Jump to content

Ariel Lots Of Noise When Hot :-(


wallo
 Share

Recommended Posts

So, where do I start.

We built an Ariel a few years ago and I just cannot get it to run when hot without making hideous noises. My initial thoughts were that the top end was getting starved of oil, I have a frame with the oil filler under the seat and the return pipe has a hole in it before it pushes the oil up to the rocker. The hole is about 5mm diameter so the oil does not bother to carry on past it.

I put an additional pipe in before it entered the return pipe, issue was the same, I then removed this and restricted the return hole by putting an inner clutch cable down the pipe along with a nipple that closed up the hole whilst oil returned, issue was the same.

So I'm a little lost, could the liner be moving or does anyone else have any ideas?

Thanks

Link to comment
Share on other sites

 

Ken,what piston are you using and what is the bore clearance when cold ? I guess its an MD short stroke barrel,without looking at mine I can't remember what the top of the liner/barrel is like.Does it shut up if you play a cold hosepipe over it ? As long as the valve gear is moist you don't need loads of lube there,can you identify the type of noise ?

Link to comment
Share on other sites

 

It's an XT350 piston std size and an MD short stroke barrel. The more I think about it, the more I think it's not oil starvation. Need to get it hot in the garage and then apply the hose :-)

Link to comment
Share on other sites

 

Hi Ken,

 

Im by no means an expert on Short Stroke ARIEL motors, there must be others with lots of experience on this forum. But have learnt a lot since mine first ran, last august ( with the help of JC & JG..), 

 

I heard yours going up section 18 - Weighbridge on the Cotswold Cup & have had similar noises from mine in the early days. 

 

The MD liner (so i understand) is a top hat liner, which should be under compression, between the alloy head and the barrel.....so unlikely to move. I use Loctite 574 flange sealer, on the head/barrel interface (not the liner ring..) 

 

I would check the valve caps, as there has been a "soft" batch of caps, that get hammered...mainly the exhaust. Also make sure they are not too long & catching the valve collects, which i made a mistake with.

Check the piston head/clearance, think i have 40thou minimum, machine a squish band in the head as required. 

I have several CNC'd barrel spacers to lower the compression/increase clearance, if you need to try one.

 

I probably have too much oil going to the valve gear & it still weeps a bit on the left side oil feed conversion

 

Im very please with the way my motor runs

 

The rider still needs more work though.....!

 

Cheers Chris

 

 

  • Like 1
Link to comment
Share on other sites

 

Thanks Chris, so you know the noise I am on about, it was bad at Weighbridge :-( I don't run caps on the push rods, but still had the same noise when I did. The more I think about it the more it pushes me towards the liner moving.

Link to comment
Share on other sites

 

I doubt its the liner, unless there's a machining problem. The top flange of the liner should be 2-3 thou taller than the barrel itself, effectively its the liner thats torqued tight to the head.

 

If you aren't using valve caps & the valve train all works OK.

 

I would check piston/head contact/clearance......if you take the head off, are there any marks around the edge of the piston, or on the dome in the head ?

 

Check the clearance with plasticine...40thou minimum.

 

I machined the squish band radius from its standard 81.8mm diameter, to a full 87.00mm, otherwise its possible to get "hot spots" on the edge of the dome, if the motor gets very hot.

 

Cheers Chris

Link to comment
Share on other sites

 

Thanks Chris, so you know the noise I am on about, it was bad at Weighbridge :-( I don't run caps on the push rods, but still had the same noise when I did. The more I think about it the more it pushes me towards the liner moving.

 

Hi,  

 

Way back when we never dreamed of short stroking the Ariel, but it was not unknown to get 'orrible engine clatters when new liners (probably not from the original materials, maybe) were fitted.  The cure was, very often, to put a plain metal head gasket in to increase the top-hat effect on the liner.

 

Just a thought.

  • Like 1
Link to comment
Share on other sites

 
 

Hi Ken,

Of course it could be a 'mechanical' problem, but also worth checking your timing. If it's way out (not set correctly, or slipped) it could make your motor run very hot, maybe cause 'pinking'?.

All a bit of a guess as I've not heard the noise.

It's worth finding out your piston-bore clearence. The XT piston is very short (slipper piston) so needs quite a tight fit to run quietly when hot.

Link to comment
Share on other sites

 
 

If its been pinking, they'll be tell tale signs on top of the Piston !

 

If it was my engine, i would be "back to basics", as you have run it for a while with strange noises, :

 

Check the crank for true & run out

Check the mains & big end

Check the conrod, make sure its straight

Check the cam bush is correctly seated in the righthand case

Build up the bottom end, make sure the rod is centered in the cases

Check the bore & piston tolerances

***Check the piston to head gap

***Squish band 86/87mm & 20degree cut on the head

Check the cam timing & ignition timing

 

***I think the noise is the piston lightly clipping the head when hot & under load, as it was a very similar noise to my HT. The bottom end needs to be good & trued, then at least a 40thou piston/head clearance....50/60thou is not a problem, as the 500 is not short on power !

 

That'll keep you busy for a couple of days.......

 

Cheers Chris

 

 

Link to comment
Share on other sites

 
 

So, the noise is still there, but the head fits nice :-)

 

Attention is now being focused on the cam and cam followers, so some questions:

 

The followers, does the one with the double holes, go to the exhaust or the inlet?

 

How precise does the end float need to be on the cam followers and cam?

 

Thanks in advance.

 

BTW The Stroud Valley trail was great today, sections were great, weather was great, just a shame about the b noise from my rattle :-(

 

 

Link to comment
Share on other sites

 

On post 51 engines, with the wider cam follower toe....the two finger follower is Exhaust & single is Inlet.

 

End float on the Cam & followers......there is not a figure quoted in the "Selly Oak Service Manual". I shimmed my Cam & Followers, so there is minimal float - cold.  As soon, as the crankcases get warm, they'll be a bit of expansion & therefore tolerance should be about right !

 

Cheers

Link to comment
Share on other sites

 
 

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
 Share

×
  • Create New...