davido wrote: Sorry Jakedude,I am confused. From what I understand,with big bores ,even if everything else is standard,you need to change your jets. Needle height and air srews are adjustable but jets need to be changed.Standard jets wont cut the mustard.
What I understood from freebyrds question,is where to start with that? Now maybe Im wrong but I would think that,yes,you start with knowing what your standard jets are but,then where do you go? Im going to be dealing with this on my own build soon so,I am very interested in how to go about it.
In your post you talk about 'finding out about stock parts' What stock parts would you need? In my carbs I have all the stock parts but as I had a rebore,dont I need different,non stock parts?(bigger jets)
Theres my confusion. So,please,how to know what jets to put in after a 1075 rebore? Or in freebyrds case a 1075 rebore and a GPZ1100 cam swap?
Freebyrd, correct me if Im wrong,Im not trying to hijack your thread.
Okay, the base bike capacity is, if I recall correctly, 998ccm on a KZ1000 So you have increased the capacity by ~80ccm, or 20ccm per piston. That's not a lot so I wouldn't expect much of a difference in jet size. The bigger pistons mean that for each intake stroke the piston will draw in more air and therefore will need to draw in more fuel as well. So you need to make the jets bigger. I would start with a rough guess of [100* (1075/998)-100] or ~8% bigger. BTW, anything that makes the bike breath easier also means the bike draws in more air with each stroke. So if you change the stock muffler for something that provides less back pressure the bike will also breath in more air. If you remove the standard air box and replace it with pods the same goes.
When I switched out my airbox for pods I increased both my main and pilot jets by 15%.
In the end, the only way to know for sure is by looking at the plugs.
As an aside, the only reason I switched from the airbox to pods was because I got tired of struggling with the boots from the carburetors to the air box. I was having trouble with flooding so I was screwing the the float needles (eventually went to viton tipped) and the float adjustment. So I had to keep taking the carburetors on and off the bike. After switching to pods and making a bracket to support the cabs, removing the carbs was a snap. Yeah, I had to increase the jets sizes, but after deciphering the confusing K&N instructions I figured they said for my bike to increase by 15%. The plugs look good so I'm happy. Many on this forum say the bike runs better with the air box and I see no reason to doubt them, but my performance seems great even in the rain and wind.
Perhaps one more thing on jets. Previous owners may have changed your jets. The jet size is marked on the jet. So from my previous post you should be able to figure out if they have been changed. Now some people drill out their jets if they want them bigger. I good mechanic will also file off the jet size marking on the jet when they do that, but most don't bother.
