Jetting '86RZ 350F2 - I think I'm close but not quite right.

[hilltj]

Guys, I tried replacing the banshee needle with the standard RZ one with 290 mains;
1) lowest position (C5) ran like a fat dog.
2) C4 ran like a dog.
3) c3 ran a bit better (greyhound?) but not as well as with banshee needles @c2, felt rich upon gentle acceleration @ about 5,000 Rpm.
4) thought that if it was rich, then I should try 280 mains (as I reckon that I was restriction the main jets anyway with the needle so far up).
5) Ran like a slightly obese dog at C5 (RZ needle).
6) Ran a bit better at C4 bout would not really rev cleanly seemed rich.

I'm thinking that I'll try the Bansee needles starting & c5 with 280mains. This seems to be approaching the jetting that g0zer has settled on. I think that it I'm using 290mains, but restricting them with Banshee needles @C2 for best results so far, then it may be logical to go 280 mains with a lower needle. What do you think?.

[g0zer]

i think thats a good sign, sounds like you are starting to zero in on the overlap point between needle and main.

you want to be careful to maintain overlap, ie: you dont want a lean hole at your high speed cruise rpm. remember it is a slide carb you need to ride the needle. it can be rich at a certain rpm with an open throttle but that doesnt necessarily mean it will be rich at that rpm when cruising. that is to say if you accelerate by whacking the throttle open and get low rpm bog doesnt mean it will be rich with a cruise throttle opening at that rpm, especially if you have over-jetted the main.

at the same time the main must supply enough fuel at 6th gear WOT redline, carb's being the imperfect devices they are you inevitably must compromise in places... ie: be too rich in places.

finally be careful of jetting too tight on a hot summers day.

[seahorse]

i think thats a good sign, sounds like you are starting to zero in on the overlap point between needle and main.

you want to be careful to maintain overlap, ie: you dont want a lean hole at your high speed cruise rpm. remember it is a slide carb you need to ride the needle. it can be rich at a certain rpm with an open throttle but that doesnt necessarily mean it will be rich at that rpm when cruising. that is to say if you accelerate by whacking the throttle open and get low rpm bog doesnt mean it will be rich with a cruise throttle opening at that rpm, especially if you have over-jetted the main.

at the same time the main must supply enough fuel at 6th gear WOT redline, carb's being the imperfect devices they are you inevitably must compromise in places... ie: be too rich in places.

finally be careful of jetting too tight on a hot summers day.

Good feed back hillt, and followup Gozer, and just clarifying, If you do your "tight jetting" on a nice warm day, come winter or a cool change there is a danger of leaning out at the warm settings.

[hilltj]

Update: Tried 280mains, banshee needle c5 - rich all the way. Tried C4, a bit better but would still not pull cleanly above about 5,000rpm (Rich still I think). Will now try c3 today if time permits. I think this will be close (particularly as 290mains & c2 with same needle, was the best I've had it run so far). I'm still worried about the apparent "bog down" after running @constant 80-90k's (4,000rpm), could be unrelated to jetting & possibly a tank vent prob. I've re-routed the tank breather hose. Stay tuned.

[hilltj]

PS - how come I see reference to such large main jets when a trawl the internet?.

[seahorse]

I find it hard to believe that you have not sorted the suspected vent issue as posted in the first thread, yet you have put some real effort into re jetting, sort of cart before the horse.

[seahorse]

PS have a look at your plugs, I bet there black and wet. Cheers.

[Skut]

It is a conspiracy that readily available fuel-injection systems are not available for T2s? Emissions and fuelling issues would be a thing of the past...

[seahorse]

It is a conspiracy that readily available fuel-injection systems are not available for T2s? Emissions and fuelling issues would be a thing of the past...

ECOTRONS - Small Engine Fuel Injections | EFI | ECU | Wideband Controller | LSU 4.9 | CJ125 | Engine control | Engine Management System | Lambda meter

[hilltj]

Seahorse, I did have a look at the tank vent & it may have been clamped between the seat shell & tank. Have rerouted it & intend to get a squeeze bottle & blow air up the end of the tube with the vent pipe in situ, that way I can be sure that the vent is open. I't a bit difficult to see whether the vent tube has been pinched when locating the seat.

[hilltj]

How about that 2stroke injection kit. Wow. Know anyone with one fitted to an RZ? Man, would I like to play with one of those.

[hilltj]

How come I see so many references to what I'd consider to be really large main jets when a trawl the internet? eg 400's etc. I'm playing with 280's!. What logic am I missing?.

[seahorse]

[QUOTE=hilltj;2509974]How come I see so many references to what I'd consider to be really large main jets when a trawl the internet? eg 400's etc. I'm playing with 280's!. What logic am I missing?.[/QUOTEI

Hilltj, I think your a bit like me a perfectionist. Mate relax lets get back to basics and look at the original Jetting specs of 22.5 Pilot for an 83, and I think 27.5 Pilot for an 86, I think the 250"s had a 25 pilot, and I think Banshees have a 30 Pilot. Iv tried all four. I run Boysen reeds (temporarily ) and Pod filter at the moment. I have settled on 25's, Air screw at just over 1 1/2. Out. What i have read and been told by tuners that its a good thing to be about 1 1/2 out hence on my bike It idles at its highest with a 25 pilot on this air setting, the throttle response is crisp, and the revs come down quickly, (eg some times to big a pilot and your bike will be slow to come down off revs, and when riding will sound like a pee shooter when backing off, going down a hill. You need to get the pilot circut right first.

Now mains on these bike (350 ) have varied as well, as you know for PJ and Non PJ. Briefly the 83 non PJ had 240 Mains. I think if you add the PJ and Main on the PJ you end up with this figure of 240. Thousands of these bikes were sold and ended up all around the world. Not one would have leaned out and holed a piston on the standard settings. ( And they fly standard).

