86 rude 140 runs rich at idle

kgw · Feb 29, 2004

i have 86 rude thats blubbering and rich at idle ive owned this motor since new.this is what ive done so far new gas tank & lines ect. new vro pump & pick up assy.(warning horn prob)rebuilt all 4 carbs.& enricher sol valve. I am a experienced harley mech. but this two stroker is driving me nuts. this motor has aprox.1500 hrs on it mostly trolling.ive de carbed it every season.the problem is worse when the prop is in the water (more back pressure causing a richer mixture ?) will massive de carbing clean the exhaust ports or removing the power head the only way? am i on the right track? i wont be able to try all the suggs. right away its still a little cold up here thank in advance ken

Solittle · Feb 29, 2004

Re: 86 rude 140 runs rich at idle

Have you by chance pulled the T-stats? Those motors do not idle well unless they get up to the specdified operating temp.

kgw · Feb 29, 2004

Re: 86 rude 140 runs rich at idle

thanks for fast reply,yes both therms are new. ken

Dhadley · Mar 1, 2004

Re: 86 rude 140 runs rich at idle

What spark plugs and type fuel? When the carbs were gone thru are you sure the idle and mid range jets didnt get reversed?

kgw · Mar 1, 2004

Re: 86 rude 140 runs rich at idle

carbs and jets went back in the same place all carb passages flushed and blown out. had problem before carb rebuild. Sunoco 91 oct.,champ L77JC4 gap .040 thanks for reply Ken

Dhadley · Mar 1, 2004

Re: 86 rude 140 runs rich at idle

Are the heads stock or have they been cut?

kgw · Mar 1, 2004

Re: 86 rude 140 runs rich at idle

heads are stock as is the rest of the motor.this prob.has been gradually getting worse over the past three years but after a good 5 mile run out in the lake it will slow troll all day thanks ken

seahorse5 · Mar 1, 2004

Re: 86 rude 140 runs rich at idle

Back in '95 or so, the sparkplug recommendations were changed. Now the recommended plug is a Champion QL78YC ( .030" )with the extended nose, just like a late '79 and up iron head Harley plug. Get a factory manual and go through the recirculation system, cleaning and checking the valves, hoses, and fittings. Use an infrared temp gun to make sure the cylinderheads are close to 140 degrees at idle. Check the idle and midrange air bleed jets with the parts book to make sure someone wasn't playing switcheroo with them.

Dhadley · Mar 1, 2004

Re: 86 rude 140 runs rich at idle

With stock heads and porting the correct fuel would be the 87 octane. When the carbs were "flushed and blown out" perhaps all the passages didnt get cleaned. I would soak them and the throttle bodies too. Pay close attention to the two small tubes going up into the idle and mid-range passages. make sure the emulsion tubes are not brittle and deteriorating. Make sure the plates on the side of the carb are sealing. What were the carbs flushed with?

kgw · Mar 1, 2004

Re: 86 rude 140 runs rich at idle

thanks seahorse & dhadley,i have factory manual & parts book .carbs were flushed with alcohol all jets and passages are clear nothing leaking. idle jets are # 28 intrm. jets are # 16 starboard # 20 port. re cerc hoses are clear if they were leaking wouldnt it be running leaner?. i checked head temp with a electronic pyrometer appox 130 de. those re circ hoses and valves are a mystery to me,is this a epa thing the manual isnt very clear on what the do ? thanks again trying to get all info i can before i tear into it again thanks ken

Dhadley · Mar 1, 2004

Re: 86 rude 140 runs rich at idle

Start with the basics. Flushing with alcohol probably hasnt cleaned the tiny passages and other places gum/varnish can hide. Lets soak the carb bodies and throttle plates to have a "clean" starting point. And lets switch to the recommended 87 octane. Keep us posted!

kgw · Mar 2, 2004

Re: 86 rude 140 runs rich at idle

thanks dhadley,Im sure all passages clear i used a large hypo to power flush and all passages flowed freely carbs realy were not gunked up at all.after reading a lot of the other posts on carb jets im statring to get confused from what i know about carbs these are AIR jets and the larger the jet the leaner the mixture.some of the post suggest the opposite is true ??? some thing is wrong here. thanks again KEN

Dhadley · Mar 2, 2004

Re: 86 rude 140 runs rich at idle

Air jets indeed meter air so you are correct -- the idle and mid range jets on looper carbs are regulating air. The larger the jet the more air so it is leaner. Your high speed jet meters fuel so the larger that jet is, the richer the motor will run.

kgw · Mar 2, 2004

Re: 86 rude 140 runs rich at idle

Thanks Dhadley, now back to my orignal prob.the snow finaly melted so i can go out and give it another look . Im still inclined to just re jet leaner but i dont know why i should have to my elevation hasnt changed a bit may be its the change in gas over the years.? Thanks again

Dhadley · Mar 2, 2004

Re: 86 rude 140 runs rich at idle

No problem, let us know how you make out. Good luck!

kgw · Mar 20, 2004

Re: 86 rude 140 runs rich at idle

after mutch trouble shooting and checking everthing again im still maybe chasing a symton that may not be part of the prob. wet plugs when running at idle on muffs. ive come up eith theory and would like to know what you think of it. If im running on muffs at idle 1500 rpm the timer base is still mechanicaly set for 650 rpms . this timing is not adequit for proper ignition at the 1500 rpm piston speed therefore wet plugs would be normal. what do you think ? also my original problem blubering at the ramp with prop in water being in the water may not be the prob. either,it maybe the 15 mile ride to ramp with motor at full tilt up because after replacing water pump {had motor full up to do it}it started blubering on the muffs .floats in carbs have been rechecked thanks in advance ken

kgw · Mar 21, 2004

Re: 86 rude 140 runs rich at idle

^

Terry H · Mar 21, 2004

Re: 86 rude 140 runs rich at idle

KGW...I have similar motor with jetpump...and similar problem...changed sparkplug to the QL78YC and dang near solved the problem...and gained 200rpm to boot. I was about to get into the carbs when someone recommended the plugs...well, there's my story and I'm sticking to it. There was one other plug recommended if this one didn't do the trick, but I can't remember which one, I'll go thru my notes, cause I'll use it next time

...just a Thought

kgw · Mar 21, 2004

Re: 86 rude 140 runs rich at idle

thanks thought101, yes i took seahorses sugg. and am using QL78YC thanks ken

kgw · Mar 22, 2004

Re: 86 rude 140 runs rich at idle

^

86 rude 140 runs rich at idle

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