clutch drag/shifting trouble

[erik]

When the engine is hot, it's impossible to get it into neutral when my bandit is stopped with the engine running.

With the bike on the centre stand with it running in first gear, when the clutch is pulled in and I try to stop the rear wheel from turning by holding the rear tyre, I can feel the clutch is still dragging quite a bit as it required a fair bit of force to stop the rear wheel.

The clutch is correctly adjusted and when the engine is hot and I pull the clutch lever, the clutch plates still move 1.5mm to 2mm.

When the engine is cold it changes into neutral from first and second fine and there isn't nearly as much drag on the rear wheel when doing the above centre stand test.

I looked in the manual which mentioned uneven springs or warped clutch plates might make the clutch drag, but I've pulled it apart a couple weeks ago and the plates were fine with still heaps of life left in them (which is pleasing particularly since the bike's done almost 70,000km). The springs were all the same length.
I did notice the nut holding the centre bit of the clutch on the shaft was loose though. The nut was still held in place by the lock washer (?). I tightened it up before putting the clutch back together. I'd hoped that maybe since the clutch gets its oil through the RH countershaft bearing that maybe with the nut loose it wasn't getting enough oil, when I pulled it apart, some of the plates looked quite dry.
But now after a week or so of riding after tightening it up, it's dragging just as bad as before.

Anyone have similar problems or can think of what might be making the clutch drag?

Here's some photos of the clutch and plates when I took it apart: photos

[BrianM]

It's the steel plates that warp when heated, and they often retain their warp when cool, it's just much reduced.  To check them, you'd need to remove and clean them, then place one on a flat plate (a piece of safety glass, the kind with the wires running through it, is about the best you're going to find for cheap) and try to slip a feeler guage under it at several different points.  If it'll go in some sports, but not in others, then they're warped and should be replaced.  

This is common in Abused clutches (hard starts, burn-outs, etc), but not really in normal wear and tear.  And what you're describing is Classic symptoms of warped steel plates.

[pmackie]

yup, I agree with BrianM...likely warped steel plates.

Too thick an engine oil will cause some minor drag (IE 20W-50) in cold weather, but would get LESS noticable once warmed up.

[gsxr400 racer]

Those steels look rather glazed to me they could do with a good sanding to deglaze then cleaned off with brake cleaner.

[erik]

When I pulled it apart, I put the steel plates on a small piece of granite bench top and they seemed flat. I didn't try sliding a feeler gauge under them though. They stuck to the granite like a really flat thing would. They still had a bit of oil on them when I did it. I don't think they're warped but I could be wrong.

Warped plates would make it drag if the clutch wasn't pulling apart enough so the plates were still pushing together, right?

Could glazed plates make them drag more?

If I've got time on the weekend, I'll pull it apart again and have another look at the plates and give them a sand.

I ran the bike on reserve last friday and today it sounded like it was running on 3 cylinders at idle, I guess some of the dirt/rust from the bottom of the tank has blocked up an idle jet... I tried just draining the float bowls this eveining, the gas that came out looked clean. If it's still doing it tomorrow, that's something else I'll have to look at on the weekend. Lucky it's a long weekend here. :)

[Thief400]

Thats one fryed clutch, what are you running for oil, Looks like the oil broke down allowing the steel plates to gall up and warp, at a bare minimun replace the steels. As for your carbs you will have to flush out the tank, and take apart the carbs to clean the water and crap from the jets. I have never seen just draining them work. The jets in a 400 are too small to pass water and you should get the rust out of the bottoms of the bowls so it doesn't replug the jets

[erik]

pulled the clutch apart again today and checked the steel plates for warping. I put them on a granite benchtop and used a 0.1mm feeler gauge (the manual says 0.1mm is the service limit).

1 of the plates was right on the limit, the gauge could just slip under it at one point. there was anohter plate that was also close. Is such a small amount of warping enough to make it drag? It doesn't look like much to me. When the clutch is disengagued, it moves 1.7mm from the fully engauged position, so I'd think the plates would need to warp a lot to take up all that clearance.

I'm wondering if the bike might be getting too hot and making the oil too thin to properly lubricate the clutch?
Maybe I'll check the thermostat and thermo switch next weekend.

I figured out which cylinder wasn't running at idle and cleaned the jets on that carb out. I didn't see much dirt in there at all, it wasn't clear where it was blocked. But it's back together now and running well.

I also gave the clutch steel plates a light sand with 400 grit paper before putting it back together. Even if the plates do need replacing, I need it back together so I can get to work.

[BrianM]

Yes, even that little warpage is enough to cause drag.

[Red01]

Yes, even that little warpage is enough to cause drag.

+1

Ever notice with the bike on a centerstand/pit stand and the engine running in gear with the clutch in, the rear tire will still turn unless you hold it?

