PDA

View Full Version : Exhaust and jetting question?


chrislen32
07-08-2010, 01:18 PM
Is it absolutely necessary to jet a bike if you upgrade to a full exhaust system?I want to put a full VH exhaust and headers on my 1995 600 but I can't afford that and a jet kit. Should I just forget the exhaust and save up for the jet kit or will it work?

Kreylyn
07-08-2010, 01:26 PM
I would strongly suggest doing both at the same time. It's possible to do some work arounds to use that exhaust without the jetkit, but you will loose some performance and may have a few trouble spots in certain rpm ranges being too lean.

Krey

chrislen32
07-08-2010, 01:31 PM
I would strongly suggest doing both at the same time. It's possible to do some work arounds to use that exhaust without the jetkit, but you will loose some performance and may have a few trouble spots in certain rpm ranges being too lean.

Krey

thanks krey. Just out of curiosity what are we talking for work arounds? And will I notice a huge performance decrease if I wanted to bolt on the system in the meantime?

Kreylyn
07-08-2010, 02:00 PM
thanks krey. Just out of curiosity what are we talking for work arounds? And will I notice a huge performance decrease if I wanted to bolt on the system in the meantime?

Some possible work arounds would be using a #4 washer to shim the needles (make them sit higher) and/or adjusting the float heights slightly for the midrange. Also increasing the turns out on the A/F screws to compensate for a leaner idle. With out going full on larger jets, not much can be done for WOT or topend, but... Most riders normally are not consitantly in that range. It would take some trial and error on your bike to get the right settings between all 3, but... It's possible to get it close enough that it won't cause any major problems until you get the jetkit.

Problems with running lean = much higher running temps and depending on how lean and for how long... possibly decreasing the life of the engine due to increased wear from the higher heat. On the flip side, a leaner running engine tends to be slightly more responsive and push out slightly more umpf.... at the risk of damaging the motor.

A good running engine is a balance... and one way too much either direction = problems.

Depending on your reason for the switch though, there are other possibilities. If your primary reasons for doing the swap is symphonic or aesthetic then it is possible to counter the increased exhaust flow by using an insert in the ehxuast to slow it down a bit. It's the increased exhaust flow that = the need for the jetkit to counter and keep the fuel mixture correct. Just about all of the products out there are about increasing that flow though, so you would be looking at a hard to find product, or custom...

Krey

JamieKatana
07-08-2010, 02:24 PM
Look up http://www.ignitionproducts.com/Ignition/mufflers.html for an item that will do what Krey is talking about. I bought one to go into the end of my D&D slip-on because it was way too loud. I think it was about $30, so you could use it until you got the jet kit.

I suspect that the previous owner of my bike did not do anything jet-wise to the carbs when he put on the D&D. I think it runs a bit smoother with the insert. (I could be deceiving myself, too...)

scottynoface
07-08-2010, 02:57 PM
My bike still had the stock jets in it when I bought it with the yoshi 4 to 1 and uni filter. Let's just say the jet kit opened it up a lot...

Idrivetoys
07-08-2010, 05:14 PM
i loved when i upgraded to the fp stage 1 jet kit, now im super excited to try a timing advancer soon as well