Jetting question RZ350

General forum on engines, transmissions, gearing and modifications to each

Moderator: rztom

Post Reply
Message
Author
zorba75482
Posts: 112
Joined: Tue Mar 12, 2013 11:50 pm
Location: Texas

Jetting question RZ350

#1 Post by zorba75482 » Fri Aug 01, 2014 10:39 pm

Rebuilding an 84 RZ350, Stock head and new first oversize cylinders, no porting, new crank and stock carbs.

Bike came with D&Gs and K&N pods and I would like to keep same set up. I ran it for just a few miles before I stripped it. Seemed to run OK but wouldn't idle. Carbs were filthy. Mains were 270 with 20 pilots. Found some posts that recommend 25 pilots so intend to fit them with new 270 mains.

Anyone have this setup and does it sound about right or should I go larger for running in?

Cheers
Steve

RZ350 1984 project D&Gs, Y Boot
Laverda 750 SF2 1974
BMW R90S 1974
Ducati GT1000 2009

User avatar
pushstartrearset
-----
-----
Posts: 1339
Joined: Thu Mar 17, 2011 4:20 pm
Location: Vancouver, WA

Re: Jetting question RZ350

#2 Post by pushstartrearset » Fri Aug 01, 2014 11:57 pm

Clean the carbs real good 1st!

I'd ditch the pod filters and get the Y-boot w/ K&N tall filter, especially if you have the K&N pods w/ the hard "chrome" end caps....runs like crap w/ filters like that.

Economy Cycle sells the full setup. bolt on and go. The y-boot allows some distance (tuned) between filter and carbs that is needed, reversion wave stuff and all that.
1984 RZ350L (U.S.) Old Toomeys, oil injected!, Y-boot K&N. loctite throttle cable holder on left carb!! , 410 mains, Dynojet needles 2.0 clip, #20 pilot @ 1.5 turn a.s., 240/512 p.v.

zorba75482
Posts: 112
Joined: Tue Mar 12, 2013 11:50 pm
Location: Texas

Re: Jetting question RZ350

#3 Post by zorba75482 » Sat Aug 02, 2014 1:11 am

Carbs cleaned real well. Soaked them and used a few cans of cleaner followed by air. Heard the Y boot is the better option but spending a bunch on projects at the moment so will give a try with the pods. The few miles I ran it before I stripped it seemed pretty good. No stumbles below the powerband just no idle which I put down to the crap I found in the carbs. Do the 270's sound OK for mains?
Steve

RZ350 1984 project D&Gs, Y Boot
Laverda 750 SF2 1974
BMW R90S 1974
Ducati GT1000 2009

hondaror
Posts: 2828
Joined: Mon Mar 03, 2014 8:44 pm
Location: Alberta, Canada

Re: Jetting question RZ350

#4 Post by hondaror » Sat Aug 02, 2014 2:15 am

I've never tried the Y boot, but love the pods. Ran them on my LC for 7 of it's 9 years with me.
Rory
2 1984 RZ350s
1985 RZ350
9 1986-1990 RZ350s
2000 ST2
2005 749
2005 749 with 999 engine

User avatar
pushstartrearset
-----
-----
Posts: 1339
Joined: Thu Mar 17, 2011 4:20 pm
Location: Vancouver, WA

Re: Jetting question RZ350

#5 Post by pushstartrearset » Sat Aug 02, 2014 7:08 am

Man, i tried searching for mains for the DGS and your setup, but found nothing for pod filtration. I do know that if you put the airbox back on and the bike was totally stock w/ only the addition of DGS, you may not have to change anything (this being a bike w/ stock needles and stock main jets), possibly running the stock main jets, but no more than 1 or 2 main jet sizes tops w/ an otherwise stock bike w/ stock airbox, stock NEEDLES and stock filtration. Removing snorkels and divider obviously would affect the mains a couple sizes. I do know DGs jet differently than Toomeys main jet wise.

The idle problem, again is most likely dirty carbs..mine had jelly ALL over them. Didn't need to change from stock pilot size. I am running a dynojet III kit (specifically designed for K&N filtration).

If you have needles w/ adjustable clip settings, then your needles are not stock and most likely dynojet needles. Wish i could tell you the main jet, but have not run DGs.

