Suzuki 1500LC/C90 Forum F.A.Q.
Mamba Forum member since 12/01
Many Thanks To Mamba for creating this FAQ!
Now Maintained by Crow and Fritz
Suzuki 1500LC/C90 Forum F.A.Q.
Mamba Forum member since 12/01
Many Thanks To Mamba for creating this FAQ!
Now Maintained by Crow and Fritz
No reserve feature is provided, but a light on the dash starts to flash when you have consumed between 2.7 and 3.0 gallons, and illuminates steadily when .7 gallons remain. The official tank capacity is 4.1 gallons total. Average range is 140 miles, so plan on looking for a gas station every 100 miles or so. Note that the C90 has an even smaller tank at 3.7 gallons total, due to the displacement of the fuel-injector pump.
Check out the GTank from Forum member "GMan" at GMan Industries Ltd.
See the Garage section at Mocc's Place
See the Garage section at Mocc's Place
There are several filters you can use (lawnmower, automotive Purolator Pro #804, etc) without having to buy an OEM replacement. If you prefer a high-performance filter, buy a Pingel high flow filter (stainless steel with washable/replacable screens). Note that without the 90 degree bend of the stock filter the hose is too short, so you'll need a piece of rubber fuel hose (regular 5/16" ID fuel Line) and 3 hose clamps. No fittings, just slips on. You can buy a GFilter Pingel kit from GMan.
Courtesy of Forum member "Coolhand"
Rejetting refers to changing the "jets"
in the carburetor. These are interchangeable orifices (kind of like nozzles)
that control the amount of fuel that is sent into the engine. There are
different jets (pilot, main, etc) that control fuel flow at different throttle
positions.
Changing jets is required to get the full performance out of the bike when you
change the exhaust pipes. The stock pipes are pretty restrictive...they don't
let the exhaust gas out fast enough. Putting a set of aftermarket pipes on will
allow the exhaust to flow more feely, which in turn takes some of the load off
the engine (it's not working as hard to push the exhaust on through). Since
you're now more efficient at exhausting, you're also more efficient at
intake...that's where the jets come in. In conjunction with the high-flow K&N
air filter, it allows more fuel to be mixed with the increased air flow. More
air and more fuel equals more torque and horsepower.
It's already been mentioned that the dealer jet kits are not good. The reason
for this is that the needles these kits use (needles are tapered, needle-shaped
valves, for lack of a better term) are extremely rough. The emulsion tubes (the
orifice that the needles ride in) are fairly soft, and are not easily
replaceable like other carbs are. Some carbs have replaceable tubes that just
thread in...ours are press fit. The needles will wear these tubes oval in no
time, and then fuel can leak around the needles...causes extremely rich
conditions (high fuel-to-air ratio), which in turn causes decreased performance
and very poor mileage. It can be fixed (by Half_Crazy via his mail order
service), but it's best to avoid it if possible. Half_Crazy (who is also a forum
moderator) sells jet kits that are made to HIS specifications and are FOR the
LC. The kits are very reasonably priced, and he'll even do the rejet for you if
you can send your carbs to him.
Should I Re-Jet?
So you put some pipes on the bike and you are wondering if you should rejet?
Maybe this will help you decide. This tip assumes that your bike is in a good
state of tune with good plugs, a clean air filter, and no exhaust leaks.
You're driving through a neighborhood at say 20 MPH in 2nd gear and every time
you let off the throttle she says "Poppity, pop, pop, pop". At idle
the motor has "interruptions" in it's running. When you rev the motor
in neutral, it takes a second to return to idle. These are good indications that
you need a bit more fuel from your mixture screws.
You blip the throttle from idle and the motor just "coughs" and
doesn't rev up. This would indicate leaness in the pilot circuit (or your carb
sync is WAY off). If your mix screws are already out to the 3 turns
neighborhood, you need some bigger pilot jets.
At a steady highway cruise, say 65 MPH, you find it difficult to hold a steady
speed. If you hold the throttle still the bike wants to slow down. When you roll
the throttle on gently, it seems like 1/4 turn before the bike responds to the
input, and then it takes off. This is an indication of leaness in the needles.
You are pulling up a hill and you have the throttle wide open. You slowly back
out of the throttle and the bike picks up speed. This is a good indication that
the main jets are lean.
We all want our bikes to perform as best they can. If your bike has any
"bad manners", they can probably be tuned away quite easily.
BUT....
It's not that simple. The pilot/idle circuit is still feeding fuel at wide
open throttle and the circuits bleed all over each other. The engine can't "SEE"
the air inlet until the throttle is open past like 1/2 way. SO, the only
difference between a stage 1 and stage 3 is the size of the air inlet and the
Main Jets (wide open throttle circuit, in theory).
How much time do you spend with the throttle wide open? In normal riding you see
wide open throttle very little. If you ran around at wide open throttle a lot,
the stage 1 would get better mileage. In normal riding, the stage 3 makes more
power, so you don't have to open the throttle as far to MOVE OUT, so it gets
good mileage thru efficiency.
