May 2010 10

Motorcycle 650 Yamaha
I am looking to find how the throttle cable attaches to the carb. Right now the throttle doesn’t return after you twist the throttle open.
I would really like to find a description and a picture of the system.

Hi Jmax,

If your throttle isn’t snapping back there are four possible causes.

1. The carb slides are dirty (this will make turning the throttle difficult too).

2. The springs by the attachment point on the carb are worn (unlikely).

3. The cable is worn. If your cable is old it is the most likely culprit. Detach the cable from the carb and from the throttle tube.  Move the cable back and forth by hand. The cable should practically free fall through the sheath – there should be very little resistance. If there is resistance at all, replace it.

4. Your throttle tube is gummed up inside the housing or on the handlebar. You can remove the throttle, open it up, and clean the tube and handlebar thoroughly.

I checked out your tips. The cable was gummed up near the handle bar.
Thanks for your help. I love your site.

Great! Glad you got it sorted. Ride on!

Hi Evan:

I have been following your motorcycle adventures and your writings about motorcycle repair and I have nothing but marvel at your skills.

I have a KLR that has recently developed initial starting problems. Especially when it is cold, it is really difficult to start. SOmetimes I’d be trying 5-10 min in 20 or so deg temps to get it started. Other than that once it starts and it warms up it will start and run OK all day long.  This problem became aparent to me a day after I changed my oil.

So far have looked at the spark plug, seems to look OK.

Do you have any advice on what might be causing difficult starting?

TIA

Hi Sasho

Hard starting can have a variety of causes.

Because it is so cold out when you are having trouble it’s likely just a couple things.

Compression. How is the compression? Get a hold of a compression gauge and check the compression of your motor.

What oil are you running? In 20 degree temps you aught to be running something pretty thin. I would read the recommendation in your manual for the best weight oil in your KLR for low temps. Cold oil means poor circulation means poor lubrication means low compression.

If the bike was cold starting fine before then your carb settings are likely ok. In cold weather you’ll want to run richer jets than in warm temps. In either case it’s not a bad idea to pull your carb and check the jets and choke passages to make sure they are clean.

First things first. Check your compression cold. Then warm the bike up and check your compression hot.

I have a vstar 1100 clasic and it burns head lights,I checked the voltage at the light and battery and it seemed all right, i put in a new light it burnt the low beem in 20 miles so i ran on high, it burnt the high beem 150 miles. I recheck the voltage at the battery and it was ok while i was trying to find the problem i checked the voltage at the battery and this time it was jumping all over the place (13v to 18v). I would like to know if the regulator can jump all over the place like that or should i look some place else for the problem, i thought the regulator would over charge or under charge not jump all over.The battery has problems if that makes a diffence

First things first. If you are ever having an electrical problem, make sure your battery is in good condition before diagnosing it. If the batter is old or worn out, replace it.

Erratic voltage can be caused by a few different things. It can be caused by a bad stator/generator OR a bad regulator. The regulator can definitely be the problem.

The first thing I would do is double check all my connections and grounds. A faulty ground can cause some very strange problems. Check your main battery ground. Check that the wire from the regulator to the battery is not damaged or shorting out. Check that the stator wires are not damaged or shorting out. Check that your fuses are all clean and oxidation free. Check that all connections to the regulator look clean. Check all wires on the main battery terminals to make sure they are mounted solid.

If all the wires look good then unplug your stator and run the bike. Verify steady AC current coming from the stator – I’m not sure the exact specs for your bike, but your dealer should be able to tell you (or a manual). If the stator checks out, then your regulator is on the fritz and should be replaced.

Let me know how it goes! Cheers.

Hi Even had to move on to something else for a couple of days but i finaly got back to the bike as it turned out to the battery. I put a new one in and have run about two hundred miles and have not burnt any lights and the bike is running and starting good thanks the advise.

Glad to hear you are back on the road.

I would still recommend you do a little monitoring. With the bike running you should check the voltage across the battery again. It should be stable. A good battery can act as a ballast and mask other problems.

If the voltage is stable then you’re good to go! If it is still jumping around its possible your regulator is on the way out. I bet your fine though.

Congrats.

So I have a 1981 Yamaha XJ650H Bobber that I blew the #2 piston on last fall. Long story short, after a long night of mods and a clutch install I forgot to add oil and started for about 5 seconds. I found a 1983 XJ750J in decent shape but it hadn’t been ran in a while. I have the 750 motor out and am getting ready to replace the “Oil Pan” gasket. Next step is to put the motor in and get it running. I have 2 questions, 1. The Carbs from the 650 are in good shape and worked fine last year. I poured stabil in them to prevent gumming over the winter. Shoud I use thes carbs as is, rejet to stage 3.5 for the 750, or clean the crap out of the 750 carbs and use them. I plan to rebuild the 650 motor one day and use it in the 750 frame. I know this sounds crazy but I want to ride NOW and I have less money to spend on the motor rebuild. question 2: The ignitors for these 2 bikes are slightly different. They have different numbers and the pigtail on the 750 has a wire with a bullet connector on it that I am not sure wher it goes. DO I use the 650 Ignitor or the 750 Ignitor? ANY help would be useful!!

