93 vulcan carb question

[ametekfan]

I have a 93 model 500. Had the carbs rebuilt. There is two T lines... One is top and one is bottom. The guy hooked the bottom to the main fuel, but bottom let unhokked. I bought the bike used and nothing was hooked up anywhere. But I know as a fact this bottom had a hose hooked to it, because he said he broke the T when he took off the hose. So my question is. What hooks to the bottom T. Im having some low power issuses with the bike. He says its a vaccum line prob somewhere. All the vaccum lines and carbs boots ARE in bad shape and will be placing soon. But Im curious about the bottom T not being hooked up.He says its a vent but shouldnt it be attached to something? Thanks so any help.

[Triangles]

I have a 93 model 500.The guy hooked the bottom to the main fuel, but bottom let unhokked. I bought the bike used and nothing was hooked up anywhere. But I know as a fact this bottom had a hose hooked to it,

Might want to read what you typed before posting. What you posted makes no sense but, if you were trying to say he hooked the fuel up to the top and left the bottom open, that might be part of your problem. The top tee is a vent for the float bowl This should vent to your air intake box. If the PO deleted the air box as did mine I just put a little bit of hose and a small breather filter on it. If this doesn't make sense I'll take a picture for you. The bottom tee is where your fuel line should hook up to. I would imagine the carb would do funny things with the fuel line hooked up to a vent instead of the float bowl.

[ametekfan]

Yep had it reversed in my question. Couldnt really remember. Also was at work so there ya go..My excuse. So Triangels you just put a small filter on the end of the vent hose? Mine had a hose but seemed like it was hooked up somewhere cant find any spot on the airbox where it could have went. Could I just leave it open with out a hose or anything attached? The guy said yes but Im not so sure.

[burkbuilds]

Although you could leave it open, you always run the risk of getting something up in the hose. Triangles idea with a small filter should work well and I'd go with that if I were in your situation.

good luck.

[Triangles]

I saw in a pic you have pods on your carbs. Did you have to put bigger jets in them?

ABSOLUTELY!!! The stock air box creates a restriction. The resulting low pressure that develops in the intake as rpm goes up pulls more gas thru the jets. Without this restriction the engine will go very lean as rpm goes up. I strongly recommend against removing the stock air box as it will hurt your fuel economy and it will be nearly impossible to maintain the smooth consistence of your throttle response. Also you get some LOUD obnoxious intake noise when you go wide open throttle. All this for a barely noticeable few xtra butt-dyno HP.

There are many articles on the net the tell how to tune a cv carb. The only way I've been successful at is by first; choosing a main jet that is good at 3/4+ throttle(freeway speeds 70+), Second; adjust the needle (done by moving a clip or adding/removing shims) for mid throttle (40-55mph-ish), third; tweak the idle. usually not much if any adjustment needed here. Tuning a carb is somewhat of a black art and quite frankly very time consuming and a pain in the ass. If you're not familiar with how air/fuel ratios affect the engine operation you should probably bite the bullet and pay an experienced mechanic. Also if your needle is way off you may have to go back to step 1 and recheck the main jet.

the PO of my bike installed a Dynojet stage 3 jet kit. when he installed the jardine exhaust and K&N pod filters. The Dynojet included jets and an adjustable needle. My bike had Dynojet 140 main jets which are approx equivilent to 152 Keihin main jets. It was either a 148 or 150 main jet that I ended up at. I would recommend buying an assortment of jets say 145 to 152 as a starting point. You may need to go larger or smaller. Keep in mind if you have or buy a Dynojet kit they supposedly aren't an exact cross reference to the OEM Keihin jets.

Below is a horrible copy and past of a chart from jetsrus.com I had a good experience with them and their prices are reasonable. I had to place a second order as I initially guessed 130-140 is what I would need. It was way lean.

The table below is an approximation, results in the carburetor will vary.

KEIHIN DYNOJET MIKUNI
92 92 85
95 94 87.5
98 96 90
100 98 92.5
102 100
105 102 95
108 104 97.5
110 106 100
112 108
115 110 102.5
118 112 105
120 114 107.5
122 116
125 118 110
128 120 112.5
130 122 115
132 124
135 126 117.5
138 128 120
140 130 122.5
142 132
145 134 125
148 136 127.5
150 138 130
152 140
155 142 132.5
158 144 135
160 146 137.5
162 148
165 150 140
168 152 142.5
170 154 145
172 156
175 158 147.5
178 160 150
180 162 152.5
182 164
185 166 155
188 168 157.5
190 170 160
192 172
195 174 162.5
198 176 165
200 178 167.5
202 180
205 182 170
208 184 172.5
210 186 175
212 188
215 190 177.5
218 192 180
220 194 182.5
222 196
225 198 185
228 200 187.5