Micron GP pipes jetting help

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rztom
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Micron GP pipes jetting help

#1 Post by rztom » Sun Jul 16, 2017 4:44 pm

I am posting this topic for club member BoldRZ, who is currently unable to post due to an ISP blacklist issue. - Tom

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I purchased some Micron GP's about 10 years ago. I'm looking at putting these pipes on shortly and was thinking about jetting so hopefully someone here can provide some insights.

I live at about 5500 feet above sea level - Boulder, CO

My current setup:
-I have the stock Mikuni carbs but they are the ones that have the linkage that connects them at the carb bodies and don't have the circular caps on the top where the throttle cable pulls from the top. Anyone know the model of these? There aren't any markings on them.
-SpecII pipes
-Individual K&N pod filters
-Main Jet: 240 I've been told that these should be too lean but the bike has run well before I took my hiatus from riding and the plugs always looked good.
-Pilot: I'm assuming stock. 20?
-The needles in the carbs are stock and not adjustable. There is a little spacer under the needle clip and it has a tiny locator pin when the needle seats in the slide.

My future setup:
-I do have a Y-Boot and filter and that will go on when I put on the Micron GPs.
-I'm thoroughly cleaning the carbs and removing the varnish and gunk.

So from reading many different threads here, I thought my jetting would be with the Microns and new filter setup:
Main Jet - 420
Pilot Jet - Stock 20 or 20.5
Needle - 2nd position from the top (do I put the spacer that has the tiny locating pin under the clip?)
Air screw - 1.5 turns out.

From reading about Microns in the Elsie sub-forum, it was mentioned that the stock mains (240?) might be too rich for the Microns so now I'm confused.

Any help is greatly appreciated!

Nils

BoldRZ
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Location: Boulder, CO

Re: Micron GP pipes jetting help

#2 Post by BoldRZ » Tue Jul 18, 2017 11:58 am

Tom,
Thanks for posting. I think my posting problems are fixed.

With regards to the subject, any general or specific advice is welcome.

Thanks!

Nils

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Questo vecchio rz
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Re: Micron GP pipes jetting help

#3 Post by Questo vecchio rz » Wed Jul 19, 2017 5:56 am

Hello, Before going all in, have you considered leaving it as is?
The reason I ask is, You already have aftermarket pipes (Spec2) & (Indavidual "open" filters).
You will be changing only to (another brand of exhuast & a different open airfilter.)
You mentioned it has always run safe & well with your current setup,so for a road bike, I'd think..... you would be quite close.
I had a RZ with Toomey replicas , and it ran flawless with no jetting changes on a stock airbox and filter, probably put 30k on that bike with that setup.
Just thinking out loud to your inquiry, as the Carbs can be a 'pandoras box topic" which more often than not from years of reading leaves many chasing their tails, and the personal opinion regarding filters 2-1, pods,, Uni or K&N,stock airbox vs Modified airbox etc..& that's only filters...wait until you start fiddling w various jetting choices.
Sure you can optimize the jetting, but since you have a good thing going...I'd be tempted to run the same setup, and see how it runs and reads vs your current induction & exhuast setup.
That's all I got, for what it's worth...
Banshee (Baja) race bike,+ 2 A Arms,L.E.Ds, Toomey, +4 stroker IMS tank, run flats.
96 GSXR SRAD, Future Yoshimura rep.
85 custom Tri-Z
RZ/YZR bike(project)
86 VFR750 RC24 Merkel replica (project)
Royal Enfield Bullet 500

BoldRZ
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Location: Boulder, CO

Re: Micron GP pipes jetting help

#4 Post by BoldRZ » Wed Jul 19, 2017 6:33 pm

This Old RZ,
Great response and point of view. I had a number of folks tell me that the y-boot and filter were much better.

I figured if I was changing one, I'd change the other and I'd need to change jetting. Definitely a good place to start as you said.

Going through the carbs has caused another problem and I'll be posting about that. The guy who owned the RZ ahead of me messed up the head of one of the air screws. I tried taking the air screws all the way out and replacing them and now I have a stripped head on one of my carbs. That problem is for another posting.

Thanks again!

Nils

Bare
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Re: Micron GP pipes jetting help

#5 Post by Bare » Wed Jul 26, 2017 12:52 pm

Your bike isn't running is it?
Tough to do sans carb tops :-)
Also sweating over some crappy carb screw suggests that you are either new to these or are just fumbling in the dark.
Used Mikunis for these Bikes are abundant and inexpensive .. as few actually want them.
Lotsa info about 350s'... time to take a few weeks and do due diligence. It will pay off.

Microns run Fine on oem jettings.
That assumes an oem airbox..though.
Which, unless fitted to a Race only track bike makes Mo' power than Any of the aftermarket variants.
If interested? Research the topic... there's lots of it.

BoldRZ
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Joined: Tue Oct 07, 2003 5:17 pm
Location: Boulder, CO

Re: Micron GP pipes jetting help

#6 Post by BoldRZ » Wed Jul 26, 2017 9:10 pm

Bare,
Thanks for the response. My bike was running but not very well due to sitting and the carbs needing to be cleaned/rebuilt.

I'm not sure what you mean about it being "tough to do sans carb tops". In the original post, I was describing my carbs. My carbs are complete.

I saw the thread in the Elsie forum that you commented in and referenced that was where I saw some different information from what people had told me and from reading about jetting on different threads on this site. I was going to post in that thread but I don't know what is all different between an RD350LC and an RZ350. Since I have an '85 RZ350, I also wasn't sure that was the appropriate place to have RZTom ask my question so I asked it in this forum. So I have been doing research and will continue to do so. I just thought it was okay to ask a question when I came across potentially conflicting information and I was looking for advice.

Thanks for responding that stock jetting works fine on the OEM airbox. As was written in the original post, one of the previous owners had removed the stock airbox and put on K&N pods.

But as This Old RZ said, and I think is a great idea with great rationale, I'm going to start with the way the bike was currently setup and work from there.

Thanks much!

evan_calgary
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Re: Micron GP pipes jetting help

#7 Post by evan_calgary » Thu Jul 27, 2017 12:46 pm

Your altitude will have a lot to do with it too. Suspect that stock jetting will be as rich as you would want to go and likely quite a bit smaller. 240 to 420 as indicated in first post you may as well just pour gas into your intakes. I would be surprised to see the bike run on the throttle if you do this.

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