Rod kits

[DavidTetley]

Can anyone tell me if its possible to buy rod kits for Arrows? Is there an alterative? My engine is +60thou so I believe is can use X7 pistons on a 2mm oversize to prolong the life of the current cylinders without having them relined. I believe the small end will need a reduced little end bush making. That just leaves me with the problem of where to get rods to rebuild my engine. Thanks in advance,

[bh.sprint]

Evening David,

Replacement con-rods with new big ends and little ends used to be available from DRAGS. There are some modern con-rods available which can be made to fit the Arrow/Leaders but they either need new crank pins making or the flywheels boring out to take the bigger pins, which all = expense.

One of the club members has some +80 thou or 2 m/m over size pistons in a Leader engine but I'm not sure how he got on, I think there was a problem with them. These were copies of the original Ariel pistons but made of modern materials and with piston rings similar to the ones on the Suzuki X 7 pistons.

One of the club members makes the little end bushes to go with the X 7 pistons, if Drags have not got any in stock.

Brian.H.

[DavidTetley]

Hi Brian, I've just got my X7 pistons through the post. The skirt is approx. 5mm shorter than the pistons that came out. I don't suppose you know if I've ended up with the wrong model pistons or if I've got to play around with the cylinder/height to get the inlet timing back?

[nevhunter]

You could weld a piece on it to restore the length. Nev

[Roger James]

David, The X7 pistons are shorter but its not all at the bottom affecting inlet timing, you'll find that the piston length is also shorter above the gudgeon pin meaning that at TDC it does not reach anywhere near the top of the bore meaning you are losing out on compression, that said the majority of owners fit these pistons and happily ride off into the sunset with no apparent loss of performance, perhaps they rev them a bit more. I don't think the change in inlet timing is detrimental to the running perhaps helps the overall performance if its allowing more fuel to be drawn into the crankcase, again I would leave that to an expert to pass comment.

I now use the Suzuki X7 pistons in most engine rebuilds due to ease of availability, price and of generally better material with lower expansion rate than Ariel or Hepolite pistons but even genuine Suzuki pistons are getting harder to find now, plenty of reproduction pistons around but its still best to fit genuine rings if you can get them.

To restore compression on those engines I use on track for Parade Riding I have the top of the barrels skimmed by a local engineer, I've attached a couple of pictures of an X7 piston in the bore at TDC showing it sitting low in the bore even though this barrel has been lightly skimmed also, the other photo shows a barrel that's had a good skim as a comparions although at moment cannot find the picture showing the piston at TDC in this bore. If you go down this route of having the top of the barrels skimmed be aware that the crown of the X7 pistons is more pronounced and you can end up with the piston hitting the head so you sometimes need to have the squish band machined also.

Roger