PLUG CHOP PROCEEDURE

Trav
It sounds like you have fuel starvation by the time you are hitting 5th gear. replace you fuel filter and set your petcock to avoid the vaccuum driven feature and see if this makes a difference.
or,
Back off the throttle and let the float boals fill up and hit 3/4 throttle and see if the stuttering still occurs.

Spock

Hm, no I have already done that to the petcock, and it runs GREAT if I am at FULL throttle.. I'm not talking about a WOT run to 5th (actaully 6th) though.. I'm talking zooming down a back road from a stop, and only opening the throttle to about half or so in say 3rd or 4th to maintain cruise speed (like 50 mph or so).

WARNING! DO NOT TAKE AS GOSPEL. I'm relatively new to MC mechanics.

If ignition is right...

If it keeps stuttering at that middle throttle opening I'd suspect the needle jet/jet needle. If it's momentary and is worse for quickly going to WOT but not present when you slowly go, then I'd suspect the accelerator pump. No pump! When you go immediately to WOT there is not enough velocity through the venturi to pick up enough fuel to maintain the mixture and you get a burst of lean condition. This is worse with the VM series carbs. The CV carbs compensate well by letting the vacuum control the throttle position. The tradeoff is that they are slightly less responsive.

IMO all this stuff is difficult to resolve quikly on an old bike because things are usually out of whack all around. Sticky advance, weak advance springs, leaky ignition, worn points that won;t hold setting, bad bushings in carb linkage, air leaks, valves out of adjustment, sub-optimal compression in one or more jugs, slack camshaft chain(an xs650 I worked on would barely run because the slack in the timing chain let the valve springs push the cams around).

-Duck

Yea true.. 3 years ago that was the case..

Right now though, with a the direct power relay installed for the coils, and new dyna coils, wires, plug caps and plugs, fresh cut valves in a completely cleaned head and clearances to spec, new big bore / higher compression pistons, advacer has been taken apart, cleaned, lubed, reinstalled and timing and advance checked with a light, and the stock electronic igniton..

Well it runs better than it ever has! Oh and I picked up a set of carbs for 'parts' and they ended up looking so practically mint that I decided to make them my main setup.

Want to point out that if you use Loctite to secure a rotor on the end of the crankshaft that if you heat the area, this kills the magnetism in the rotor. Once partially demangetized, the rotor won't produce suffient AC. Heat seems to kill magnetism.

For those who wish to learn more about heat and magnetism:

Curie Point

Ferromagnetism wikipedia

Ferromagnetism hyperphysics

Be sure to read about hysterisis and remanence, links within aforementioned articles. Curie point is also explained on the hyperphysics site.

-Duck

The Captain turns to his Science Officer and says, "Thank you Data!".

Geesh Duck, we be motorcycle guys... where do you get this stuff? Do you really read it? I was on the football team in school and reading wasn't really required hehe...

I knew about the link between heat and magnetism from personal experience (ooops type thing)...

You mean you didn't watch Mr. Wizard on TeeVee when you were a kid? I did. Then I took the TeeVee apart

In HS? Football? Swim team here. The science teacher's daughter was on the swin team. I tried everything I knew at the time to catch that beaver I could see outlined by her speedo.

-Duck

See? he might be smart, but he's still one of us :laugh:

Seriously, very impressive range of knowledge! You might be 'new' to wrenching on bikes, but I'm sure it's just learning the particulars.. the general knowledge and application of physics and other sciences seems to be very helpful to the rest of us. I've always found physics interesting myself, but I don't grasp quite as much of it yet. But your posts are very helpful to improve on that!