need some 330esr 4mil stoker jetting advise

[thornton]

just wondering if any one knows what size jet i should be running. i have a new honda 330esr 4mil stroker motor it has a boyesen rad valve a keihin cpw carb a k&n open air set up and a fmf gold series fatty pipe and silencer. and should i be running race fuel or pump gas. took it for a ride today and it fell flat on it face about 1/4 throttle, any help is greatly apprecaited thanks

[RubberSalt]

You'll want to do some reading up on jetting. But the main things are plug chops. Pull the plug and look at the color of the porcelain. It should be tanish brown, like cinnamon. 1/4 throttle will be you pilot jet. Adjust your air/fuel screw. 1/4-3/4 is your needle position/main jet. 3/4-WOT is your main jet.

My advice, adjust the air/fuel screw until it runs well. Then swap your main jets until it runs right when WOT. After that, adjust your needle position up or down accordingly.

It's very hard to say which jet you need. Elevation, temp can play into jet size. carb size, port work, etc play into it even more.

Pump gas is all you need. If you’re at 190psi+ on a compression test, look into running e85 or equivalent for fuel. Most people blow cash on race gas not knowing that e85 will normally give them more power.

Race gas (usually VP110): ratios at least 13:1(200PSI). Expensive and not as beneficial as some other fuels, must advance timing (runs somewhat cooler than gasoline)
e85: 85% alcohol 200-250psi. There is a race version of this, c85, provides ~4% more power. Must advance timing (runs somewhat cooler than gasoline)


My advice, get it dyno tuned, It'll be perfect for you then.

[RIDE-RED 250r]

First, your new ESR big bore could have been set up for either pump or race fuel. It is the customer's choice and you should have been asked which dome you wanted. If you asked for pump, run 93, if you asked for race then 108 is minimum.

If you look at the shiny material immediately around the sparkplug hole (this would be the only part of the dome you can see without removing the head) it should say either "pump" or "race". This indicates which dome is installed in the head. My ESR dome has this.. It is enscribed in fine lettering, but you should be able to see it. But you will have to remove the fuel tank.

As to a starting point for your jetting... 190 main and 55 pilot with a DGH needle on the middle groove should get you safely on the rich side for break-in. Of course elevation and temp plays a factor, but those numbers should get you started safely unless you are in Death Valley and it is 20 below zero....;)

[RIDE-RED 250r]

Wait a minute.... What is a Keihin CPW carb?? Haven't heard of that one...

[thornton]

carbs a flat side keihin with a cpw sticker on it. other than that dont no much about it. thanks for all the info greatly apprecaited. when i got the motor i never asked him if he had it built for pump or race. it was another guys project that i accuired and there was to many shiny parts and powder coated stuff so i forgot to ask the important questions

[barnett468]

Hello


Nice find, got blinded by shiny parts, lol. CPW is the distributor for Keihin carbs, see link below. Your carb could be 1 of 3 different types, PWK, PWM, or PJ.

Here’s a couple of potential causes of your problem, cylinder ported excessively, ignition too retarded, carburetor too large, jetting incorrect.

Race gas if fine and better for now until we know more, it will significantly reduce your chance for detonation [pinging] which can damage your piston.

Running a 2 stroke lean can cause piston seizures etc. I would suggest not riding it until you do the following.

Was it “burbling/sputtering” [rich] under acceleration or did it simply fail to “go” [possibly lean]?

What are all the numbers on the carb?

Check main jet size and go up by 3 sizes.

What is your plug number? A 9 is safest [if it is not a champion] until your bike is broken in and problem determined.


CPW EAST COAST DISTRIBUTOR FOR KEIHIN CARBS AND STOCK JET SIZES

http://www.carbparts.com/keihin/katv.htm


Hope this info helps.

[thornton]

plug is a 9 the carb is a pwk it has the numbers 566a2 qen on it and it has a 160 main jet and a 55 pilot. couldnt see anything scribed on plug hole

[JasonB]

Great suggestions above, but the main thing you really need to do here is pick up the phone and call ESR. They put that together for you, or atleast the top end (didnt read enough sorry!). They will give you a base jetting given your mods and motor build. Congrats on the motor, if it wasnt already said in here than you absolutely NEED to go join trx250r.net and start posting jetting questions over there. The population on that website can answer these questions in their sleep lol not downing 3ww, just saying that forum plays with our 250r motors and knows them in and out. Carlos and the rest of the group over there wont steer you wrong

[RIDE-RED 250r]

160 sounds too lean for a 330 stroker unless you are high in elevation!

