'09 Sherco 320 4T Rebuild Blog

[proper]

Hello there,

 

A few weeks back I swapped my pristine Beta Rev3 for a buggered Sherco 320. 

Why? Because they are different, great sound and they are becoming quite rare.

Also, I'm more of a 4 stroke guy. 

 

I know the reputation these bikes have. Hard to start, pulls like a train from low revs, wears you out.

But mine starts easily, every time, even from cold. I have no trouble taming the wife's vicious sherco 290. That gives hope for handling the 320.

It did wear me out pretty quickly. But I had the feeling that was mainly caused by the handlebars being too far from the pegs. 

 

It needs some TLC:

- Heaps of play on the back wheel. Has new bearings though. Strange.

- Massive forkoil leakage. 

- Chipped fork tubes. (yep, black coated tubes)

- Dragging front brake

- Rusty frame and rear shock spring.

- Broken rear fender.

- Worn Chain 

- Worn everything that can wear, really

- Engine makes a slight ticking noise. Could be normal, or the chain tensioner. Could be anything.

- Big dents in the exhaust header pipe. It has a nice welded balancer box though.

 

Condition as I got it:

 

 

The previous owner wasn't the spanner type, and didn't have the money to sort it out.

He just did the regular maintenance, and that's it.

I could hardly drive it in it's current condition, the dragging front brake being the main culprit.

 

But it's all fixable and doable. It will take some time, and investment, but this is hobby to me.

Having a bike build from the ground up, gives confidence and reassurance. I just like it that way.

 

I have made some room in the garage, and stripped the bike in one long evening.

Pretty surprised to see to bike is actually in a pretty good condition. No rounded bolt heads, no stripped threads, it was really easy to take apart.

(A nice change from the Beta Rev3, I can tell you that!)

 

I ordered a box of goodies from Splatshop. Just all the things that need replacement

 

A picture of a nice 320 in black/red/white was found:

 

This is what I'm going to try to achieve. Sort of. 

 

The idea is to create a kind of blog, logging the bike's rebuild over the coming months.

 

Best regards,

 

Vincent

 

 

 

Edited November 1, 2016 by proper

[proper]

First up is the frame. It had a thick yellow coating, pretty hard, maybe powdercoated, but I'm not sure.

I sand blasted the rusty bits, and used a special fiber disk with the angle grider to get rid of all the yellow coating. 

That worked like a charm for the larger area's. For the small bits and openings I used a power file.

 

The frame got a base Zinc coating, three coats of black metallic Motip, and multiple coats of Motip clear varnish.

 

 

Pretty satisfied with the end result. 

 

[proper]

Next up is the Olle rear shock. The spring is badly corroded, but he shock itself is in good shape. No rust on the shaft, and the thread is undamaged. Found the disassembly instructions from Splatshop.

http://www.splatshop.co.uk/blog/2012/11/fitting-a-spring-to-a-olle-shock/

That spring wire clip is very nicely hidden. 

 

The sherco parts book probably has it covered too.

 

The bump stop is knackered and should be replaced. I don't want to send the shock off for service, because I then would rather have a new TRP or öhlins.

Don't know how to solve that one on the cheap. Suggestions are welcome.

 

Sandblasted the spring, will be painted this weekend. 

 

Edited November 1, 2016 by proper

[proper]

Next up is the engine. The plan is to lift the head and cylinder to check for wear. Got some new cam chain guides, and want to check the cam chain tensioner. I'm also seeing something odd through the exhaust port:

 

 

It's hard to capture, but there seems to be some strange shiny patch at the far end of the valve opening.

 

Got a new iridium sparky. This should be easy to replace, but I've tried all four of my spark plug sockets, none will fit the small bore hole on the 320. Even my box spanner wouldn't fit! Any ideas appreciated.

Right now I'm tempted to grind the box spanner to a smaller outside diameter. 

 

I'm also looking for advice on a suited engine oil. The bike will mainly run club non-stops. 

