RZ350 racing Questions
gl...@cs.umass.edu
I am setting up an 85 RZ350 Yamaha for racing at Louden (New Hampshire int
raceway)AMA this year. this is my first time Roadraceing so I have a few dumb
questions to ask. I will probley be racing lightweight superbike,
I have stripped the bike down and pulled the engine which I am starting to
clean-up ( I am not going to port the engine just bring it to factory spec)
A few things about the bike it has an aftermarket exhaust (Factory pipes)
stock shock (need new spring at least) A steering dampner is installed, I
am going to put a fork brace on. I have stripped the body work off as I don't
want to destroy it(I do want the bike to be streetable again) and am going to
replace the fairing with an aftermarket unit.
I am trying to decide if I should run the oil injection or pull it for racing.
The reason I am thinking about running the oil pump still is so I won't have to
play with the jetting again. As the jetting is spot on at this point. and I
would have more time to worry about getting used to the track. I was wondering
if rear set foot-pegs are worth the time to make. I don't plan on using them
at this point but if they are worth the hassle then I will make a set.
I am putting clip-on handle bars on the bike. Plus safety wiring etc..
I plan on using Metzler ME-1 race tires . OH I was also wondering if
anyone has been able to get the damn fuel restricter out of the tank without
messing it up too much.. Any input is appreciated..
Glenn
Team Jackalope
Blue Blaze Irregulars racing.
Robert B. Ciotti
>
>I am setting up an 85 RZ350 Yamaha for racing at Louden (New Hampshire int
>I am trying to decide if I should run the oil injection or pull it for racing.
>The reason I am thinking about running the oil pump still is so I won't have to
experience. Injectors do go bad, and when they do, its an expensive bad
scene. Just think, hangin' it out at 150 on some sweeper and all of a
sudden - seisure - Pure gas seisures are also the worst, nothing like
a jetting, port, or air seisure - quick and stick. RZs may or may not
be succeptable to failure, your risk.
Bob Ciotti
- don't be sad, cause two out a three ain't bad -
Ivan D. Reid
One other reason for using premix is if your injector is driven
after the clutch. I think the RZ still injects with the clutch in, but I
runined my crank the first time I raced my RG250 at Westwood (expensive to
freight a new crank from Oz :-(). Locked up in the hairpin and revved it
too much restarting before the thought came through the adrenaline that I was
in 2nd instead of first.
Mark Joseph Andy
I'm also hoping to be racing an RZ350 this season. I'd thought (out
of the ether apparently) that the oil injection system would inject
BEFORE the carb and that pulling it out and running pre-mix would have
no effect on anything. Is this not the case? Will I have to re-jet?
Mark
Ivan D. Reid
way too rich already. Consider that a jet flows X amount of liquid per
second. Now change the fuel from 100% petrol to (say) a 20:1 premix. The
engine now only gets about 95% of the petrol it used to -- i.e. it will run
lean and the jets should be increased to compensate. How much? I forget
if the RZ jets are sized by diameter or flow; ask a race mechanic.
BTW my mates who ran Yamahas in 250 Proddy racing back home used to
just stick a bearing ball in the oil line rather than yanking the pump. I
always doubted the legality of running premix in a production class, but
since that wasn't the reason they always beat me, I never complained. Note
though that proddy rules limit the change in jet size from stock, so running
premix was one way of leaning out a really rich bike without overstepping
the boundary.
Jim Brewer
> I am setting up an 85 RZ350 Yamaha for racing ...
Ahhh near and dear ..etc.
> A few things about the bike it has an aftermarket exhaust (Factory pipes)
> stock shock (need new spring at least) A steering dampner is installed, I
> am going to put a fork brace on.
Pitch the stock shock. They're wasted in 4000 street miles and a good
shock will make a world of difference. Also, respring the forks .. the
thing is probably undersprung if you weigh anything more than Jay Gleason.
> I am trying to decide if I should run the oil injection or pull it for
> racing.
