Jetting or electrical?

[Jonzilla]

It's got 115 mains in it. I think that is stock size. The hole in a couple jets looks off center. I wonder if they were drilled.

[BigD_83]

Can you post a picture of the jets? A couple of people on here have a very keen eye for that

[Jonzilla]

I just tried some pics but my camera won't focus close enough. I have some gas orifice pin gauges at work but won't be there til Monday...

[Suzuki_Don]

Just go and buy 4 new main jets, they're only $10 ea. from Suzuki dealer. Then you know they are right. Mikuni do not drill holes off center in their jets.

[snicrep5]

Thanks for the replies. I'll get the oring kits. I may skip the bowl gaskets since I've had the bowls off and on already and they don't leak. I'm trying to do this thing on the super cheap. This is a $400 bike.

One question I keep throwing around in my mind however is: If it was a carb related issue, would this be happening while revving in neutral also? This missing/sputtering/wall is ONLY happening under load. I realize the carb rebuild is a must do on an old bike regardless. But I'm wondering if a lean or rich condition would only cause the sputtering under load and not in the garage too.

i have a $275 bike thats probably cost me 1000 so far but im gone too far to quite now.

[tatu]

Worth getting a new filter too.

[Jonzilla]

I"m thinking I will get four new stock jets. And since they'll probably be lean with my 4-1 vance and hines pipe and the pods I'll drill them to the next size til they are correct. I have access to a fixture/drill press made for gas orifices so as long as i don't go overboard I should be fine.

These are CV carbs btw.

[Jonzilla]

Worth getting a new filter too.

I'm wanting to run pods since I'm doing the jetting now so I'm thinking I'll get new k&ns. I've got a set but they're are blackish even after I washed them. aren't they supposed to be light in color? does this matter?

[Steve]

I"m thinking I will get four new stock jets. And since they'll probably be lean with my 4-1 vance and hines pipe and the pods I'll drill them to the next size til they are correct.

I'm sorry, but this really bothers me.

You are having problems now because somebody apparently drilled the jets to some unknown size.

Now you are going to buy new jets "so you know what size they are" just so you can drill them to an unknown jet size?

Suzuki_Don said that new jets are $10 at the dealer. That might be true, but they are only $1.74 at Z1 Enterprises. At that rate, you can get several sizes relatively cheap. (Quick, too.)

With your setup of stock airbox and a header, I would get three sets of jets: 120, 122.5, 125. At $1.74 per jet, you will be looking at a total of about $25, including shipping. This will let you fine-tune using known values and will make it easier on the next owner, so he won't be cussing "that #$%@ PO".

.

[Jonzilla]

I'm sorry, but this really bothers me.

You are having problems now because somebody apparently drilled the jets to some unknown size.

Now you are going to buy new jets "so you know what size they are" just so you can drill them to an unknown jet size?

Suzuki_Don said that new jets are $10 at the dealer. That might be true, but they are only $1.74 at Z1 Enterprises. At that rate, you can get several sizes relatively cheap. (Quick, too.)

With your setup of stock airbox and a header, I would get three sets of jets: 120, 122.5, 125. At $1.74 per jet, you will be looking at a total of about $25, including shipping. This will let you fine-tune using known values and will make it easier on the next owner, so he won't be cussing "that #$%@ PO".

.

That did cross my mind as well. I didn't want to buy 2 or 3 $40 sets of jets. The Z1 jets are great to know about. Thanks for the reply

[tatu]

Its always a bad move to drill jets, as at that level of accuracy it's unlikely that they will all be drilled the same size.

[Suzuki_Don]

Suzuki_Don said that new jets are $10 at the dealer. That might be true, but they are only $1.74 at Z1 Enterprises. At that rate, you can get several sizes relatively cheap. (Quick, too.)
.

Thanks for the update Steve. GOOD STUFF.

[Darin Jordan]

I'm sorry, but this really bothers me.

You are having problems now because somebody apparently drilled the jets to some unknown size.

Now you are going to buy new jets "so you know what size they are" just so you can drill them to an unknown jet size?

Suzuki_Don said that new jets are $10 at the dealer. That might be true, but they are only $1.74 at Z1 Enterprises. At that rate, you can get several sizes relatively cheap. (Quick, too.)

With your setup of stock airbox and a header, I would get three sets of jets: 120, 122.5, 125. At $1.74 per jet, you will be looking at a total of about $25, including shipping. This will let you fine-tune using known values and will make it easier on the next owner, so he won't be cussing "that #$%@ PO".

.

I wish this forum had a "LIKE" button... This is perfect advice... as usual!!

[Jonzilla]

Update:

I ordered some jets from Z1 earlier this week and I got them yesterday. I was correct about my old jets being drilled out. When I looked at them next to the new 120, 122.5, and 125 jets they were visibly MUCH larger than all of them. Hogged out. And they (the old ones) had 115 stamped on them too.

Anyway I installed the 120 jets first with my stock airbox and filter and magically, the bike ran great! It had no stumbles or studders at any range. I didn't have time before it got dark to do plug chops (no headlight yet). I did get to do a top end plug chop and coast into my driveway though. I ran clear through 1st 2nd and 3rd then shut it off and coasted into my garage After riding around for 15 minutes. The plugs were all very light tan. With a touch of greyish on the squared edges. Does this sound good or a little lean?

Thanks for the help from everybody.

[Jonzilla]

backfiring when running hard

So I have been running for about a week with the new 120 jets. I have the stock airbox/filter and a V&H 4-1 exhaust. I shimmed the carb needles too. And adjusted the valves over the weekend for good measure.

Now that I've gotten a little seat time with the modifications, my only problem seems to be a pop/backfire when shifting at high rpms. Like near redline. It doesn't pop while engine braking but only during that moment while the clutch is pulled in and shifting gears at high rpms. I've done all the plug chops as described on cliff's site. The colors are in the light tan/barely touched of grey on the edges range. Would the popping from the exhaust be a lean condition? Any suggestions?