Mikuni RS34 Flatslides Help

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Re: Mikuni RS34 Flatslides Help

06 May 2011 10:30 - 06 May 2011 10:36
#449200
Andy-

I do fully agree with you that regardless of identical specs that jetting will end up being slightly different for any two bikes. You might only get it close on one bike using identical carb settings as the other bike that runs perfect even if everything else is identical as well.

All-
My only surprise about upping the size of the needle jets in the one example is that they had to up the needle jet size for a relatively stock engine with only a header and pod filters. (BTW, I'm the one that started this confusion, I initially read "Jet Needle" instead of "Needle Jet" which is what Injected originally listed) I didn't say it was wrong... just surprising, you know? Anyway, all my jets should be here either today or tomorrow. I will be doing a lot more testing out once they are, provided the damn weather cooperates somewhat. The jets I ordered are all the large round style, which is correct for these carbs though as mentioned earlier that the small round style are interchangable with the same flow ratings (They are both Mikuni brand obviously).
'79 1000LTD
1075 Kit
RS34s
Mild Port&Polish
Kerker Header
Last edit: 06 May 2011 10:36 by six862m6.

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Re: Mikuni RS34 Flatslides Help

06 May 2011 21:39 - 06 May 2011 21:53
#449312
Sorry - I don't post here too often... I can ask my buddy what needles sizes he ordered - one thing he did bitch about was how much $$ it was to swap them out...

I am only offering up this example because I read in your post about a WOT bog on some RS34's - I rode the bike when it was like this and it was very unpredictable... almost dangerous.

If I can help you or anyone with this example its worth the time.

The guy who owns said bike is an ex Kawasaki service mechanic (1978-82) - so he rode and tuned a lot of 900s when people were converting from air boxes and stock pipes to pods and headers... they use to throw the stock pipes that customers didn't want in a trailer and take them to the dump at the end of the month!!!

Anyways he knows his way around these motors... he tunes by ColorTune and plug chops - old school.

Attachment DSC_5138-6.jpg not found



Pic without the air box
1978 KZ650B2 w 1197cc Z1 engine
1977 KZ650B1 w 750cc Spectre engine
1979 KZ650C3 w 831cc Hot Rod engine
1978 KZ650C2 w 762cc DFI project
1977 KZ650C1 stock restoration project
1978 KZ650B2 modified project
1978 KZ650B2 Injected Drag 831cc
1980 Z1 Custom Frame Drag 1327cc
1981 Z50R Honda tow bike

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Last edit: 06 May 2011 21:53 by Injected.

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Re: Mikuni RS34 Flatslides Help

07 May 2011 00:37 - 07 May 2011 00:46
#449362
I checked with buddy and he said that the RS34's come standard with a #9DZHO1 jet needle which is the leanest they list for the RS series... he is using the #9DZH04 which is 2 sizes richer. The standard needle jet is a #P4... The tech at Mikuni said that if that needle was not rich enough he would be required to go to a #P5 (richer) needle jet and its matching leanest jet needle. He first started changing out the pilots jets as he had extras on hand... he went as big as #25's,but once he changed the needles he went back to the standard #17.5's... mains remained constant at 122's.

The jet needle accounts for throttle settings from 1/4-3/4, so that is half the throttle input...
they are special on the RS because they have two distinct tapered sections which I believe could result in more of a "tune up" window.

Sorry for the lingo confusion... I casually just use needle, bleed pipe, and main/pilot - that's all I have ever know.

This solved a particular issue for someone - I just wanted to pass it along if you think it could be of any use... I think he mentioned it was around $60 to swap them out!
1978 KZ650B2 w 1197cc Z1 engine
1977 KZ650B1 w 750cc Spectre engine
1979 KZ650C3 w 831cc Hot Rod engine
1978 KZ650C2 w 762cc DFI project
1977 KZ650C1 stock restoration project
1978 KZ650B2 modified project
1978 KZ650B2 Injected Drag 831cc
1980 Z1 Custom Frame Drag 1327cc
1981 Z50R Honda tow bike
Last edit: 07 May 2011 00:46 by Injected.

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Re: Mikuni RS34 Flatslides Help

07 May 2011 01:48 - 07 May 2011 01:50
#449374
I'll put my .02 in since I have RS34's also. I have an 1105 kit in mine and the carbs are set with 135 mains,17.5 pilots and slot #3 on the needles. Has a little hesitation till around 2500 and then runs like mad all the way to 10,000rpms. Cruises right along with no problems,but I am running a 37 tooth sprocket also. Oh also,they are 1/4 turn out on the idles. It does seem to run a little rich,but the plugs do look ok. Hope this helps. Good luck with it. Plus I live in S. Indiana near KY.
1980 kz1000g 1105 34mm Mikuni flat slides Kerker exhaust custom paint stock ignition(Dyna 2000 soon) Accel coils and wires stock cams w/ heavy springs for more rpm. My 2nd 1000.
Last edit: 07 May 2011 01:50 by Kawiman80.

