| Author | Message | ||
     Aaomy |
when is the last time you cleaned your air filter? as a filter gets dirty it creates more vacuum in the carb,, in turn this pulls more fuel threw the carb causing the carb to " richen up".. eventually the bike will become so rich it wont run.. | ||
| Toniportray |
Anyone know a place to buy cheap carburetor jets? I'm looking for jets for multiple bikes. I keep finding web sites that sell after market jets for under $3, but then they rape you on shipping. $8 to ship something that can be sent in a $.42 stamped envelope?! Ridiculous! How 'bout a place like Kragen or Checker? My experience with mainstream shops like that is they don't sell motorcycle parts, but you can bring in a part and they'll look for another brand that might fit. Any websites anyone can recommend? I hate paying $12 for a brass screw... I wish Harbor Freight Tools sold carburetor jets. They have just about everything else one needs. | ||
| Swampy |
Toni, ANY V-Twin shop has carb jets. There are at least 4 in every town, the older/grungier shop the more likely you will find what you want. And usually they will not look at your Blast as a non-motorcycle | ||
| Gearheaderiko |
Bike Bandit Pay shipping or pay gas + tax + time | ||
| Twisty_mcwrister |
ok so say ur jetting ur bike and u notice that the needle has multiple slots for the c clip thing instead of one dedicated slot and a solid stop . is that needle from a jet kit? | ||
| Ezblast |
Nope from a Sportster - try setting it 3rd from the top of the needle - whats it set at now - count from the needle top. EZ | ||
| Gearheaderiko |
But it could be from a jet kit too! Got the part # for that adjustable needle? Ordered one, but adjustable aint what I got! | ||
| Twisty_mcwrister |
i figured it was either that or a jet kit. being a sportster needle at third from the top, what jetting should i be running? | ||
| Twisty_mcwrister |
i'm hooking up an air/fuel gage tomorrow so any fine tuning tips send my way ok? i.e. which jet/needle/mix screw controls what parts of the throttle/mixture. i'm a newbie but i think i've got it close. and what would advancing or retarding the timing do for my mix? if anything | ||
| Imadreadhead |
pics of the air/fuel setup...PLEASE!!! | ||
| Twisty_mcwrister |
yeah i will post pics of that and the tail chop i did! | ||
| Ezblast |
48/175 | ||
| Twisty_mcwrister |
kool i have 45/175 in there now. when i hook up the air/fuel what should i look for to see if that 45 is too small? | ||
| Gearheaderiko |
Adjust the timing as needed. Start with recommended. Get your carb dialed in. Then fool with the timing. Since its Summer now is the time its most likely to knock and ping, so thats what you should set it at. Since somebody's already 'tuned' your carb, I'd see what jets its got. Some needles will use different jets. Both jets and the needle should have a number. Check them (write them down). If you have a K & N jet kit and start mixing in stock jets you're going to be in a would of trouble. The jetting recommended here will be close. Slow jet controls mostly idle, main jet controls full throttle, needle controls the transition between the two. (very oversimplified). Again, check the numbers on the needle and jets. As far as the A/F 'tester': Wide open throttle under acceleration/load should be about 13:1. Constant running about 14.5:1. See what you're tester shows and make sure its working before you start messing around.If its reading 6.5:1 (for example) and you start adjusting for that, you're in trouble. 6.5:1 would be impossible! Just my thoughts from my experience. Not concise and there are much better and more detailed explanations elsewhere. Just remember, close enough is going to be good enough for a newbie. Very doubtful you'll be an expert off the bat and run too lean and you'll be buying an engine. | ||
| Gearheaderiko |
I wouldnt worry too much about the 45. The main and needle is where the performance is. | ||
| Gearheaderiko |
PS stock is 42. 44, 45, 46 and 48 are available (higher than 48 and you're really kidding yourself). Big Twins run a 48 with much richer main jetting. My bike will run cold on a 45 without a choke. I think a 48 just wastes gas! (though in reality slow jet size depends a lot on how much you have to adjust the idle mixture screw). Again, thats just my opinion. See what your A/F gauge reads. ` | ||
| Twisty_mcwrister |
it had stock jets 42/165 . nothing else written on them. looks just like the stock 45/175 i just put in. mix screw is at 2 1/2 turns. new slide assembly cause the goof that messed with it before didn't seat it in right. k&n filter with a v&n . new boot(not over tightened) and a new exhaust seal. so it perfect time to dial it in. i have played with the timing a bit and when i advance it starts to ping but if i back it off it has trouble starting when warm(need some throttle). | ||
| Gearheaderiko |
Did the needle have a number? | ||
| Ezblast |
Try to keep your AF between 14 and 12 - 14.5 I do not recommend because that leaves you little room, in case of a lean condition developing - ie - das boot - to keep motor in a good state, and at 45 primary you are at 14.5 most of the time with higher peaks, the 48 is better for the launch and safer. EZ | ||
| Twisty_mcwrister |
