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[Daiwiskers]

To go from a 17 to a 20 tooth front sprocket is a big jump I can't remember off hand but I think it's the equivalent to going down about 9 teeth on the rear sprocket
Anyway it's more than I would go in one step

Keep safe all Dai

[stinkwheel]

It's a big step, but a 612 conversion is a big step in power too. More than double depending on how you did it. I'm running a 21t and close ragtio gearbox on mine and it pulls like a train.

[Daiwiskers]

Wonder if there's any chance of a dyno run

[Daiwiskers]

It's a big step, but a 612 conversion is a big step in power too. More than double depending on how you did it. I'm running a 21t and close ragtio gearbox on mine and it pulls like a train.

You're bike run's really well

I can't remember what carb you have fitted

If it's a 34mm mikuni perhaps the two carbs are set up differently

Then again your running a spacer plate to drop the compression so your bike will be more tolerant

I can't help but think that the two problems with this bike are related
Running weak then overheating accentuating both the clutch and the pinking problem

[Adrian]

@ Vince,

the O.P. says he's riding in Seoul, S. Korea, so Asian city traffic! Constant stop-start/traffic lights are going to exacerbate anything else that might be wrong.

A.

[stinkwheel]

I can't help but think that the two problems with this bike are related
Running weak then overheating accentuating both the clutch and the pinking problem

I think bulletwhisperers comment in the other thread is very pertinant. He's running standard cams. The cams that go with our hosts tuning kit open the valve sooner, wider and for longer. The OP has bumped the compression and lengthened the stroke but is still on a standard valve timing profile. I would be very tempted to try the much vaunted one-tooth retardation of the the inlet cam on this particular machine to soften things a bit.

I have the opposite problem with my clutch. It slips badly at anything over 80mph. I really need to have a word with Mr Newby before my planned Euro-run this autumn(if we are allowed to go). I actually even have a Newby clutch centre sat in my workshop that came with a gearbox the previous owner had swapped out for a 5-speed...

I must admit I'm having trouble with understanding how engine performance would cause clutch crabbing after a period of running, other than the potential heat issue. Sitting in traffic with the clutch in will cause most standard bullet clutches to crab though.

[Lee June woo]

Problem solved!

Last week I opened primary case and check the clutch push rod. Then I found the main cause of dragging.

push rod lubrication was bad so it makes lot of friction and abrasion on tip of push rod and metal ball.

this is the picture.

I replace those push rod with ball and grease enough.

oh, and I loosen primary chain tension little too.

Now, there is no more clutch dragging and slip.

even I don`t have to adjust clutch lever screw while I ride. (In Seoul traffic!)

I`m little embarrassed because it was simple problem.

However thank you very much giving me a lot of advice.

I will upload topic again when I`m in trouble.

Thanks for read.

Lee June Woo.

[stinkwheel]

You have to wonder if the end of that pushrod was properly hardened.

I made a new one for my 612 out of EN8 steel round bar and hardened the tip then tempered to a brown/purple. I'm also using a ceramic ball bearing which risky in terms of load but much better thermal properties. It's holding out so far. Easily replaced if it fails.