1992 GSF400 Carb Conundrum

[lknbandit400]

From that website, here's what each section means:

[Maelstrom]

Ok, so the N model does not use the rectangular rings in the slide housing then that just leaves the P and V models as possible candidates.

[SevenThreeSeven]

Remember that with Suzuki you have to be careful to specify Motorcycles vs Cars, although I think they use the same number/letter conventions with both it's much more interesting for us to see the specific breakdown of our motocycle's VINs, especially the VDS (Vehicle Descriptor Section) and the Engine Code (stamped on the crankcase).

http://www.suzukicycles.org/_misc/identification.shtml

[lknbandit400]

Remember that with Suzuki you have to be careful to specify Motorcycles vs Cars, although I think they use the same number/letter conventions with both it's much more interesting for us to see the specific breakdown of our motocycle's VINs, especially the VDS (Vehicle Descriptor Section) and the Engine Code (stamped on the crankcase).

http://www.suzukicycles.org/_misc/identification.shtml

Good point - I saw the link your posted but it didn't make sense apart from the context of the decoder website I found. A second look, yes that does offer a lot more detail about where each character comes from.

The one part that I'm missing is what those last 6 digits mean - somewhere buried in there is what number the bike was off the line.

[SevenThreeSeven]

The one part that I'm missing is what those last 6 digits mean - somewhere buried in there is what number the bike was off the line.

Well, I don't think there's not a lot of mystery that might be revealed by knowing the exact production-run position of your B4 (its individual production serial number). There just wasn't that much variation in specifications during the B4 production run, especially within the short span of the U.S. imported bikes.

Differences in the 1991 and 1992 models of the B4 were pretty much limited to whether the bike was built as an E-33 code (California bike) or an E-3 code (all other U.S. imported bikes). An E-33 bike meant the addition of fuel system evaporative control which caused a small reduction in fuel tank capacity and, the most significant change, a slight reduction in valve lift - 6.5mm for the E-33 vs. 7.6mm for the E-3. This change reduced the valve overlap period between intake and exhaust, thus reducing emissions. Suzuki never published a different horsepower rating for the E-33 (which only represented a very, very small amount of the overall production number) even though there absolutely had to be a reduction in horsepower due to the reduced valve lift.

The only major change in the U.S. imported B4's was the engine horsepower specification change that occurred with the 1993 bikes, when the horsepower was reduced from 59 to 54 horsepower (a reduced camshaft lift - 6.2mm, a different CDI box that was programmed with a slightly reduced maximum ignition advance setting, and a different pulse generator trigger wheel configuration).

Apparently the law allowed Suzuki to use up their existing production line stock of 59 horsepower engines so there are some 1993 B4s that got the 1992 engine. I have a 1993 bike so I had to do a bit of detective work to determine which engine was installed on my bike. I discovered that my B4's serial number was the 38th '93 model that came off the production line with the 54 horsepower engine. Really the only thing that makes this important to know is the valve clearance settings are different for the 1993 engine.

'91-'92 Spec: IN - .10mm to .15mm, EX - .15mm to .20mm
....'93 Spec: IN - .13mm to .18mm, EX - .20mm to .25mm

[lknbandit400]

Well, I don't think there's not a lot of mystery that might be revealed by knowing the exact production-run position of your B4 (its individual production serial number). There just wasn't that much variation in specifications during the B4 production run, especially within the short span of the U.S. imported bikes.

Well, I'd still like to know what number mine was off the line or know more information about the production number. You seemed to have figured yours out below - I want to know for the same reason you figured yours out, even though mine didn't occur right after an engine spec change :)

Differences in the 1991 and 1992 models of the B4 were pretty much limited to whether the bike was built as an E-33 code (California bike) or an E-3 code (all other U.S. imported bikes).

Thank you for that explanation of the California model! That makes sense in light of the carb variations as well.

Apparently the law allowed Suzuki to use up their existing production line stock of 59 horsepower engines so there are some 1993 B4s that got the 1992 engine.

No need to waste good engines, right? A lot of my work is in manufacturing plants for injection molded parts. Automotive is a whole new level. Too many regulations for me.

[lknbandit400]

On another note, I was notified that my parts from Partzilla were shipped today! I should be able to assemble carbs back to stock in about a week, maybe even by the weekend.

Hold tight for that. I plan to post up tons of pics step by step to eliminate all doubt that I'm doing something wrong.

[lknbandit400]

Okay! Stupid question time. I'm not ashamed :)

Carb bench syncing is the topic:

From what I have read (even though I can't find confirmation of this in the manual), carbs are numbered from left to right while sitting on the bike. So, from left to right we have 1,2,3,4 where #1 is far left (with vacuum line) and #4 is far right. Is this correct?

I have also read that to bench sync, you start with #2 because this carb is only impacted by the idle adjustment screw. All others are impacted by the screws between carbs.

So, from what I've read, the process is as follows: 1) adjust carb 2 using something thin, like a thin needle so the needle just fits between the throttle bore and butterfly. Then adjust 1 to 2. Then adjust 4 to 3. Then adjust 3-4 to 1-2 because 3-4 moves together using carb 3 screw.

It's probably easier to do than to type. Hopefully I'm not way off. Would appreciate your help on this.

For reference, I held the throttle wide open and measured the distance from the flat of the slide (because the throttle was open and the butterfly is more or less horizontal now) to the bore. Numbers 3 and 4 were within .15 mm from each other, as were 1 and 2. However 1-2 and 3-4 combinations were about .5 mm apart.

[SevenThreeSeven]

It sounds like you're proceeding in a thoughtful/logical manner and that's what bench-syncing a bank of carbs is all about.

As you've mentioned the only Suzuki GSF400 Service Manual prescribed procedure for getting this done correctly is the order of linkage adjustment. Page 4-13 (Fuel and Lubrication System) says that when you balance the carbs you adjust the linkages in this order: A. the linkage between carbs 3 and 4, B. the linkage between carbs 1 and 2, C. the linkage between carbs 2 and 3.

[lknbandit400]

Well that was easy! Thanks for posting that section of the manual. Doing it is much simpler than trying to explain it for sure.