Ok, as most of you know, I'm installing the 351 kit. I've seen two different schools of thought on the jetting for this mod.

School of thought one: 132 Main and stock Pilot

School of thought two: Whatever you are running with the 250 piston, just up the Main by two and the pilot by one.

Are there any other thoughts out there?

I'm running the stock pilot with a 128 Main right now. If I go with school of thought number one, that means I'll keep my stock pilot and go up to a 132. I have that jet in my tool box right now so I wouldn't have to purchase anything.

If I got with school of thought number two, I need to buy a new pilot jet. I am running after market exhaust,header, air filter, and kdx snorkel.

What are others doing? I know what CousinLarry and GaryC are doing (they are my only references so far).

Also, if I do need a new pilot jet, can anyone tell me where to get it and what size? I've got the stock carb.

Help please!

 

Since you have the 132 jet already, and you're at the same elevation I am, and have basically the same mods (except you have snorkel, I have no cover) - I would just throw the 132 in and see. The bike runs perfect for me like this. Starts up within a second, idles cleanly, and goes like a bat out of hell.

 

My bike runs flawlessly with a dj132 main, stock pilot, 4th notch from top on needle, 2.5 turns out on fuel screw. I was having problems with my idle until I adjusted the float level. My current set-up is a bb351 kit, lid on, no snorkel, backfire screen removed, smog stuff removed, uni filter, muzzy full exhaust.

 

^^ Yep - that's it.. I have the 4th knotch, and 2.5 out also. Runs perfect. Just try that first armycopter and see how you like it.

I also plan on getting it to a dyno soon to see the A/F ratio it's running to be 100% correct. But I've been using those settings since I put the 351 on about 6k miles ago with no probs so I'm guessing it's pretty spot-on.

Good luck!

 

A local motorcycle dealer (happens to be a Kawi dealer) charges $50 for 3 dyno runs. That's right $50 for 3 pulls.

That includes sticking an exhaust analyzer up the pipe (not as accurate as an O2 sensor in the header, but better than nothin'). You get the data afterward of course.

They make the runs cheap cause they're hoping you'll let them fine tune your jetting for another $250 - $300.

Point being, in the eon's I've been riding I've know about two guys whose "seat of the pants" judgment was actually close to reality.

Heck, with 3 - 6 dyno runs even I can appear to be a jetting guru. And you learn what really works and how each change effects which part of the power band.

A great deal IMO, and you quickly uncover Myth/Urban Legend vs. Reality. Things like "high flow snorkels" and "removing back-fire screens in air boxes". Oops, best to sometimes let Myths/Urban Legends be.

 

your best bet is to look at the plug.
Every racer "reads the plug".
You will need to make a 5 to 10 second run at Wide Full Open, Kill the engine before the RPM's drop too long. Glide to a stop and pull the plug. It should be a tan to grey color. If it is white, or light grey, too lean. If it is dark dark brown to black, you are too rich.
once you have your WFO jetting set, work on the mid range by doing the same process at part (1/2) throttle. Adjust your needle / pilot jet accordingly. last thing on the list is after you have it good and hot, turn your air screw in, until the idle drops, then out until it makes no change. If you are out more than 3 turns from seated, you need a bigger pilot jet. after all that is done,,,, check the plug for the last time at WFO , and 1/2 throttle. I'm not sure this is the very best method, but it IS the old school method before O2 sensors and dyno's were available.
Hope this helps rather than confuses.
http://forums.bimmerforums.com/forum....php?t=1282968

BTW; i still have the stock pilot in because i haven't gotten the new motor broken in yet. after it is broken in, i intend to do this process.
The 40 pilot was Bill Blue's recommendation, and I don't know if i need it yet.
Gary

 

I had my 351 kit fitted by my local Kawi dealer. Just for some background, I have a Staintune full exhaust system and Bill Blues tm34 carb, no snorkel and I think at some stage a dealer cut a few extra holes in the airbox.

Normally when the dealer does any tuning they tend to provide absolutely no information what so ever as to what changes they have made. This time I insisted and they advised that they fitted a 137.5 main as that was the largest they had that would fit the carb.

After the first couple of hundred Km's of riding and my legs almost being set on fire by the enormous amount of heat being generated from the engine (and I don't just mean on the exhaust side), I sent it back to be dyno tuned. Once again, I now have no idea what changes were made, but at least now my pants are safe from spontaneous combustion.

-Justin

 

I went with the 132 main, stock pilot, and 2 turns on the screw. I plan to fire it up next tuesday. With any luck, this setup will work and my motor won't explode from something stupid I did on the inside. The 351 just seemed too easy so I must have done something wrong.

 

No, you're right, it is very easy.. It'll be fine!

 

Interesting. Could you elaborate?

Thanks,
Ron