Geoff the giant small bike

**Drew** · 20th August 2012, 16:36

Originally Posted by ducatilover

Geoff's running well again

Just letting it cool to do clearances then I'll jet it for the mighty 250cc motor.

New engine plans

If I keep a GN barrel, I can take it out enough to get 340cc out of it on standard stroke.
I'll try keep it as "GN" as possible eh?
340cc, cam, reshaped combustion chamber, ported head, TM33 carb even moar compression.
I reckon that'll see a healthy 35hp at the tread

Now to find an 84mm piston with a similar compression height and 18mm gudgeon!

It is heartening to see someone throwing caution to the wind, and for the sake of just doing something to find out what a snapped crankshaft actually looks like.

We will get a picture of it I hope.

**bogan** · 20th August 2012, 16:42

10 bucks says the main roller bearing shits itself before the crank snaps

We should fully setup a failure mode sweepstake

**Drew** · 20th August 2012, 16:49

Originally Posted by bogan

10 bucks says the main roller bearing shits itself before the crank snaps

We should fully setup a failure mode sweepstake

Four stroke that doesn't run shells?

**ducatilover** · 20th August 2012, 22:17

Originally Posted by Drew

Four stroke that doesn't run shells?

Ball bearings my friend lol

the box is needle rollers, balance shaft and crank are ball bearings... very big ones may I add

Originally Posted by Drew

It is heartening to see someone throwing caution to the wind, and for the sake of just doing something to find out what a snapped crankshaft actually looks like.

We will get a picture of it I hope.

Can't have a practical bike now can I? This motor build is going to take a while and a lot of boring research (I fucking love research by the way!) so you'll have to wait a wee bit.
One thing I'd like to figure out is if I can stick a DR350 crank in, longer throw, and run a different rod to retain a similar deck height
Seeing as my rod is ball bearing big end, I'll be able to mod one to fit fucking anything

Originally Posted by bogan

10 bucks says the main roller bearing shits itself before the crank snaps

We should fully setup a failure mode sweepstake

I'll have to agree there lol going to be a fair bit off stress on the poor thing.
The clutch won't last 5 minutes though

Good news, the .5mm kit runs well, have done the clearances and flushing the oil over night, will top it back up tomorrow and tune it (hopefully I got them clearances right!!!!)

**ducatilover** · 20th August 2012, 22:19

And fuck yes, pics will be plentiful when it snaps the crank!

EDIT:

After some google love I'm very keen to try fit a DR350 crank in, the crank swaps in to DR250 cases, so... in theory lol

What I now need to do is find a fucked 350 bottom end or just the crank and try it in my DR250 cases which are the same as the GN (minus elec start)

If it works, on an 84mm bore it'll be just over 394cc which means I can run a smaller bore but still have plenty of cubes

Anyone got a munted DR350 crank floating around? No point buying a decent one 'till I know fer sure that I can do it.

**ducatilover** · 21st August 2012, 22:50

After doing the clearances I was still getting a top end rattle, nothing big, but my bike has to run PERFECT!!!!
So I took the valve cover off after checking clearances again (had already eliminated cam chain tensioner, swapped 'em over, counted the turns out etc)
And it turned out to be the cam sprocket, 4.9mm on the top of the teeth, cannot remember what the other was, but it was near .5mm bigger or so.
There be the problem! Cam chain movement isn't my favourite thing.

So me, being me went a bit over the top while the valve cover was off.
Blanked the tach drive properly as it was seeping.
Got the original GN valve cover, whipped the rockers out and compared them with the DR ones.
The DR ones look like the cam follwers have been re-faced and are in much prettier condition, so I kept them.

While those rocker shafts were out I noticed the factory spacers for the rockers on the shafts would cause a bit of drag, so I assembled on with the original spacers and one with Dougtastic ones, I was right!
Realised I had yet again worked on a GN for several hours being pedantic as fuck... so I'll pop the cover on tomorrow... and have to set the fucking clearances again!!!

**ducatilover** · 23rd August 2012, 00:23

Unlike everyone on this forum, I own motorcycles and come here to discuss them.
So, today I did things and stuff to do with motorbikes (I know, I'm talking about bikes on a bike forum, WTF right?)

Was still getting a rattle after doing the cam sprocket, so I've cranked the shits with the top end and have pulled it down (the noise is probably my parinoia?)
Putting a different cam chain, tensioner, rockers/rocker shafts and the old head (which admittedly has moar port work done anyway)

I haven't checked everything over yet, but the noise was very loose tappety type, or bent/stuck valve, was more prominent on the overrun
I'm thinking it might be a good idea to mod one of the tensioners to a manual one?

Does anyone here actually read this thread as it's about a motorcycle? Maybe I should enter it in parliament and give it a gay marriage with my Kawasaki

**Drew** · 23rd August 2012, 06:50

I read it Doug, we just can't believe how sick you are sometimes, so don't reply.

Carry on.

**willytheekid** · 23rd August 2012, 08:05

I read ya stuff mate...you tells bestest storys!

, Keep up the great work Doug, some of us are interested...honest! (Im mean, its NOT like we are waiting for you catch fire or somthin

)

ps: one word for ya...SUPERCHARGER! ....

**unstuck** · 23rd August 2012, 08:16

Less about the fuckin bike, and more about bitches, bitch.

**caseye** · 23rd August 2012, 14:05

Theres more than one or two of us out here hanging on every word.Afterall it is about bikes, ain't it?
Keep up the good work, looking forward to hearing how things are going when it's all done. Ha, yeah right! all done.

**banditrider** · 23rd August 2012, 17:13

We just wanna know when you're gonna bolt on a super-charger...

**ducatilover** · 23rd August 2012, 17:22

Cheers chaps

It is gagging for a supercharger

I'm surprised I haven't caught fire, all the smoking I do in the garage...

Well, replaced the cam chain etc etc etc
Still rattling.
I'm dead set on it being my feeler guages being too wide over the valve stem, they're hanging up on the retainer a bit.
Will cut some down and try clearances again.

I just want to ride the fucking thing!!!!

I threw my toys out the cot today in typical Doug fashion, this involves me putting my tools in the correct place and firing the coffee machine up, pretty fuckin' intense! As long as it doesn't cause me to have another nervous breakdown I'll be right...