As Bob Ciotti and Ivan suggested, it's not too cool to lose an oil pump,
cable or whatever while in a fast sweeper. It's cheap insurance to just
run premix and forget about the injector. Since totally removing the pump
makes a gaping hole in the case, I plumbed the pump to just circulate oil
on itself and took out all of the hoses and cables for the injectors.
BTW the pump runs off the crank ..
In article <UdR7rEy00...@andrew.cmu.edu>, ma...@andrew.cmu.edu (Mark Joseph Andy) writes...
> I'd thought (outof the ether apparently) that the oil injection
> system would inject
> BEFORE the carb and that pulling it out and running pre-mix would have
> no effect on anything. Is this not the case? Will I have to re-jet?
Nope, it injects it after the slides. You might have to rejet. Don't
fool youself into thinking you can jet and forget. You'll get real good
at R&R'ing the carbs ... welcome to racing. Personally, I ended up with
stock mains and dropping the needles .030".
In rec.motorcycles.racing, iv...@erich.triumf.ca (Ivan D. Reid) utters:
> How much? I forget
> if the RZ jets are sized by diameter or flow; ask a race mechanic.
The stock RZ carbs are just yucko round slide Mukunis so they use the
regular 'long' Mukuni jets. The needles are what makes the bike snappy
but, alas, the stock ones aren't adjustable. Nonetheless, there's a thick
plastic washer under them that can be sanded down to drop the needle, or
shimmed with washers to raise it.
> I always doubted the legality of running premix in a production class, but
> since that wasn't the reason they always beat me, I never complained. Note
> though that proddy rules limit the change in jet size from stock, so running
> premix was one way of leaning out a really rich bike without overstepping
> the boundary.
Hmmmm. prod rules out here allow all the jetting changes you want. They
also allow you to get rid of the oil pump and run premix as more of a
safety issue than a performance advantage.
In rec.motorcycles.racing, gl...@cs.umass.edu utters (again):
>I was wondering
>if rear set foot-pegs are worth the time to make. I don't plan on using them
>at this point but if they are worth the hassle then I will make a set.
I'd wait and see if you need 'em first.
> OH I was also wondering if
>anyone has been able to get the damn fuel restricter out of the tank without
>messing it up too much..
I didn't try it -- I used a funnel with a screwdriver stuck in it to hold
the little flapper open. Chiseling it out seemed unsavory and I really
resist using a torch on a gas tank. If it bothers you that badly .. go for
it. Just don't make any sparks.
Is Peter Ecclesine reading this group? IMHO, he is the RZ expert in this
forum. Also, I have a file where I kept all the changed I did to my RZ
when I was racing Production. Let me know if you want it.
John De Armond
>> I am trying to decide if I should run the oil injection or pull it for
>> racing.
> As Bob Ciotti and Ivan suggested, it's not too cool to lose an oil pump,
>cable or whatever while in a fast sweeper. It's cheap insurance to just
>run premix and forget about the injector. Since totally removing the pump
>makes a gaping hole in the case, I plumbed the pump to just circulate oil
>on itself and took out all of the hoses and cables for the injectors.
I'll argue the counterpoint. (It's uncool to loose the main bearing in
a turn too. Moral? Mechanical failures and trees hurt :-)
I advocate using oil injection, and always have on my racing engines
when possible, simply because an oil injected engine can make more
power. How, you say? Easy. Two factors. A lesser factor is that
the oil in the mix occupies a small but significant percentage of the
available volume in the intake, crankcase and combustion chamber. Since
the oil is mostly non-combustible, it dilutes the working fluid. In
other words, you have less gas/air mix to burn and push the piston.
The second and much larger factor is the fact that oil is a very low
octane ingredient which increases the propensity of an engine to detonate.
