carb help needed...these things are picky

[Ivan]

The backfiring along with no high end power makes me wonder about your ignition timing. Have you put a light on it?

If you are in time, and have black plugs with no power, I would guess that you may, in fact, be too rich. This would also cause exhaust backfire.

It is difficult to ascertain a rich or lean sound with out a "calibrated ear". The best I can say is that a lean running engine sounds and feels hot, crackly, and flat. A rich engine sounds gurgly, soggy and sluggish.

Does the engine just quit pulling, or does it start missing when you are up in the revs?

Personally, I am starting to think you might want to look into other places than the carbs. When I wrenched on old cars, carbs were always the last place to look. Everything else on the engine needs to be sound before the carb can do its job, even if it is perfect. The fact that carbs are 1 part science, 1 part luck, and 8 parts voodoo doesn't help the average joe much at all.

Too bad you're not closer, you could bring it to "Fat Ive's Garage". anything is possible to fix, with enough beer.

[LegendJet]

i have put a light on it and it was dead on the F mark per the clymer manual. I reved it up to 4K rpm and the thing that was odd was the timing showed it was all the way past 60....I believe in the clymer manual it said that at 5200 RPM the advance should be 31 or 36 degrees, even so, its past the 60 degree mark at about 4K rpm.....i meant to mention that eariler, i have no idea how i forgot that, but that seems alittle odd to me....any idea what they might mean?

[dbeardslee]

You mentioned earlier that you found a vacuum line dangling. Are you sure you got the lines back in the right place? The vacuum advance should connect directly to the #2 carb tap, while the vacuum for the petcocks draws from the carb boot tap. Also, when you checked the timing, did you do it with the vacuum advance disconnected and plugged at the carb?

[TopCatGr58]

Hey Legend,

Yeah, black plugs are probably too rich.

The vacuum advance under little load adds up to 16 degrees additional advance, to the static/cent. max of 36 for a total of 52 MAX! With the bike just sitting, even at higher rpms, there's no real load on it, so there's very little vacuum going to the advance unit, and will allow it to advance to max amount which is NOT good for POWER but is good for fuel economy. With increased load, vacuum increased, retards timing back to the 36 degree range which is MAX BEST advance for POWER.

Yes, recheck timing with Vacuum adv. CAPPED OFF, and if you still see it go way past 36 degree mark, then the timing plate parts may be messed up, or weak springs on weights, etc.!?

Try setting the floats back to stock/leaner setting. Would be nice to find those 145 jets!

T.C.

[LegendJet]

Mechanical advance goes no more than 36 degrees. they are dead on. one thing i also noticed is that there are accel coils on here and i forgot to mention that, but i have been reading that i have to bypass the ballast resistor. The PO didnt bypass it, and i read its no more than connecting the 2 wires from the resistor, but are there any adverse effects? i mean will it screw the ignition module up or anything??? also i know the valves and cam chain are way out of adjustment i just have been avoiding it. could that be causing all m probs??? i have to do it anyways, but i have been wondering also, lets say that the cam chain jumped a tooth and timing is really screwed up, how can i tell if the cams are still in time? like on some cars the cam gears have marks to line up on the block and same with the crank. are there any marks like this on the yamaha?? thanks!!!

[dbeardslee]

If you jumped a tooth on the cam chain you'd know it as your head would probably be trashed. The only adjustment you do is for tension to compensate for the stretching of the chain. If your chain is making a lot of noise, adjust the tension. Takes two minutes, but if you let it go too long you're liable to find out what jumping a tooth does

My understanding of the ballast resistor is that it keeps the stock coils from getting the full 12 volts to them at low rpms, and it also figures in to the resistance of the coils. I run Mikes XS coils with the ballast resistor bypassed, and if memory serves they are 3 ohm coils. Bypassing the resistor is just a matter of unplugging it and plugging the wire connectors you're left with together. Assuming you have 3 ohm coils you should be able to just get rid of it. Don't know if it would cause your problem - maybe.

[Ivan]

checking the cam timing requires the removal of the valve cover. When the crank pointer is aligned with the TDC mark, the cams should have the marks aligned with the marks on the caps. Hard to explain with text, but pretty easy to see once you lay eyes on it.

The extreme advance: Do you have a timing light with an advance dial on the light its self? The kind that you dial to the point that it aligns the mark with 0, and you read the advance on the timing light? If so, the waste spark system may foul that up. A spark on every turn in stead of every other turn could be a problem with that. Also, unless you have a VERY high quality advance timing light, I would not put much stock into the accuracy of the advance. It is a simple RC circuit that does the advance, and when dodgy rheostats and capacitors are used, the accuracy can vary immensely. Best is to leave it on zero and read the engine marks. When I was wrenching on cars, my boss and I both had Slip-off (well, actually Snap-on) digital advance timing lights. Between the two, setting the average Chevy truck to 10º advance would cause about 5º difference between the two lights.

Does the engine start running rough at high rpm, or does it stay smooth and just give up?

