RZ/RD 350 & Misc. 2-Stroke Tech BBS

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PostPosted: Sun Mar 09, 2014 11:39 pm 
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Joined: Mon Mar 03, 2014 8:44 pm
Posts: 2873
Location: Alberta, Canada
I used to run the first gen LCs. Great upgrades include, RZ350 carbs and petcock with RD jetting. I ran this set-up for a # of years. TZ250 F or G clutch springs. I went through 2 sets of stock springs, and surprisingly no plates. After I put my TZ springs in, no more slipping problems. My clutch was still original, less the springs, at over 100,000 kms. I used to drag race guys Friday nights, with multiple launches very regularly.
RZ350 exhaust gaskets. Never have to replace those crappy RD crush gaskets again.
I used to run 1000ccs of tranny fluid, not 1500cc. Greatly reduces gear drag, and that bullit proof tranny withstands it.
Other than those mods, DG pipes and K&N filters. Spot on jetting. A modified Harris full fairing. Clip ons. No rear subframe with a replica TZ seat kit. No centre stand, ever. I even cut off the side stand and used to lean the bike on walls. The bike was fast, much lighter, lower centre of gravity and extremely reliable. Top end rebuilds every 50,000 kms.
I will post pics of the old bike, asap. I have to find them.

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PostPosted: Fri Sep 14, 2018 9:17 pm 
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Joined: Sat Feb 08, 2014 5:39 pm
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Location: Vancouver Is. Canada
Every find those photos Rory? Be interested in what they looked like.


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PostPosted: Sat Sep 15, 2018 7:52 pm 
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Joined: Mon Aug 20, 2012 1:37 am
Posts: 1809
Location: Calgary, Alberta
Bigger carbs are fine on a racebike that is always running at high RPM but they will seriously degrade the midrange on a street ridden bike as air velocity through the larger carb bores won't be sufficient for good fueling.

I am running the larger single spigot petcock with a splitter. This is mostly to make it easier to install and use a quick disconnect fuel line fitting.

I haven't had any issues with the LC clutches but the clutch in our RZ drives me a bit batty.

For sure the later style copper exhaust gaskets are much better. IIRC I also run them with a paper type gasket between the head and the pipe flange? I'd have to go look to confirm that.

One mod that seems to be overlooked by most people but to me is a MUST, is a set of 6mm reed block spacers. This simple and inexpensive mod virtually eliminates the 6000 rpm hole in the power curve. The downsides being that fitting and removing the carbs from the stock airbox is a GIGANTIC PIA when there is 6mm less room between the airbox and the reed block. To eliminate the possibility of reed block air leaks I use an extra paper gasket and cover the gaskets w a spray gasket product. Works like a charm.

After several years of fighting with the carbs every time I wanted to remove or install them I had had enough and yanked the airbox. It got replaced by a set of dual stage full foam UNI filters. Now, removing the carbs is a quick and simple task, which immeasurably improved my life.

I am running stock pipes but with the higher flow "loud" baffles. Until I find the $1k for a nice set of expansion chambers, this setup is a nice compromise between stock and modified. I also have a fast response EGT system installed into the pipes. Its nice to be able to monitor what the motor is doing at all times. I figure if it saves me melting the motor just once it will have paid for itself.

Chassis wise, the first thing I changed was to junk the entire front brake system and install a set of Blue Spot calipers, steel lines and a modern master that resembles the original one.

We run Conti Classic Attack radial tires and these are lightyears ahead of bias plies.

Suspension wise I've got a Nitron shock in the rear and a set of 83 RZ forks up front. It all looks more or less stock but works a lot better.

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'81 RD350LC hybrid project bike - in pieces currently
'82 RD350LC in '81 colours - Built by "Solo 2" OEM pipes, UNI filters
'90 RZ350F2 with 31K motor, OEM F2 pipes & airbox


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PostPosted: Sat Sep 15, 2018 8:05 pm 
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Joined: Mon Aug 20, 2012 1:37 am
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Location: Calgary, Alberta
Smaller things that are not stock on my bike are:

Bars: The OEM LC bars have an awful bend to them and are way too high. Lower and flatter bars feel way better and create a slightly more aggressive front weight bias, which the LC needs as it has way too much weight on the rear tire.

Grips and adjustable levers. Mostly stuff from eBay that was inexpensive and looks better than the OEM parts.

Mirrors: I kept a set of sexy and expensive Aprilia mirrors from another bike and they look and work great on the LC

Stainless Steel Bolts: Norbo's SS head bolts make the engine look so much nicer. The bike has a sprinkling of SS bolts where the fasteners are visible. Rearsets, pass pegs etc.

