Got me bigbore kit now

Do you offer your services to build engines for people Max?as not all of us have the know how and/or space to do it in

Thanks Brummy.

It ain’t no bother disturbing the balance timing. Just line up the 2 dots on the helical gears and sorted again. This is with the crank locking tool at top dead centre of the rear cylinder. The crank locking tool  should always be in place for the cylinder you are working on. You can see it on one of the photos above sticking out of the cases.

I’d remove the flywheel and sprag now. Its easier to get the timing wheel bolted down to the crank tightly that way. I think it would be flimsy if you attach one to a 14mm hexagon  socket/bolt. There would be a bit of play between the crank and timing wheel. However you may improvise it well, so just preference really. Have you got the  M22x1.5 flywheel removal tool? Locktite 648 and standard strength too? Crank locking pin?

The end gap for piston rings is important. It needs to be tight enough to prevent too much blow by, but loose enough for the ring to expand with the heat of combustion. Forced induction and nitrous needs bigger gaps than naturally aspirated. It may be that the rings supplied with your pistons and matched, bored + plated barrels have already been gapped. The tool I use is basically a cordless dremmel with a grinding disc. This is bolted down to a piece of wood that has a metal stage either side of the grinding disc with a plastic ring guide. The guide ensures the rings are squarely pushed into the grinding disc from both ends. It is important to only grind from the outside to the inside of the ring. This is so the external ring coating does not chip away. Using the tool involves measuring the end gap of the ring with feeler gauges when it is square in the bore of the cylinder, then grinding a small amount. Backwards and forwards between bore and grinder until the desired end gap is reached. Small steps every time to prevent too large end gaps. The grinder apparatus ensures that you get a square and even grind to the fragile rings. I know some people have used files, but I think it is very difficult to get the ground edges to be square to each other. Once the end gap is achieved, very lightly hand file any burrs from the top, bottom and back edge. I use 0.45 mm compression end gap, 0.5 mm secondary ring end gap and 0.38mm oil ring end gap.

Yes the solder strip is the best way to do the piston to valve clearance check.

Washers are standard small steel ones that have a blob of weld on that has been ground into the correct shape and height to protrude over the internal edge of the sprockets so that they just sit on the camshaft raised edge. I tried using just the bolts, but they just tore up leaving little swarfs of metal, so I improvised with these washers and they work perfectly.

I use 106/109 and I have not tried any other timing.

I use a Motty for fuelling with a lamda in front and rear headers. I believe the PC5 can do a similar thing too, but the Motty’s data logging is useful for sorting problems. Im using gen 1 denso injectors. My bike is a mixture between the early and later bikes. Best bits of both in my opinion, except for the looks :)

When torquing the stud nuts up, just use the spec torque with the tool coming off the end of the torque wrench at 90 degrees. Once it clicks, you’re done.

One thing though. It is easier to have a friend help when dropping the cylinder and cylinder head down the studs over the installed pistons and rings. One controls the cylinder and the other pushes the rings into the cylinder skirts. I use the chunky grip end of a cable tie to push the ring into the ring lands while the cylinder skirt gently drops over the ring. Don't use a metal tool at all! Some people have used a cable tie to compresses the ring and the cylinder slides down and displaces the cable tie while the ring springs into the bore. This didn’t work for me as piston ring compressors didn’t. It is fiddly but you’ll get the knack. I actually really like this part of the process. Its like engine therapy :)

Im based in central Nottingham. And pictures speak a thousand words ..........

Just found this link:
http://www.jepistons.com/PDFs/TechCorner/SCPDrawings/piston_instrc4032.pdf
Also, make sure the piston wrist pin offset is correct on assembly!

My head hurts.....time for a breather.

They are very flimsy in the bore so its easy to get a false feeler gauge measurement, especially with the oil scraper rings. Use the loose piston to push them into the bore squarely before end gap measurement. Always measure the rings when they are at a depth in the bore that they will pass during normal combustion. I like to measure at about an inch from the top of the cylinder.

Dont forget to get the correct staggering of the ring end gaps when installing the cylinders onto the pistons. You'll have to google for the best staggering cause I cant remember off the top of my head.

I just use cheapo mineral oil for running in. I also drop it after the first 5 minutes idling to inspect its condition. Obviously, you keep a very good ear to an engine that is started the first time after a comprehensive build. Also drop it after 20 miles to check it again. They only need mineral for the first 5000 miles. I don't believe in babying the engine during its running in period either. None of this is gospel, its just my opinion.  This is a very interesting read:
http://www.mototuneusa.com/break_in_secrets.htm

It was Halfords 10W40 mineral last time.

BrummyMax wrote: And another thing ....... Its worth lapping the valves in and getting the valve clearances sorted on the loose heads. Quite a nice job this one, at the kitchen table. Also, and this might be obvious: after working on one head at top dead centre, you need to rotate the crankshaft either 300 or 420 degrees to get the other cylinder at top dead centre before installing its cams etc.

Temp stop for the moment.

i dont know if its easy to do on these, but I matched the exhaust manifolds to the heads with the porting tool too, there was a slight misalignment and a large lip to start with.

I think we talking cross purpose because I wasnt clear, I dont mean the manifold and pipework should not step, I'm just talking about the mating faces of the two parts, casting lips and minor tolerance issues where they butt together, thats best smooth as possible so no turbulence on the exit of the head

BrummyMax wrote: There is a good book called "Four Stroke Engine Performance Tuning" by Graham Bell. Its packed with information and is where I got the above from.

Skullface wrote: I think we talking cross purpose because I wasnt clear, I dont mean the manifold and pipework should not step, I'm just talking about the mating faces of the two parts, casting lips and minor tolerance issues where they butt together, thats best smooth as possible so no turbulence on the exit of the head

Actually Janspeed proved the opposite a good while back,they found a definite mismatch to be beneficial.

They actually had a port sized spigot welded inside an oversized manifold tube so that there was an actual lip around the lower part of the port so restricting the gas reversion when the pulses went negative.

As I recall it scavenged the cylinder better as it reduced the volume of exhaust gas contamination but still used the reverse wave efficiently.

These trends come and go,it's a bit like the world beating crankcase breather thing that Harris produced that enabled the then Airwaves Duc's to dominate BSB. 

Not listed on their website anymore although Neeves put his long term Gixxer thou on their dyno and then went out on a roadtest and raved about the results in this vid

http://youtu.be/Y017jVmLYi8

Yawn ....... you're such a big bore.

Any chance of pictures? Id love to see the pistons, rings, head gaskets and a closeup of the cylinder sleeve. How does the skirt height compare to stock pistons? How about the cylinder skirt cutaways compared to stock cylinder skirts?

Guilty pleasures with the curtains drawn ....

Actually, Im off to see a Gamelan orchestra and have a meal. £5 all in at a Malaysian restaurant. Not sure how good it'll be. If Im really lucky, I can come home to some nice closeup pictures of engine components