If you think stage 1 is for you, there is no shame in that. Stage 1 is a great
running set-up. The engine is very happy at that level of tuning and it's so
close to stock that it's easy to tune and it's user friendly.
How does this all relate if you have a C90 (fuel-injected instead of
carbs)?
An engine is an air pump. To be an efficient air pump it needs a ratio of
between 13 and 14 parts air and one part gasoline. If you open up the exhaust it
will pump more air, so it will also require more fuel to keep the ratio
right.The air inlet to the air filter is a little hole about 1-1/4" round.
Keeping that size inlet is stage 1 tuning. Enlarging the inlet to the air filter
would be stage 3 tuning and you would need to add a whole lot more fuel to
maintain the correct ratio of air to fuel.
Like a recipe, if you add more flour, you'll also need more milk and eggs.....in
which case you just recalibrate the FI instead of changing carburetor jets.
Note: There is no "Stage 2" for LC/C90s. Stages can vary depending on the bike, ie, here is a good article on the 4 stages for Harleys. - Mamba
Right-click and "Save Target As" this PDF document (1.2MB) for directions
Send your carbs off to HCCW for professional rejet & tune by "the carbmeister", Half-Crazy.
Courtesy of Forum moderator "HC"
You can get the K&N filter and install it with a 115 front and 112.5 rear
main jets and set the mixture screws to 2-1/2 out. That's a stock pipe stage 1
(for sea level). <all you need is one #115 jet for this set up, $5 + K&N>
Cut the top out of the K&N and use like 162.5/160 or 165/162.5 mains, for a
stock pipe stage 3. <all three jets for this suggestion would be $15 + K&N>
With the stock exhaust she'd probably be all done by 5000 RPM, but there would
be significant increases in the low to midrange power
Courtesy of Forum moderator "HC"
They are different. The rear needle is skinnier at the pointed end.
There is a number stamped in each needle under the E-clip groove.
XX D XXXXX Front
XX E XXXXX Rear
Courtesy of Forum moderator "HC"
You put the bike on a dyno and you jam
a sniffer up the pipe. You run the bike and read the air/fuel ratio and the HP
and Torque graphs. You play with the jetting and baffles and ignition curves
until you get it where you want it. Then the bike is said to be DYNO TUNED. The
problem? Dyno pulls are typically done in 4th gear and wide open throttle... no
provision for drivability, manners, part throrttle response, etc. Basically you
are tuning the main jets and that's about it.
The dyno is a great tool to check yourself and make sure you are operating
within the proper parameters of air/fuel mixture, but you gotta fine tune by
riding it to get the "manners" dialed in.
I usually dial in the bike to run the way I like and THEN do some dyno pulls to
verify that it's right and there are no wierd things going on with the graphs.
Don't buy one from the Suzuki dealer unless you have $ to burn. Several auto gas caps will fit the LC, such as the Stant 11834 gas cap (Honda Civic), or one for a '90 Chevy Cavalier, '84 Grand Prix, etc.. Just be sure to get a vented cap. You can also check at the local gas stations...often they have a box of "lost caps" that you can dig through for free.
Yes, this has been a problem on some LCs due to poor design of the mount for the "real" gas tank (under the driver's seat). If you smell gas or happen to have the side covers off you should inspect the area around the mounting tabs. It's usually the right side front tab area where it was welded to the tank. Note that this problem HAS been reported to the NHTSA, and there IS a recall in process, so if you've not yet received your recall letter do contact your local dealer for more info.
Otherwise..to fix it yourself read on....
***
Find the top right forward mounting bolt and bracket for the tank after taking
off the (usually right) side cover. There is an area between this bolt and the
tank proper and it's curved. Just before the metal curves look very close for a
hairline crack. It might just look like a very thin scratch in the paint. You
can use a finger nail to catch it. It's easy to overlook. If you find the
scratch it's actually a crack and chances are it goes all the way through. If
you have any sticky or gummy residue you have the crack. If the crack is new you
might not have the residue build up yet.
If you use JB weld or the maritex stuff (Or whatever it's called) sand down the
entire area well beyond the perimeter of the crack.
Make sure to get right down to bare metal. Clean the area thoroughly and leave
no oily substance. It must be a dry roughed up bare metal surface.
Make sure the gas cap is off or loose. If not pressure from inside the tank will
bubble up gas vapors through the JB material and not allow it to set up
properly.
Apply a liberal bead of JB and using some type of plastic or wood object, smooth
over the crack and well beyond its edges. I put an extra large bead there. I did
a larger than necessary bead probably but I did it to support the tank more.
Leave it alone in the suggested temp range on the instructions and let it set up
good. I had to use a heat lamp because my garage is not heated. Too much heat or
too much cold and it won't set up correctly.
Now you can sand it, leave it alone or whatever. I rode it around before putting
the cover back on to see if it would leak. Paint over the stuff and put the
cover back on. You should have no more gas smells.
One added note. After a few days of curing paint over the JB and sanded surfaces
or rust will set in.
See this Service manual section
Courtesy of Forum moderator "Half_Crazy"
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Courtesy of Forum moderator "Half_Crazy"
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