2000 YZ426F - Metal Shavings and Cam Wear

[moto-vation]

Hello all.

 

First, I would like to say that there is an incredible amount of information on this site, and thank you to all of those who contribute.

 

I recently picked up a 2000 YZ426F Supermoto (17" wheels, big brake kit, FMF exhaust) for a good price. The bike, for the most part, is in good shape and running with good compression. The bike is titled and street legal. I believe it is running a WR426 stator and wiring harness, although that will need to be reworked. The seller also had receipts for a new top end (cylinder, piston, rings, and gaskets) from last June. The infamous square key/drive gear rattle is very pronounced, and will be addressed this week.  

 

With anything I purchase used, I like to do a full service/inspection to really see what I'm getting myself into. The first thing I did was change the oil, and flush the coolant. I noticed when I drained the oil that there was a slight silvery tint to it, and some fine flakes, but for the most part it was clean. This was the case for the crankcase drain, and the oil tank. However, when I changed the filter, I was pretty shocked at the amount of metal flakes present. The filter, also looked extremely old, and not changed recently (maybe not changed all last season). I have not tested to see if the majority of the flakes are aluminum or steel. I will be running a magnet over the filter today to see what I can pick up. The coolant flush was fine, and there was no contamination. 

 

I moved to the valves to inspect the clearances and shim where necessary. The bike is easy to start, seems to have good compression with no smoke, so I figured the valve clearances should be pretty close to Yamaha's specs. After checking the clearances, the only valve that needed adjustment was the Left Exhaust Valve. It was out of spec on the tight side, but was back in spec in no time. However, I noticed I have an exhaust Hot Cam with automatic decompression. It seems that there is some abnormal wear on the shaft and the lobes. It appears that the left exhaust valve (the valve that needed to be shimmed) lobe is wearing the most. I wonder if the tower was over torqued, and torqued unevenly? Does the cam look like it needs to be replaced, and is it possible that metal shavings found in my filter were caused by the cam/cam journal? Are there other problem areas that could cause metal flakes to show up that I should inspect?

 

I plan on replacing the top end, and swapping the crankshaft with a 2001 crank to permanently fix the square key this winter, but was hoping I could get through the season without any major repairs. I would rather replace the cams when I do the full rebuild, but if I need to now then I have no choice. 

 

Thanks!

 

 

 

 

 

 

 

[toten]

The way that filter looks I sure would want to flush everything out very well, and run a magnet. Probably time to split the cases, though... and make sure you flush the frame well. 

[moto-vation]

Should I flush a couple of rounds of cheap acceptable oil?

 

It definitely appears that the filter did it's job, but I really wonder for how long.

 

I'll run a magnet over it this evening and update what I find. 

[grayracer513]

The filter is packed, and was probably bypassing as a result.  You should remove the oil line fitting from the frame and clean the filter attached to it.  You'll need a 1" or 25mm six point deep socket and some help to hold the bike.

 

The cam journal is perfectly fine.  The "wear" on the lobes, or whatever it is, is in the non-load bearing area of the lobe, so I don't know exactly what to make of it form the picture. 

[moto-vation]

The filter is packed, and was probably bypassing as a result.  You should remove the oil line fitting from the frame and clean the filter attached to it.  You'll need a 1" or 25mm six point deep socket and some help to hold the bike.

 

The cam journal is perfectly fine.  The "wear" on the lobes, or whatever it is, is in the non-load bearing area of the lobe, so I don't know exactly what to make of it form the picture. 

 

Thanks for the tip. I will definitely clean the oil line filter. I wonder if my top end was somewhat starved of lubrication due to a clog of shavings. I will update after a couple of flushes.

[grayracer513]

From the picture you provided, there's no evidence of a problem with your top end oiling.

[toten]

At that point, I imagine it would make more sense to replace the oil filter. HiFlo makes one similar to the later versions. Not too many shops stock it, though, so I ordered several online.

[moto-vation]

I have already replaced the oil filter. I meant to say I will clean the oil screen in the oil tank. Sorry about the terminology I used. Hopefully the shavings were just an accumulation over a long period of time. Thank you for the replies!

