I would not consider the cam timing mod complete until the exhaust has been done as well.

 

Both exhaust and intake are done. I did both.

 

Thanks for the heads up! I'll be sure to remember to bring it with me.


Sorry, I'll keep my experience to myself. I'm just trying to offer my observations in case anyone else was curious what the 351 kit would be like with the cam/exhaust mod.

Initially, I followed Bill Blue's directions for the main and pilot jet. The bike was running fine after I did this. While in the process of securing the oil leak, I went ahead and did the cam/exhaust mod and left the jetting alone. After doing this, I did a little test run ***** to the wall 100% on the bike and then cut the power without letting it idle or anything after the bike was nice and hot. I pulled the plug and noticed that it looked brand new like it had never been in a motor before. The bike also had a lot off decel popping. I then went inside again and upped the main jet to the biggest jet that came with the DJ kit(132) and moved the clip on the needle down a notch to the 4th notch. I repeated the same process as before with the plug and it still looked the same, although the decel popping did go away a little bit. Everything I did one factor has stayed the same - the pilot jet. That's what I'm going to change next.

I don't mind harsh criticism whatsoever, I appreciate it most of the time as it gets me thinking straighter. See above for how I determined the bike was running lean. Also, note that I did take the advice from other members of the forum reset everything back to normal as far as jetting goes and dropped the clip on the needle back down to the third position. If you care to elaborate how I can more throuroughly test the fuel/air mixture, I will gladly do so and report back on the results of my findings. However, he harsh decel popping and clear, dry plug indicate to me that the bike is running lean. I know it's running lean from middle to low because the throttle is not really snappy and almost hesitates slightly when I roll it off a idle in neutral.

No problem at all with tough love lol. Perhaps I should have taken everything slower, but most of the stuff I'm doing has been done before under similar circumstances so I didn't find it all that necessary to every step one by one. Time is something I very much value and I didn't have hours upon hours of time to spend removing the carb 15 times.

I did the 351 kit alone without the cam mod first. This was when I noticed the oil leak. So I did have a taste of the 351 alone, although it was still in it's fetus.

I'll wait to hear what someone else has to say about the 351 kit with the cam/exhaust mod, analyze their conditions, and then change accordingly. Until then, I'll most likely up the pilot one spot first, see what the bike runs like doing that, and then up the main jet and see what that does.

If anyone knows of a more certain way of testing leaness/richness, please let me know. Sorry to have dumbfounded this forum with questions and my results. Thank you all for your continued patience and helpfulness.

 

The plug chop method you describe is a pretty crude way of trying to tell if your jetting is correct, and in this day and age with fuel additives and iridium spark plugs (if you have one) it is VERY difficult to "read" teh plug. You'd be well advised to post pics of the plug to see if others on the forum that have experience reading plugs can confirm your observations. Even then, it is nowhere near as accurate as dyno-ing the bike. I would be working on getting the bike running half decently from closed throttle to mid-throttle first, then get the bike dyno'ed to fine tune it. I know that contradicts Marcelino's advice of starting with the main and working backwards to the needle height then pilot though, so the choice is yours. Read below for why I think you need to focus on the pilot circuit...

You see, here is a perfect example of misdiagnosing IMO. Popping on hard deceleration is generally accepted to be caused by a "too lean" situation and/or an air leak in the exhaust system sucking extra oxygen in and detonating unburnt fuel. Assuming you have checked your exhaust system, we can work on the premise that it's because of a "too lean" situation. Now think about how the carb works... with the throttle shut off completely (as it will be on hard deceleration), where is the fuel coming from in the carb? It should be primarily being sucked through your pilot jet as the main jet is plugged up with the fuel needle (assuming the needle is not set too high). A small amount of fuel may be pulled through the main jet, but the fuel is mostly being sucked through the pilot on hard decel. So, that being the case, it would be more logical to bump up the pilot jet or open the air/fuel screw more (remembering that as soon as the a/f screw is more than 3 turns out from fully seated you need to go up a jet size). So changing the size of your main jet to compensate for decel popping is pointless... at some stage it will probably start helping, but that's coz it will be so big that the needle cannot plug it properly with throttle fully off and you will be WAY too rich through the rest of the throttle range.