My .050" over OEM cylinder with PWK36, pipe, reeds and K&N is happy with a 160.

My ESR 350 settled on a 200 main....

I know every build is different based on other mods, and every situation is different based on environment.. But I would bet you my last paycheck that 330 stroker needs much richer than a 160 main. Like I said, most times a stock topend will require similar jetting with just some good bolt-ons....

Is it a 76mm bore WITH a +4 crank (which makes it closer to a 350)? Or is it a 330 including the +4 crank?

Re-reading your initial post, it seems most likely your main is too lean. At about 1/4 throttle your engine is beginning to fully transition from pulling fuel from the pilot jet to the main jet circuit regulated by the slide needle. If you are way lean on the main, it will begin to fall on it's face any time after 1/4 throttle.

You need to know the difference between a lean bog, and a blubbering rich bog.

Like Barnett eluded to, when the engine bogs due to a lean condition it will be smooth as it cuts out. When it is too rich, it will be blubbery, bubbly sounding yet still lose power. Also, excessive smoke is usually present with a rich bog.

My advice is to leave your pilot jet at 55 for now, and install a 190 main jet. Then begin to gradually work leaner with the main jet till you get good power. Once it is strong on a full WOT acceleration with no bogging out, do a plug chop to make sure it's not too lean.

For the plug chop, warm the engine up on a used plug. Install a new, properly gapped plug and proceed to make several high speed WOT runs. On the last run, while still holding the throttle wide open, kill the engine and simultaneously pull in the clutch.

Pull the plug, cut the threads off with a hacksaw and read the plug porcelain, and strap. A perfect plug will be paper bag brown on the porcelain and the ground strap will be blackened a little more than halfway up from the base. A plug that comes back like that should have you in a good state of tune, yet safe enough not to have to rejet for a 10 degree temp change from one day to the next.

[JasonB]

I actually run a 170 main on my 310 motor, and ran a 178 in california in the dunes.


but none of this matters, he posted this bike for sale in the classifieds section at noon lol

[RIDE-RED 250r]

]I actually run a 170 main on my 310 motor, and ran a 178 in california in the dunes. [/B]


but none of this matters, he posted this bike for sale in the classifieds section at noon lol

Precisely my point. ;) :beer

From what I see, most guys running various 330's end up with main jets in the 180 range for final tune. And my 350 doesn't like anything leaner than 200. With a 195 she has an ever so brief hesitation. 200 makes it go away and my plug color and piston wash is spot on.

And yeah, I just saw he posted it for sale.... That thing is a beauty!
Is it wrong that I found myself wanting it??!! :D

[JasonB]

lol it sure is nice looking! so clean! but now i cant find the post, did he take it down already?! or did someone pony up 5g's that fast!!!!

[fire1]

I'm running two similar big bore setups and run 188 main, 50 pilot,dgh needle in third slot. The other is 192 main,52 pilot,dgh needle third slot down. I use c12 fuel in both

[thornton]

i put a 185main in it today and moved the needle third slot down it runs better but still going to have to run a bigger main 185 was as big as the local shop had. and its nasty outside so couldnt really tinker with it to see how much better its running. hopefully this weekends nice so i can mess with it.

[RIDE-RED 250r]

Sounds like you are on the right track...

Check out Jetsrus.com. Every size jet made is available there. Flat shipping is right around $7 which isn't too bad these days.

You can find your jets by carb make and model... Easy peasy.. :)

I have been buying my jets there... Going to have to get a few more if I get into ice racing next winter. My 200 main I am running now is the biggest I have.. Gotta get the next few sizes higher for running in the cold on the ice ovals! :D

Keep us posted.

[JasonB]

Second the jetsrus suggestion, I went on there and bought a dozen jets when I first got my ESR motor so I could make sure when i started dialing and breaking it in that I would have any jet size i needed to do it right and safely

[thornton]

thanks for all the help guys but i got rid of it yesterday. again thanks greatly appreciated