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Hp engine running 15 Nov 2021 18:41 #857972

  • Sayonara
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Finishing an Hp engine for street KZ early model,Undercut tranny, Lock up clutch,Crankshaft welded,MtC 1428 Block pistons-rings,J model head with bronze guides, oversized valves, ported to 40mm intake, shim under bucket,CM Z7 Cams,Ape tower,Ape tensioner,V&H sidewinder.
I am going to fit a set of Mikuni Rs 40 so what suggestion in terms of jetting you guys think I should start for Pilot and Main.
Thanks in advance.
I grew up riding and fixing all sort of small bike until I inherited A 1977 GS 750 when I was 16, that changed my life completely I love metric bike and I own a few fully working and have some projects.

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Hp engine running 17 Nov 2021 12:46 #858009

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What fuel will be required for such an engine to run properly on the street?
1982 KZ1100-A2

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Hp engine running 17 Nov 2021 17:25 #858018

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The Mikuni flat slide manual suggests 17.5 and 140 main.
I know you won't even be able to start it with that pilot jet, I would put in a 30 pilot to start and check the burn at idle with a Color Tune plug.
For the main jet I would try a 145 and do a plug chop somewhere safe, the best place to do that would be on a Dyno or the drag strip unless you know someone who has a really long drive way. Most Dyno's are equipped with a tail pipe sniffer O2 sensor if your pipe does not have a bung, no disputing AFR numbers.

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Hp engine running 14 Dec 2021 19:31 #859088

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Thanks for the reply I knew with those 17.5 would not even start or will be really lean, to start with 30 and how many turns in the mix screw, I found out the 3 quarters as the manual says is for like stock engines no mods. thanks for the reply I just got the bike back today from the guy that was doing the decreeing for me.I will be using higher octane gas pump no race gas, the J head is suppose to lower compression so it should be OK 
I grew up riding and fixing all sort of small bike until I inherited A 1977 GS 750 when I was 16, that changed my life completely I love metric bike and I own a few fully working and have some projects.

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Hp engine running 14 Dec 2021 19:32 #859089

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Gas pump not race as it has J head and lower compression. just got the bike back today as it was being degreed the cams I should be finishing that project soon.
I grew up riding and fixing all sort of small bike until I inherited A 1977 GS 750 when I was 16, that changed my life completely I love metric bike and I own a few fully working and have some projects.

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Hp engine running 15 Dec 2021 06:31 #859096

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Thanks for the reply I knew with those 17.5 would not even start or will be really lean, to start with 30 and how many turns in the mix screw, I found out the 3 quarters as the manual says is for like stock engines no mods. thanks for the reply I just got the bike back today from the guy that was doing the decreeing for me.I will be using higher octane gas pump no race gas, the J head is suppose to lower compression so it should be OK 
 

The Mikuni RS Pilot Fuel Screw spec is between 1/4 to 1/2 turn out max (FSM spec N/A). 
RS carbs provide ample opportunity to invest in jets.  IMO, using Genuine Mikuni jets saves money and frustration over the long run.

www.dynoman.net/carb/pdf/mikRS-access.pdf
 
1982 KZ1100-A2

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Hp engine running 16 Dec 2021 18:51 #859186

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If you don't have AFR capability or a Color Tune plug then dial the fuel screws out and start it, idle it, and adjust in till it dies... back out 1/8 turn and you should be OK. There is no issue running it rich till you seat the rings, a black plug is OK. Make sure to run a fan on the motor and don't idle it too long. Make sure there is heat in the barrel before adjusting those pilot screws.

Be careful not to over tighten those screws when turning them in closed, they get ruined real quick. If storing the bike for a while make sure to lube those screws from the throat side with WD40 or similar light spray lube because they can lock up with gas tarnish.

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