Someone school me in jetting a pinger...

[Thorpe]

Yes, I have read the jetting 101, many times... It's very informative, but didn't address my exact question. And to be fair, I am primarily a 4 poker, but... Picked up a 1985 Honda Oddyssey 350. I know it's not a trike, but I am handi-capable... (Or that's my excuse for awhile till my ankle heals) Redid all the fuel lines and filters, and the vacuum line to drive the fuel pump, but it's breaking up at the mid to higher revs. I adjusted the needle up a notch, it ran worse, I dropped it down (maxed out) and it runs much better... It's very close, but it's still got a little room for improvement.

So the question at hand, how much dies a guy change the main jet? (Made up numbers, since it have not pulled the carb yet,) say the main jet is a 150 currently, I have heard that the odd (example :145 jet) is a half jet and say a 140 is a full jet difference... Or have I been given poor information? With the needle leaned as much as I could on the current jet, it's much improved, but not perfect... Thanks in advance!

[hoosierlogger]

Go down to a 145 on the main and put the needle back at half way and try it. Plug color is more important than anything on a 2 smoke IMHO. Make changes slow rather than too far too fast.

[Thorpe]

Thanks Hoosier... That's what had me a bit perplexed, the plug is tanish in color...?

[hoosierlogger]

Tan is correct. Black is bad rich, and white is a death sentance to a 2 smoker.

[atc007]

JMHO here Thorpe,,She's been sitting and all gummed up. Clean the carb again. Likely no one has re jetted it . So ,while you're cleaning the carb very thoroughly,match the jet sizes up to Hondas oe specs. I bet they're stock or close to it. Clean the heck out of it with 175 psi of air,and I bet she straightens up. Could be clutching too,,,I know,I know,,how could clutching seem like jetting! It can :) :) I would clean and service the clutches,,blow them all out ,lube the 3 weights and rollers,blow out and lube the driven. Make sure your belt is withinn spec,and you'll have a fun lil ride for sure! Hope that ankles getting better!??

[DohcBikes]

Also remember that odysseys love to foul spark plugs.

Jetting numbers are basically just part numbers. Yes they are relative to the size, but the specific number is of no matter, kinda like you stated already.

Regardless of half numbers or whatever else, if you were to want to jet leaner,,,which you should be careful doing, you would get the next smaller numbered jet. Smaller is leaner, bigger is richer.

[Billy Golightly]

Clean and LIGHTLY (emphasis on lightly here, I've seen some filters that looked like they were dipped in oil) oil the air filter. Check your plug gap, no more than .018, and with the 30 year old ignition systems I've had to gap them down to .012 before to make them not get blown out at high RPM. Consider a hotter plug range if you arent already running an 8.

Verify there are no air leaks.

Basically, check everything else before you start messing with jetting. All those issues above will make you chase your tail thinking its jetting when its not, been there done that :)

[Dirtcrasher]

One reason Billy says to "lightly" oil the filter is because there is less air when the filter is oiled; similar to taking the air filter lid off; Adding more air.

Even the oil mixture changes everything. More oil means less gas.

Get the carb specs and see whats in there.

So once you have the motor all set with those, check a new plug. Then get another one and you may not want to plug chop it (WOT) just yet because if that air cooled motor is lean, you'll smoke it.

That needle being all the way up means "I want a bigger main jet!!" : So, starting fat or too rich is the best way to start.

Yes, jetting gets expensive; But, if your in the game with numerous models then extra jets won't hurt. If I thought a 150 was too lean, I'd bump up to a 160 and see how it acts.

Guess what happened to me this weekend?? My jetting on the 87 200X still wasn't quite right and I had no low or midrange power or pull. I messed around with jets and such and recalled that when I did this "20 day build" that I lightened the flywheel. I changed it back to an OEM flywheel and it definitely improved those 2 areas of jetting. I didn't have to touch the jetting once I swapped the flywheel. There simply was not enough weight to keep the motors rotating mass happy.

