| Author | Message | ||
     Bholmes |
I've been workin on my bro's buell for him. I'm actually a ZX10r owner so this is a little different to me, but a motor is a motor. I put a free flowing conical filter on the bike and fabbed a free exhaust for it (2.25" glasspack essentially) and his bike runs fine up to 3k rpm, then it runs horrible! i'll turn the throttle 1/8 or 1/16th of a turn, and it'll bog like crap then it'll take a while and "catch up" to it's self. But it never runs really well in the top end. My questions are: 1) sound like jetting? and 2) when does the secondary/main jet start to work? any pointers on these carbs? I was thinking 1) it may be way to lean now (it's been around 20 some deg too) 2) vaccuum leak 3) exhaust pulses reflecting at improper lenghts due to changed exhaust. What's the concensus/opinion? | ||
| Oldog |
Carbed or FI? which model buell? Pix, please the reflected waves are not likely to cause this on the surface it sounds like lean run condition, note low / no restriction exhaust can cause this drag pipes are known to cause symptoms like this. | ||
| Ratbuell |
If you're jetted too lean, a straight pipe will just magnify the problem. My tubers with race air filters and Buell race exhausts (NOT straight pipes, these bikes like backpressure) are jetted with 45/190 combos, and 2.5 turns out on the mix screw. Straight pipe, you may want to try upping one of the jets - I'd bump the msin to a 200 and see how it does given your rpm problem-range. One popular vacuum leak is the manifold to head seal. Start the bike, let it idle, go to the left side and spray some carb cleaner at the points where the intake runners go into the heads. Stumble/choke = leak. No change means you're OK. | ||
| Littlebuggles |
Listen to Rat, back pressure helps these bikes keep power where they've really got it - right there in the middle. | ||
| Bholmes |
OK it's a 02 M2 cyclone carburated. here's some thoughts i've had on it....it ran gereat w/ a similar air filter and the open pipe w/ stock jetting. I had some issued w/ the carb coming loose and wonder if i might have damaged the vacuum advance (i think that's what it is). I didn't see it was hooked to the carb and tugged at the carb and it didn't come loose so then I found where this unit was attached to the carb. I'd get pics if I could, but I don't have the time, I'm a pharm school student and I barely have time to get on here and try to figure out what's up w/ his bike and do school. Regardless it has a vacuum line to the carb, goes into a unit that has two wires coming out of the other side. I assume this is the vacuum advance. I'm guessing I can test it by attaching vacuum source to it and checking resistance on the wires. Sound pheasable? THe bike starts and idles fine. I shimmed the needle on the carb several times till I got the plugs to foul to verify jetting was not to lean. So that's not the issue. | ||
| Bholmes |
Well I did some research and figured out my "vacuum advance" is a VOES somethin or another which is a switch that changes the timing. I tested that bad boy and I got infinite ohms at 0 vac and once vac was applied I got 0 ohms which sounds appropriate for a switch. So I think that's performing properly. My plug wires ohmed out right too so next on my agenda is test the coils power source and coil itself. | ||
| Spiderman |
and this is where we learn a motor isn't a motor... You will need to check Jetting. If the carb is coming loose it sounds like you removed the carb mounting bracket which will need to go back on, which may have lead to damage to the intake seals. My suggestion replace all the intake seals including the carb to manifold seal. Re install the carb mounting bracket and get the bike on a dyno. Even then that may not sole 100% of the issue with a 'home made' exhaust... | ||
| Bholmes |
Well, it ran fine w/ the homemade exhaust before the carb coming loose. I've checked all over for vacuum leaks and seems OK. I do have a bit of concern for the manifold to carb seal. I do have the carb mounting bracket back on. I love buell engineering, but hate harley engineering! Either how. my coil checks out w/ 10k ohms on the secondary? coil (plug wires) and my primary coil shows around 0.3 ohms, so it looks to be good to my understanding. My white wire to the coil provides power to the coil it seems and it gets 12v when grounded to the head, but when grounded/run back through the pink wire (white wire, volt meter, pink wire, bypassing coil alltogether) i get 8.5 ohms. Is that correct? If it doesn't turn out to be this little rabbit trail, it's gotta be vacuum. It just idles and starts to well to be vacuum leak, at least so it seems to me. Also I wonder if the slide is opening properly. | ||
| Bholmes |
also forgot to mention that the pink wire reads 18-20 ohms when grounded to the head or battery. Is that proper or is it a lead to my malady? | ||
| Ratbuell |
Get the bike running and spray carb cleaner from the left side of the bike, at the intake seals. Head-to-intake, and carb-to-intake. If it coughs or dies, there's your vacuum leak. If you've had the carb apart (it sounds like repeatedly) to shim the needle, you could also have a rip/pinhole in the diaphragm at the top of the carb. You're overthinking it. Start simple - the systems on these bikes are very stout, it's rare to have a 'partial' electrical gremlin - they're usually good, or they're bad, no gray areas. | ||
| Bholmes |
Sounds like a plan rat, thanks for the advice. I tried to check the diaphram for a tears, but it may be to hard to see. I put a light film of oil on it to look so the oil was absorb into the crack if there was one. Do you think the open air filter would decrease the vacuum pressure enough to cause the slide to opperate imporperly? I think it should be OK really because I had a similar filter on it when it was running good. Well, I'll put it back together and test for the sugested vacuum leaks and then get a new diaphram. It is worth my brothers' while to get an aftermarket slide and diaphram (with a jet kit?) or no? Thanks again. | ||
| Bholmes |
Part of the problem turned out to be an obstruction in the throat of the carb. I'd used electrical tape as a temporary bushing to get the air cleaner to fit while I was sorting every thing out... well it got hot and started to sluff off into the opening of the carb making it essentially 1/3 it's actual diameter. So it runs a good bit better, but on the top end i lose power and it will die on me and then not restart, if i jiggle wire and sit a while it will start again. It seems to be OK if i don't romp on it and get up in the rpm. any thoughts? | ||
| Skntpig |
It sounds like a bad ground in the electrical somewhere if you jiggle a wire and it fixes it. Redo all the grounds you can find and make sure you don't have any shorts. | ||
| Sparky |
Does the free flowing conical air filter mount to the carb have a vent hole for the float bowl? If not, then the carb could starve for fuel at high speed because it's not vented properly. If the mount does have a vent hole, make sure it's properly lined up with the carb's vent hole. | ||
| Sleez |
do you have a fuel filter installed? i had one added to my carb'd S1W and it would starve the motor on the top end, if you sat for a few minutes it would work again at low speeds. it was weird, worked fine one day and went bad the next. removed the filter and all is fine. need to find a higher flowing filter. note; these bikes don't come with a fuel filter, but it is not a bad idea to add one. the other thing to check is the tank vent. i think the wire wiggle is coincidental. |
