TOPIC:

Just put on some new carbs from Wired George, having some issues (probably else related, but not sure)

I got to ride the bike this afternoon thanks to some warmer weather. I am having some issues and was hoping I could get your insight... The issue is between 4-5k rpm, i get a bogging down of the bike.. When I get in that range, The more gas I give it, the more it wants to stall out... If I can gradually get past that range, 6k +, its screams... If I just nail on it and keep the rpms up, it screams... but drop it down around 4-5k rpm with any type of load on the motor and it bogs down.

I still have points on this bike.. So I took the cover off and one of them looked as if it wasn't opening so I adjusted the points properly (with the help of my father who knows how to) and then I rotated the plate slightly... This helped a little, but I still get the bogging.

I also noticed that the bike backfires way more with these carbs than the others. Its more of a pop pop pop anytime I let off the gas and start to decelerate. I verified that I have no air leaks on the intake (they are brand new) - It has to be an electronic issue or a carb issue. Do you have any words of wisdom to help point me in the right direction?

Well I can help you with the popping from my past experience with my 650. I had the spark plugs gapped too wide and they constantly backfired. As for your bogging at 5000RPM, it really sounded like your timing was off and it still might be. Have you ever tried a timing light?

If it ran well before the new carbs its probley the carbs.sounds like they are lean.You should try to find out if thay are rich or lean.Try adding choke to see if it helps if it does raise the needle.If you got these from George Im sure he would be more than happy to help you out .give him a buzz.Im sure he knows more about carbs than I do.

I emailed George directly and he promptly answered.. He also feels its the timing and I am starting to lean towards that theory. Ive always had some form of the symptoms regardless of the carbs, but now it just shows up a little more/different. Here is his reply. I will keep you posted on the fix.

--

I road tested the carbs and the test bike didn't behave as you describe. You really need to get a strobe type timing light and time the ignition. The timing light has an inductive pickup that you clip over the #4 plug wire and two power wires that clip to the battery. Loosen those three screws on the points plate and start the bike. At IDLE, the mark on the engine case and the T mark on your mechanical advance should line up. Turn the plate one way or the other till they line up. When they do, shut it down and tighten the 3 screws... Next, put the inductive pickup over the #3 plug wire. At idle, you want to adjust timing for the 2/3 cylinders but you can't rotate the plate as it is setting timing for 1/4 cylinders (already adjusted). There are a couple of small mount screws on the RIGHT HAND set of points. Loosen those and slide the points up or down just a tad to make the mark on the case line up with the T mark for the 2/3 cylinders. Rev the engine to about 3K rpm and make sure the advance moves freely towards the F mark for 2/3... You might want to remove the advance and clean/lube it as this is part of regular maintenance as well. It isn't a great idea to mess with the timing without a timing light. When was the last time new points and condensors were installed? Did you gap the points?

Treat yourself to a new set of points and condensors and set them properly. Install new spark plugs, then go out and ride the bike.

If the condition is still there, lightly lift the enrichener as was suggested already. You only need to just barely lift it to feed a tad bit of fuel to the dead spot. Don't pull it all the way on.

If adding fuel helps, go back home, lift the needles one position, synch the carbs and go for another ride. If for any reason you can't synch the carbs, don't worry about it for now. Have them done by a good mechanic later on. DO get them synched though.

You can't always setup carbs on a test bike and then mount them on another bike and get the same results.

I bought a timing light and proceeded to follow the above instructions. However, it mentions to line up the "T" mark above. I never could get it close, only to the "F" mark at idle. Which one should I be trying to line up. I am going to order a new set of points/condensors on Monday just to make sure everything is ok there. I still get the dead spot around 4k depending on load .. Runs fine above that. Choke doesn't help at all. I'm starting to think its something other than carb related. Both carbs had this dead spot, just shows up more with the new carbs. What else could it be?

If you couldnb't even get close to the T mark, it sounds like the points are warn out. Wait for the news ones to get here and let us know the difference.

Could it be the exhaust you're running ? It looks pretty wide open to me.

My Supertrapp seems to create a lean spot around 5K as well, popping and everything. Whenever I tighten it up and increase back-pressure it goes away. You may need to add some baffling in the exhaust.

I'm just living with my lean spot though, cause I like the power the exhaust gives me up high.

I had just come back from a very long trip buying bike parts and was tired when I answered Chris. I was thinking about static timing and not strobe light timing. To time the bike:

1. hook up the light with the inductive clip over 1/4 plugwire
2. start the bike and shine the light at the timing mark
3. At idle, the F line should line up with the timing mark on the case - if it doesn't rotate the points plate to align the F and timing mark using the strobe light
4. stop the bike and connect the inductive pickup to the 2/3 plug wire. Loosen the 2/3 point mount slightly so the points can be moved/rotated and start the bike. Move the points to line the F mark with the timing mark on the case. Also, rev the bike and check to see if the advance is advancing.

If you get it lined up with the T mark, your timing will be very late. That's TDC. the F mark and the " advance marks are your target marks.

I got the timing set to "F" and it is advancing to || at 3k rpm. I spoke with Z1 Enterprises and he suspects a weak spark - I am going to do some coil checks etc etc... I may end up replacing the ignition with a Dyna S and new coils.

I will let you know what I find.

I finally got back to working on the bike. Between cold cold weather, rain and sick kids...

Ok I was on the verge of replacing everything with a Dyna, but with money being tight at the moment, I thought Id look at this again.

I talked to the guy over at z1 and he gave me some tips on testing the coils.

I got 4.1 ohms on each coil from the back side and I got 14.4 and 14.3k ohms on the plug side. He said the back side was good, but mentioned that 15-20k was the range on the plug side. Can anyone confirm this for me?

I also got 12.2 volts at the coil power wire right before it plugs into each coil.

I then chopped off a little of each wire and then put the caps back on.. Went for a little ride and guess what? That dead spot is gone! It runs much smoother now. Maybe just a tiny hint of it now and then, but 98% improvement over what was going on before?

Is it possible that I was getting a weak spark because of the plug wires not contacting the plug caps properly? Maybe something else was going on that I wasn't aware of when I unplugged everything and plugged it back up.

I'd still like any info I can get on the coil ohm range on the plug end.

Also - this bike has a single petcock outlet and the carbs I have need two inputs. I think I'm not feeding enough gas to the carbs. When I really nail on it for a good period of time, It feels like I am running out of gas. Do you think I should replace it with a dual outlet petcock.. Is that what was stock on the bike?

Post edited by: thetemples, at: 2006/11/23 11:11