully disassembled and deep cleaned? Have the carbs been synced on the bike? Did you check the valve clearances before doing the carb sync?


Krey

I've attached a picture of the exhaust. The collector terminates just even with the drain plug.

I'll take pictures of the existing jets... frankly, I haven't a clue who makes them or what they are. Again, didn't want to start making any changes 'til I got the new exhaust in place.

carbs have been deep cleaned (soaked overnight in carb cleaner, scoured, scraped, re-assembled. I'll do it again when I install the jets. Just got a manometer and am excited at the idea of getting a real (non-mechanical) balance done, for the first time.

Thanks,

Andy

[e30bradley]

picture doesn't work for me. And thanks! I'll come pick it up sometime soon. Maybe tonight?? I'll take a look at your bike, maybe I can help. I'll bring my morgan carb tune and show you how to synch em. (your problem most likely has nothing to do with being out of synch though)

hmm your about 60 miles from me. I cant come today. Maybe once I'm healed up from the crash I had yesterday I'll ride out to you.

[Aaron-71]

I've attached a picture of the exhaust. The collector terminates just even with the drain plug.

I'll take pictures of the existing jets... frankly, I haven't a clue who makes them or what they are. Again, didn't want to start making any changes 'til I got the new exhaust in place.

carbs have been deep cleaned (soaked overnight in carb cleaner, scoured, scraped, re-assembled. I'll do it again when I install the jets. Just got a manometer and am excited at the idea of getting a real (non-mechanical) balance done, for the first time.

Thanks,

Andy

Just following your thread, and don't have much input (just reading for info).

I also can't get your picture to work either. Try using Photobucket and uploading your picture to their website, then use their "[IMG]" links to post pictures here on the forum.