Moorespeed pistons

Just back from my first decent ride with the Omega pistons, finally up & running after a few set backs the latest being a stripped tappet adjusting bolt.

The short story: Yes, they are a good thing and give a significant boost in performance. Yes, you will need to run 98 octane fuel. No they don't transform your airhead into a fire breathing monster. Quick and easy way to get a bit more ommph from your old rattler.

Acceleration feels more urgent. The engine is more responsive. Power increase is there right across the range to red line -maybe more noticeable between 5000-7000 rpm. Handy to have more power on tap to tighten cornering lines. Less gear changing required on windy roads as the bike will pull nicely from lower revs.

Can't comment on engine vibes until I re torque the heads, redo valve clearances and a carb tune and balance.

Pre ignition was evident under hard acceleration, the fuel I had in the tank was 50/50 91 & 95. I will be running 98 from now on. Quality fuel is readily available in most populated parts of Oz so no issues there. Extra cost of 98 is no issue because I ride my bikes for fun and am happy to pay for the improvement in performance.

If you are planning a trip to a country with poor fuel just change back to the original pistons.

Overall I've ended up with nice bike now after doing the following (easily reversible) mods:

Engine: Omega/Moorespeed pistons. Combustion chamber clean up. Standard muffler free flowed.

Suspension: Wilbers progressive front springs preloaded to suit me. 10w oil in compression leg, 15w in rebound. White Power rear shock.

Brakes: HEL 320mm disc, HEL braided line and twin pot caliper. Rear brake linings matched to drum.

Comfort: Airhawk cushion

To do: Rebuild the gearbox, not urgent but the box on my Mystic is magic by comparison. Clutch at the same time (not urgent) and do something about the poxy standard screen.

Hope this list is of use to anyone contemplating a few improvements.
 
Great - thanks for the feedback. I think many of us are considering these pistons and so are interested in your feedback.

Please send out an update when you have been for a run on the 98 octane fuel.

I am just about to embark on an engine build so this is my understanding on this topic - if I am wrong then someone out there please correct me:

Re the detonation : it could be pre-ignition or post-ignition detonation. Detonation happens when the fuel combusts due to compression and heat without a sparc. Reading about it it seams many tuned airheads suffer post ignition detonation when tuned much above 10:1 - due to the huge width of the piston and the sparc plug being on one side. In this case it is often post-ignition detonation happens where basically the sparc flame front hasn't spread across the piston top before the compression on the other side of the piston gets so high the fuel explodes again. This is often cured on airheads by dual plugging, where two sparks start at the same time on opposite sides of the piston. There are slight benefits from this in terms of performance and economy, and of course stopping post-ignition detonation. With dual plugging - as the fuel burns faster the ignition advance should be retarded slightly. Retarding the ignition would exacerbate a pre-ignition problem.


Richies pistons run at a whopping 11:1 or may be even 11.5:1 to get the best possible performance out of the size of the swept piston area, so the problem may well be pre-ignition, where detonation happens before the sparc even fires.

If the problem is pre-ignition detonation then dual plugging won't fix this and the suggestion is to run higher octane (as you indicate) or a lower temperature spark plug (as the detonation is triggered by hot spots)

I would like to know if its possible to tell practically the difference between pre or post ignition detonation on a running engine: anyone know?
 
Good to see you finally have it running - my GS has been in bits for a year due to problems with the guy who rebuilt the box and driveshaft- how does welding the UJ bearing caps to the yokes grab you?

I set the timing on my twin plug 1000cc G/S by road test, then had it confirmed on a dyno.
I ended up with a indicated 26/27 degrees advance, around 3 degrees less than the usual tip for twin plugged motors.
Remember that unleaded fuel burns faster than the leaded that was around 40 years ago when BMW first set the figure at 32 degrees. As far as I know it never changed, and it is hard to see it being the optimum figure for every bike they have made since the first 750. I would try a few degrees less advance anyway, just to see how it runs.

You also mention you have cleaned up the combustion chamber. When you get to high compression ratios the squish clearance can be critical , lets hope you havent upset things with your "cleaning up!
 
Beemerboff said:
You also mention you have cleaned up the combustion chamber. When you get to high compression ratios the squish clearance can be critical , lets hope you havent upset things with your "cleaning up!
Click to expand...

My mistake -meant to say cleaned up the ports :D Polished the combustion chamber to reduce carbon adherence. Interesting to see what Richie Moore has found with timing and the high comp pistons.
 
