TOPIC:

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.

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.

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.

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.

Brady 154 wrote: 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.

Would this work? www.z1enterprises.com/ItemDetails.aspx?item=ZSM-VM29FT

mtbspeedfreak wrote:

Brady 154 wrote: 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.

Would this work? www.z1enterprises.com/ItemDetails.aspx?item=ZSM-VM29FT

that may very well work. phone them and find out. i use a drain bolt from an old set of carbs for my rs 34's. I can remember what carbs the drain plug came from though. i just drill and tapped the drain plug and threaded in a nipple, just like that 1 from Z1E.

The special fitting isn't essential.

I use a clear hose inserted into a cone-shaped rubber grommet. And hold it in position while performing the clear tube test.

Others report using a snug fitting short length of automotive fuel hose instead of the grommet.

It shouldn't leak, but minimal leakage doesn't invalidate the test.





Good Fortune!

Patton wrote: The special fitting isn't essential.

I use a clear hose inserted into a cone-shaped rubber grommet. And hold it in position while performing the clear tube test.

Others report using a snug fitting short length of automotive fuel hose instead of the grommet.

It shouldn't leak, but minimal leakage doesn't invalidate the test.

Good Fortune!

Thanks Patton--I'll give that a try.

I also looked at that tool on Z1 Enterprises, but I'm not sure if it'll fit. I took measurements of the bolt size and thread pitch, so I'll call them tomorrow and see if it'll work. Would be nice to have for long term use.

Hey, I'm gonna jump in on this older thread and ask a quick question about a set of RS36s. Back in the 80s, I saw a set of sleeves for 33mm smoothbores to neck them down to around 31mm throats for better throttle response on smaller engines. Are any of you old timers familiar with this?
I have a set of RS36s I was contemplating sleeving down to 34mm.
Any thoughts?????

i have only heard of that. i suppose it might work if it was an oval shape. the problem is that larger bores supply less of a vacuum signal. if an insert was round it would inter-fear with the signal at low throttle openings and restrict at large openings.

i would suggest that u try a larger needle jet first. since the needle jet delivers the largest percentage of its function at 1/4 throttle, right when the vacuum signal decrees.

Sounds to be easier to buy 34s for the 1075 . Do you need a good set of 36s for the KZ1200?

BlackZ1R wrote: Sounds to be easier to buy 34s for the 1075 . Do you need a good set of 36s for the KZ1200?

try them, until u find something better .
the only thing u have to do is accelerate slowly, while under 4500 rpm's.
this is normal for a large carb on a small cc bike. all of the manufacturers have solved this by adding a diaphragm that does this for u. they call them cv carbs lol.