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 Post subject: Exhaust Sizing
PostPosted: Sun Dec 13, 2015 7:59 pm 
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998cc
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Joined: Sat Jun 12, 2004 8:12 pm
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Location: Wollondilly
I have some maniflow LCBs and a single box rc40 waiting around for my 1360 project. Wanting to jump the gun and put em on my 1098, are they likely to be too big?? Pipe measures about 44mm od (1 3/4" ?)

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 Post subject: Re: Exhaust Sizing
PostPosted: Sun Dec 13, 2015 9:35 pm 
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Location: near Baulkham Hills, NSW
It'll work just fine with 1-3/4 main pipe.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R. :mrgreen:


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 Post subject: Re: Exhaust Sizing
PostPosted: Mon Dec 14, 2015 6:24 am 
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998cc
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BEAUTY :) Thanks :)

Edit: just a thought. It won't require a re tune of the carby or anything will it?

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 Post subject: Re: Exhaust Sizing
PostPosted: Mon Dec 14, 2015 7:56 am 
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You might need a new intake manifold too if you've got the stock one now (or chop it apart). What size carb do you have now?

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 Post subject: Re: Exhaust Sizing
PostPosted: Mon Dec 14, 2015 12:26 pm 
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998cc
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I believe it's a 1 1/4" I also think I have a lynx manifold in the shed to suit :) if not I'll just chop a std one

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 Post subject: Re: Exhaust Sizing
PostPosted: Mon Dec 14, 2015 12:40 pm 
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Location: Wollongong, NSW
It might be worth upgrading to a 1 1/2" HS4 at the same time on a nice manifold while you're going to the effort.

Mine has a maniflow exhaust manifold, RC40 and HS4 on a minispares alloy manifold and goes pretty well for a standard 998.

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 Post subject: Re: Exhaust Sizing
PostPosted: Mon Dec 14, 2015 1:06 pm 
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998cc
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I think I have a hs4 at the folks place :)

Would I have to tune/change the needle? This is basically all temporary until I get all my bits sorted for my other motor to go in so I don't want to spend too much.

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 Post subject: Re: Exhaust Sizing
PostPosted: Sat Jan 16, 2016 1:34 pm 
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What inlet setup have you got for the new engine? Twin HS2s, extractors, 1 3/4 inch exhaust and a single hot dog for a muffler work on my 998, but will work with a 1275. If you have twin HS4s, they should be fine on a 1098 and better on the 1360.

Mark.


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 Post subject: Re: Exhaust Sizing
PostPosted: Sun Jan 17, 2016 5:15 pm 
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I have a mini spares inlet manifold With a 1 3/4" that I planned to use. But now considering twin hs4 :)

Got a single hs4 for the 1098. Can't get the tune right though :)

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 Post subject: Re: Exhaust Sizing
PostPosted: Sun Jan 17, 2016 8:14 pm 
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I just looked at seven mini in UK at their needle chart- 1098 single HS4 standard needle is a CZ, rich is DL, single HS6 for a 1275 GT standard is AC, and rich is BQ, twin HS4s is the same, AC and BQ. Start with the richer mix for the bigger motor unless they gave you a better needle.I hope this helps as a basis. You may need aƧcess to a wideband O2 guage to tune it better if needed.


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 Post subject: Re: Exhaust Sizing
PostPosted: Mon Jan 18, 2016 11:55 am 
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998cc
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Thanks for the Info. I tried running with an ADF as I had it. but no luck. Now getting varied responses as to what needles to try so I think its time to invest in a wideband and a colortune.

as per viewtopic.php?f=2&t=91479

Another thing i have noticed is that the inner driveshaft joint is fouling slightly on the exhaust. Annoyingly.

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