1 – If you already have the carbs on your bench you should probably just open them up and check that the jets are clean and the floats are moving smoothly. It only takes 15 minutes. You will need to upjet a bit to compensate for the extra 100cc of displacement – but I would be inclined to run them as is and make my jetting adjustments afterwards.

2 – The XJ650 and XJ750 ignitors have the same function, but are wired slightly differently.

Here is the XJ650 Ignitor wiring

Here is the XJ750 Ignitor wiring

When i pull the clutch lever in the rear wheel continues to spin instead of slowing and stopping. the cable is pulling the tab at the case but nothing is happening. Additionally when shifting into gear the foot lever sticks and does dont spring back to a middle position. Any ideas what could be causing these problems and if they might be related?
Thanks

Hey Griswold

A slight bit of drag on the clutch is very normal. Is the clutch not working at all? It sounds like you just have it up on the stand and the wheel spins a bit with the clutch pulled in. Very normal. If you are riding the bike and the clutch is not operating then you have a significant problem (assuming your cable is adjusted properly).

If the shift lever is sticking down then you have a worn or broken return spring and you may need to split your cases.

It  is a long story but i sent my wife out to get a battery for my 2001 yamaha vstar 1100. She came back with a everstart battery from wal mart are these batterys any good she got the right one (es14bs) i just wonder if will hold up. It is a wal mart battery after all.

The biggest factor in keeping a battery in good operating condition is you. I run cheap batteries in a lot of my bikes. Keep them on a trickle charger when not in use. Make sure your charging system is in good condition. If you are storing the bike for a period outside pull the battery and keep it in doors. There is no reason your inexpensive battery can’t lead a long healthy life!

I received a bike a couple days ago with none of the hoses to the carbs. does anyone have a diagram of which hoses go where?

Hey Griswold –

I don’t have a diagram showing the hoses mounted, but if you post a photo or two I’m sure we can show you where to mount them up.

There are a couple small diameter overflow tubes that run from the bottom of the carbs down below the bike. The fuel input is on the left side of carb #1, and the vacuum connection is on the front left side of carb #1. I believe there is a breather on carb #2, but I can’t recall exactly. Post up a picture and I’ll give you some notes.

Cheers.

Hey Griswold – looks like that bike has been hardtailed! Did you do any of the fab work yourself?

The larger diameter attachment on the right side is the fuel inlet – this should be connected to the fuel flow.

The smaller diameter attachment is a vacuum line.

Both hoses attach to the stock petcock. However, if you are running some sort of aftermarket or custom tank on your bike it may not have a vacuum operated petcock. If that’s the case just seal up the small vacuum attachment on the carb with a rubber cap, and connect only the fuel.

How it works:

On older bikes (pre 1980ish) there was only a fuel hose from the petcock to the carbs. When the carbs got dirty, or the floats were sticking, fuel would drain and drain and drain, emptying the tank. This would make either a giant mess or would fill the cylinder with gas. This was both dangerous and potentially damaging for the motor. So manufacturers started using vacuum operated petcocks. When the motor is turning over air gets sucked into the carburetor because of vacuum pressures in the intake when the piston travels downward. Some of that intake pressure gets applied to the little vacuum hose. This vacuum opens a rubber diaphragm in the petcock and allows the petcock to release fuel. This means that the only time fuel can come out of the petcock is when the motor is turning over. This prevents bikes sitting in the garage from leaking their fuel everywhere.

Personally, I don’t like the vacuum operated petcocks (or anything really). I prefer the old school system.

awesome. thanks. And yes it is hardtailed and I’ve done the majority of the fabrication myself. One more quick question. Do you know what size air filter pods fit on the bike? I’ve looked all over the internet and can’t seem to figure it out.

Griswold – Just measure the diameter of your carbs where the pods will attach and you’ll have your answer. They’re likely either 48mm or 52mm.

Cheers

My Suzuki won’t start. I filled it with gas and put in a new air filter, fuel filter, spark plug, and battery. I also cleaned the carburetor. The bike wants to start, but appears and sounds like it is not getting fuel. Any ideas?

Sounds to me like the pilot jet is still clogged. Did you pull it out and look through it to verify it is clean? Double check it.

Also, have you verified you are getting a strong spark? If you have spark than I’d bet dollars to doughnuts your pilot jet is still dirty.

Is yours a kick or electric start model?

– Make sure fuel is flowing out of the petcock.
– Make sure your choke is on
– Make sure the cylinder isn’t flooded (hold throttle wide open and kick through 5 times)
– Make sure when you are attempting to start the bike that you do not touch the throttle until it is running. Hands off! Heh.