Balance Pipe: An artist friend made a beautiful custom aluminum hexagonal boost bottle for me. Its a one-off and sexy. Sadly its not very visible tucked in above the carbs.

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'81 RD350LC hybrid project bike - in pieces currently
'82 RD350LC in '81 colours - Built by "Solo 2" OEM pipes, UNI filters
'90 RZ350F2 with 31K motor, OEM F2 pipes & airbox


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PostPosted: Sat Sep 15, 2018 8:09 pm 
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Joined: Mon Aug 20, 2012 1:37 am
Posts: 1809
Location: Calgary, Alberta
And I nearly forgot. When I bought the bike from Solo2, he had spent the time to O-ring the top of the cylinders and set the squish properly at the same time.

This is a bit more involved of a mod but it is actually quite nice to have as it makes head removal easier and cheaper. A big pack of the O-rings can be purchased for about half the cost of an OEM head gasket.

As a result of the squish being sorted, the motor feels much crisper than the loosey goosey OEM setup.

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'81 RD350LC hybrid project bike - in pieces currently
'82 RD350LC in '81 colours - Built by "Solo 2" OEM pipes, UNI filters
'90 RZ350F2 with 31K motor, OEM F2 pipes & airbox


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PostPosted: Tue Sep 25, 2018 12:32 pm 
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Joined: Mon Mar 03, 2014 8:44 pm
Posts: 2873
Location: Alberta, Canada
Oh, no to larger carbs. I don't recommend that. RZ power jet carbs are great to run.

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PostPosted: Tue Sep 25, 2018 2:08 pm 
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Joined: Fri Nov 22, 2013 10:49 pm
Posts: 1470
Location: Houston texas
Rearset pegs ?

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350LC,Athena 392 big bore,stock porting,swiss cheese air box,stock reeds,spec11 pipes.(now TSA big bore pipes)
She might not be pretty but she will always be a fun ride


1982 YAMA RD350LC
2004 BMW R1150RT
1989 FZR1000
1994 FZR1000


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PostPosted: Thu Oct 11, 2018 2:08 pm 
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Joined: Sun Jan 29, 2006 2:18 am
Posts: 1104
Location: vancouver
hondaror wrote:
Oh, no to larger carbs. I don't recommend that. RZ power jet carbs are great to run.


Really!? A pair of 28mm PWKs is THE most /best first upgrade possible


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PostPosted: Thu Oct 11, 2018 2:47 pm 
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Bare wrote:
hondaror wrote:
Oh, no to larger carbs. I don't recommend that. RZ power jet carbs are great to run.


Really!? A pair of 28mm PWKs is THE most /best first upgrade possible


I would second Rory's no to this above.


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PostPosted: Thu Oct 11, 2018 7:03 pm 
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Joined: Mon Aug 20, 2012 1:37 am
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Location: Calgary, Alberta
Larger carbs will kill bottom end, which is exactly the opposite of what is wanted on a street bike. On a race bike I can see the bigger carbs for more top end but doesn't make sense on a street bike.

OEM carbs, reed spacers and properly sorted squish make my engine work fantastic. Very crisp and responsive.

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'81 RD350LC hybrid project bike - in pieces currently
'82 RD350LC in '81 colours - Built by "Solo 2" OEM pipes, UNI filters
'90 RZ350F2 with 31K motor, OEM F2 pipes & airbox


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PostPosted: Thu Oct 18, 2018 1:56 pm 
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Joined: Sun Jan 29, 2006 2:18 am
Posts: 1104
Location: vancouver
PWK 28's are NOT large carbs.
But then...what could the general Yama community (outside of Alta) know though?
Certainly a contrary opinion to ...anyone ....who has at least ridden a 350 fitted with PWK 28's.
PWK 28's give an amazing improvement in the low end and midrange power And throttling.

My pore 350 as small example :smt004 ..runs WOT from 3500 on to rev limiter without any bogging or even a single burble or missfire.
A straight linear pull. nicely impressive.
Complete proof is in the riding


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PostPosted: Thu Oct 18, 2018 2:30 pm 
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Joined: Mon Aug 20, 2012 1:37 am
Posts: 1809
Location: Calgary, Alberta
Well ................ I am in the lower mainland. Maybe I just need to test ride your bike to see the proof in the pudding. :smt003

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'81 RD350LC hybrid project bike - in pieces currently
'82 RD350LC in '81 colours - Built by "Solo 2" OEM pipes, UNI filters
'90 RZ350F2 with 31K motor, OEM F2 pipes & airbox


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