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Re: Mikuni RS34 Flatslides Help

07 May 2011 09:56
#449409
Injected wrote: I checked with buddy and he said that the RS34's come standard with a #9DZHO1 jet needle which is the leanest they list for the RS series... he is using the #9DZH04 which is 2 sizes richer. The standard needle jet is a #P4... The tech at Mikuni said that if that needle was not rich enough he would be required to go to a #P5 (richer) needle jet and its matching leanest jet needle. He first started changing out the pilots jets as he had extras on hand... he went as big as #25's,but once he changed the needles he went back to the standard #17.5's... mains remained constant at 122's.

The jet needle accounts for throttle settings from 1/4-3/4, so that is half the throttle input...
they are special on the RS because they have two distinct tapered sections which I believe could result in more of a "tune up" window.

Sorry for the lingo confusion... I casually just use needle, bleed pipe, and main/pilot - that's all I have ever know.

This solved a particular issue for someone - I just wanted to pass it along if you think it could be of any use... I think he mentioned it was around $60 to swap them out!

Can u help me understand this. u are calling the needle and jet the same thing so i need clarification. did he change both the needle and emulsion tube or just the needle?
is there are range of needles that match the tube, and if that is not enough fuel u would then increase to the next size tube and its smallest matching needle?
as u know, i have a small low end bog, so this is of great interest to me. i have not the resources to tackle an air box like his, but it would be worth trying some dif jetting.
Did he do this before or after he added the airbox ?
Thanks
M
76 KZ, frame gusset work,1200CC.Ported by Larry Cavanaugh, 1.5mm.over intakes, Carron Pipe, ZRX12 rear end, and seat,96zx9 front end.
01 CBR600F4i Track bike.
Cobourg, Ont. Can.

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Re: Mikuni RS34 Flatslides Help

07 May 2011 10:44 - 07 May 2011 10:47
#449414
RS34 Parts & Tunning Manual:

RS34 Parts & Tunning Manual

Follow the HS series for tuning, pretty much the same...;)

HS Series Tuning
1976 KZ900-A4
MTC 1075cc.
Camshafts: Kawi GPZ-1100 .375 lift
Head: P&P via Larry Cavanaugh
ZX636 suspension
MIKUNI, RS-34'S...
Kerker 4-1, 1.5" comp baffle.
Dyna-S E.I.
Earls 10 row Oil Cooler
Acewell 2802 Series Speedo/Tach
Innovate LC1 Wideband 02 AFR meter

Phoenix, Az
Last edit: 07 May 2011 10:47 by Old Man Rock.

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Re: Mikuni RS34 Flatslides Help

07 May 2011 11:11 - 07 May 2011 11:32
#449419
mark1122 wrote:
Injected wrote: I checked with buddy and he said that the RS34's come standard with a #9DZHO1 jet needle which is the leanest they list for the RS series... he is using the #9DZH04 which is 2 sizes richer. The standard needle jet is a #P4... The tech at Mikuni said that if that needle was not rich enough he would be required to go to a #P5 (richer) needle jet and its matching leanest jet needle. He first started changing out the pilots jets as he had extras on hand... he went as big as #25's,but once he changed the needles he went back to the standard #17.5's... mains remained constant at 122's.

The jet needle accounts for throttle settings from 1/4-3/4, so that is half the throttle input...
they are special on the RS because they have two distinct tapered sections which I believe could result in more of a "tune up" window.

Sorry for the lingo confusion... I casually just use needle, bleed pipe, and main/pilot - that's all I have ever know.

This solved a particular issue for someone - I just wanted to pass it along if you think it could be of any use... I think he mentioned it was around $60 to swap them out!

Can u help me understand this. u are calling the needle and jet the same thing so i need clarification.(No-I pointed it out the # in the exploded view) did he change both the needle and emulsion tube or just the needle?(just the needle)
is there are range of needles that match the tube(Yes), and if that is not enough fuel u would then increase to the next size tube and its smallest matching needle?(Yes - all info is available in Sudcos Mikuni catalouge - pg126-7 pg129-30)
as u know, i have a small low end bog, so this is of great interest to me. i have not the resources to tackle an air box like his, but it would be worth trying some dif jetting.
Did he do this before or after he added the airbox ? (He figured it out when the pods were still on but he had already started the air box... the box ended up making it run even better, but it might have not been necessary - he called Mikuni and Winners Circle about the needles)
(He had a stock air box on his bike from a 82 KZ750 (one with 34's) and it fit - he said it could be adapted to work with the RS34's, but it looked ugly to him)
Thanks
M
1978 KZ650B2 w 1197cc Z1 engine
1977 KZ650B1 w 750cc Spectre engine
1979 KZ650C3 w 831cc Hot Rod engine
1978 KZ650C2 w 762cc DFI project
1977 KZ650C1 stock restoration project
1978 KZ650B2 modified project
1978 KZ650B2 Injected Drag 831cc
1980 Z1 Custom Frame Drag 1327cc
1981 Z50R Honda tow bike
Last edit: 07 May 2011 11:32 by Injected.