A high rpm (10k) WFO plug chop should help w/ main jets. For safety, you could do it in say 3rd gear up a hill.
1984 RZ350L (U.S.) Old Toomeys, oil injected!, Y-boot K&N. loctite throttle cable holder on left carb!! , 410 mains, Dynojet needles 2.0 clip, #20 pilot @ 1.5 turn a.s., 240/512 p.v.

User avatar
mountaincycle
-----
-----
Posts: 179
Joined: Sat May 04, 2013 4:03 pm
Location: South Carolina

Re: Jetting question RZ350

#6 Post by mountaincycle » Sat Aug 02, 2014 7:57 am

agree :smt023 - strip and clean your carbs really good.

I have y-boot w/ K&N filter, 410 mains, 20 pilot, 2.0 clip down, 1.5 turn on the set screws..

good luck

zorba75482
Posts: 112
Joined: Tue Mar 12, 2013 11:50 pm
Location: Texas

Re: Jetting question RZ350

#7 Post by zorba75482 » Sat Aug 02, 2014 11:34 am

mountaincycle wrote:agree :smt023 - strip and clean your carbs really good.

I have y-boot w/ K&N filter, 410 mains, 20 pilot, 2.0 clip down, 1.5 turn on the set screws..

good luck
No clips, so I have stock needles. 410 mains are way bigger than the 270s I took out, but plugs looked OK. May try 300 for initial break in just to be safe, then work my way down with plug chops.
Steve

RZ350 1984 project D&Gs, Y Boot
Laverda 750 SF2 1974
BMW R90S 1974
Ducati GT1000 2009

User avatar
pushstartrearset
-----
-----
Posts: 1339
Joined: Thu Mar 17, 2011 4:20 pm
Location: Vancouver, WA

Re: Jetting question RZ350

#8 Post by pushstartrearset » Sat Aug 02, 2014 4:10 pm

i found two answers for stock airbox. 1 guy recommended stock airbox w/ snorkel removed at a 250~260 main. Smurph recommended stock airbox also at 280 main for starting point and stock pilot w/ stock airbox.

With that being said. I think your 270 is going to be too lean w/ individual pod filters.

I keep thinking a 340 might be a good starting point w/ no airbox and individual filters. Thinking the range would be 320~380 mains? Just a guess, but WAY better to start rich and foul than to go lean and seize. plugs are relatively cheap. I use the cooler BR9ES in the 84 (US) RZ350.

so have two sets of plugs on your person and a plug wrench when experimenting so you don't get stranded by the roadside!!
1984 RZ350L (U.S.) Old Toomeys, oil injected!, Y-boot K&N. loctite throttle cable holder on left carb!! , 410 mains, Dynojet needles 2.0 clip, #20 pilot @ 1.5 turn a.s., 240/512 p.v.

User avatar
aaronmvrider
-----
-----
Posts: 6607
Joined: Tue Sep 02, 2008 7:44 am
Location: Central Coast N.S.W Australia

Re: Jetting question RZ350

#9 Post by aaronmvrider » Sat Aug 02, 2014 7:27 pm

i would be starting in 400 area for mains....

possibly bring a trailer if doing plug chops with 270 mains
1 x 4mm stroker rz 375cc 1983
1 x 7mm stroker rz 443cc 1984 (under construction)
1 x rz 500
1 x mv agusta 1000

zorba75482
Posts: 112
Joined: Tue Mar 12, 2013 11:50 pm
Location: Texas

Re: Jetting question RZ350

#10 Post by zorba75482 » Sat Aug 02, 2014 8:43 pm

400 it is. Cheers
Steve

RZ350 1984 project D&Gs, Y Boot
Laverda 750 SF2 1974
BMW R90S 1974
Ducati GT1000 2009

User avatar
aaronmvrider
-----
-----
Posts: 6607
Joined: Tue Sep 02, 2008 7:44 am
Location: Central Coast N.S.W Australia

Re: Jetting question RZ350

#11 Post by aaronmvrider » Sun Aug 03, 2014 3:37 am

me... lomas pipes and y boot.... 420 main 25 pilot
depending on how your pipes carbs and filters work i suspect it would be close to that..
1 x 4mm stroker rz 375cc 1983
1 x 7mm stroker rz 443cc 1984 (under construction)
1 x rz 500
1 x mv agusta 1000

bryanaverill
Posts: 42
Joined: Mon May 13, 2013 3:20 pm

Re: Jetting question RZ350

#12 Post by bryanaverill » Tue Aug 05, 2014 4:00 pm

I have pretty close to your exact set-up. Stock engine other than +2.00mm pistons, DG pipes, K&N tapered pod filters. Stock 48H carbs.

