Calling Chris Bennion...

Chris what was your problem with 002?

Did you sort out inlet tract length?

Can you message me - port timmings, bore size, comp ratio (head volume), ignition timming (static) and i'll comment -
that bike should be flying!!

Here to help.....

Be carfull Mike dont borrow you a water pump well make sure he gets part out of the blue box not the green one, they all have something wrong with them, you have been worned

Thanks Mike - appreciated.
The O-ring betwen barrel and head blew, pressurised the cooling water and sprayed a litre of water into my mush via the overflow. I suspect the head bolts weren't torqued sufficiently. Have since found 30ftlbs in the notes... Will respond on timings and suchlike tomorrow.
Regards
Chris

Chris that scares me!! They must be Aidens notes...
Norm is Combustion Chamber 15ftibs Water Jacket Head 10ftlbs both done dianogally in stages - hand tight -8-11-13-15 then WC head- hand tight 8-10. Is O ring melting? Is groove in head to shallow? hence flame melting o-ring? Something is not right?
At 30ftlbs the next thing you will do is strip the threads in the cases.

If o-ring melts - clean melted bits away grease oring in groove with burn faced into the groove not the barrell..

Not sure if 002 still has the same set up as it did in my day but we were unable to cure a bad water leak at one meeting. The reason was the head had been skimmed but we had forgotten to skim the same amount off the four spacers that went between the combustion chamber part of the head and the water jacket part of the head, consequently the water jacket part of the head wasn't pulling down tight on it's "O" ring.
If memory serves right the torque we used on the head bolts was 12 lbs and not realizing at the time what the problem was we went to 14 to try and cure the problem.
Chris if I had gone any where near 30 lbs Tom would have had my guts for garters.

Thanks Guys - saved in the nick of time! Actualy 30ft lbs did seem a tad on the big handful side. Have capped them at 15 ft lbs with grease around a new ring. Exactly the same as during the winter re-build. Big clue following Pembrey : The head nut nearest the blow was finger tight...

Port timings as measured during the Winter re-build were :
Exhaust opens 102 BBDC
Transfers open 70BBDC
Inlet opens 80 ABDC

Piston Bore is 55.25mm

Squish band depth was reduced from 45thou to 30thou (inches) over winter. Compression ratio on swept volume thus increased from 11.3 to 11.6. Now on 25:1 Avgas /Rock Oil Synphasis 2 pre-mix.

Ignition timing set such that at TDC the T mark on the rotor aligns with a dot on the adjustable arm.
At 15 thou (inches) BTDC, the stator pick up is central on the raised portion of the rotor.
I suspect the ignition is retarded somewhat at this, but have no confirmation.

Open to offers?

Chris

Chris On the inlet timming is that 200degree total opening?
Ignition T line on rotor should line up with line on stator..

I would :-

Short term - Advance Timing 0.1mm so T line on rotor/line on stator line up at 0.1mm btdc instead of tdc. Then if ok advance to 0.2...
run a B9plug / set carb up...

Long term - Lower cylinder a little(remove some gaskets/packing?) to get 98/99 exhaust, that will make Transfers 67/68. New piston smaller cutaway(or fill inlet floor) to give 99/100 Inlet. Remachine head to get your squish back to .030"(your brave i wouldn't go under .035") Measure compression hopefully it will be somewhere in the region of 13/14:1....

Think reason bike not flying compression to low... Which number head have you got? 03? (I've got 02 and 04 our heads are interchangeable or were once?)

Hi Mike
Thanks for the info. I have 2 heads, one's on the bike and the other's in the garage. Will check out the one in the garage.
Chris

I've got heads 02 and 04. I think you have 03 on bike and a battered 01...

What do you make of this piccy Chris?

Mike

Blue bikes suit you bettter. The front end had changed, inc top yolk, when I bought 002. The current level of spit'n'polish hasn't....

The spare head isn't identified as 03 or similar - just the compression ratio 12.25:1 is stamped on the side.

Regards

Chris

Oh right ? there was a battered head ref Elvington when Alan was riding/then after the lower comp head/Aiden bought bike
then I forget??

The piccy is 001 but colour changed by computor by son Jake when I was considering a "Red" bike a couple of years ago...
note no 33 on my back and a few shady areas....

