Single Cylinder Engine Tuning

[szrdave]

I'm about to drop the engine out of the 660 again to get the broken-off exhaust stud repaired, and while I'm at it would like to get the head looked at as I would have thought there is the potential for some improvement.

The Wiseco high comp piston I've got on the shelf can go in as well, so I'll need the cylinder honed and the rings fitted to the piston and the piston into the cylinder (I haven't got a ring expander or compressor).

I've spoken to Slipstream on the phone, and they were pretty helpful and seem to know their stuff, but I'd need to give them a bare head and the cost (not including the repair) is already towards the top of what I'd like to spend.

Engine spec - Full exhaust system, FCR35s, otherwise currently stock

Use - Commuting and track days

The questions I have are:

1. Is the head work worth it? If it's not likely to make that much of a difference I can just get the repair done and the piston fitted and chuck it back together
   
2. Any recommendations of other people to talk to regarding the above work? It would be handy to find someone who could do all the work at the same time
   

Any and all advice appreciated!

[porter_jamie]

slipstream certainly seem to know what they are doing, and chrage accordingly.

in my opinion, engine tuning follows the Keith Bontrager saying of cheap, light, strong - pick two

ie, cheap, fast, reliable, pick two.

getting a head done is a lot of work and i would imagine the cost to be within the 500-600 pounds mark easily

[garage19]

Porting a head takes a lot of development time.

If i was get a head ported i would take it to a company that does that head not one that claims they can port any head.

[Superdunc]

Sound advice from eastern massive. Tuning engines is about matching all the mods, High compression pistons need to be matched to the combustion chamber volume, squish height, and cam timing to get the most out of them. Then the porting needs matching to the valve size and lift, etc... Go to someone like slipstream, and get them to blueprint it. i.e . match all the components together, porting the head wont gain you much unless everything else is right. so ask the to fit the piston, machine the head and piston so the squish and compression are optimised, and get them to dial the cam in. That on it's own should find you decent gains once yur carbs are set-up to suit.

[phildawson8270]

I've always had the philosophy of building performance engines from the bottom up.

The first things that should be modified start at the crank, and then working up towards the head, finishing with carbs and an exhaust system.

These items don't gain much power alone but allow you to make the most of everything that is before it.

[szrdave]

Thanks for the replies.

As much as I'd like to give the engine to Slipstream for a full rebuild and tune, I haven't got a spare couple of grand to pay for it! Points taken though, I think I'll leave the head as it is, the money can go towards the suspension instead.

My next (possibly fanciful) question, would it be feasible to get the head repaired with the engine complete and in-situ?

This is the bit that's loose:

And this is where it should go:

I can't see the welding heat being too much of an issue, access is pretty tight though and there is a bit of an overhang.

[garage19]

Yes. Chuck the old bit. Build it up with weld and then drill and tap and shape the rest with a die grinder.

I could donut if you were local to Ipswich.

[Superdunc]

It would be a pain in the arse to do on the engine. 1. Because the area around the break will have to be cleaned back to clean metal, which will means a lot of grinding, and keeping the swarf out of the engine internals will take a lot of care. 2. Aluminium castings need pre heating before welding, and it will take a LOT of heat to get the area up to welding temp, as the rest of the engine will act as a heat sink.