Edited November 1, 2016 by proper

[billyt]

Where are you located in the world.......

 

[beta_blocker]

Hi Proper

I have a 2009 320 R which I've had for about a year and have learned quite a bit about it and may be able to help you with some of your questions and your rebuild.

the shock probably has lost its damping abilities and should be (if you can find someone and the correct parts) be rebuilt or replace it.

I tried having mine rebuilt several times by a local shock guy and we had trouble sourcing the internal piston seal and were never (after several tries of modifying KTM shock parts) able to get the right amount of damping restriction. We found the inner seal was melted, possibly due to the proximity of the hot muffler and the shock body after all this I finally gave up and got a TRP.

Since replacing the shock I added a thin layer of insulation between the muffler and the metal heat shield and an additional rubber "drape" that hangs between the backside of the muffler and shock to help curb the heat effect.

Obviously your fork seals are toast and should be replaced but cleaning up the scraches in the fork stanchions is a must. I've heard of people using super glue plus accelerator to kick it off to fill the scraches and then smoothing them with fine sand paper. You could also probably use an epoxy like JB weld which has fine metal particles in it.

The front brake could be many different things.

Check that the disk isn't bent, that it's correctly mounted (it is a floating setup and should have play in it) that the correct pads are in and that the caliper Pistons move in and out and are not stuck. Their is more to check but that's a start.

The motor. Your ticking noise could be several things. Usually cam chain noise sounds more rattle like then ticking. Metallic Ticking from the valve area can be made by the rocker arms and either a gap between the valve shim and the arm is too large (The valves have small metal shims that are used to fine tune the gap so that it is correct and prevents burned valves and proper closing for compression) or their is wear in the cam follower roller.

The roller has needle bearings that can easily get oil starved and start to deteriorate.

I've had the experience of these needles wearing and had to replace the exhaust rocker arm.

I also had the replacement rocker arm fracture at the weld for the pin that runs through that bearing and shear in half, but that's another story.

Pull your valve cover and use the Sherco procedure to check the valve clearences, then remove the pins that hold the rocker arms in place and check to see if their is movement in that bearing that is up and down. If their is that movement you must replace the arm before you can adjust the valve clearance. When adjusted correctly these motors still make some ticking noises as the proper clearences are a little on the large size compared to some othe motor specs.

I can't see in your picture the silver area in the exhaust port so I can't comment on that.

As far as the spark plug socket. I think splat shop sells one or maybe Ryan Young products if your in the US that fits. If not Buy the thinnest walled spark plug socket you can and grind it to fit in the hole that's what I did.

For engine oil I run Motul 300V 15W 50 it works well with the clutch. Make sure you drain and fill both sides (2 drains, one bolt and the oil screen)

Have you downloaded the manuals? That's about all I can handle with typing this on my phone so I hope this helps.

Vic

[proper]

@Billy: nice catch, I've updated my profile.

 

@Vic: Thanks for your insights on the shock. I know Splatshop in the UK rebuilds the Olle shocks for 120 Gbp. The bump stop is another 30 Gbp. Then the double postage for shipping. And probably extra costs because of melted seals inside. Obviously, TRP is the better solution.

 

Thanks for all the insider tips and tricks. Your bike looks great! I like how the gas cable goes through the number plate. That front fork looks bullet proof, with all the protectors. I'm planning Jitsie socks, which I've already fitted on the 290 after replacing all fork seals. 

 

Did you modify the exhaust?

[proper]

I've found a workshop round the corner which specializes in suspension service for MX/enduro/trial. They can check my rear Olle shock. It might not be as bad.

The other option I came cross is a new Reiger shock from a '14 Gasgas racing for even less than half the normal price.

It might not fit though. But worth having a look.

[beta_blocker]

Glad to help

The exhaust is what I believe comes stock on the R model which has a titanium header pipe and a carbon fiber heat guard. I added metal guards on both sides of the header to protect it and the thing on the end of it is a spark arrestor.