Streuth... this is all getting serious.... compression ratios, squish, detonation.... am I on the right site? I do find this interesting though.

Anyway, I run RS250 Honda 2-stroke race bikes and we continually play with the jetting, squish, compression and timing to suit fuel and weather. Totally different setups for avgas, race unleaded and vpower.

Detonation can burn away material from any combination of the piston, cylinder and head. However, it often occurs in the squish band in the hottest areas i.e. close to the exhaust. We use "det counters" so that we can monitor dets and usually try to get a few dets / km so that we know we are lean enough without fear of major damage. When we start to get more than a few hundred dets / km then we may have a problem.

If you were deadly serious you could probably connect the output from a det counter and the ignition pulse to a high-speed data logger and check whether the det occured before or after the spark.

In the real world, I'd just inspect the piston top and try and see if there is any pattern to where the dets are occuring. Even if the piston isn't damaged, you might see evidence in the carbon build-up. On a single-plug bike, you'd imagine the dets would occur on the exhaust squish area furthest away from the plug if it was post-spark and more evenly if it was pre-spark?

My 1964 Bonnie pinks if I give it too much throttle at low revs unless I put some avgas in it....

Sean
 
Sean Kelly said:
We use "det counters" so that we can monitor dets and usually try to get a few dets / km so that we know we are lean enough without fear of major damage. When we start to get more than a few hundred dets / km then we may have a problem.
Click to expand...

Interesting - how does a "dets counter" work? What is it and how do you fit it? very intrigued.

Your suggestion on tying this into the ecu sounds like a very neat idea!
 
“The short story: Yes, they are a good thing and give a significant boost in performance. Yes, you will need to run 98 octane fuel.”
Very bad news… :(

Did you try only with 95? I use the bike every day and the price difference in Portugal is relevant!

And what about fuel consumption?

“If you are planning a trip to a country with poor fuel just change back to the original pistons.”
:( :( :(

“Standard muffler free flowed.”
What did you do?
 
its good to see that you have tried my pistons, after a lot of testing on the dyno i found that the ignition advance was important to get right, i also found that most of the ignition triggers over advanced due to ware of the plastic bushes on the stops,some of the bikes that i tested when set to the s mark at idle when checked at 4000rpm were making between 38 and 42 degrees when cheked at the ot mark with a strobe, this made the engines feel crisp but not best for hp the best power came between 30 and 35 max depending on squish clearance and fuel i cant comment on 91 oct as we dont have it. i now have a programable ignition so that i can retard at high rpm and switch to a second curve when on poor fuel.
 
Did you try only with 95? I use the bike every day and the price difference in Portugal is relevant!

If I run straight 95 I will let you know the outcome.

And what about fuel consumption?

Never bother working out fuel consumption, I just ride them for fun. :thumb

“Standard muffler free flowed.”

What did you do?[/

Hole saw in through exhaust tip end and drill out the baffle plate. A lot of the rest of the guts of the muffler has come adrift over time and I periodically shake out a handful of loose metal -"auto free flowing". :D
 
Hi

A det counter is basically a glorified knock detector as fitted to modern cars. Knock sensors themselves are cheap and there's loads of stuff on the net about them. I use the (expensive) HRC det counters which are getting harder to obtain but they are similar to these from:

iane: http://www.iane.co.uk/store/honda-r...s/rs125/rs250-detonation-counter/prod_34.html

The HRC piezo sensors are a washer that mounts between the spark plug and the head which means a longer plug reach is needed. The electronics magically pick up the detonation events, counts them and also generates a signal for the data logger. To test the system I clamp the sensor between two large nuts(!) on a fat coach bolt and "tap" the head of the bolt with a hamer. It's amazing how hard you have to hit in order to simulate one det, no wonder it can wreck a motor. I think the sensor on iane's april systems det counter bolts to one of the head studs.


Sean
 
Sean Kelly said:
Hi

A det counter is basically a glorified knock detector as fitted to modern cars. Knock sensors themselves are cheap and there's loads of stuff on the net about them. I use the (expensive) HRC det counters which are getting harder to obtain but they are similar to these from:

iane: http://www.iane.co.uk/store/honda-r...s/rs125/rs250-detonation-counter/prod_34.html

The HRC piezo sensors are a washer that mounts between the spark plug and the head which means a longer plug reach is needed. The electronics magically pick up the detonation events, counts them and also generates a signal for the data logger. To test the system I clamp the sensor between two large nuts(!) on a fat coach bolt and "tap" the head of the bolt with a hamer. It's amazing how hard you have to hit in order to simulate one det, no wonder it can wreck a motor. I think the sensor on iane's april systems det counter bolts to one of the head studs.