The oil is doing that.

[erik]

The bike's been sitting in the garage this past week, luckily my work is on the way to my mum's work so I can get a ride.

I tested the thermo switches and thermostat on monday since it was a holiday.

I tested the thermo switches in a bowl of oil on the camp stove and the thermostat in water, like the manual says. This kind of stuff really makes me appreciate having a manual for my bike.

http://i38.photobucket.com/albums/e118/edorp/bandit%20cooling%20system/IMG_0638e.jpg

The fan thermo switch should turn on at about 95°C and off at about 88°C according to the manual.
The switch that was in there has "98 - ON" stamped on the side, so I guess the 95°C isn't that critical.

I tested it twice, the first time it turned on at 110.4°C, the second time at 114.3°C.
It turned off at about 94.4°C both times.
I was heating it as slowly as I could to make sure it got up to the same temperature as the oil.

The warning light thermo switch is supposed to turn on at 117°C and off at 110°C. The one on my bike had "120 - ON" stamped on it.

When I tested it, it never turned fully on. The first time it dropped to about 500ohms at 130°C. It turned off when it got back to 120.1°C. The second time it did not drop below 11k ohm resistance and didn't reach that till about 149°C!

The thermostat tested ok though.

http://i38.photobucket.com/albums/e118/edorp/bandit%20cooling%20system/IMG_0641e.jpg

So I'm going to try and get some thermo switches before trying to get new clutch plates. A local car parts shop has a catalogue and I've found a switch that looks like it should do the job for the fan, just have to put different connectors on it. But I haven't seen one with the right thread (M16x1.5 I think) and a high enough temperature for the warning light. They mentioned they have a catalogue from another manufacturer, so maybe I'll ask to look through that.
I got prices back from a bike shop today for genuine parts, they'd have to come from japan, 7 to 10 days and would be NZ$144 for the fan switch and NZ$133 for the warning light switch!
The car parts place switch would be around NZ$38.

[Red01]

I got prices back from a bike shop today for genuine parts, they'd have to come from japan, 7 to 10 days and would be NZ$144 for the fan switch and NZ$133 for the warning light switch!
The car parts place switch would be around NZ$38.

OUCH! Even the auto parts price sounds high.
(NZ$38 = ~US$28 at today's rate.)

Do you have the Suzuki p/n's?
Just out of curiousity, I'm wondering what they'd cost here in the US.

[erik]

I didn't know the part numbers, but a search on google took me to bike bandit (awesome site by the looks of things). From their list:

19: SWITCH ASSY,WAT  493063-001  $49.86
20: SWITCH,RADIATOR 486034-001  $54.25

which is still heaps cheaper than the bike shop prices here. I often hear people complaining about the shop prices here, so it doesn't surprise me.
I might try getting a switch for the warning light through bike bandit if I can't find a suitable one at the car parts store.

[Red01]

Those would be Bike Bandit's personal p/n's, they don't use the OEM p/n's. They used to, but folks were using their site to get p/n's and buying from cheaper sources. Typically, BB's prices are pretty close to what average dealers charge. Some of the discount dealers, like Ron Ayers, sell for less... but I don't think Ron's online parts catalogs cover the B4, but if you had the Suzi p/n's you can plug them into their site and it'll spit out their price... which is why I asked if you had the p/n's.

[erik]

Oops, I assumed they were the suzuki numbers.

Actually I've got the bandit 400 microfishe, I should've just used that, but didn't think to look since I haven't used it before.

Ron Ayers (another site I hadn't heard about) lists the fan switch (part no 17680-06C01) at US$48.80 and the warning light switch (part no 34850-10D00) at US$44.85.

Took some stuffing around to find the warning light switch, the microfishe is a bit blurry and the D in the part number looked like a 0.

[El Dopa]

Erik, I saw this on the FactoryPro site a while ago (slightly edited):

"Q: I have a '93 Bandit 400 that has always had poor carburation, right from the factory. What advice do you have?

A: Part of the problem is, like ALL of the 93-95ish watercooled Suzuki's, that it's got a very low temperature coolant thermostat ~170f, or so. Makes them seem to run lean and not idle well when the fuel screws are set for best idle after a good ride. Install a higher temp thermostat from, perhaps a cbr600f3. We use ~190f  thermostat, which is a bit higher than the f3, but 190f is where the engine runs the best and makes the best power. Either way, changing the thermostat is mandatory (trust me!). Then you can tune the carbs for best throttle response with the kit.

It won't make the bike run too hot, it will just keep it from running too cool when just cruising around."

Dunno if that's any help.

Also, if you're after parts, there's a Bandit 400 being parted out on TradeMe at the moment (local Ebay equivalent, for those that are wondering).