650 jets

Hey guys,
Had some trouble with my carbs lately and was wondering if someone can give me some advice.

First off I have a 79 kz650C all stock except pods.

Well I took my carbs off and wanted to get them cleaned and tuned professionally so I took it to the kawasaki dealer and had them do it. Well Put it back on the bike and it ran decently for a little while.... but they wanted more money for this and that to get it all dialed in so... I figured a little spare time and I could do it myself.

After taking the carbs apart myself and checking them out... it looks like they re-jetted my carbs with spare parts around the dealership. All of my pilots were 15 but the jets were 122.5, 115, 120, 127.5.... which did not amuse me after spending a lot of money at a dealership.

Anyhow, I talked to the guys at Z1 and they got me 100's and 17.5 pilots.

So I guess I am asking that it seems there is a big difference in the discrepancy of the size of the jets from 127.5 to 100. Is this gonna work? And also any tips would be awesome. Like I thought that you were not supposed to screw the pilots in all the way?

Anyways, all input will be greatly appreciated and helpful.

There is a HUGE difference between a #115 main and a #127.5 main jet. I believe you are a kinder person than I am because I would have taken those jets back to the Stealership that ripped you off and shoved them into a place where the sun will never shine on them without applying lubricant... and I would have gotten my money back.

I'm no expert at jetting pods.... in fact there may not be any expert way to jet pods. Most pros say that they never run exactly right, but can be made to run OK. Whatever the stock main jet is for your bike, you probably need to go about one or two sizes larger if you have pods. You may also have to adjust the needle position. Wired George knows a lot about this.

I just checked Babbitts OEM parts drawings and your bike shows a range of main jets available from:

92.5 - 107.5

100 is about in the middle, so it might be a good place to start. I would not be surprised if you had to go bigger.

Personally I would either put the stock airbox back on or at least put a 4/1 pipe on. Doesn't do much good to add all that extra air into the engine if it can't get out a fast. Your bike probably came with the lean jets and 102.5's would make it run better. With the pods and stock exhaust I would think you need to be in the 105 area but then every bike is different. I run stock box with a K&N filter with a Kerker 4/1 and run 105's and it runs great, but other guys with similer setups run 107's or 110's. You should have "air" screws which should be about 2 turns +/- 1/4 turn. And on a personal note I would go back to that "dealership" and throw a big bitch! Anybody here would never throw in 4 different jet sizes, they need to make it right or refund your money. Just my 2 cents...

Bluemeanie wrote:

Personally I would either put the stock airbox back on or at least put a 4/1 pipe on. Doesn't do much good to add all that extra air into the engine if it can't get out a fast.

Good point. From what I read on forums, pods are a major PITA to get to run right in the best cases, and running them against the stock headers is probably worst case scenario. Ebay or dismantlers sell air boxes pretty cheap. You'll save a lot of time and money not having to buy jets and burn away your life messing with it.

well, ever since i changed the jets the bike has been backfiring a lot.... basically all the time at low rpms.... would this be directly associated with smaller jets or do i have another issue to resolve?
I dont fully understand why it would be backfiring....

No drivebility guru here but what size "smaller" jets did you put in? Still running pods? Have you checked timing? Someone else with more smarts will chime in...

brianpclarke wrote:

well, ever since i changed the jets the bike has been backfiring a lot.... basically all the time at low rpms.... would this be directly associated with smaller jets or do i have another issue to resolve?
I dont fully understand why it would be backfiring....

When the pilots were too lean on my 750 Twin, it backfired like crazy especially when I let off the gas.

Did someone say Jet?
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