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Re: Mikuni RS34 Flatslides Help

07 May 2011 16:52
#449452
I have a j motor 1100 with 34s on it. Mine is currently 125 main with 17.5 pilot. clip on #3. works ok but I think my pilot is still just a little lean waitng to buy expensive jets after I install 83 gpz head.moving my clip 1 spot did make quite a difference.maybe just play with that and see how it works out.

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Re: Mikuni RS34 Flatslides Help

07 May 2011 19:23
#449472
Injected wrote:
mark1122 wrote:
Injected wrote: I checked with buddy and he said that the RS34's come standard with a #9DZHO1 jet needle which is the leanest they list for the RS series... he is using the #9DZH04 which is 2 sizes richer. The standard needle jet is a #P4... The tech at Mikuni said that if that needle was not rich enough he would be required to go to a #P5 (richer) needle jet and its matching leanest jet needle. He first started changing out the pilots jets as he had extras on hand... he went as big as #25's,but once he changed the needles he went back to the standard #17.5's... mains remained constant at 122's.

The jet needle accounts for throttle settings from 1/4-3/4, so that is half the throttle input...
they are special on the RS because they have two distinct tapered sections which I believe could result in more of a "tune up" window.

Sorry for the lingo confusion... I casually just use needle, bleed pipe, and main/pilot - that's all I have ever know.

This solved a particular issue for someone - I just wanted to pass it along if you think it could be of any use... I think he mentioned it was around $60 to swap them out!

Can u help me understand this. u are calling the needle and jet the same thing so i need clarification.(No-I pointed it out the # in the exploded view) did he change both the needle and emulsion tube or just the needle?(just the needle)
is there are range of needles that match the tube(Yes), and if that is not enough fuel u would then increase to the next size tube and its smallest matching needle?(Yes - all info is available in Sudcos Mikuni catalouge - pg126-7 pg129-30)
as u know, i have a small low end bog, so this is of great interest to me. i have not the resources to tackle an air box like his, but it would be worth trying some dif jetting.
Did he do this before or after he added the airbox ? (He figured it out when the pods were still on but he had already started the air box... the box ended up making it run even better, but it might have not been necessary - he called Mikuni and Winners Circle about the needles)
(He had a stock air box on his bike from a 82 KZ750 (one with 34's) and it fit - he said it could be adapted to work with the RS34's, but it looked ugly to him)
Thanks
M

Thanks again Alex.
76 KZ, frame gusset work,1200CC.Ported by Larry Cavanaugh, 1.5mm.over intakes, Carron Pipe, ZRX12 rear end, and seat,96zx9 front end.
01 CBR600F4i Track bike.
Cobourg, Ont. Can.

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Re: Mikuni RS34 Flatslides Help

09 May 2011 09:48 - 09 May 2011 09:54
#449821
Well guys, as stated time and again; EVERYONE's bike is different. You just really have to feel out what your bike likes I think.

I had a great riding weekend! I ran the gamut of all the mains I bought and the best performing were the 127.5s. I have ordered a set of 125s because I want to try them out too. But I KNOW the 120s were too lean though, so I'm just about in the right area for my bike. I have very little issues now, other than if I crack the throttle to WOT at 2K or below, it stumbles somewhat... I'll try to fix this if I can but honestly its not even that important to me as I rarely ever want to do that anyway. And its only WOT; I can pop it open to 3/4 throttle and the acceleration is GREAT. I pretty much gave the bike the full riding conditions test too; from riding curvy country roads with all the decel and accel involved to cruising fairly highspeed on the interstate when I ran it in to Indy for a small bike event that was going on. Other than noticing that it was idling too high when I'd stop or have to slow way down, I was completely happy with the performance. I still have to richen my pilots; I have my thumb screw backed all the way off because if not they try to idle at around 2.5-3K. They do eventually die off (and die period) without any throttle (or thumbscrew) at all added. If I let the bike idle for a decent amount of time and check the plugs, they indicate a lean condition so I just purchased a set of 22.5s and 25s for pilots.

That being said, again, overall I'm VERY close. Stock needles/needle jets, Needles on #4 position, probably going to end up with 125 or 127.5 mains and I'm guessing 25 pilots.
'79 1000LTD
1075 Kit
RS34s
Mild Port&Polish
Kerker Header
Last edit: 09 May 2011 09:54 by six862m6.

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Re: Mikuni RS34 Flatslides Help

09 May 2011 09:50
#449823
Kawiman-

We ought to hook up and go riding sometime, maybe a semi local event if you know of one. I live in mid-southern IN I guess you would call it; about 30 mins south of Indy.
'79 1000LTD
1075 Kit
RS34s
Mild Port&Polish
Kerker Header

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Re: Mikuni RS34 Flatslides Help

14 Aug 2012 15:20
#542581
Does anyone know where to get (or how to make) a fuel level gauge tool for these RS34 carbs, so I can do the clear tube test? The drain plug is single purpose and it is very large--takes a 17mm wrench.
1976 KZ900 LTD, resto-mod
-1075 Piston Kit
-PSP 3X Cams (degreed to 106)
-Mikuni RS34 Carbs
-Pod Air Filters
-Dyna S Coils and Ignition
-Race Tech Valve Cartridge Emulators up Front
-Ohlins Shocks out Back :)

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