- Wed Nov 04, 2020 3:10 pm
#93804
Right well I said it might take a while and it has. The piston from China never arrived and was cancelled but I ordererd another and it came last Sunday. Its a 88mm piston from a Honda generator XK 390 I think it is.
So any way the new piston is half the weight and has a 20 mm gudgeon pin, distance from the pin to the crown is 2.5mm less but this will make up for the massive extra 4 mm sweep.
The old piston at 4000 km had no wear at all yet fit like a sausage in a sleeve. I did not want to order another like that. The ring land was at least 1mm less and I could see the rings with the piston in the cylinder.
I found a great machine shop in Chonburi which many machines and guys with glasses on boring all kinds of cylinders, many of them laying on the floor. (Not the guys the cylinders). An old wooden cabinet stretched the entire length of the shop with boxes of pistons.
1 hour later and 4 passes at 1mm each I had a 88 mm bore, the Himalayan is 87mm, he honed it till the piston just gently fell through. The line was thin, we knew that but at 1.97mm Its ok.
The piston slap seemed not to be the problem . The entire engine was stripped down and I looked for anything that could make noise. A new crank bearing was replaced on the timing side from a Chekoslavakia to a Japanese, ----a big difference.
The liner sleeve sticks out of the cylinder by a long way, maybe 5 inches or more and this is unsupported. You would think such a long sleeve would be supported but it is not, it has a .017mm gap and can not be clamped. Im sure that this cylinder sleeve was clanking against the crank case, more on this later.
I gapped up the rings at 12 thou greased them and put them on the piston. I made a new base gasket from my favorite cereal packet and measured the distance from the crank case boss on the liner. There is 2 bosses and I coated them with shilac.
Shilac is a gasket compound we would use years ago, it is still available on eBay as Indian head shilac. This stuff is not the crap silicone rubbish that goes brittle and drops off in the case blocking oil pump gauzes.
I also shilac'd the cylinder at the point of the bosses.
The head gasket was seperated into the 3 parts and opened up to 88mm. Each part was again shilac'd and the three parts put back together
The cylinder and head were bolted up together at ( as tight as I can with one hand with a 3/8 drive socket and ratchet). About 23 foot pounds.
Bit of confusion over 2 different length of push rods and the hydaulic tappet locked and not giving way but 20 minutes at TDC on exhaust stroke sorted that.
Its in incredibly quiet now when running, I am delighted with it, it sounds like a Honda.
I am convinced the piston slap is liner slap as the liner fits in the case. The shilac may not keep it quiet long, I dont see why not at .017mm but at least I know what it is.
it would need a huge mod to stop the liner slap. All engines I have ever seen has a supported liner be it wet or dry. I had considered cutting a slot for an o ring but the bosses are very thin. Its not surprising Re has stopped further production the of 500
These RE engines are noisy, my 500 was intolerably so but not any more, it is delightfully quiet I was going to sell it but not now.
Now you now what it is.
So any way the new piston is half the weight and has a 20 mm gudgeon pin, distance from the pin to the crown is 2.5mm less but this will make up for the massive extra 4 mm sweep.
The old piston at 4000 km had no wear at all yet fit like a sausage in a sleeve. I did not want to order another like that. The ring land was at least 1mm less and I could see the rings with the piston in the cylinder.
I found a great machine shop in Chonburi which many machines and guys with glasses on boring all kinds of cylinders, many of them laying on the floor. (Not the guys the cylinders). An old wooden cabinet stretched the entire length of the shop with boxes of pistons.
1 hour later and 4 passes at 1mm each I had a 88 mm bore, the Himalayan is 87mm, he honed it till the piston just gently fell through. The line was thin, we knew that but at 1.97mm Its ok.
The piston slap seemed not to be the problem . The entire engine was stripped down and I looked for anything that could make noise. A new crank bearing was replaced on the timing side from a Chekoslavakia to a Japanese, ----a big difference.
The liner sleeve sticks out of the cylinder by a long way, maybe 5 inches or more and this is unsupported. You would think such a long sleeve would be supported but it is not, it has a .017mm gap and can not be clamped. Im sure that this cylinder sleeve was clanking against the crank case, more on this later.
I gapped up the rings at 12 thou greased them and put them on the piston. I made a new base gasket from my favorite cereal packet and measured the distance from the crank case boss on the liner. There is 2 bosses and I coated them with shilac.
Shilac is a gasket compound we would use years ago, it is still available on eBay as Indian head shilac. This stuff is not the crap silicone rubbish that goes brittle and drops off in the case blocking oil pump gauzes.
I also shilac'd the cylinder at the point of the bosses.
The head gasket was seperated into the 3 parts and opened up to 88mm. Each part was again shilac'd and the three parts put back together
The cylinder and head were bolted up together at ( as tight as I can with one hand with a 3/8 drive socket and ratchet). About 23 foot pounds.
Bit of confusion over 2 different length of push rods and the hydaulic tappet locked and not giving way but 20 minutes at TDC on exhaust stroke sorted that.
Its in incredibly quiet now when running, I am delighted with it, it sounds like a Honda.
I am convinced the piston slap is liner slap as the liner fits in the case. The shilac may not keep it quiet long, I dont see why not at .017mm but at least I know what it is.
it would need a huge mod to stop the liner slap. All engines I have ever seen has a supported liner be it wet or dry. I had considered cutting a slot for an o ring but the bosses are very thin. Its not surprising Re has stopped further production the of 500
These RE engines are noisy, my 500 was intolerably so but not any more, it is delightfully quiet I was going to sell it but not now.
Now you now what it is.
