Proper jetting for Micron exhausts

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LC Cnd
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Proper jetting for Micron exhausts

#1 Post by LC Cnd » Thu May 11, 2017 3:50 am

What is the proper pilot and main jetting for an Elsie (stock air box) with short canned Microns? Read stock (22.5 pilot, 220 mains) should suffice. Others advise jump up 2 sizes on both jets and carb needle moved fm the middle mark down one. Also I have a bit of an exhaust leak at the head of the left exhaust port eventhough the stub bolts are torqued to spec on new studs and the exhaust new springs fits proper with new OEM gasket rings. Right exhaust is fine. Mis-fitting left rear set to the Micron rear hanger perhaps?

chalpkin
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Re: Proper jetting for Micron exhausts

#2 Post by chalpkin » Thu May 11, 2017 5:21 am

The only way to be sure the jetting is right, is to do a plug chop, aim for a biscuit brown colour, from memory of when I fitted Microns to my old elsie back in 1980, I had to go up in main jet size (sorry, my memory's not that good!), I can't remember to what though! And I'm sure I had to raise the needle a notch too, but all engines are different, do a plug chop and start from there.

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Bare
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Re: Proper jetting for Micron exhausts

#3 Post by Bare » Thu May 11, 2017 1:29 pm

Dunno what will be posted.
I.. found that 230's worked perfectly on microns, being a bit rich (intentionally) verified by the light brown plug condition resulting.
Remember that Pipes are AFTER the combustion process.

LC Cnd
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Re: Proper jetting for Micron exhausts

#4 Post by LC Cnd » Thu May 11, 2017 9:06 pm

Is that 230's with stock pilots and stock positioning on the needle?

hondaror
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Re: Proper jetting for Micron exhausts

#5 Post by hondaror » Fri May 12, 2017 4:44 am

chalpkin wrote:The only way to be sure the jetting is right, is to do a plug chop, aim for a biscuit brown colour, from memory of when I fitted Microns to my old elsie back in 1980, I had to go up in main jet size (sorry, my memory's not that good!), I can't remember to what though! And I'm sure I had to raise the needle a notch too, but all engines are different, do a plug chop and start from there.

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Plug chop is for the main jet only. Stock pilot should rarely ever be changed. It is part of the idle circuit. Get out to a dyno if you can. 3 days of jetting accomplished in about 2 hours of dyno time.
Rory
2 1984 RZ350s
1985 RZ350
9 1986-1990 RZ350s
2000 ST2
2005 749
2005 749 with 999 engine

LC Cnd
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Re: Proper jetting for Micron exhausts

#6 Post by LC Cnd » Fri May 12, 2017 3:12 pm

Gunna have to be the 3 day plan as the nearest dyno is 200kms away. Lowest I've got is 240 mains.

hondaror
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Re: Proper jetting for Micron exhausts

#7 Post by hondaror » Fri May 12, 2017 11:22 pm

Scott, I'd be willing to bet the 240's are way too rich.
Rory
2 1984 RZ350s
1985 RZ350
9 1986-1990 RZ350s
2000 ST2
2005 749
2005 749 with 999 engine

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2smoke
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Re: Proper jetting for Micron exhausts

#8 Post by 2smoke » Sat May 13, 2017 12:05 am

Rory is right.
I would start with the stock 220 and go down from there.
Use stock pilot jet size only. Anything else will waste your time in a big way.
Plug chops are dangerous(to you) and not needed. I never do them.
Do a plug chop at the end when you are super close if you want.
If you modded the airbox then that would need way bigger jets.
Which needles are you using, whats written on them?
Use high temp rtv on the leaking pipe manifold.
Have fun!
Colin
79 RD400F Daytona Special
81 RD350LC
89 TDR250
75 Kawasaki H1 500
77 Can-am Tnt250

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Re: Proper jetting for Micron exhausts

#9 Post by hondaror » Sat May 13, 2017 12:15 am

Don't hold me to it, but I think I was running 170 mains in my LC in Toronto with DG pipes back when the bikes were current. I could not blow that bike up. It ran so fantastic.
Rory
2 1984 RZ350s
1985 RZ350
9 1986-1990 RZ350s
2000 ST2
2005 749
2005 749 with 999 engine

LC Cnd
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Re: Proper jetting for Micron exhausts

#10 Post by LC Cnd » Sat May 13, 2017 12:49 am

Thx gents. It appears I will be shopping for some new mains. What kind of high temp rtv do you recommend Colin - permatex 2000? I'm thinking something that will survive 1200F + and won't turn to powder. Furnace cement was suggested but I can see that vibrating to powder too.

RuZty
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Re: Proper jetting for Micron exhausts

#11 Post by RuZty » Sat May 13, 2017 5:47 am

I've always used Permatex Ultracopper on exhaust pipe stubs and it still looks the same the I remove them years later. I think they do Ultrablack too which has similar properties but less noticeable. Don't get carried away with it, more is not better, it spreads out a long way when you bolt parts down.

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Re: Proper jetting for Micron exhausts

#12 Post by 2smoke » Sat May 13, 2017 10:23 am

Yep, permatex ultra copper from Canadian Tire is what I use.
Colin
79 RD400F Daytona Special
81 RD350LC
89 TDR250
75 Kawasaki H1 500
77 Can-am Tnt250

LC Cnd
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Re: Proper jetting for Micron exhausts

#13 Post by LC Cnd » Sun May 14, 2017 4:19 am

The area where the exhaust leak is at the end of the arrow. You can see where the exhaust flange is moving inside the pipe fitting. So, spread some prematex outside the exhaust flange, push it back in place, let it cure & then fire her up, ta-da?
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Bare
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Re: Proper jetting for Micron exhausts

#14 Post by Bare » Mon May 15, 2017 11:19 pm

Dunno What you guys are doing to get your Permatex Ultra (copper swill) to work in your microns.
I tried it twice... the crap turned to liquid goo within a 100 miles . Thinking this was Not what I expected..
tried again with Another new tube of Copper Goop... let it cure for several days rather than overnight as in previous application.
Same damned result ..The stuff turned to watery jelly and dripped out. Not happy.
So I gave up on the 'Gooping it ' notion and now wipe the odd drops from the sliding joint as part of my end of ride cleanup.
The leakage is quite small.
Plus Not Gooping that joint shut allows it to Slide in and out ..exh pressure/rpm dependant.

Just as the designers intended it to :smt002

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Re: Proper jetting for Micron exhausts

#15 Post by 2smoke » Tue May 16, 2017 10:35 am

LC Cnd wrote:The area where the exhaust leak is at the end of the arrow. You can see where the exhaust flange is moving inside the pipe fitting. So, spread some prematex outside the exhaust flange, push it back in place, let it cure & then fire her up, ta-da?

Yep, you got it . I cover both pieces liberally and shove them together. You want some squish out.
So bolt the little manifolds on to the cylinders, goop the parts, install the pipe. Let em dry overnight if possible.
That's it. The stuff stays hard.
Colin
79 RD400F Daytona Special
81 RD350LC
89 TDR250
75 Kawasaki H1 500
77 Can-am Tnt250

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