So in summary, take the advice given several times and up the pilot jet to a #38 (and have the main jet and needle set to what Dynojet recommend... those dudes have a pretty decent idea of what they're doing - I promise!)

As above, you are probably right, just trying to treat the problem by changing teh wrong jet.

More evidence to suggest the pilot circuit is lean, not the main.

Little rule to help you focus on the right carb bits when tuning:
1) Throttle fully shut off - play with the idle circuit (pilot jet and a/f screw) till the bike returns to idle nice and quickly after a blip of the throttle then at running temp.
2) Throttle fully open - play with the main jet till the bike is reving to the rev limiter without a strong smell of unburnt fuel while the bike is under load. To be honest with you I will be VERY surprised if you need to go bigger than the #132 Dynojet main!
3) 1/4 to 3/4 throttle - play with needle height. Again, if you have pretty much the right main jet installed and follow Dynojet instructions is should be close enough. Any further fine tuning would best be done with dyno runs.

A/F probe down the exhaust (which is basically a wideband oxygen sensor I believe). Just get it on a Dyno and let a Dyno guru work their magic.

 

I'll try to find a local shop to get it on a Dyno, but for the time being I'm going to follow your logic. I'll go to the bike shop tomorrow and pick up a pilot jet and another main jet just one size up just in case. The bike just doesn't pull like it should mid range so I don't know, it could even be running rich mid range because it's kind of muddy and slow pulling through the middle gears.

 

Man, jhoffy22, you have been going through some convoluted processes. I don't think you will ever get all these things straightened out unless you stop shooting in the dark. It will take a systematic, well thought out method of attack to get things right.

Let me make a couple of points, in no particular order:

1. Trying to read spark plugs with modern fuel is mostly an exercise in futility. They will essentially look white, like the bike is running lean.

2. In my opinion, almost all "jetted" bikes are too rich. I think yours is, too.

3. It is much easier to "feel" a lean condition than a rich one. If you are jetting by performance/driveability, adjust until you know for sure it is too lean then go back a step in the rich direction.

4. Trying to jet by throttle position on a CV carburetor doesn't work. What is important is the position of the slide. The relationship between the two is not constant.

5. Bill Blue is an outstanding machinist. He may not have as much expertise in carburetion. His recommendations have always seemed too far to the rich side to me. BTW, I have a 351.

6. It is impossible to jet over the internet.

7. I would suggest reverting back to as close to stock as possible. That would be your baseline. Then change ONE thing at a time and record your results.

8. I prefer jetting in this order: idle circuit; needle circuit; main jet. Get one right before moving on to the next.

8. Once you gain experience, jetting by "feel" is as accurate (or more so) than jetting by the various analyzers available. Are you aware that even after dyno testing/adjusting the bike is ridden to check the adjustments?

9. It may take 15 times of taking the carburetor off to get the jetting right. That would probably take less time overall than just guessing.

---------------------------------

I have been designing and manufacturing infrared exhaust analyzers for years. The reason I mention this is just to let you know I have some experience in exhaust measurements and what they mean. That being said, I choose to jet my bikes by "feel". I usually check them with the exhaust analyzer afterwards just because I can.

Jetting with a wide band O2 sensor in the header pipe is probably a more viable way of jetting if you don't have the experience to do it otherwise.

I hope I haven't offended you with all this. It appears to me that you have the desire, but are lacking experience. The way to gain the experience is to analyze first, make the change, then verify. If you do it systematically, the experience will come quickly.

Good luck and hang in there...

Ron

 

This. ^^^^^


All I would add is to do some research and reading BEFORE attacking a project.

There is a wealth of information on this forum posted by very talented and knowledgable people.

All you have to do to benefit from it all is do a little searching and reading.

 

Yeah, what Ranger Ron said. All his points are correct to me.

Also, pop on decel has nothing to do with how the bike performs. The pop is from the aftermarket exhaust, so making tuning assumptions because of it is wrong.

I think when it pops on decel, idle is really close to correct.

David

 

Hey - did you guys hear that there's a recall on the 09/10 gas tanks?

 

hahahaha