JCB 8025ZTS & BOBCAT E25

[V8Druid]

I race PRE65 now (as well as having a couple of pit bikes and a modern RMZ250 I practice on!), but the bike in the pic is the one I’ve had most success on, it’s a 1964 Cheney Jawa, that is a replica Cheney frame with a 1964 2 valve 500cc Jawa engine (those engines were mainly used in the early days of Speedway), of course nowadays they’re allowed to be developed internally a bit so there’s a lot of titanium stuff in it, a modern speedway clutch, electronic ignition etc....

We also have 3 BSA Victor GP’s, a Triumph Tribsa, a BSA Metisse, as you can tell we quite like our bikes!!!!

Tribsa' s a rare animal these days ..... once saw a 4 pot trident in Haslemere ... guy there had grafted a fourth pot onto a trident ... was in all the mags in the 70s ... sounded lovely

 

[V8Druid]

Yes mate, all three days, it was a great event as you say that got messed up for whatever reasons but probably money at the end of the day...

Some pics of us at Cholmodley!, me 96, 4th from left, Peter 7th from left.....oh and we did party a bit!!!

never seen anyone at a scramble in a DJ or suit before

 

[Cheneyjawa]

Tribsa' s a rare animal these days ..... once saw a 4 pot trident in Haslemere ... guy there had grafted a fourth pot onto a trident ... was in all the mags in the 70s ... sounded lovely

Tribsa's are definitely getting rarer but a 4 pot Trident, i'd like to see that!!

 

[V8Druid]

Tribsa's are definitely getting rarer but a 4 pot Trident, i'd like to see that!!

seems a few have been done

this was the guy in Haslemere I believe George Pooley .. wonder if he was any relation to Amey (duck girl)?

 

[craig]

seems a few have been done
View attachment 17179
View attachment 17180

View attachment 17181 this was the guy in Haslemere I believe George Pooley .. wonder if he was any relation to Amey (duck girl)?


View attachment 17182

Speaking of bike engine modifications, does anyone watch Allen Millyards creations?
https://www.youtube.com/user/millyardviper/videos

 

[Cheneyjawa]

Did you get anywhere with this? Whilst I was looking for some info for another job I found someone having a similar issue to yours. Have you checked servo pressure? There is a block that regulates pump pressure down to Servo pressure located near the main pump. Usually a gold coloured block, there are shuttle valves inside that can pop apart and cause the symptoms you describe. Worth a look I reckon? They are located behind the Allen bungs.

So I've eventually got back onto the 'bain' of my life this JCB!!

Very helpful @jd6820 suggested i take a look at the shuttle valves on the gold test block, along with someone else (in the know 'wink wink'!) suggesting if all is well with the shuttle valves and the block in general to cap P2 & P3 off (hoses and the block) and see if that makes any difference.

So today i took the block off to have a look at primarily the valves first before capping P2 & P3, however what i have found does not look right!!

1 - CT1_P2 - When the fitting is removed there is nothing behind it, I expected to see some form of shuttle valve, however there is the ‘pitted’ fitting and what looks like a damaged ‘seat’ within the valve block, I also retrieved a small piece of metal which I suspect is the remainder of a ball bearing.

2 – CT2 - When the Allen bung is removed there is again nothing of any substance beneath with the exception of another Allen head screw/valve deeper inside, when I attempt to extract the valve it just ‘wobbles’ inside the block and doesn’t come out.

3 - PT - I removed Pt to see if I could get a better look at the Allen head screw/valve deeper inside CT2, as it is you can see it very slightly but not nearly enough to make head nor tail of what’s going on, however what was of more concern when I removed PT was a small ball bearing lurking within.

It all doesn’t seem right!, again especially on a machine that has done 1700 hrs!

This might seem a silly question but is the general diagnosis one of it's fooked......!!

 

[jd6820]

So I've eventually got back onto the 'bain' of my life this JCB!!

Very helpful @jd6820 suggested i take a look at the shuttle valves on the gold test block, along with someone else (in the know 'wink wink'!) suggesting if all is well with the shuttle valves and the block in general to cap P2 & P3 off (hoses and the block) and see if that makes any difference.

So today i took the block off to have a look at primarily the valves first before capping P2 & P3, however what i have found does not look right!!

1 - CT1_P2 - When the fitting is removed there is nothing behind it, I expected to see some form of shuttle valve, however there is the ‘pitted’ fitting and what looks like a damaged ‘seat’ within the valve block, I also retrieved a small piece of metal which I suspect is the remainder of a ball bearing.

2 – CT2 - When the Allen bung is removed there is again nothing of any substance beneath with the exception of another Allen head screw/valve deeper inside, when I attempt to extract the valve it just ‘wobbles’ inside the block and doesn’t come out.

3 - PT - I removed Pt to see if I could get a better look at the Allen head screw/valve deeper inside CT2, as it is you can see it very slightly but not nearly enough to make head nor tail of what’s going on, however what was of more concern when I removed PT was a small ball bearing lurking within.

It all doesn’t seem right!, again especially on a machine that has done 1700 hrs!

This might seem a silly question but is the general diagnosis one of it's fooked......!!View attachment 17639View attachment 17640View attachment 17641View attachment 17642

PT shouldn’t have a ball bearing behind. Within that block, CT1 is a pressure regulating or ‘maintenance’ valve as jcb describe it. That has springs and I think part of the valve/seat has broken. The ball bearing I would possibly say is part of CT1 but actually say that CT2 is a check valve with a ball bearing and is linked via a passage to CT1 and therefore PT so it wouldn’t surprise me if the ball bearing is actually from CT2 and not CT1.
Im thinking you can’t get individual parts for this block so a whole assembly is required...

 

[Cheneyjawa]

So just for an update got the new pressure maintenance valve block today (thank you JCB for helping us out, cannot fault your customer service) fitted it and hey presto everything works as it should.....

@jd6820 you clearly know your onions, and it resulted in the problem being sorted.

Having said that I can’t thank you all enough for your input, utterly invaluable......

To a certain hydraulic pump repair company in Redditch that rocked up in a BMW, fag on the go, took one look and said ’its the pump mate, don’t need to even look at it.....’, well pal you need to do one, I feel sorry to everyone that’s been conned by you.......

So hopefully now once I’ve put it throgh its paces, I can get it put completely back together and I’ll have a decent machine

One happy bunny tonight, thank you all........

 

[V8Druid]

So just for an update got the new pressure maintenance valve block today (thank you JCB for helping us out, cannot fault your customer service) fitted it and hey presto everything works as it should.....

@jd6820 you clearly know your onions, and it resulted in the problem being sorted.

Having said that I can’t thank you all enough for your input, utterly invaluable......

To a certain hydraulic pump repair company in Redditch that rocked up in a BMW, fag on the go, took one look and said ’its the pump mate, don’t need to even look at it.....’, well pal you need to do one, I feel sorry to everyone that’s been conned by you.......

So hopefully now once I’ve put it throgh its paces, I can get it put completely back together and I’ll have a decent machine

One happy bunny tonight, thank you all........

name and shame .... obviously deserves it