Killswitch69 Posted October 25, 2010 Report Share Posted October 25, 2010 (edited) Has anyone with great experience ever had to stagger jet a twin carb setup? I’ll try to make this short but here’s the story. Just put a Vito’s 10 port 66mm Cylinder kit on with Coolhead and 21cc SB domes machined to .047” squish and compression at 185psi after break-in. Toomey T6 and stock carbs. Running VP110 @ 40:1 mix. Carb jetting is 340 mains, 30 pilot, vito’s needle on 3rd, 1.6 air jet, and 0-8 needle jet. Air screws at 1.5 out. On break –in it seemed that left side ran rich on bottom end. Put new plugs in and did a couple plug chops. Right side had 2mm light brown ring at base and no color above (new plugs thinking not in long enough to get low speed color yet) and left side had slightly darker 2mm ring at base and tan brown above ring. Figured I needed to buy Sync tool and get carbs right. Did that and same deal with left side running rich on bottom. I went through carbs and cleaned, rechecked three times. I checked choke and tube. Finally yesterday morning I built a pressure tester and found that it would not hold pressure. After an hour I found the leak coming from behind the left cylinder case drain ( that hole that drains the top of the transmission of water) So I pulled the motor and tore it down. There was a bad seal between the left cylinder case halves that was causing a leak in that drain area and into transmission case for the left cylinder. I cleaned and used all new seals and put her back together. I pressure tested again and it held 6 psi for over an hour. I fired it up last night and sync the carbs. It still seems like the left side is running rich. Left side at idle fires but pipe feels much cooler that right side. Give it a little blip to maybe ¼ throttle and see more smoke from left that right. Now I will put some fresh plugs in and do a high speed plug chop tonight after work and see if the low end jetting evens out but my hunch is I will still be fat on left. Has anyone ever had to stagger jet twin carbed banshee’s? if this is still fat on left cylinder what else can I look at? Edited October 25, 2010 by Killswitch69 Quote Link to comment Share on other sites More sharing options...
KlotzBanshee Posted October 25, 2010 Report Share Posted October 25, 2010 I have heard of staggering the jets on twins, but not on a banshee. Idealy both cylinders should be running the same. What is the temp and elevation in your area? Adjust air screws to 2 - 2.5 turns out. If that doesn't help, I would drop the pilot to 27.5 and go back to 1.5 turn out on the air screws. I think 30 pilots are too big. Quote Link to comment Share on other sites More sharing options...
Larry's Shee Posted October 25, 2010 Report Share Posted October 25, 2010 If all things are good other than carbs, tempararely swap carbs using long choke tube. Could be internal leak. If issue swaps , there you go. Several different places could be leaking. JMHO, your results may vary. Quote Link to comment Share on other sites More sharing options...
Killswitch69 Posted October 25, 2010 Author Report Share Posted October 25, 2010 I have heard of staggering the jets on twins, but not on a banshee. Idealy both cylinders should be running the same. What is the temp and elevation in your area? Adjust air screws to 2 - 2.5 turns out. If that doesn't help, I would drop the pilot to 27.5 and go back to 1.5 turn out on the air screws. I think 30 pilots are too big. i'm at sea level and it has been about 60 F when testing. I'm going to try it tonight and hopefully the case leak was causing the issues. I'll post up tomorrow morning with the plug chops and low speed results. Quote Link to comment Share on other sites More sharing options...
Killswitch69 Posted October 25, 2010 Author Report Share Posted October 25, 2010 If all things are good other than carbs, tempararely swap carbs using long choke tube. Could be internal leak. If issue swaps , there you go. Several different places could be leaking. JMHO, your results may vary. That is a great idea! I'll try tonight and if the plugs come in different I'll swap the carbs and try again. Let you know in the morning Thanks Quote Link to comment Share on other sites More sharing options...
AKheathen Posted October 26, 2010 Report Share Posted October 26, 2010 normally, there is slight variation from right to lesft, but not even near 1 jet size, or there is a problem. also, try swapping plug wires and see if that makes a difference. remember to only change 1 thing at a time Quote Link to comment Share on other sites More sharing options...
bansheesrtoys Posted October 26, 2010 Report Share Posted October 26, 2010 just a thought but i hear the t6's are made for a stock motor maybe your pipes r the prob? not saying for sure just a thought Quote Link to comment Share on other sites More sharing options...
sleeper06 Posted October 26, 2010 Report Share Posted October 26, 2010 plug caps,ignition system ,it will have you chasing your tail,ohm the caps out Quote Link to comment Share on other sites More sharing options...
