#6

[F5 Dave]

I have a super reasonable brand new std bore MB100 piston & rings on my desk here.

[speedpro]

Nice of you to offer, but 2mm clearance is probably getting a bit on the loose side. A nice brand new crank would likely be of more interest. There has been a little interest expressed in a run of offset big end pins. It's getting tempting to check out current costs for say a run of 5. Throw in a (legal)rod kit and a bit of crank machining and it could still end up being quite expensive but you save by using cheap KT100 pistons and being able to step up in .05mm steps extending the life of each cylinder.

[husaberg]

Nice of you to offer, but 2mm clearance is probably getting a bit on the loose side. A nice brand new crank would likely be of more interest. There has been a little interest expressed in a run of offset gudgeon pins. It's getting tempting to check out current costs for say a run of 5. Throw in a (legal)rod kit and a bit of crank machining and it could still end up being quite expensive but you save by using cheap KT100 pistons and being able to step up in .05mm steps extending the life of each cylinder.

Offset gudgeon are you meaning crankpins?

Did you check the scooter ones i posted a while back against the STD mb/H100

Actually the T5 eccentric pin looks like it could work with limited mods as its only 2mm short

The width at the big end is workable? with thinner thrust washers

Rod the right length but the little end is to big, so bugger.

http://www.sip-scootershop.com/en/pr...+pin_4043ad213

http://www.sip-scootershop.com/en/products/crankshaft+pin+drt+eccentric_4043ad179

[cotswold]

Another subject: - "world domination of bucket racing with a fleet of MB powered buckets" - Gary got a 3rd and 1st today on his and I don't think he was trying too hard. Only a playday though. Tokoroa should be fun next weekend with both Gaz and Dave M riding, and Rick though he has some pussy Suzuki motor.[/QUOTE]

You may want to talk to Av and ask her to slow down a bit

[F5 Dave]

Nice of you to offer, but 2mm clearance is probably getting a bit on the loose side. A nice brand new crank would likely be of more interest. There has been a little interest expressed in a run of offset big end pins. It's getting tempting to check out current costs for say a run of 5. Throw in a (legal)rod kit and a bit of crank machining and it could still end up being quite expensive but you save by using cheap KT100 pistons and being able to step up in .05mm steps extending the life of each cylinder.

yeah I'd still be keen.

[speedpro]

F5 was saying about a problem he had with clutch slip and a problem with incorrect springs. Up till then I'd always assumed mb5s and MB100s used the same springs and never took any notice. I've now measured them up and found the MB100 springs are about 2mm longer but wound with thinner wire, about 2.7mm versus 3mm. I had been keeping sets together and the MB5 clutch pack I have had 4 short springs and the MB100 clutch packs both had longer thinner springs. Gary has had an engine problem so I'll be checking the springs in his clutch once I have it out.

Gary's bike died at Tokoroa in the last race. I've found two little pieces of steel in the exhaust port and in the pipe. Both have obviously been through the engine with clear marks on the head and piston. The big end "looks" OK and the little end is fine. The piston has been hammered good enough to trap the ring tight. The gearbox oil has come out black and horrible so I'll need to check what's up with that. The crank rotates freely but there is a very faint crunchy noise and feel about it. The bike died because a piece of steel pushed the plug gap closed which probably saved it from further mayhem.

[Yow Ling]

. The crack rotates freely but there is a very faint crunchy noise and feel about it.

Any free crack sounds dodgy to me

[speedpro]

Finally got the ignition rotor off Gary's crankshaft and got the cases apart. It isn't pretty. Stock bearings are good for all sorts of revs and I have never had one let go, on a MB. The amazing thing is the motor was still running sort of OK. The bearing is shagged, bits have been fed through the motor, the seal to the gearbox is not good and is probably where the crap got into the gearbox oil which is black and crappy, and the ring is trapped in the groove. Seems like it's time for a refresh, new piston, nice straight clean bore, and a couple of nice new C3 bearings, and new seals.

[husaberg]

Finally got the ignition rotor off Gary's crankshaft and got the cases apart. It isn't pretty. Stock bearings are good for all sorts of revs and I have never had one let go, on a MB. The amazing thing is the motor was still running sort of OK. The bearing is shagged, bits have been fed through the motor, the seal to the gearbox is not good and is probably where the crap got into the gearbox oil which is black and crappy, and the ring is trapped in the groove. Seems like it's time for a refresh, new piston, nice straight clean bore, and a couple of nice new C3 bearings, and new seals.

I have but it was a crap bearing obviously assembled by a cheapskate non C3.
I am kind of surprised it wasn't hammering the ignition?

[Buckets4Me]

Finally got the ignition rotor off Gary's crankshaft and got the cases apart. It isn't pretty.

do you know how many pistons that engine has eaten ?

i belive it's a few

[bucketracer]

The amazing thing is the motor was still running sort of OK. The bearing is shagged, bits have been fed through the motor, the seal to the gearbox is not good and is probably where the crap got into the gearbox oil which is black and crappy, and the ring is trapped in the groove. Seems like it's time for a refresh, new piston, nice straight clean bore, and a couple of nice new C3 bearings, and new seals.

Main brg fails, bits of metal through the motor and still the 2-stroke was running, sort of. New Brgs, piston and a re bore and its racing again, strokers sound pretty robust to me........ compared to those rather fragile and expensive 4-strokers.

[speedpro]

With the crank out I've found the big end pin isn't central in the crankshaft but is a good 2mm to one side. I haven't measured it but there seems to be a lot of clearance between the rod and crank wheels. Not good.

[Hilleye]

Main brg fails, bits of metal through the motor and still the 2-stroke was running, sort of. New Brgs, piston and a re bore and its racing again, strokers sound pretty robust to me........ compared to those rather fragile and expensive 4-strokers.

As long as it crosses the finish line it can still win.

[speedpro]

I've been looking for a good big end bearing for Gary's bike. Whilst at the kart shop I checked out a KT100 rod kit. Turns out the big end bearing is 26X20X13.8, EXACTLY the same as a MB100. Moral dilemna for a bit. They are a bit different to look at and I could spot one even if it was all assembled onto the crank/rod. Further research has come up with a same size bearing with a description that makes it similar design to the KT part. Moral dilemna over. It does mean if you wanted to build a cheater engine which handled 16,000rpm that the parts are available from your local kart shop.
Just in case anyone thinks I honestly thought for more than a second about using an illegal bearing, anyone is welcome to have a look inside my engine, or Gary's but you'd have to ask him about pulling his one apart.

[kel]

I've been looking for a good big end bearing for Gary's bike. Whilst at the kart shop I checked out a KT100 rod kit. Turns out the big end bearing is 26X20X13.8, EXACTLY the same as a MB100. Moral dilemna for a bit. They are a bit different to look at and I could spot one even if it was all assembled onto the crank/rod. Further research has come up with a same size bearing with a description that makes it similar design to the KT part. Moral dilemna over. It does mean if you wanted to build a cheater engine which handled 16,000rpm that the parts are available from your local kart shop.
Just in case anyone thinks I honestly thought for more than a second about using an illegal bearing, anyone is welcome to have a look inside my engine, or Gary's but you'd have to ask him about pulling his one apart.

Have you sized up the AM6 rod and bearings? I know they have all manner of rod lengths with differing big and small end pins and of course the AM6 (OEM or after market) are all legal as they're after market parts for a road going engines. I seem to remember the Metrakits rev to 14.5k all day long.
I guess the real question is why aren't you coming to TePuke and will you have Gary's motor back together in time?