Mike

Moving away from cylinder heads and ignition timing, how about exhaust tailpipe size?

The currently fitted Gibson pipe has a tailpipe internal diameter of 32mm. In with the spares is a near identical pipe (albeit bashed about a little) apart from one item. This has a 24mm dia tailpipe.

Any significance? Could this be a eureka finding

What's the best method of sealing the pipe to the barrel sub?

Chris

Hi Chris

hows the bike running after the water leak problem?
have you been back to the dyno to fine tune the carburation?
On your pipe issue check the diameter of the pipe at the end of the last cone of the expansion chamber ,this is a critical dimension .I think Derek has altered this on his pipe as i did with the air cooled last year.i suspect its something between 22mm & 24mm.The silencer dimension seems a bit odd but perhaps Mike can give the explanation.

Cheers Nick

ps. are you persisting with the TMX? see Mike was sporting a nice Dellorto at Pembrey .

Hi Nick
Thanks for comments.
Holidays are delaying 002's fire up 002 - going to have to be the weekend before Cadwell! Finger's crossed.
Was able to insert a 30mm dia broom stick right up into the middle cone section. Like a ferret up a ....
Have a TMX on both bikes now, so makes sense to persist. The 175 is fine in that department - so it's just a matter of time and patience....
Regards
Chris

Chis - Exhaust to stub I use silicon sealer.
- Tail pipe dia 22-24 like nick says the baffle cone to bleed pipe, normally silencers are a little bigger 23-25
30-32 is to big (throwing heat and power away) I supplied Aiden with two pipes neat narrow looking(code -Tomsbant2)
and a battered (Flexi Flyer pipe). Aiden had the Gibson made as a copy of Flexi flyerpipe. Suggest go down on tail pipe dia..

Mike

Chris have you got 002 sorted yet?

Hi Mike

002 was up and running yesterday. No loss of cooling water during a full afternoon session adjusting needle settings and pilot jets on the 34mm TMX Mikuni.

Succumbed to fitting the exhaust with the 24mm dia tailpipe - this just had to be done! Because of this, and to minimise changes, I have gone for ignition timing with the T mark aligning with the line on the backplate at TDC, rather than advancing any from this point.

On advise from Alan, I tried various combinations of pilot air screw settings including a blank screw. Best throttle response was achieved with the 61 needle in midddle groove, 37.5 pilot jet with no airscrew fitted. As a comparison, the pilot jet fitted at Mallory and Pembery was a size 25. (The 175 currently runs quite happily on a size 50 pilot with standard air screw). However, fuel vapour is being released from the carb intake at low throttle openings (indicating richness of mixture or too wild an inlet opening period ?) but this clears when on main jet. Alan - any comments?

The plot sounds quite business-like on a fist full of throttle, but unfortunately my gravel drive prevents any pull-away testing.

All in, a whopping 1.75 litres of Avgas was used - an overall consumption of zero miles per gallon!

Roll on Cadwell!

Chris

Chris I've found the "bsabantamracing.com" decals for you.
I'd put them in a safe place!

Hope your developement is making progress.....

Thanks Mike.

Current development on 002 is concentrating on a programmable ignition system with Alan taking centre stage on supply and fit.

At Cadwell with the Gibson expansion box replaced and timing set to spec it literally wouldn't pull the skin off a rice puddin'. Tom thought it sounded retarded. I advanced the ignition a little, but in the scratch race performance was no better and it ran out of sparks after a few laps. Later confirmed one of the wires to the stator had severed just behind the stator backplate. The engine has equivalent resistance to compression at the rear wheel as 001 and is pressure tight. Something fundamentally very adrift methinks.

In the meantime the 175 took umbridge for being thrown down the road at Barn by breaking 2 teeth on its layshaft press-on gear, splitting the cage in its small end bearing and welding its PVL rotor to the stator with the accompanyment of a very load bang! All currently being fixed up for Mallory.

Chris

We will get it sorted out Chris! then maybe get to a dyno and fine tune the carb as well?
Cheers,
Alan

Hi Chris great to hear you have found t=some of the issues, out of interest,

do you have spare press on gears, I have plenty of never used, new one's, all made for the club back in the day, if you need please just send your address will post to you.

regards Derek

Hi Derek
Thanks for that. Have sent you a PM!
Chris