TOPIC:

I recently ran without an air filter (long story) and weas really suprised at how much effect it had on how the bike ran- sooo- is it clean?
(I'm too new to have more educated suggestions!!

rickj wrote:

I recently ran without an air filter (long story) and was really suprised at how much effect it had on how the bike ran- sooo- is the air filter in and clean?
(I'm too new to have more educated suggestions!!

Looks like I quoted myself!!

someone must have retarded my spark!!

Post edited by: rickj, at: 2006/05/23 11:20

RickJ, Thanks for the suggestion. I'm running generic pods on the bike and they are very clean.

I had run the bike without the pods for a couple of days with no noticable difference in performance, when I had the original heavy smoke on the right side problem (now sorted) but, I haven't tried this since my most recent bogging at 3,5000rpm problem.

I'll take them off this evening and give it a try.

I suspect that removing the pods will result in a leaner mix going to the pots so, if my "I need larger Pilots" theory holds good, the bogging SHOULD get worse? We'll see.

Could the ignition advance mechanism be sticking (draging) at certain RPM's and then advancing correctly at higher RPM's ?
It has been my experience that often times carburators are blamed and have little to do with certain problems.
Harry

Harry,

I had the advance out about 12 months ago and totally cleaned it down and lubed it so I think unlikely. I will however pull it again and redo the clean/lube and make absolutely sure everything moves smoothly and evenly and that the springs are in good shape.

Thanks.

Your engine should be timed so that at full advancve it should be firing at 38-40° BTDC, 40° BTDC is stock at the full advance mark. The stock 76 advance unit is 20° BTDC approx. at the F mark. With 10-1 compression, use 89-93 octane gas minimum. You don't want to run the advance at 43-44° that is too much advance. This is not any new timing info but what has been practiced successfully for years on a setup like yours by many..........mod

Post edited by: modprod, at: 2006/05/23 21:59

So ModProd, If I'm reading you correctly....are you saying that the 76 stock timing is fine for 10:1 running on 89 octane." Time to the "F" (20deg BTDC at IDLE) advancing to 40deg BTDC at full advance?

In other words don't advance from the stock 76.

At what RPM will it be at full advance? 2,500?

I'm also changing out the pilots tonight. I "think" I've got #15's in there right now so I'm going to throw some #17.5's in and see if it makes any difference to the 3,500rpm "cruise" bogging. Pulls hard and smooth, just when you back-off to 1/8-1/4 twist, she bogs?

38 BTDC fully advanced would be what I would shoot for. Yes around 3000 it should be fully advanced but it depends on the condition of the advance springs about how quickly it advances.
One rule about tuning: only change one thing at a time. That is the only way you know what did what. You go changing jets,gas and timing for example at the same time and it runs worse or better, what did it? the jets, the gas or timing? I personaly only set timing on these to what I want at full advance because you run almost all the time at full advance. I would look at timing at idle but if your hitting full advance properly but it's off at idle you have an advance mechanism problem....mod

lean lean lean. put the timing back to normal or youll lose top end and cause undo adverse presssure onto the crank assembly. Your almost there!

Thanks guys. Didn't get to it last night other than to change the oil. I'll pull the spark back to stock advance this evening and report back. If that helps, I'll swap out the #15's with some #17.5's and see if that helps further.

If one of my 17.5 pilot jets plugs while im riding the result is a sound like vaaaak vaaaak when i twist the throttle, so dont let anyone tell you the pilot does not supply gas off idle. When one or more pilots get dirty power goes down. when u get things square, timing on etc, and the motor kicks back when u start it, the timing is too advanced and the motor will never see the top end power and smooth running its capable of. youll feel this as vibration during roll ons at around 80mph in fith gear. When the compression is increased the mixture is tighter causing the fuel-air to heat faster. When spark occurs the gas expands at rate much more rapid. The expansion occurs so fast it pushes back down on the piston before it rolls over the top. That will be the telltale vibration. If u have 15 and 35 tooth sprockets, youll be tacking 6000 at 80mph. The motor should pull clean to 8500. If it vibrates and isnt clean, thats when u want to back the timing down. You'll know when its where u want it to stay.

Post edited by: nads.com, at: 2006/05/26 00:45

Post edited by: nads.com, at: 2006/05/26 00:50

Post edited by: nads.com, at: 2006/05/26 00:53

Nads.com, Pulled the spark, at full advance, back to the stock 40 deg mark. Somewhat smoother idle and up to 3,500rpm. I had originally set it for the 89 octane at about 44-45 deg (too much). Pulls clean at 1/2+ throttle all the way up but STILL, just like clockwork, at CRUISE 1/8th - 1/4 throttle, anywhere between 3,400-5,500 I'm getting the same bogging/hesitation.

I will drop in the #17.5's this weekend and probably lift the needles 1 clip/notch. If I've got enough time I'll do the pilots first then test, then go back in and do the needles.