Mixing oil with gasoline in a sufficient concentration to be effective
as a lubricant puts it in an ideal environment to cause detonation -
atomized along with the gasoline. A properly engineered oil injection
system, on the other hand, will meter just the minimum permissible
amount of oil to the anti-friction bearings. A second injection point
will meter onto the wall of the intake the bare minimum oil needed by
the piston. Properly injected, this oil will flow along the wall of the
intake port and lube the piston skirt. Air flow studies using flow
benches and clear heads (done both by myself and in published reports)
show that oil so injected tends to flow along the major turbulence
path until it passes out the exhaust port. Very little gets vaporized
or mixed with the combustion mix. That's why a properly engineered
oil injection system rarely if ever smokes.
It's pretty easy to see this gain on the dyno. For me it was one of
those shocks one gets when one witnesses conventional wisdom slain. :-)
>> I'd thought (outof the ether apparently) that the oil injection
>> system would inject
>> BEFORE the carb and that pulling it out and running pre-mix would have
>> no effect on anything. Is this not the case? Will I have to re-jet?
> Nope, it injects it after the slides. You might have to rejet. Don't
>fool youself into thinking you can jet and forget. You'll get real good
>at R&R'ing the carbs ... welcome to racing. Personally, I ended up with
>stock mains and dropping the needles .030".
Yes you will have to rejet across the board if you eliminate the oil
injection. The reason is that the oil now mixed in the gasoline and flowing
through the carburator jets displaces its volume in gasoline. If you
use a 20:1 mix (just to make the math simple) you'll have 5% less gasoline
flowing through the jet, all things being equal, because you now have
a 5% oil solution. You'll probably be able to compensate the idle
mix with the air screw if your carbs have 'em. You'll need to raise
the needle and/or go with a smaller one. Main jetting will definitely
require enlargement not only to compensate for the 5% oil mix but
also to be slightly richer to ensure no detonation.
>> How much? I forget
>> if the RZ jets are sized by diameter or flow; ask a race mechanic.
Jets are sized by flow.
>> I always doubted the legality of running premix in a production class, but
>> since that wasn't the reason they always beat me, I never complained. Note
>> though that proddy rules limit the change in jet size from stock, so running
>> premix was one way of leaning out a really rich bike without overstepping
>> the boundary.
One thing you can do if the rules require "stock" jets is to "blueprint"
'em, "blueprinting" being defined here as modifying the jet as needed
to achieve optimal power :-) The number on the jet represents how many
CCs of gasoline flows in a defined interval given a defined head pressure.
It's been way too long for me to remember the specifics but they don't
matter. You'll need to set up a flow arrangement so that you can make
comparative measurements on your blueprinted jets. A large diameter,
shallow container (so the fluid level [head pressure] won't change
much while testing) suspended overhead, plumbed to a jet holder a known
distance below, a graduated cylinder to receive the jet discharge and
a stop watch are needed.
In practice, you measure the flow of the stock jet several times and average
for your baseline. Then you enlarge the hole and flow the "blueprinted"
jet again. I'd suggest making up a series of jets in about 2%
increments. That is, each jet flows about 2% more than the previous one,
NOT 2% more than the baseline jet. This is known as a constant
percentage progression.
The best and more repeatable way to enlarge the hole is with jewler's
broaches. These are tiny tapered square crosssection tool steel
reamers that are used to enlarge the holes in clock hands and the like.
A set will cost perhaps $20 and will handle a range of hole diameters
from about 0.010 to perhaps 0.1 inches. In use, you simply insert
the broach into the jet and rotate. It machines the hole as it sink
into it. A chart tells you how much you've enlarged the hole by how
far your broach has sunk into the hole. A source for these is
Just For Fun Jewelry supply company here in Atlanta. 404 455 1871.
You'll need to keep track of which jet is which since they all will
be stamped the same. I use a carbide or diamond scribe and make a
series of tiny dimples on one wrench flat (or on the end of the round
jets), one dimple for each increment. The first jet above baseline
has 1 dimple, etc.
>> OH I was also wondering if
>>anyone has been able to get the damn fuel restricter out of the tank without
>>messing it up too much..