EvilBanshee Posted October 26, 2010 Report Share Posted October 26, 2010 (edited) i was having a exact issue like your having. i had acouple of problems. 1 the plug boots were junk. and 2 the carbs i bought "used". had 1 sizre different needle then the other. But the main issue was the plug boots. Edited October 26, 2010 by EvilBanshee Quote Link to comment Share on other sites More sharing options...
Killswitch69 Posted October 26, 2010 Author Report Share Posted October 26, 2010 normally, there is slight variation from right to lesft, but not even near 1 jet size, or there is a problem. also, try swapping plug wires and see if that makes a difference. remember to only change 1 thing at a time I ran it last night and it runs much stronger. Hard running and plugs look pretty close, but left side still way richer than right on low speed (1/8-1/4 throttle). Running it around and keeping throttle at 1/8 to 1/4 I pulled the plugs and right side looks clean/dry and left very dark and wet. I backed out the left air screw 7 turns and got the plug to dry up a bit but still rich. I tried swapping plug wires and no help there. The wires are new as well as the caps. They ohm out at 16.5k from cap to cap. I am running the NGK resistor caps. The coil with out caps ohms 5.5k and each cap is a 5k ohm cap so 16.5k is about right. Should i not be running resistor caps and just resistor plugs? Not sure it matters. Quote Link to comment Share on other sites More sharing options...
Killswitch69 Posted October 26, 2010 Author Report Share Posted October 26, 2010 plug caps,ignition system ,it will have you chasing your tail,ohm the caps out Ignition is good, cap to cap ohms out 16k ohms. Caps and wires are new. Quote Link to comment Share on other sites More sharing options...
Killswitch69 Posted October 26, 2010 Author Report Share Posted October 26, 2010 just a thought but i hear the t6's are made for a stock motor maybe your pipes r the prob? not saying for sure just a thought Sorry guys the pipes are T5's and NOT t6. Quote Link to comment Share on other sites More sharing options...
sleeper06 Posted October 27, 2010 Report Share Posted October 27, 2010 Maybe im wrong but factory spec sais nothing over 7.5 so if using resistor caps puts you over dont use them,i use parts unlimited caps w/ the clamps never had a problem,if it was me i would lose those resistor caps to much resistance will lead to a coil malfunction.Im an electricial by trade and when im troubleshooting coils and controls im costantly working off ohm readings,same consepts should apply,try it caps are cheap.Also might have trouble with lead touching cap Quote Link to comment Share on other sites More sharing options...
Killswitch69 Posted October 27, 2010 Author Report Share Posted October 27, 2010 (edited) Maybe im wrong but factory spec sais nothing over 7.5 so if using resistor caps puts you over dont use them,i use parts unlimited caps w/ the clamps never had a problem,if it was me i would lose those resistor caps to much resistance will lead to a coil malfunction.Im an electricial by trade and when im troubleshooting coils and controls im costantly working off ohm readings,same consepts should apply,try it caps are cheap.Also might have trouble with lead touching cap I thought that stock caps were resistor type. Is this not true? Could it be that one side will pull a better spark if the resistance is too high? Now in conjunction with resistor plugs am I adding even more resistance? Edited October 27, 2010 by Killswitch69 Quote Link to comment Share on other sites More sharing options...
Killswitch69 Posted October 27, 2010 Author Report Share Posted October 27, 2010 (edited) Maybe im wrong but factory spec sais nothing over 7.5 so if using resistor caps puts you over dont use them,i use parts unlimited caps w/ the clamps never had a problem,if it was me i would lose those resistor caps to much resistance will lead to a coil malfunction.Im an electricial by trade and when im troubleshooting coils and controls im costantly working off ohm readings,same consepts should apply,try it caps are cheap.Also might have trouble with lead touching cap Are you talking about these caps? PARTS UNLIMITED KLG-TYPE PLUG CAP Edited October 27, 2010 by Killswitch69 Quote Link to comment Share on other sites More sharing options...
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