ES Shock Low Gas Pressure

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Mar 10, 2019
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Wales, UK
#1
On my last trip I felt the back end was becoming even softer and a bit lower, also a post in the "re spring shock thread" saying that someones gas pressure was low caught my eye so I ordered a £10 nitrogen needle from flea bay and with a MTB shock pump measured the pressure. It was approximately half what it should be at 85psi !!!

For back ground.
The bike has never had a pillion, I weigh 84kg kitted up, the most luggage I carry on a trip is just two Pelican cases and a tank bag. The bike was new(a pre reg/leftover) in March this year and now has almost 12k, most of which has been done with the luggage. So the bike has not been heavily loaded at any time and mainly used on road. I usually use one helmet and luggage or two helmets.

As a reference I also checked a Ohlins shock on my old Fireblade, it has been on the bike for 15 years and 50k miles....the pressure was 165psi, so the pressure gauge was there or there abouts in my book.

I pumped up the shock to 165psi and checked the bike sag, it increased 8mm but have not had the time to ride it yet. I'm just wondering what has escaped from the shock, gas or oil ???? Have not seen any oil but have only just started looking for it. I also don't want to get into the pros and cons of using air in the shock, this subject has been discussed at very great length on other forums and my solution is only temporary.

I know there are many guys on here heavier than myself and carry more luggage so it my be worth checking your gas pressure.

Maybe because the shock spring is weak the shock tends to operate near its fully compressed size a lot of the time, thus increasing the pressure in the shock, and either some gas and/or oil has escaped.
 

scott123007

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#5
I don't know what a pre-reg/leftover is in the UK but if it was bought from a dealer in this country, it would come with a one year warranty from when it was purchased by you. Is that not the case?
 
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#6
This is quite timely for me. I have an '18 es with 12300 miles and noticed in the last week that the suspension has changed, sort of soggy with lots of bounce over even little things like white lines and cats eyes, and the cornering has gone right off. I thought it might be my imagination as I did a 2500 mile tour of Germany early September and was delighted with how it handled and behaved, and thought I was having post holiday blues... So are we saying this is a fault that should be covered under warranty?
 

Squibb

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#7
You have a 2 year warranty in the UK from DoFR, so this should have been left to a dealer. OK checking the shock pressure but it would have been best if you hadn't added compressed air as now who is to say how/why the shock lost pressure/oil, when it will now appear correct. Thus Yamaha could deny a fix under warranty.

Given the weight loads & usage you talk of, the OE shock should be perfectly adequate. Whatever, you need to get that air replaced with nitrogen soonest.
 
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#8
Re pre reg in the UK.
Sometimes dealers will register a bike to boost their sales figures and not even uncrate it. Yes bikes in the UK have a 2 year warranty from date of first registration....mine runs out early next year.
I plan to monitor the sag/pressure in the short term, it is very easy to put the pressure back to what I found if I decide to go to Yamaha. I just wanted to flag this up as this is the second bike to have this problem that we know of.

I think the problem should be covered under warranty, but the problem I see is that a dealer may not have the facility to measure the gas pressure and so will try to fob you off/deny it and just say wind up the damping etc etc. The trouble with that is that with our bike you change both ends at the same time. Loosing gas pressure will reduce the effective spring rate thus lowering the rear end and reduce the damping, so the rear will drop causing the bike not to steer as sweetly and be bouncy as well.

As said above I do not want to get into the pros and cons of nitrogen vs air.
 
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#10
Thanks Bart. That helps me understand the problem should the dealer try and fob me off. Hopefully they will be very helpful.
I'll look forward to what they have to say, good luck.

These days as I run more than one bike and with advancing years means it is easy to forget what you have done, so I keep a log book for each bike. Today I found some sag numbers I took just after getting the bike and with the shock now pumped up it is sitting at the same level as when new. Maybe if you have any sag numbers from new compared to now could be a bit more ammo when talking to the dealer.
 
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