Never had to do it on a bike but on a car tank I fill the tank with
water to eliminate explosive vapors, stuff a rag underneath the
restrictor plate and use a hole saw to cut it out. Then flip
the tank upside down and while water is flushing the filings out,
pull the rag and debris out. One or two rinsings will clear all
the metal out.
John
--
John De Armond, WD4OQC | "Purveyors of speed to the Trade" (tm)
Rapid Deployment System, Inc. | Home of the Nidgets (tm)
Marietta, Ga | "It's not a bald spot, its a solar panel for
j...@dixie.com | a sex machine."
Ivan D. Reid
(I said)
>>> I always doubted the legality of running premix in a production class, but
>>> since that wasn't the reason they always beat me, I never complained. Note
>>> though that proddy rules limit the change in jet size from stock, so running
>>> premix was one way of leaning out a really rich bike without overstepping
>>> the boundary.
>
>One thing you can do if the rules require "stock" jets is to "blueprint"
>'em, "blueprinting" being defined here as modifying the jet as needed
>to achieve optimal power :-)
This (restriction on jet flow change) was in Australia. I think the
idea was to restrict increases in jet size in 4-strokes, but unfortunately
the wording was "change", not "increase". Since most 2-strokes were delivered
set "safely" rich (Suzuki used to supply a set of leaner jets to be installed
after run-in, but this stopped sometime in the 70s), we had to lean them out
considerably to get a nice plug colour. My '78 X-7 for example was leaned
out terrifically for Bathurst '79 (Bathurst is an elevated track) by a mate
who broke the lap record & came 4th. I think he went 4 sizes lower! My first
flying lap back at Adelaide, without rejetting, I saw well over the ton on
the speedo, much faster than previously, and I nearly shat myself worrying
that it was too lean & would seize in the turn. Straight back to the pits,
but the plugs were lovely, so I continued.
The only time I saw the jets checked was when the top placegetters were
checked after the Advertiser 100 in Adelaide in '83. The scrutineer used a
method like your jewellers' broaches. He had a carb needle marked with the
distances it fit into jets at both ends of the legal range. I must say, that
was the only time I was ever involved in post-race scrutineering tho' -- one
of my mates had placed. When Ian placed at Bathurst, they just impounded the
top bikes and waited for any protests, and let the bikes out without any
scrutineering when there were no protests, so the smaller jets weren't found.
In fact the jet numbers were within the 10%, but since they were sized by
diameter, the flow was less. I hoped that any scrutineer would assume they
were sized by flow...
ivan
George Tatge
'86.
1. I would (and did) definitely remove the oil injectors. One less thing
to fail, and you can run with much less oil. Less oil means less
fouling and more power.
2. I used lots of brands of oil and ended up having best all around
results with the Yamaha racing oil (Yamablend or something like that- comes
in a black plastic bottle).
3. You can remove that stupid restrictor in the gas tank but be patient.
One of my tanks still has about half of one rattling around. If I remember,
it was a combination of chisels, hammers, long screwdrivers and lots of
four letter words that will remove the little beggars.
4. Do not leave the pits without a good steering dampner! I raced
for awhile without one and the RZ is beastly undamped.
5. I never used rear set pegs but that is mostly a matter of preference.
6. You mentioned the jetting was "spot on." If you get the bike
into its potential power range (via porting, reeds, etc.) you will
find there is no such thing as generic spot on jetting. Temperature
and humidity will play a big role. I have about 30 sets of jets for
two different sets of carbs. Of course, I also had serious elevation
changes to deal with also racing in the MRA. Even without elev.
changes, you'll find that what is "spot on" in the cool morning during
practice is total garbage come afternoon race time.
BTW, I still have both RZ's with radical engines and more spares than god.
I'd be happy to sell everything or some of it.
George TAtge
(303) 229-3585
Peter Ecclesine
I had replied by mail, but this discussion of RZ jetting should be public.