forgot to check the needle. sorry i notice there is a hole in the power right off of idle. i just figured it was pre power band blues but maybe the 48 would fill the gap | ||
| Ezblast |
Thats what the shimming should do - take away that hole - try 5 clips down from the needles top if 3 isn't working. Or get a regular Blast needle and shim it the recommended. EZ | ||
| Gearheaderiko |
Concur(with previous post). The needle can make a BIG difference and it'll be much easier to tune (with references here) if you have the same needle most are using. It'll probably run rich at idle anyway and dont forget to check it when its fully warmed up. If you shut it down, then restart it, there's a very good chance (according to the manual) that the choke will be on, giving a false rich reading. While I dont disagree with the 12:1-14:1 assessment I do know this: You can spend many, many hours to get it at the right A/F ratio all through the powerband. Idle (even with a 45) is probably going to be at 12. A stock jetted Blast will run at leaner than 15:1 during many parts of the powerband. I'm very doubtful after moving up to a 45/175 that you'll run dangerously rich. Also jetting too rich can make your bike run like a violated primate, but you'll hasten the need for a top end. If the 48 improves the hot starting problem, keep it. It may also make it worse. Get your A/F gauge working, start to play and please post the results. It should be noted that EZ has spent many, many, hours (and years) dialing in his carbs. While I have only a minor disagreement with his advice, I dont question the results he's gotten on his bikes. | ||
| Ezblast |
the stock dyno AF was scary - 14.5 base and then constantly spiking to 15 plus, 45 usually hangs around the 14.5 area - sometimes down to 14 spiking to 14.6plus a few times - 48 spent almost all its time between 14 and 13 with 2 dips towards 12.5 where the needle and primary first meet and needle and main first meet. The shimming minimizes that affect. EZ (Message edited by ezblast on June 26, 2008) | ||
| Ezblast |
The real trick is dialing in the main for a the different mods - for a Bub, D&D, V&H, Jardine with quiete core, Pro-Series, or Kerker - 175 should be the max - even with a totally open intake. Jadine, White Brothers 175 with slightly modified intakes, and 180 with a maxed out type intake - read free breathing - 180 for a Force, or Poorman's Force (Jardine/WB Header mated to a D&D can), or an LSR Header with 4" Suppertrap with 12 discs. The shiming is a woundrous thing, especially with how much it helped the Forces bottom end on the stocker, and if I really want to launch her - bring it to around 3600 quick and drop the clutch - new riders please don't practice this till you are familiar with your bikes traits while riding, you loose a lot of bottom end on the Force making it safer to do this, once you've wound it out of first gear it easy enough to keep shifts with in the powerband - lol - of course since it was built for mid to top end - it was to be expected. The LSR Header with the Suppertrapp taking care of noise with only minimum restriction just makes everything move much quicker quietly - what a wild design! EZ | ||
| Twisty_mcwrister |
so should i do the slow jet first or the needle shimming? didn't get the gauge in due to a time crunch. hoping for sunday night. you blasters will be the first to know the results of the mounting and a/f mix results. i have access to a hd video camera so might even film the gauge during testing and what not. | ||
| Twisty_mcwrister |
i'm thinking needle first then after the gauge is on i can see if i need the 48. | ||
| Ezblast |
The V&H - hmm - I'd start with the shimming, and 45/175, air screw 2 2/3rds out from bottom, then go from there. EZ | ||
| Gearheaderiko |
Main, needle, slow. IMHO. The needle is directly related to the main jet. The slow jet is idle and just off idle. Kind of a waste to initially spend a bunch of time on where your bike is rarely going to be running and will increase only a very small percentage of performance. Theoretically you get the main jet right first, then work on the needle. Every time you change the main jet you change the needle mixture. The rpm range of mixture stays the same, but a bigger jet will make that range richer. Once you get the main jet right at WOT, then fool with the needle. Since your running a very common set up, its very likely going to be the 2 shims/175. Needle choice can make a very big difference, hence not knowing what needle you have in there, it will be difficult to know what exactly its tendencies are. You will definitely notice a difference when shimming though(or moving the clip). I dont know if there are any good write ups on Badweb on carb tuning, but I'll try to find the links I had. Have you looked at the Nightrider site? | ||
| Twisty_mcwrister |
no haven't checked nightrider yet. this forum is more than helpfull. | ||
| Reuel |
Ok. Here it is as well as I can remember. The idle screw adjusts idle and slightly off idle. The slow jet affects up to about 1/4 throttle. The needle affects from 1/4 to 3/4 throttle. The main jet affect 3/4 to WOT. Each factor affects each other factor to some degree. The best way to get good results is with an exhaust analyzer of some sort. My opinion: 14.7:1 is ideal, but from 3/4 to WOT, dropping to about 13:1 is good for getting extra power. |