Sean
Click to expand...

very cool

richie moore said:
.i now have a programable ignition so that i can retard at high rpm and switch to a second curve when on poor fuel.
Click to expand...


Hi Richie Moore

It would be really cool if this sort of detonation detection thing could be built into your ignition unit!!

cheers

-Pete
 

" i now have a programable ignition so that i can retard at high rpm and switch to a second curve when on poor fuel"

Richad can we have more info about this progrmable ignition?
 
hi all to answer pete first, to make use of knock sensor is hard you really need an ecu so that when it picks up det it can back off the ignition ,this is how most modern engines live with high comp and lean mixture. i use them when on the dyno with the climax 1500cc v8 I bolt it to the block and listen through headphones as we take power runs and play with the ignition and injection. the system that I have is programable 3d with tps, I developed it for my sidecar race engines where I can only use it 2d no tps but what I did find is that you dont want a linear advance curve. my system uses a crank trigger and you can program 1 degree every 100rpm. I have developed quite a few curves depending on engine spec from dyno tests.the system holds 2 curves which you can swap at the flick of a swich. I will program the system with a power curve and a bad fuel curve, or for my race engines a wet wether curve to help stop wheelspin. the system has a spark voltage of 45000 volts and helped me find 110hp from 980cc single plug and win the classic sidecar championship.
 
Haven't tried running straight 95 yet but did my first tank on straight 98 yesterday. Still getting some pre ignition under heavy acceleration from lower revs. Will have a play with the timing but at the moment don't have the time or equipment to make specific degree changes to the timing, I'd only be using trial and error.

The pre ignition is not so bad that you can't ride around it by down shifitng.

Once I get the timing right I will run a tank of 95 and report back here -won't happen for a couple of weeks though.
 
Read today that if you set the OT mark to line up with the timing mark (using a timing light) you retard the timing 4-6 degrees. I set mine at about half this which nearly eliminated the pre ignition, can still be induced if you try hard. This might be a good ball park setting until I buy an advance timing light and can set degrees accurately. The only one I could find today in town was $250 :eek
 
fayeslane said:
Read today that if you set the OT mark to line up with the timing mark (using a timing light) you retard the timing 4-6 degrees. I set mine at about half this which nearly eliminated the pre ignition, can still be induced if you try hard. This might be a good ball park setting until I buy an advance timing light and can set degrees accurately. The only one I could find today in town was $250 :eek
Click to expand...

Hi - this is interesting. I guess more input from Richie would be useful. Twin plugged engines retard the ignition as two plugs firing at opposite sides of the piston cause the fuel to burn faster. I wonder if Richies high compression squish in the head does the same thing? Ultimately on a twin plugged engine the hall canister should be modified to reduce the advance from 26 to 22 degrees .. so I wonder if your pistons warrant the same type of mod?
 
Ritchie has already posted on this somewhere, but basically every engine is different , and on the dyno the best figure varies from 30 to 36 degrees for single plug engines.

Twin plug motors run best with a different curve as well as 2/4 degrees less advance.
I have a dual plug Boyer Micro Power fitted into a points bean can on my G/S and it works much better than stock retarded 3 degrees that the POs mechanic had set it to..

Nothing wrong with setting by trial and error if you dont have dyno, or as in my case, a working tacho or timing light. - I ended up with 26/27 advance on my twin plug 1000cc G/S, tuning for mid range up a decent sort of hill, and when I had it checked on a Dyno it was spot on.
 
pete.keys said:
Twin plugged engines retard the ignition as two plugs firing at opposite sides of the piston cause the fuel to burn faster.
Click to expand...

The difficulty with the twin plug setup is that you need less advance at lower RPM but more at higher RPM's where the twin plug setup is less efficient. I believe the correct way of setting the ignition is a couple of teeth retarded at tickover but bend the ears in the bean can to allow for more advance at the top end. I spent hours messing about with a twin plug setup I installed a few years ago and gave up on it in the end, put the ignition back to standard and just rode the bike. Apart from a crisper tickover I could see no benefit to the bikes running at all.

Richies adjustable ignition sounds interesting.
 
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