Pinking & Wiseco Pistons

[RALPHARAMA]

The Old Gurl has always "Pinked" regardless of fuel type, timing etc. Following the advice of Jam after a Dyno session I increased teh size of the main jets by two sizes which has lessened the effect but she still does it, mostly when running at a slow speed, two up under load at low revs.

I was chatting to a mate who is a zed head and pretty knowledgable, who told me that Wisco pistons increase the compression ratio of the engine by a substantial enough margin that pinking will occur if an octane enhancer isn't added to the fuel. I think I might try increasing the octane of my fuel to see it it makes any difference.

Any one add any info to this? I find this very interesting and want to learn more

[chrisu]

try checking your timing. I've got wisecos in my Z1R and do not have this problem.........

[Pigford]

Mine does it all time under load/low revs....

Back timing off....

Or Higher octane fuel....

Or light throttle until ervs rise.....

Wiseco is a performance set up so try AVGAS....

[tlc]

Mine doesn`t do it at all !

But then running stock pistons, points and coils it probably only produces 50 HP anyway.

[dr.rod]

My Suzuki Katana had a 1260 Wiseco kit with huge piston crowns and it pinked like buggery. I ended up using Millers Octane Booster which helped. I also filed the pulser coil backplate mounting holes out to slots so I could vary the timing, then spent a weekend doing lots of test mileage; kept stopping to move the backplate slightly until the pinking was minimised. Set up like this and running on the highest octane pump fuel I was revving it 1200rpm into the red on the drag strip, no probs.

[PJones]

My Suzuki Katana had a 1260 Wiseco kit with huge piston crowns and it pinked like buggery. I ended up using Millers Octane Booster which helped. I also filed the pulser coil backplate mounting holes out to slots so I could vary the timing, then spent a weekend doing lots of test mileage; kept stopping to move the backplate slightly until the pinking was minimised. Set up like this and running on the highest octane pump fuel I was revving it 1200rpm into the red on the drag strip, no probs.

Hi Dr Rod how are you?

[Steve R]

Hi Ralph,
Standard compression is 8.5 to 1 wisco 1075 pistons increase this to 10.25 to 1 a substantial increase.

I used to have a Lotus elan which was designed to run on leaded 5 star.
running on unleade plus castrol valve master with octane booster it ran better than on leaded 4 star.
Both millers and castrol boost the rating from 95 to 97 octane. You can get the millers without the lead additive. A bottle of millers does a lot less fuel than a botttle of castrol so it will be easier to judge how much to add to the small amount of fuel in the tank of a bike. Also the millers comes in a flat bottle with a proper lid which will be easier to carrry, unlike the castrol which has a poxy leaky lid (voice of experience )
i am putting the 1075 kit on mine and will use the Millers product.

What size mains are you now running Ralph, what other mods have you got and what did it make on the Dyno?

[debben1]

How old is the Wiseco kit ? the older kits used to have sharp edges around the valve seat pockets, we used to remove these sharp edges on the engines we built as these sharp edges can cause detonation when hot, the latter kits are already softened when they arrive from Wiseco now. Regards, Steve

[debben1]

Hello Ralph, just had another thought about your pinking, have you measured the compression ratio? the 10.25:1 quoted by Wiseco is only a guide, it would be impossible for them to know the final build compression ratio. They are suppling 1 part of the engine but the compression ratio will depend on many factors with in the engine. Even in a completly stock new bike the compression ratio will vary due to a stack up of intolerences, add into this a 30 year old engine where the valve seats have been recut, head skimmed, different gaskets ect and you could be some where off from the designed target of 10.25:1. It takes only minutes to measure the compression ratio and the only tools you need ara a 50cc syringe and a plug spanner, Regards, Steve

[Steve R]

Thats interesting the kit I have ready to go in has pretty sharp edges round the valve pockets, what do you do just take the edge off with a bit of wet and dry?

The head has been skimmed on mine is it a good idea to fit an extra base gasket as some one has advised me to do , I would not have thought a light skim would really make much difference?

Cmon Ralph what horse power was it making?

[Donaldson]

I put a kit on my Z1-R this year have done about 2500 miles so far with no problems, running dyna coils and points set up.