I played around with jetting quite a bit. Here's my setting for general purpose street riding:
Pilot: 22.5
Air screw: 1.75 turns
Main: 300
Needle: stock with stock plastic shim (no spacers)

It runs great and gets 45 mpg just tooling around at approximately the speet limit. It runs very smooth and pulls strong up to 9k rpm. Spirited riding drops mpg accordingly. Idles perfectly.

#20 pilot = too lean, #25 pilot = too rich on my bike. I played with the needle a lot and everything was worse than stock. Never played with the main because it rips at w.o.t.

Drill out the air screw plugs if you haven't already. Super easy.

Make sure the carbs are perfectly balanced after they are installed (look up technique).

No sure what the dama is about the Y-tube intake. I've read all the scientific explanations. All I can say is it's not my experience.

zorba75482
Posts: 112
Joined: Tue Mar 12, 2013 11:50 pm
Location: Texas

Re: Jetting question RZ350

#13 Post by zorba75482 » Wed Oct 22, 2014 8:13 pm

OK, finally got it back together. Ran through 3 heat cycles on the bench and motor sounds crisp and revs clean, up to about 5500, still taking easy as new crank and bores.
Took out for first ride tonight and it won't pull low revs, absolutely gutless. Slightly better with choke on but still nothing below about 5000rpm.

Set up is D&G pipes, pods, stock motor, 390 mains, 25 pilots based on advice from this thread. Bought as a project and had 270 mains in it and it pulled nicely but didn't get to run it much as head bearings were dangerous!

Carbs are cleaned multiple times. Petcock rebuilt and flowing fuel.

Will take a look at plugs when it cools down but last time I looked after bench running they were clean and too new to tell much but did have an oily film on them.

The mains are the biggest change I made but I would think I am not using mains until 3/4 throttle and that's where the bike runs better.
Last edited by zorba75482 on Wed Oct 22, 2014 11:20 pm, edited 1 time in total.
Steve

RZ350 1984 project D&Gs, Y Boot
Laverda 750 SF2 1974
BMW R90S 1974
Ducati GT1000 2009

zorba75482
Posts: 112
Joined: Tue Mar 12, 2013 11:50 pm
Location: Texas

Re: Jetting question RZ350

#14 Post by zorba75482 » Wed Oct 22, 2014 9:26 pm

Re-reading your post Bryan, I am thinking I an way to rich on then pilot circuit with 25 pilots and 1.5 out on the airscrews. Should have read closer


Sent from my iPhone using Tapatalk
Last edited by zorba75482 on Thu Oct 23, 2014 11:26 pm, edited 1 time in total.
Steve

RZ350 1984 project D&Gs, Y Boot
Laverda 750 SF2 1974
BMW R90S 1974
Ducati GT1000 2009

User avatar
pushstartrearset
-----
-----
Posts: 1339
Joined: Thu Mar 17, 2011 4:20 pm
Location: Vancouver, WA

Re: Jetting question RZ350

#15 Post by pushstartrearset » Thu Oct 23, 2014 6:23 pm

I would do Bryan's setup. Try his Main jets also along w/ the 22.5 pilot and airscrew settings. Sounds like a good setup. Main jets can affect the midrange too. Remember that fuel first goes thru the main jet and then into the needle jet...so if the main is too rich, it will likely muddy up the midrange also. 390 sounds way too rich for a stock (US) needle.
Last edited by pushstartrearset on Thu Oct 23, 2014 6:30 pm, edited 2 times in total.
1984 RZ350L (U.S.) Old Toomeys, oil injected!, Y-boot K&N. loctite throttle cable holder on left carb!! , 410 mains, Dynojet needles 2.0 clip, #20 pilot @ 1.5 turn a.s., 240/512 p.v.

Post Reply