Dead at 6000 RPMs

[psyguy]

Maybe it is the igniter...

Dan

the more we talk about it the more i think it would pay to switch the ignitor out with somebody and see what happens

[salty_monk]

I may get a Dyna S or use Ed's that he offered earlier to test it out. I can always use a Dyna S on my 78 if that's not the issue.

Ordered a new Cam chain today, split type with a master link.

Dan

[49er]

hi 49er

not sure how long "forever" is, but mine were shot at less than 90k kms
i would think the wear would also depend on how hard you push them

however, in this case it doesnt seem to be the issue
cheers

Hi Ivor
Mine hasn't exactly been parked in a monastry the last few years!
It's done 83ks now, and sees 10k on the tacho, off and on.
It's obvious when the springs are sad. You'll never forget the sound of valve bounce once you've experienced it. Then it's time to replace the springs. I guess you decided to changed yours after measuring their free length. That's the recommended guideline.
Cheers

[psyguy]

I guess you decided to changed yours after measuring their free length. That's the recommended guideline.
Cheers

i see what you mean, they would last past their factory specified service limit before they actually cause any damage
yes, i changed them after measuring free length, better safe than sorry kind of approach

[49er]

i see what you mean, they would last past their factory specified service limit before they actually cause any damage
yes, i changed them after measuring free length, better safe than sorry kind of approach

Valve springs are one of the most forgotten items during top end rebuilds. In most stock applications, they can be overlooked, without dire consequences. Once you fit high lift/high overlap cams, you need to fit matching springs. Those who dont, risk spring bind causing serious cam and spring coil damage.
My springs were still in the middle of the suggested free length range.

Just checked your 850's pic again. How are you finding the Cycleworks 4-1 slash pipe?
The baffle on mine started to rattle when cold. I removed it last week and drilled some extra holes to improve the upper mid range. It's only marginally noisier than before, the exhaust note, not the rattle!

[argonsagas]

I would put this down as ignition only, especially after reading that the usable RPM range has dropped.

You might look at the ignition rotor and be sure it is not a bit bent, which would make its movement eccentric and at higher RPMs that could cause the effect you mention.

I notice someone already suggested a plug check. This might tell you if a coil was failing.

If the others check out, you need an ignitor.

[salty_monk]

It's happening at pretty much all RPM's now so I guess it's failing & plugs are likely fouled. I will check it out asap. Want to check I have good voltage at the coils etc, maybe run some tests on the ignitor from the Clymer manual.

Thanks again,

Dan

[salty_monk]

Well this explains something I think.... at the coils I have 9.5V at 3 of the connectors & 1.5v at the other (engine off, ignition & kill switch on).
At the battery I have about 11.5v (because the headlamp is on by default on my bike, it's fully charged as I charged it last night).

Now to find out where I'm losing all those volts (would explain why number 3 plug is fouled whilst the others are clean...)

I think I should also have 12v (or the same as the battery) at the other points too... can anyone confirm?

Guess I'm going to have to chase my way through that part of the loom & see what I find.

Dan