[toten]

I believe the 426s came stock with a cleanable brass filter, so I wanted to make sure. And yeah, a few changes without much ride time each makes sense.

[grayracer513]

The bronze mesh filters in the '02 and earlier models were not intended to be cleanable/reusable, and they weren't very good filters.  They would only filter to about 50-60 microns absolute, for one thing, well short of the 35 a Scotts stainless filter does, and teh bronze mesh is too delicate to be trusted to maintain that level of filtration if it gets roughed up in the least during cleaning.  They're disposable, and that's the best thing you can do with them.

[moto-vation]

Well I flushed the oil, and the filter quickly filled up with shavings again. I knew I had to pull the clutch cover ASAP to figure out what was going on. It didn't take long to figure out the source of the noise, and the metal shavings. I can't believe this bike ran as well as it did. 

 

I am going to flush out the oil tank, screen, and lines tomorrow. I will also clean all of the bearings and gears (drive gear and counter balance). It looks like I will need knew clutch plates, and some of the retaining washers for the gears. Is there a specific company that you would recommend for clutch plates and springs? The clutch basket looked to be alright, but would it be smart to replace it anyways? I also read about upgrading the clutch pack to the 2001 model. Would that be more beneficial?

 

Any other pointers, tips, or suggestions are welcome!

 

 

[cowboyona426]

It looks like I will need knew clutch plates, and some of the retaining washers for the gears.

 

Those retaining washers are supposed to be bent like that, it keeps the nut from backing off.

[moto-vation]

Thanks cowboyona! That's good to know. I was hoping it didn't get that hellish in there.

[grayracer513]

 

Is there a specific company that you would recommend for clutch plates and springs? ... I also read about upgrading the clutch pack to the 2001 model. Would that be more beneficial?

 

 

Yamaha OEM parts.

 

The fault with the 2000 clutch was that it was grabby and near impossible to slip smoothly.  This Appears to have been addressed in later models with clutch lining material changes, and the special plate, spring and seat washer may not be needed any longer.  Here's a link to the info on the parts:

 

https://www.thumpertalk.com/topic/391092-the-01-clutch-mod-for-the-2000-yz426/

[toten]

Is it reasonable to fit a WR450 clutch on a YZ426? I think Pinepig (here and on SMJ) managed to make a 2014 YFZ450 stock slipper work in a WR450, and it was reasonably priced, so if he needs a bunch of new clutch parts anyway it might make sense.

[moto-vation]

I will be making the switch to the 2001 clutch assembly. I have priced it out to cost $220.47 (yamahapartshouse.com) not including shipping for the later model clutch parts and OEM friction plates and clutch plates. Now I just need to make sure I clean out the clutch area as much as possible, and flush the lines and system. Looks like the biggest pieces didn't make it into the oil lines. Thanks for the help.

I am curious about the YZ450 slipper clutch though.

[grayracer513]

 I think Pinepig (here and on SMJ) managed to make a 2014 YFZ450 stock slipper work in a WR450,

 

 

The '14-'16 YZ450 clutch isn't a "slipper".

[toten]

He was saying the YFZ (quad) clutch was, not the YZF (bike). The parts fiche certainly shows more complexity of the pressure plate than I'm used to, and http://atvillustrated.com/content/ride-tested-time-machine claims it has the first factory slipper. I don't know if it's any good.

[grayracer513]

 

He was saying the YFZ (quad) clutch was, not the YZF (bike)

 

That's different.

 

Never mind. 

 

Personally, though, I wouldn't want one on a dirt bike.

 

It should be fine, though.  Yamaha has had BTL clutches in the R-1 and R6 models for more than ten years, and they've been reasonably fault free.  The Quad clutch is more of a one way than a back torque limiting design, though.  I'm pretty sure I would hate it, myself.

[toten]

I wouldn't have mentioned it if it sounded like this bike was for dirt/dual sport. He said it's a supermoto, and they're nice there.