The stock 230 main jets are WAY rich. On warm days it can run 175 main jets,
190s on cold days. You should raise the needles with two thin washers, and put
the pilot airs at 1 turn out. Then get some dyno time and observe the 5% CO
reading for max power. Adjust the pilot air for 5% up to half throttle. Use
synthetic oil, and you can keep the stock oil pump setting. If you remove the
oil pump, Yamaha has a small plug to cover the hole. This hole must be
reliably filled, or your crank is junk. Same for the hole the kickstarter used
to fill. If you keep the kickstarter, use some tiewraps to hold it to the
frame, or else the ball will dimple the socket and the arm will not swing out.
If you have aftermarket pipes with 26mm or 28mm carbs, you will use 260 mj
on warm days, and 270 or 280 on cold days. If you port the bike and use 35mm
carbs, you will be at 270 or 280mj. If you use 38mm carbs, you will be at 310
to 330 mains. Buy a box or two of the W27ES-U plugs to check your jetting,
and race with Zus. Bend the pipes up closer to the shock linkage and remove the
Teflon chain guide from the left linkarm. Saw off the last three threads on the
linkage bolts and swing arm pivot (just kidding).
My frame will be done this week, so another season begins.
Peter
--
___-----___-___-___ Pete Ecclesine, pet...@cirrus.com __----____-----___
______-_____-_-____ AFM #83 1:59s at Sears Point __-___-______-____
_____-________--___ 7 years racing RZ-350s __----______-_____
____-----___-___-__ ZX-11 'a smile every mile' __-____-___-----__
Marc Alexander
>In article <l5l...@dixie.com>, j...@dixie.com (John De Armond) writes...
> (I said)
>>>> I always doubted the legality of running premix in a production class, but
>>>> since that wasn't the reason they always beat me, I never complained. Note
>>>> though that proddy rules limit the change in jet size from stock, so runnin
>>>> the boundary.
>
> This (restriction on jet flow change) was in Australia. I think the
>idea was to restrict increases in jet size in 4-strokes, but unfortunately
>the wording was "change", not "increase". Since most 2-strokes were delivered
>the speedo, much faster than previously, and I nearly shat myself worrying
>that it was too lean & would seize in the turn. Straight back to the pits,
>but the plugs were lovely, so I continued.
It appears I was wrong in regard to rejetting the U.S. spec RZ's,
and shouldn't have made assumptions that they are jetted the same as
we get them here :(
It was quite common here to remove the oil pump, and use the leaner
effect of the oil displacing the fuel to their advantage....
Practically all the Aus. spec two strokes come out too rich, I assume
that the U.S. spec ones are more optimum because of the tighter
emmission laws..
Stock mainjet size for my RD350 is 220, I have 200's in it, with
expansion chambers, which also cause it to run leaner than normal,
and it is jetted just right now, this is with street use, too...
There seems to be a good point to the effect of the two-stroke oil
running out of the hole after the needle, and lubricating the
piston skirt with reduced smoke, as someone mentioned here (sorry,
can't remember the name...)
So, you pays your money and takes your chances!
If anybody would like the needles, or information on the carbies
or whatever on the Aus. spec RZ350's, send me a note, and I'll
try to find them for you. The needles in our RZ's are adjustable,
with a small circlip and grooves at the top, but I have no idea
if they will fit into U.S. Mikuni's....
Marc Alexander |Internet m...@mullian.ee.mu.oz.au
dept. of ee eng ,uni of melbourne |UUnet uunet!munnari!mullian!maa
parkville 3052 australia zx-10rd350jex500rx2dod144
fax +61 3 344 6678 voice 3447689 "Interesting Concept!"
Dana H. Myers
>>> I am setting up an 85 RZ350 Yamaha for racing ...
>
>>> I am trying to decide if I should run the oil injection or pull it for
>>> racing.
As long as the rules allow it, pull the thing. The little tiny hole
that is left over can be plugged quite easily with a little plate I
got from Spec II/Telefix. Put the plastic cover back on, and no one knows
your pump is missing.