If you can find someone who can rebuild the shock they will have to install a very small version of a valve to recharge the nitrogen. You can sort of see its location in this picture, it's under the red cap.

[proper]

O boy, that TRP is nice. It's probably an acronym for Trial Rebound P0rn.

 

 

This is the Reiger shock. Only has rebound and classic compression adjustment, like the Olle.

The Olle has 270mm length, the Reiger is 10mm longer at 280mm.

Spring diameter is the same, as are the mounting holes. 

Spring has the correct weight for my bulk mass. (it's not that bad)

 

Asking price is 330 usd. He's been advertising for months.

The slight scuffing on the spring is normal. (they all have it)

He says it has been used for a very short time, and got replaced by a Raga version.

He's got relatives working at Reiger (Dutch company) and got the raga Reiger on the cheap.

 

I'm not sure if it's worth the hassle. Might have to modify the top mounting, or bottom linkage. Or both. Could be a straight swap.

Better check measure my frame/swingarm/linkage for options first.

 

Vincent

[proper]

 

Some unfinished parts to block the exhaust ends. Going to try to inflate the exhaust and heat the dents with a torch.

Edited November 3, 2016 by proper

[beta_blocker]

Their is a slight modification that needs to be done with the top shock mount for the TRP.

A bit of the frame needs to be ground to clear the shock body by the shock eye.

If the Riger shock is in good working condition and importantly will fit correct and the spring is correct for your approximate riding weight it sounds like a good buy. Make sure that the end of the shock that is connected to the lower linkage clears as it's pretty tight fitting in there.

The different shock length may effect the steering as it can change the fork rake and trail.

With a rear shock link set up a basic rule of thumb would be the difference in shock length usually doubles what changes at the rear axel. Ex. 10mm longer shock = 20mm raised at the axel and reverse. This is not a hard fast rule but a loose approximation as linkage ratios are all different. This can change the bikes steering/handling geometry.

[proper]

You're right, Vic. I've fitted the swingarm, shock (without spring) and linkage, and there's definitely no room for the Reiger. Around the swingarm it's very very tight, and around the top mount, the airbox and frame members are very close. The reiger's shape deviates too much from the Olle/TRP/Ohlins shocks. The 10mm extra shock length translated to a good 50mm extra rideheight. It's just not right.

 

After examining the Olle, there's plenty of gas pressure, and rebound adjustment works great.

I'm keeping the Olle for now, and will try a redneck solution for the damaged bumpstop. 

 

Vincent

[beta_blocker]

Sounds like your shock is in good shape. Start saving for the TRP maybe next year it's a great improvement.

These bikes can have a lot of power right off the bottom and depending on your terrain can be a real handful to ride and wear you out.

Changing gearing on mine made a huge difference in my ability to learn to manage and ride it. You may want to go to a smaller countershaft sprocket (depending on your current gear combo). As your ability on the bike gets better you can alter the gearing to suit.

[proper]

Been working on the other bikes. (290 & 2 Osets for the kids) Those are finished now, and moved to another storage. Now I've got plenty of space to work on the 320.
Grinded down a box spanner to remove the sparky. It was a bit rusty, but otherwise fine.

Measured the valve clearance with piston TDC and the markings on the flywheel matching the markings on the casing:

Inlet: zero  (Manual specs 0.10mm)
Exhaust: 0.25mm & 0.20mm (Manual specs 0.15mm) 

That's not within spec at all. The engine does have some ticking sounds, but otherwise runs and starts great. 
I want to remove the valves for further inspection. My valve spring removal tool doesn't nearly have enough space to grip the springs. It's a tight fit up there. My plan is to use a huge bar clamp with a DIY piece of wood to compress the spring valve cup and remove the half cones with a magnet. That means removing the head. Sure hope the head gasket stays in one piece, because that's an expensive one. 

Removed the rockers, because I want to check the chain guides for wear.

Anything special to check for on the cam chain tensioner? Is it spring loaded?

Edited January 31, 2017 by proper