Seeley (replica) Framed Project Road Racer

[Suzukidave]

Looking REALLY good on your racer there Geoff Question .. i dont remember you saying but does your engine have squish band heads ?

[Zunspec4]

Hi SD,

The engine has modified Std heads with centre plugs and squish. Using the deposited aluminium from the melted piston as a substitute "Plasti-gauge" the squish was approximately 0.75 mm. Ideally it should have been 1.00 mm but the difference may be down to the base gasket compressing. I did want to fit some centre plug squish heads that Pete Odell was producing but he is still waiting on his supplier to come up with these heads. My dilemma is that the dyno runs did not show any problems so the engine failure mechanism still needs to be assessed before I shell out on a new piston and re-build etc.

All good fun, but that's racing . Overall the bike was going well and the Seeley chassis felt rock solid, just needed the rider to provide the balls to go faster

Cheers Geoff

[Suzukidave]

I was wondering as looking at the picture with the holed piston it looked like the squish was tighter .. but i forgot you said nothing showed up on the dyno runs .

[Zunspec4]

With dyno runs being so short in duration I would guess that problems might not actually be easy to spot compared to flat out thrashing on a race circuit. When I re-build the engine I will take the time to ensure I have equal squish etc. (although I have to learn how to do that). I also want to modify the crank to run on pre-mix vice the pump so can also ensure that crank-pins are 180 degrees apart and crank seals are good at the same time. If you want to push the boundaries of any engine (and this one WAS making 50% more power than std.) I guess you have to be meticulous in your preparation to ensure reliability. I'll put this occurrence down to experience and get on with preparing for next year.

Cheers Geoff

PS: I appreciate all view points and help from forum members, it gets you thinking.

[Suzukidave]

Checking the squish is really easy just useing solder .. useing acid free solder cut off 2 pieces long enough that each piece can be bent into a L shape . The lower side of the L has to be long enough so when you insert it into the spark plug hole it will extend across the top of the head to the edge of the cylinder . One piece across each side of the inside of the head parallel to the wrist pin . Then just rotate the engine across TDC a couple of times to flatten the solder .. remove the solder pieces and measure .. perfect squish measurement

[Zunspec4]

Thanks SD,

I'll have a go at that, seems simple enough, cheaper than melting pistons .

Cheers Geoff

[Suzukidave]

Sure enough i forgot to say purchase solder thats fatter than the desired squish so it will flatten some . The first time i tried this myself i got solder that was too thin not even thinking and the piston / head didnt even touch it

[ja-moo]

Sorry to hear about the piston!

One thing, I was looking at your picture, and it might be the angle, but "it looks" like you are almost out of ground clearance, with not a lot of lean angle. One thing that might be a problem when you get up to speed.

[Zunspec4]

Hullo ja-moo.

The apparent lack of ground clearance is due to the angle of the photo. The pipes actually run very close the centre-line of the bike underneath and then flare out (so to speak). I did do some static tests in the workshop and could easily lean it over by 50 degrees without anything touching. Some suspension travel would need to be taken into account in any riding situation but I think I'll be OK.

Cheers Geoff

[ja-moo]

Cool! I busted my butt one time from pipes grounding out. So it's something I look for.

[old racer]

Hi Geoff did the new tyres work.

[tz375]

What was the final prognosis on that overheated and detonated piston? Both pistons were a deadly shade of gray indicating that they had overheated. We like to see a much darker piston and would normally run much higher octane gas than that. What was your diagnosis?

[Zunspec4]

Long time no post (I've been hi-jacking Chris's thread ).

I just picked up on tz373 post: Basically the old engine is toast It seized big time at Lydden (April 2014), 2nd meeting), including total destruction of the needle bearing small end. So I started again from scratch which has taken some time. Since then the following work has been carried out:

New WM4 rear rim to take the Avon AM23 130/650x18 Cantilever tyre (soft).
New WM3 front rim to take the Avon 22 110/80x18 tyre (soft).
These mods required a 9mm off-set to the chain run, sorted by some custom front sprockets made by Talon Sprockets (got spares for sale in 14 & 15 tooth) and re-working the rear hub/sprocket carrier by Alf Mossell Racing. Alf also modified the swinging arm to allow proper clearance for the wider rear tyre.
New Seeley seat from Minnovation Racing
New Maxton rear shocks.
CNC machined front calliper carrier.
Twin TTO digital temperature gauges to keep an eye on cylinder head heat.
HPI digital fully programmable self generating ignition.
New pipes made by Tony Green Racing ( http://www.tonygreenracing.com/home )
34mm Mikuni carbs (vice the 38mm jobbies)

Two engines are being worked on by Graham File Tuning. A top UK 2-st guy who is also applying some latest 2-st thinking, while also remembering he is working with a 45 year old design. Engine #1 will be fairly straight forward as regards T500 tuning. Engine #2 (the EVO engine) will incorporate some more radical tuning (nothing as crude as just raising the Exhaust port and lowering the transfer ports). Next up will be dyno time and track test. Hopefully back on the grid before season ends, but only when it is good and ready.

To cap it all, if it is ready by August........... A parade lap of the Isle of Man TT course during the Classic TT. The Seeley will be ridden by Barry Sims. Barry is a 5 times Manx TT rider so will know his way around (if he can still remember ). They call it a parade lap but by all accounts it is a pretty fast thrash . So a whole new level of preparation will be called for, even for just one lap. Lock wire your lock wire, use thread lock as well etc. .

So, a somewhat lazy journey back to a racing bike, but hey, we only do this for relaxation and amusement , don't we?

Cheers Geoff

[garry55]

Great to hear the bike will be back fitter and stronger
Good luck at the IOM.
and thanks for the Tony Green link - will have to give him a call when the V4 needs pipes.

[titan performance]

A few of our lads are going to the Classic TT....they'll be looking out for your bike.