[Rasputin]

I have the ballast resistor bypassed on both my 78E and my 79SF and they run perfectly fine. I would bypass the ballast resistor and see what difference it makes in the way yours runs. With the resistor in it limits the voltage to your coils by quite a bit. As I understand it they then can not generate the correct spark which could cause some or all of these issues. Here is what it said about the accel's on Dennis Kirk site



-Delivers maximum spark-energy and power output
-Fast rise time - higher voltage
-May require re-jetting the carburetors richer for best results
-Designed for either street or high-revving, large displacement racing engines
-Available in kits to fit both four-cylinder motorcycles that use two coils and twin-cylinder motorcycles that use one coil
-Two types -- one for point and inductive electronic ignitions (most popular) and one for CDI systems
-20-309 and 20-310 have 3 ohms primary resistance for points and inductive pickup electronic ignitions;
- 20-311 and 20-312 have .7 ohms for CDI systems
-Includes suppression core wires with extra heavy-duty 8.8mm silicone jackets and universal, slotted mounting brackets with 3 7/8 in. to 5 3/8 in. centers
-Made in the U.S.A.
-WARNING: Use of coils with too low an impedance (resistance) will damage the motorcycles ignition system. We do not have a complete list of applications, so if your motorcycle has an electronic (breakerless) ignition, you should determine the correct set of coils by performing one of the following two simple tests. Keep in mind that the higher impedance coils are by far the most popular and will not damage your ignition system if they are the wrong choice.
-Test 1 (resistance test)-- Disconnect motorcycle coils and test one at a time. Set ohmmeter to lowest possible range. Connect positive lead of meter to battery terminal on coil and negative lead to coil ground. A reading of approximately 2.1 ohms and higher indicates inductive type; .25 to 1.2 ohms indicates CDI type.
-Test 2 (voltage test)-- Using a voltmeter or 12-volt test light, connect positive lead of tester to positive post on one of your stock coils, and connect the negative lead to ground post on the stock coil. Turn the ignition switch on, but do not engage the starter. If you have 12-volts at the coil, the motorcycle has inductive-type ignition. If there is no voltage, the motorcycle has CDI ignition.

[LegendJet]

One other thing I noticed is I was wondering whay kind of voltave the coils should recieve from the ignition module. I put a meter on it and saw that they were only getting like 1.9V does that sound anywhere near right? I read somewhere on here that they should be getting 9V stock.....so something is not adding up. this thing is getting to be a money pit...

[LegendJet]

also how many wires are supposed to be comming out of the voltage regulator? Im wondering because the larger plug has all wires accounted for, but the smaller plug only has 2 wires, but the wiring harness of the bike has 3 wires...any body have any ideas???

[TopCatGr58]

Hey Legend,

As Rasputin stated, the Accels only have the standard ignition type coils that have 3 ohms, or the Capacitance Discharge Ign. type that have 0.7 ohms....ours uses the standard. The power is routed 2 ways to the Ignition coils. During Starting, it comes directly from the TCI's circuit at full 12 volts to allow easier stronger starting. Once it's started, the TCI then routes power THRU the Ballast Resistor to the coils, dropping it about 3 volts to keep from burning up the OEM coils. The Accels need 12, so bypassing it is required for them to deliver their full power. You'll want to measure the voltage AT the ignition coil, not at the TCI!

As long as the TCI sees a 3 ohm load on the power line to the coils, either thru combo of the older coils=1.5 ohms and the ballast resistor=1.5 ohms, OR no ballast resistor and the aftermarket coils=3.0 ohms, it's happy and won't be damaged!

Check the voltage at the ballast resistor connector as well, one side should be 12 volts. IF not, then possible corrosion is inhibiting full power flow!? Cleaning the contacts of the TCI and plug may also help!
T.C.

[LegendJet]

Well, i knew the PO screwed up some of the wiring, but i didnt know how bad...I need a new wiring harness...he butchered it sooooo bad that i need to go through it and get it right. i think thats why it still wont charg right. Ive heard from someone with a xs tripple that when it wasnt charging then it made like nooo power at all. sooo does anyone have a wiring harness that isn't cut to pieces...if soo lemme know maybe we can work something out!! thanks!!

[TopCatGr58]

Hey Legend,

IF the bike isn't charging, then yes, it can affect the TCI's ability to work properly, if it gets below ~10.5 volts, it'll stop working=dead engine!

There's a tech tip and other recent threads regarding testing the charging system to determine what component is at fault. Often it's the Reg/Rect, but rarely it's the actual ALT. There are several large white plugs behind the MAIN FUSE panel that come from the ALT, need to inspect them, clean, etc.! Folks have found them melted due to resistance from corrosion. The Reg/Rect grounds to the frame, again corrosion can cause problems.

Contact Andreas Weiss for a possible replacement harness, he's good for lots of used parts! Also, what does the fuse panel look like? The old glass fuses and holder clips are also prone/known to disentegrate! I sell a simple replacement fuse holder that allows converting to the newer solid fuses!
T.C.

[LegendJet]

well i bought a reg/rect off of fleabay...stupid decision. The seller told me it worked, i put it on my bike and i thought it worked...well it didnt. I checked the rectifier part of the assembly and it is gone...so i found another one one ebay but this time it is from a legit online business called [B]rmstator[B]

http://www.rmstator.com/en/index.php...rcycles/Yamaha

odd part about it is, if you look on this site it lists a reg/rect and the other one is a rectifier...it says nothing about regulator which is kinda weird, but i sent them an email asking a bunch of questions. when i receive the reply i will post it on here for all to see.

[LegendJet]

I pulled the electrical tape off the wiring harness and i found patches of grey electrical tape. That's why I assumed the PO chopped the harness up. After I pulled the grey electrical tape off, I dont think that the PO chopped anything up. I didnt think that the factory would splice wires just in the middle of nowhere, but there was a clamp one the ground wire as a splice, or like a crimp. Also the wire that leads to the ballist resistor had another wire sodered in the middle of it; the thing is, the wired lead to where they should. Either way the reg/rect is bad so I have to replace that.