How fast does your JX go?

[roscoe]

Hi everyone,

I rebuilt my JX engine over the winter and have been enjoying using the van for a few months now. I want to ask other JX drivers what sort of power you'd expect from the engine? I ask because I don't really have a valid reference from before the rebuild as the engine was in quite a bad state, and it was a fair while ago.

I was driving home along the m25 from playing a gig the other night and just couldn't help but feel that the engine is quite under powered. Only me and a drum kit in the van. I generally try and cruise on the motorway at around 55-60mph but on some of the uphill m25 sections I would slow all the way down to 35-40mph and have to go into 4th gear (on a 5-speed gearbox) to continue up the hill. The uphill parts on the m25 are really not that steep at all!

Does this sound familiar to you guys? Or do you think I need to look into something else?

Thanks,
Ross

[simoncummins]

That does sound about right or that is how my rebuilt engine is.

[Black n Blue]

Sounds a bit slow to me.
Depends on what weight you have on board?
Is your van fully camper converted pop top and all sorts or just a panel?

[roscoe]

Thanks for the replies. Yeah so it was just me and a drum kit, not too heavy; maybe the same weight as another person in total. The van is a converted panel van but with not much extra than a rocknroll bed, so it should be fairly close to the unladen weight.

I wondered if it's a symptom of having a dodgy LDA, anyone know about that?

[ninja.turtle007]

35-40mph on the M25 is not right. It would be quite scary too.

[lloydy]

I agree with Tom, my old jx was faster than that. Would stay at 55+ on M25.
When the piston rings went on it it then dropped to 35mph. So something is up I reckon
did you put the turbo on?

[roscoe]

Yeah it is a bit on the scary side at times.

Turbo is on, but I don't know it's condition other than it's not noisy and it still blows air up the pipe to the LDA, should be ok i guess. I think i'll have to check things over again though. I'll check the timing as well.

I'm suspicious of the LDA, does anone know how to check if it's working correctly?

[nobbyfox]

Does sound slow. Dotty can do a very steady 60mph all day and if a slight tailwind 65mph
We do have to drop to 4th as you do on slight hills though. JX engines are only rated at about 55 hp

[mrdp]

My JX is very happy at 60-65 MPH on flattinsh roads. 1Mile long steep hill near where i live 40-45. flat out 74.6789mph!!! if I put my head behind the dash board!! yours does sound a bit slow to be honest ???

[nobbyfox]

flat out 74.6789mph!!!

You must have Scotty in your engine room!!......'she canne take no more cap'n'

[ZsZ]

I wondered if it's a symptom of having a dodgy LDA, anyone know about that?

I had same symptoms and those was caused by a bad LDA. You can check easily: on a warm engine open the lid and rev it up by hand for a short time. You can see the rod of the LDA moves when it is good. Or you can blow the membrane with compressed air (max 1 bar) through the nipple.

[Ning]

Sounds underpowered to me.
I can easily cruise at 120kph. With only a slight drop on inclines. And it turns out I've got sticking callipers. Yes both!
I've not tried the maximum speed. I've come from modern high performance vehicles, and am conscious of respecting the old boy.
In fact I should maybe slow the cruise to 100kph. Even though it seems happy and uses no oil.
Once I did see the needle at 130kph when over taking some motorway traffic to get out of the way of faster vehicles.
Being lowered I think helps.
Hope you sort it

[macalfie]

If I put my foot down mine might get to 65 mph on the flat with no wind but does die on the hills .rhaullt hill in north wales kills it about 25 mph all the way up not the only one on this hill though needs a good rest for a few miles after it ha ha .

[NigelM]

I have just sourced a replacement for my low oil pressured JX which I am going to rebuild and I hope to get better performance once rebuilt that what you are getting currently as I am getting a little better than that with the tired JX now! Would defiantly look at the LDA, I have looked on The Brickyard for a post Simon made about how to get the most from a JX but I can't find it, maybe someone has a link and can point you in the right direction.

[Ning]

Sat nav told me I was doing 80mph yesterday.
Yes down hill.( Down to 54mph up the same hill earlier the same day)
Ok, done it once.That'll do now!.