>I advocate using oil injection, and always have on my racing engines
>when possible, simply because an oil injected engine can make more
>power. How, you say? Easy. Two factors. A lesser factor is that
>the oil in the mix occupies a small but significant percentage of the
>available volume in the intake, crankcase and combustion chamber. Since
>the oil is mostly non-combustible, it dilutes the working fluid. In
>other words, you have less gas/air mix to burn and push the piston.
>The second and much larger factor is the fact that oil is a very low
>octane ingredient which increases the propensity of an engine to detonate.
>Mixing oil with gasoline in a sufficient concentration to be effective
>as a lubricant puts it in an ideal environment to cause detonation -
>atomized along with the gasoline. A properly engineered oil injection
>system, on the other hand, will meter just the minimum permissible
>amount of oil to the anti-friction bearings. A second injection point
>will meter onto the wall of the intake the bare minimum oil needed by
>the piston. Properly injected, this oil will flow along the wall of the
>intake port and lube the piston skirt. Air flow studies using flow
>benches and clear heads (done both by myself and in published reports)
>show that oil so injected tends to flow along the major turbulence
>path until it passes out the exhaust port. Very little gets vaporized
>or mixed with the combustion mix. That's why a properly engineered
>oil injection system rarely if ever smokes.
Too bad none of this applies to the RZ350. The oil injection on the
RZ350 feeds the carbs. I'm not sure whether it squirts it into the carb
venturi or into the float bowl, the oil injection does not connect
to the engine itself. Furthermore, this thing about oil being an
octane reducer is questionable; I called Torco one day to ask them
about this. The gentleman never said that Torco Power Stroke enhances
octane, but he did say that the oil does not detract from octane.
As for the oil diluting the gasoline, that can be accomdated by jetting
a size larger (if that much). On the RZ, the oil enters the intake tract
one way or the other (cause the intake tract contains, among other things,
the crankshaft, cylinder wall and rings). I suspect the difference is
nil whether you inject or mix. Pre-mixing has the advantage that
you'll always have oil if the engine is running.
>It's pretty easy to see this gain on the dyno. For me it was one of
>those shocks one gets when one witnesses conventional wisdom slain. :-)
I'm interested in knowing which engine was the mule for this test.
--
* Dana H. Myers KK6JQ | Views expressed here are *
* (213) 337-5136 | mine and do not necessarily *
* da...@locus.com DoD #466 | reflect those of my employer *
* "Dammit Bones, spare me the lecture and give me the shot!" *
John De Armond
[I said..]
The RZ350 injects in the intake. That's why I included the comment
about properly engineered. Properly engineering the injection on
a Yamaha would involve nothing more than adding some passages to the
main bearings, the same system that Suzuki used (and I think Kawasaki.)
This could be done either by adding another line from the pump or (if
the rules won't allow it) drilling down from the existing oil port,
through the cylinder base gasket and to the bearings.
>Furthermore, this thing about oil being an
>octane reducer is questionable; I called Torco one day to ask them
>about this. The gentleman never said that Torco Power Stroke enhances
>octane, but he did say that the oil does not detract from octane.
I've never tested any oil that does not have some octane depression.
By "testing" I mean constructing and operating an SAE spec octane engine.
Some oils are better than others, with synthetics being generally the best
but they ALL do it. On the other hand, that salesman at torco might
be right....
>I suspect the difference is
>nil whether you inject or mix. Pre-mixing has the advantage that
>you'll always have oil if the engine is running.
Why don't you do some experimenting and tell us about it. You can
then join me in speaking from experience.
>>It's pretty easy to see this gain on the dyno. For me it was one of
>>those shocks one gets when one witnesses conventional wisdom slain. :-)
> I'm interested in knowing which engine was the mule for this test.
Suzuki 125 rotary valve engine for our short track bikes and RD-350 for
road work plus a number of others not relevant to this discussion.
Our shop (B&G cycle in cleveland, Tn) sponsored a number of riders
including Dale Singleton before he made the big time.