Just 1 more thing I learned!!

[RIDE-RED 250r]

With Keihin carbs, (at least the most popular carbs found on the ATC's and ATV's) the main jets generally go in increments of 2, as long as you are under #200.

When you said it improved when you dropped the needle all the way, that should indicate you are pretty rich on the main or someone swapped in a much richer than necessary slide needle... But lets not worry about that slide needle just yet, need to get the main jet dialed in before attempting to tune in the midrange....Plus, many less informed would-be tuners forget about changing to a different profile slide needle anyway

Check out this site for genuine Keihin carb parts and jets: http://www.jetsrus.com/

Once you figure out exactly what model carb you have, you can easily order a small selection of jets for it there.

But obviously you need to verify what the jetting specs are set at currently to make an informed decision on what sizes you may need.

All of this assuming the carb and fuel delivery system is clean, clear, and functioning properly.

[Thorpe]

007, I don't think it was parked long... It fires up instantly, and only breaks up under load at higher rpms. Once in awhile it runs real good and strong, but only for short pulls. Overall, I have only dropped the clip one notch from where it was when I picked it up. Has a Uni filter, marginally heavy on the oil, will clean that up some, and a comet 102c clutch, belt is brand new now...

Billy, I just screwed in a fresh NGK, but put in the stock BR9ES (P/O had a B9ES in it, that was tanish to black, but dry) and I am gapped wider then your recommendations... I will adjust, and report back. Best way to check for air leaks to fog with propane, or do an air test on the motor?

Steve, do you think this aftermarket clutch (which appears smaller and lighter than factory) would cause similar issues?

Lastly, as I was cleaning on the motor, notices the hated "orange rtv" (should be required to pass a test to purchase!!) at the reed valves... This concerns me as rtv always does, but what effects can old worn reed valves play? Thanks for all the great advice guys!

[Billy Golightly]

Best way is with an actual gauge and block off the exhaust at the exhaust port because then you check center cases and crank seals, also, areas the propane fogger method doesnt reach. If your going to own a 2 stroke, a leak down tester is just a necessity. Its like having feeler gauage to measure valve clearance on 4 strokes, you jsut gotta have it.

I'd try gapping the plug tighter since its the easiest and in my experience also one of the most common things to be a cause. When its missing or bogging, is it smoking like a freight train, or is it just "missing" without any smoke or splooge?

Definitely thing that airfilter out, hell run it dry for a little bit atleast to establish a baseline even.

[Thorpe]

Billy- will definitely build a block off to give it the proper pressure test. Do you recommend going to a BR8ES over the 9 along with the regap? It doesn't smoke heavily (a bit when it's first fired up) when it's bogging, or have any splooge. Running fresh non-oxy 92 octane with amsoil at 32:1... I will clean the oil off that filter, suppose I could run it without the airbox too to try and lean it a bit more...

[hoosierlogger]

32:1 sounds excessive with today's oils. I could be wrong, but that just sounds like too much oil.

[atc007]

B8ES, I hate resistors. Yes,,if you have neighbors, they are a necessity,as they do what they are intended to do. Resist:). Clean filter,lightly oiled,102c clutch is fine,assuming it is for this buggy. Which,they sold many of these specifically made for the FL350. You say sometimes it runs good. Starting to sound like an air leak. Goop around intake,,sounding more like air leak,, For a damn good idea if you have an air leak or not. With it idling,spray starting fluid all around the intake,cases,and end seals the best you can get at them. IF you have any air leak,it will rev 10000 for a split second. You will KNOW it lol ! If it passes this test. You don't have a lot to worry about.

