Question about Pre-98 Yoshimura exhaust

[Andybro99]

Hey guys, I have a 1991 Katana 600 that I bought off of craigslist, seems to be running pretty well besides the need for some carb tuning (I have already cleaned them out and they are in great shape). The bike came with a K&N filter which i got rid of and replaced with an OEM filter. My question is the type of exhaust system that was on this bike. There is only a single pipe on the right side with a Yoshi RS3-looking muffler when I know the bike came with dual exhaust stock. Would this be a fully revamped exhaust system or a slip-on exhaust? I am confused. Thanks!

[ep87]

Would have to be a full system all pre's came with duals factory.
Richard

[Wild-Bill]

It's pure aftermarket. You don't want it. Drop it off at my house.

[MikeyZ]

It's pure aftermarket. You don't want it. Drop it off at my house.

You can actually just bring it to my house first..Ill bring it to Wild Bill.

[Andybro99]

So does this mean the carbs need to be rejetted? Or would that have been a given to whoever installed the exhaust years ago?

[Wild-Bill]

No rejetting is needed. The A/F screws need to be at 2.5 turns out and you need to make sure you don't have any vacuum leaks. Just like with a stock exhaust only more so. You could benefit from a FP jet kit and an ignition advancer but again, that's just like with a stock exhaust.

Oh, and let's keep in mind that NJ is between Baltimore and Boston...

[Kreylyn]

I vote yes, the bike should have a jetkit to be properly tuned to run a full Yosh system on a pre. Aftermarket headers and exhaust flow alot more than the stock does, and leans things out. From experiance, just having the carbs at 2.5 turns out didn't stop the bike from having alot of after fire...

You can check pretty easily if it is jetted. Take one of the caps on the carbs off, pull the slide out, and pull out the needle. Check it for multiple slots for the e-clip, count the number of slots to know what type of kit.

Krey

[Wild-Bill]

I ran a 95 750 Kat for 4 years with a full Yoshi 4-1, stock breather box/filter and stock jetting/needles. Ran great once I got rid of the air leaks and set the A/F screws to 2.5. Just sayin...

[Andybro99]

I remember when I was cleaning out the carbs, there was a gray needle that had a clip with 5 positions, while all 4 carbs were in the middle position if i remember correctly. Does this mean that there was jet kit already in it? Did the stock only have 1 setting??

[foxox]

I remember when I was cleaning out the carbs, there was a gray needle that had a clip with 5 positions, while all 4 carbs were in the middle position if i remember correctly. Does this mean that there was jet kit already in it? Did the stock only have 1 setting??

Some models might have come with a needle with multiple clip positions... cheapcycleparts.com, at least, lists at least one 5-groove OEM needle (on the 1989 kat 600). See this post for a bit more info:

http://katriders.com/vb/showpost.php?p=2023565&postcount=20

If you check the needle part number for your year bike on these sites like cheapcycleparts.com, ronayers.com, bikebandit.com, you should be able to find at least one with a Mikuni part # (looks like "4CZ5") in the needle part name. Then you can check this datasheet to see how many grooves that Mikuni needle has:

http://www.seas.upenn.edu/~drake/documents/katana/mikuni_needle_list.xls

However, typically there is only one setting on OEM needles, and several on aftermarket jetkit needles (my FP needles have 5, the worn out dynojet needles the PO had in had 5).

[Kreylyn]

US models OEM have 1 eclip slot. Some Euro models have more.

Factory Pro has 5 slots

Dynojunk has 6 slots.

Your bike most likely has a kit installed. Check your main jet size to confirm how far from original they went. "Stage 1" is ussually with in 1-2 sizes of OEM.

Krey

[wfo-93-750]

i have a question along the same line,i have a 93 750(cali ), 12k on it , wondering if i should go k&n pods or just stick to k&n oe replacement, also found a kirker 4 to1, and a vance and hines 4 to 1 curious about the selection i would prefer the v&h but someone told me for that bike kirker would be better.....ill leave that call to you guys

[Kreylyn]

i have a question along the same line,i have a 93 750(cali ), 12k on it , wondering if i should go k&n pods or just stick to k&n oe replacement, also found a kirker 4 to1, and a vance and hines 4 to 1 curious about the selection i would prefer the v&h but someone told me for that bike kirker would be better.....ill leave that call to you guys

Breather options: Stick with OEM box and filter. Anything else will cause major tuning issues unless you do major engine mods. If you HAVE to use pods, use velocity stacks and pod covers to reduce the air flow and turbulance.

Jetkits: Use FactoryPro Stage 1 kits. They are the best and most versatile for setups.

Exhaust: Generally speaking, there isn't a noticeable difference in performance between aftermarket exhausts for the Kat. It's just not that much of a performance machine for it to make a differnce for those reasons. Any aftermarket will flow better than OEM, but between them... it's a toss up. Pick the one you like the looks, clearance, and sound of.

Krey

[wfo-93-750]

i found some cans for an 89 gsxr 1100 that are a decent price, i would like to use the just to keep a symetrical look to the bike, im just curios though is the pipe diameter the same,been trying to find the id/od of stock 89 gsxr 1100 to see if i can use these sliponson my stock kat750 exhaust

[Kreylyn]

i found some cans for an 89 gsxr 1100 that are a decent price, i would like to use the just to keep a symetrical look to the bike, im just curios though is the pipe diameter the same,been trying to find the id/od of stock 89 gsxr 1100 to see if i can use these sliponson my stock kat750 exhaust

I don't have the specific pipe diameters right off, but yes... they can be used.

Your going to need to do some mods/fabrication anyways to mount those dual cans to the pre 750 stock dual exhaust. It's simple enough to make/buy an adapter between the two pipe sizes, or simply buy a pipe expander for smaller adjustments.

again, not sure of the sizes for those pipes, but this is what I'm talking about....

http://store.airflo.com/exad2idto3id.html

or the tool...

[ame="http://www.amazon.com/Grip-22100-Small-Exhaust-Expander/dp/B000BN392M"]Amazon.com: Grip 22100 Small Tail Pipe/Exhaust Expander: Home Improvement[/ame]

Krey