If you have your bike breathing better eg filter,chambers, then you would be close.

Who knows what other people think when they put 400's in these bikes maybe the climate,altitude they live in, mabey they race on big long open tracks in the Andee's. Maybe there running great big cheetah cylinders, or 91 fuel
Do a couple of runs on your 280's, long straight, 5th gear, wot or 9 1/2 k for 2 seconds and plug chop. If plugs are a light brown and dry then your right on the Edge, If they are dark brown and wet, then your still rich. If it blows, then your a bit lean. I think the advice from the tuners is start big and richest settings, then come down. EG Get your hands on some say 360 Mains, and try those, then start coming down, err on the side of caution. Mackay is sea level so I dont think youl need much bigger then what you are already running, unless of course your running hot, and you plugs at the moment are white.
Plug chop, Plug chop. Mate my bike is race ported, squish is 1 mil, Arrow chambers, boysens, 6525 pistons. I ran around for a while on 360's, thats the biggest i have run, have slowely come down to i think at the moment 290, and a standard needle, from the top c2. Bike will power wheelie in first, is reasonably smooth all the way through the range. If any thing its a bit sluggish off the lights. I regularly check the plugs, used to be wet and black, since the last clean up of the needle are now, light brown and dry, hence if I wanted I could probably come up to 300 mains now, but I am happy and I dont spend a lot of time at WOT. Thats all I got Bro, thats my experience.

[hilltj]

Seahorse, Just now I tried 280mains with banshee needles (& emulsion tubes as per my original brief) @C3. Bottom end up to say 1/4 throttle is now crisp, but upon constantly winding on the throttle @ a reasonable rate @ about 5k (any gear) it has a flat spot & rate of acceleration beyond this is not what it should be. It ran better on c2 with 290 mains. I get none of this power wheelie business. Plugs after a normal run (mostly I guess about the 1/4 throttle position & I accept very unscientific) are light to mid brown, with the left being obviously lighter that the right. I'll get some bigger jets, maybe 340's,320's, 300's. I did the squeeze bottle up the tank vent bit & could hear air escaping @ the cap, so that part look OK.

[seahorse]

Cheers for the feedback Hilt, it seems that you approaching you original post setting, haven taken the time to re -read myself, it may be worth getting in contact with Arronmvrider in Syd, I think his set up is similar with the programmable Zeeltronic, he may be able to provide you a powercurve setting to try. Youll get used to riding the needle, and those power wheelies will come bro. good luck.

[hilltj]

Seahorse,for your interest, I've got 2 switcheable CDI curves to choose from @ the moment, both downloaded from the net somewhere. The first is supposed to replicate an RZ 350 31K CDI & an apparent all bells & whistles one that holds about 2degrees more advance for longer. I haven't tried the second option yet. In terms of PV controller, I've elected to go with a map that opens the PV linearly from 5,500RPM to to 8,600. Got to start somewhere!.

[hilltj]

My gut feel is that my original Banshee needles 2 clips down & 290 mains is not far wrong. I think I've proved that to myself by trialling the 280mains. It seems that I'm able to get the mid range reasonable quite easily with the needles, but I know that I should be concentrating on top end jetting first! (It's just a bit of a bugger to ride if the bottom/mid range is doughy!). I fear that when I try larger mains, then I may have to raise the needle further to retain mid range ie C1 (C2 possibly). Alternatively, maybe the original needles will work for me. Oh well trial & error I guess!. Rejetting Mikuni Carbs should be an Olympic sport.

[hilltj]

Just a short update for you guys who've been providing me with excellent advice so far. It's been raining!! here on the east coast, no good for riding but is looking like clearing over the next few days, then I'll do some runs with bigger jets. In the meantime, I've been building a go kart (what else do you do when it's raining!), fitted with a honda GX160 motor, govenor removed, billet rod, +4 degree alloy flywheel, 22mm mikuni carb, straight through exhaust & 15" off road wheels. I cannot help myself!.

Cheers.

[hilltj]

tried 320's today along with banshee needles. C3 (mid position) seemed ok low. At c2 position throttle response off throttle became poor, it took a while for the revs to drop. Motor would not rev @WOT, stumbled beyond 5,000rpm!. Ran better with 290's in. Seems that all tests point to 290's being about right. I have some 300's, will try them first. Have not had a reoccurance of the unresponsiveness originally reported, but haven't been far @ constant throttle. Must have been the tank vent i think!.

[seahorse]

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Hey Hilt see your still soldiering on with reporting back on your findings, Following is a post from another site that is specific to your /our 2T RZ cause, posted by a capable operator with a noted thanks to some well known, knowledgable and helpful engineers. The results speak for themselves, and the curve it produced was as smooth as. Food for thought, regards,Seahorse.
Quote from Ian BOOM as follows:
Well, after 5 months of messing, several hours on the dyno a melted piston (my fault ops: ) and a few £'s it's all done and finished.

I started with 45bhp on a dynopro dyno (52bhp on a dynojet, so make your own mind up what my peak power is now!)

Ended up with 70.8bhp @ 9600rpm and 38.7ft/lbs torque @ 9400rpm

Stock drilled airbox with stock filter, stock carbs too! Full spec at the bottom.

Thanks to Kenny at TSA, Glyn at GPL racing, and Kev at dynopro!

Ianboom.



Spec:
RD350YPVS F2 barrels with 1.00mm over bore
Mick Abbey fast road tune
50 degree thermostat
GPL racing O ringed head
TSA stainless road pipes with short carbon cans
Stock 26mm Mikunis with 290 left main jet, 280 right main jet.
Stock air box/filter with snorkel removed and drilled air box lid
Zeeltronic PCD-10V Ignition, power valve controller
Stock unwelded crank