[Billy Golightly]

Billy- will definitely build a block off to give it the proper pressure test. Do you recommend going to a BR8ES over the 9 along with the regap? It doesn't smoke heavily (a bit when it's first fired up) when it's bogging, or have any splooge. Running fresh non-oxy 92 octane with amsoil at 32:1... I will clean the oil off that filter, suppose I could run it without the airbox too to try and lean it a bit more...

the jump from a 9 to an 8 wont make that much of a difference at this point as you are diagnosing, but will when you are riding it for more extended periods. That was just a suggestion, more suited for longer term use.


I actually try and set up my 250Rs to run on 10 (very cold) plugs when I have just cleaned and freshened the airfilter. As I ride more, particularly in sandy dusty environments down here and the filter begins to dirty up, I graduate down to a 8, or sometimes even a 7 heat range to help band-aid making up for the lack of additional air coming in. Technically its an incorrect way to counter-act that, but it seems to work for me :). When you have limited time/tools, it works.

Leave the airbox on for now - one variable at a time to change, thats very important too :)

[Thorpe]

Sounds good guys... I will start checking the suggestions, one at a time, and report back my findings... Thank you all for the input!

007, it didn't start the "occasional" running really good, till I made that last needle adjustment. Before the needle adjustment, it ran consistently crappy on the top end... What's the real difference between a resistor plug and non? (Besides for radio interference)

[RIDE-RED 250r]

In all honesty, I have run both resistor and non resistor type plugs and I haven't experienced a difference myself. I run BR9's in my R's currently and usually get a full season of trouble free running out of them...

With our old machines, I don't think it makes much of a difference. But I can tell you from experience that resistor type plugs are more important on some newer, more sophisticated stuff due to the RF interference sometimes negatively effecting some of the "smart" ignition systems. I had an '02 Ski-Doo sled with electronic reverse. When you push the reverse button it would literally kill the engine and just before all motion stopped it would re-fire and run the engine backwards for reverse operation. I made the rookie mistake of running non-resistor plugs in that sled when I first got it. It would stall and fail to get into reverse often and also going back into forward. The non resistor plugs interfered enough with the ignition system that it caused it to malfunction in this way. Switch to resistor plugs and it all went away and worked perfectly.

Sorry about the long story... just my personal experience in the matter. I just don't think it is cause for too much worry as long as the plug is in good condition and properly gapped.

[atc007]

Yes, resistors are for radio waves,,bugging your tv signal etc. And they do work. And as Ridered said, some newer sleds need to have them. Personally,, tens and tens of thousands of miles on sleds. And however many miles on R's,Quad Racers and Banshees. Resistors fouled far too quickly. JMHO,,never liked em :) Back to the Odyssey, if jetting changes affected it positively. Keep going that direction lol. I would put your needle in the middle groove and drop 2 main jet sizes. Run it around a few miles,with a good top end run at the end,and check your plug. I'm not getting into the whole"plug chop" here. This is how I've done it for 30+ years now. Nice dry brown is all pirtyy,,but I much prefer a dry black,unless you're sitting in the pits at a race track. Weather changes etc,black runs almost as good,and you have a safety blanket for a little leaner conditions....Funny reading Billy's post. I used to jet my sleds to run 10's and Idle at 450RPM,, When 8's or 9's were recommended. Now I just ride them lol...

[Thorpe]

Only had a few minutes to tinker with it today... Tried fogging some ether around all the potential air leak spots with zero rpm change. Just for kicks, left the greasy air filter on and popped the airbox lid off, and took it for a rip, and it pulls perfect everywhere thru the throttle (need earplugs for that!) gonna clean the snot out of he filter and lightly oil, reassemble and see how it acts tomorrow.

How often should reeds be replaced? Is there a large difference from oem style to say "boyesen power reeds"?

[atc007]

Reeds will give you a noticeable improvement. Not night and day,but noticeable.

[Billy Golightly]

It probably already has aftermarket ones - I'd find it unlikely to still have the original spring steel OEM type (although it is possible of course). Its a barely noticeable, but noticeable, improvement going to fiberglass ones. Changing out the entire cage assembly is what makes the difference.