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Scooterlam wrote:I have another Avanti kit with higher port timings so might go for a revvy version of what I have.
Or o might just "pour" my current set up into the new case and have a working back brake.
Eden wrote:johnnyXS wrote:pity somebody hasn't some pictures to post as this is a very interesting and topical subject . I believe and hope that Scootering will be covering this in future editions.
I can see the benefit of matching the transfer ports of the casing to the 186 engine but not if it leaves insufficient mating surface on the crankcase for reliable sealing.
Why do the 186 engine castings have such over-sized transfer ports when its surely known that the small block crankcase doesn't match and would require so much material ground away to achieve a match ?
It might be interesting to build up the transfer ports on a 186 so that less material needs grinding out of the crankcase to achieve a match and best flow characteristics. Then do a comparison to see how much HP is actually lost through the slight decrease in transfer port size.
The reason that I ask this is because it seems to me that we are all just assuming that these 186 cylinders have been produced to correct tolerances and with adequate quality control . I would question that they have .......if it is necessary in every instance to grind out your stock small block casing to match the transfer ports to such an extent that there is less than adequate material left on the casing face to be able to form an adequate seal.![]()
Too often these days manufacturers cast parts for years without any quality control checks and small errors become larger over time .
To take a case in point ...have a look at the the 20 + 'damaged' Sil crankcases and cylinders currently for sale on the Scooter Restoration site . Most if not all of the faults are due to inaccurate machining and inadequate quality control and those are just the tip of the iceburg.
With most of our parts currently being manufactured in India, I don't believe we should take anything for granted. I for one would question that the GT186 cylinders are being manufactured to the correct specification and tolerances if it is necessary to remove so much material from the stock crankcase that it is then not possible to achieve a satisfactory and reliable compression seal
Are you for real? There isn't a kit on the market that has transfer bases the same size as standard case transfers. The GT kits are made in the UK and are made to the desired specifications, if they had transfer bases the same size as the standard case transfers there would be little point in producing the kits at all.
Do you know of anyone that has a problem with the gasket face sealing or are you just presuming there is a problem in this area?
I have been taking this area of the casings out for years and out much more than the standard GT gaskets as I also increase the base transfer areas of the barrels out too and have never had a motor leak on the base gasket.
There are many photos of this work around the internet.
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