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EG 295 jetting - decel surge with major spooging

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So I have been trying to jet my new EG 295 motor for a few rides now, and while it feels great under acceleration, no bogging or anything, it has a bad deceleration surge indicating a lean condition. The plug is tan all over. The bike spooges like mad, like all the way down the tail-pipe.

Specs are:

295 top end, broad powerband w/pump gas

48/172 brass

#8 slide

NE3J 2nd clip

FMF Fatty Pipe, FMF something silencer

Running Golden Spectro at 53:1 (EG's recommendation)

Elevations ranging from 2500'-7000', but most between 2500'-4500'. 40-70F.

I just replaced the crank seal hoping to get rid of this ridiculous spooge problem. Been riding the bike in the mid-range (just on the pipe).

Has anyone else had difficulty tuning out this decel surge? I haven't been able to pinpoint where in the throttle range it occurs the most when I cut the throttle?

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So I have been trying to jet my new EG 295 motor for a few rides now, and while it feels great under acceleration, no bogging or anything, it has a bad deceleration surge indicating a lean condition. The plug is tan all over. The bike spooges like mad, like all the way down the tail-pipe.

Specs are:

295 top end, broad powerband w/pump gas

48/172 brass

#8 slide

NE3J 2nd clip

FMF Fatty Pipe, FMF something silencer

Running Golden Spectro at 53:1 (EG's recommendation)

Elevations ranging from 2500'-7000', but most between 2500'-4500'. 40-70F.

I just replaced the crank seal hoping to get rid of this ridiculous spooge problem. Been riding the bike in the mid-range (just on the pipe).

Has anyone else had difficulty tuning out this decel surge? I haven't been able to pinpoint where in the throttle range it occurs the most when I cut the throttle?

How many turns is your air screw? Might be out to far (lean) causing the decel surge.

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1.25-1.5. Will double check. Would that be causing the decel surge elsewhere in the RPM's? I have the idle set a little bit high for the Rekluse that's on the bike too. Set with a somewhat tight gap and heavy balls and light spring.

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My set up is running really nice with:

Pump gas, wide poweband

Sea level

48

178

.5 air screw

JD red needle in 4th

Slide #8

32:1 Yamalube

2007 with stock pipe and RG3 silencer.

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1.25-1.5. Will double check. Would that be causing the decel surge elsewhere in the RPM's? I have the idle set a little bit high for the Rekluse that's on the bike too. Set with a somewhat tight gap and heavy balls and light spring.

I'm not up on the Rekluse.

I originally had my a/s at 1.25 with my above setup and it also surged on decel, or when coming to a stop. It was also pinging at 1/8 throttle. I went down to .5 and it took it all away. I'm actually going to see this weekend if I can get away with .75. I went to a 50 and it lost a little snap, so my setup likes the 48.

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As far as the spoog, not sure there. All your setting seem lean enough for your altitude, perhaps the only one that might be border line rich is the pilot, but in mid-range the pilot shouldn't be given you that problem.

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Make sure you have a new gaped spark plug.

Do a plug chop.

If it persist with the same tan plug, check for any air leaks on your exhaust. Red RTV.

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i chased this for the longest time with my 2008 yz295. i thought it was my pilot and kept going richer to try and fix it. i ended up with pig rich jetting off the bottom and still a lean surge on decel. my needle was the problem. is that the stock needle you are running? i ended up with the jd blue needle which is the richer of needles in the 3rd clip. no more lean hang. i also went from 36:1 to 44:1 as the big bore needs less oil. no more spooge. i am running klotz super techniplate. no spooge at all just a nice "harvest moon" ring around the pipe.

i chased this for the longest time with my 2008 yz295. i thought it was my pilot and kept going richer to try and fix it. i ended up with pig rich jetting off the bottom and still a lean surge on decel. my needle was the problem. is that the stock needle you are running? i ended up with the jd blue needle which is the richer of needles in the 3rd clip. no more lean hang. i also went from 36:1 to 44:1 as the big bore needs less oil. no more spooge. i am running klotz super techniplate. no spooge at all just a nice "harvest moon" ring around the pipe. oh and make sure your idle isn't up too high. that will also cause a surge on decel.

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My idle is definitely high. I may need to adjust some things in the Rekluse so it doesn't require that. Going for a ride today at around 3000-4500', so will try all that and report back later. Thanks for the input.

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We should start a 300 jetting FAQ thread to help people out. Mine from Eric gorr are supposed to be here tomarrow 1 yz and 1 rm so I'll have two that I need to test and tune I can't wait

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Double check your chain tension, quite often it sounds like a knock on decel. Just a thought.

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What, so too tight or too loose of chain tension can sound like it?

This is definitely a surge coming from the engine that you can feel through the whole driveline.

Got the Rekluse sorted out to where I could bring the idle down a bit, and that seemed to help a lot with the surging. Who knew? I guess now that I have that sorted, I may still be a little rich on the brass which would explain the spooge. False positive for lean condition due to the high idle/surging, originally compensated for with a step richer on both jets is what is seems like.

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My bike is at a similar altitude, running jetting that almost identical. The ONLY difference between what you've listed is I am running Yamalube r at 32:1. It runs clean, no spooge, and is as close to jetted perfectly as any bike I've ever had.

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Interesting. I have done a little research on oil flash points. Found most are hovering around a flash point of 200F +/- 15F. I had to run a gallon of 50:1 Motul 800 mix through there a few rides ago (due to availability) which started making it REALLY spooge bad. That oil has a flash point around 400F! I can see why it didn't burn off. It has been 3 rides since then so I've gotta think that oil should be out of the system by now? Maybe it's just still pooled in the pipe and the cylinder packing? Hadn't thought of it but I guess that's possible. Was using Spectro ~50:1 before and after that. I could always clean out the pipe and replace the cylinder packing and start fresh on that.

What's your pilot and main at? I like the needle and slide combo with this motor - very nice linear feel in the middle. Power right when I need it and perfect control.

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I've done five of these conversions now, and they all have a lean spot around 1/8 throttle.

Most of the threads here call for a larger pilot and a smaller main, this is true to a point i think.

When idleling the motor uses a combination of the pilot and the straight section of the needle, so what has worked for me is a standard or smaller pilot and a JD red or blue needle which has a richer straight section at the start of the taper. :bonk:

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What, so too tight or too loose of chain tension can sound like it?

.

Too loose

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