small issue...need input

i retorqued head for the second time after 3 warm/cool down sessions and installed accel coils and wires....i still have a problem....bike runs and sounds great above say 1500 rpm....any attempt to set it to idle at anything less than that and it grinds like a coffee grinder....been like this since rebuild.....i had crap throttle cables and replaced them as pull one was way too tight and wasnt letting assembly return fully and push one just wasnt right...cables are fine and lubed and adjusted decent....
my first inclination is to adjust cam chain to rule that out..i didnt do that part, as my second set of hands did that part as i was slowly turning motor...so, i will do that to rule it out ...if it doesnt end up being that, should i be thinking carb synch?....i pulled bowls and tops and did some experimental jet work and polished (somewhat) tops, but i didnt mess with any adj other than replace pilot screws
on bottom of carbs......any ideas? thanks

check cam chain tension and or synch carbs would be a starting point.

PLUMMEN wrote:

check cam chain tension and or synch carbs would be a starting point.

thanks...i hope one of the two does it...i ll be swingin if its just the chain.....

A few questions, please.

With ign switched ON (engine not running), what is measured voltage at coils?

Is oem points ignition being used?

What is condition of battery and state of charge?

Has ignition timing been checked with strobe type timing light?

Has spark quality at each plug been visually inspected?

Have carb float bowl fuel levels been checked using the clear tube method?

Has compression test been performed?

Are valve clearances within specs?

If not already done, would address above matters to eliminate other possible deficiencies before syncing carbs.


Good Luck!

i guess i took it for granted the simple checks were allready done :laugh:

Patton wrote:

A few questions, please.

With ign switched ON (engine not running), what is measured voltage at coils?

Is oem points ignition being used?

What is condition of battery and state of charge?

Has ignition timing been checked with strobe type timing light?

Has spark quality at each plug been visually inspected?

Have carb float bowl fuel levels been checked using the clear tube method?

Has compression test been performed?

Are valve clearances within specs?

If not already done, would address above matters to eliminate other possible deficiencies before syncing carbs.


Good Luck!

fresh top end with mtc pistons 10.5 to 1 comp, fresh jugs, refurbished head with 3 angle cut, valves blast beaded, new guides , new oil seals,
stems trimmed to length, andrews 2x cams, top end shimmed by builder/machinist, new cam chain, all new guides and rollers......im guessing compression and leakdown should be within spec...dyna ign and new accel coils and wires...battery good....
had same problem after rebuild with old coils...so we can probably rule them out...

carbs were fine on old motor/top end....just thinking i might have overlooked something stupid/obvious......thanks

keith1 wrote:

Patton wrote:

A few questions, please.

With ign switched ON (engine not running), what is measured voltage at coils?

Is oem points ignition being used?

What is condition of battery and state of charge?

Has ignition timing been checked with strobe type timing light?

Has spark quality at each plug been visually inspected?

Have carb float bowl fuel levels been checked using the clear tube method?

Has compression test been performed?

Are valve clearances within specs?

If not already done, would address above matters to eliminate other possible deficiencies before syncing carbs.


Good Luck!

fresh top end with mtc pistons 10.5 to 1 comp, fresh jugs, refurbished head with 3 angle cut, valves blast beaded, new guides , new oil seals,
stems trimmed to length, andrews 2x cams, top end shimmed by builder/machinist, new cam chain, all new guides and rollers......im guessing compression and leakdown should be within spec...dyna ign and new accel coils and wires...battery good....
had same problem after rebuild with old coils...so we can probably rule them out...

carbs were fine on old motor/top end....just thinking i might have overlooked something stupid/obvious......thanks

While the low rpm noise may indeed be resulting only from an improperly adjusted camchain and/or out-of-sync carbs, where possible issues have been ruled out as to compression, spark quality, and battery condition, other remaining possible issues would imo include:

Voltage reaching good coils;

Ignition timing;

Float bowl fuel levels.

If camchain adjustment and carb sync fail to resolve the low rpm noise issue, would address the three areas noted, and then re-sync the carbs.

As known, carb performance at top end doesn't significantly relate to lower rpm performance governed by the pilot circuit.

Good Luck!

PLUMMEN wrote:

check cam chain tension and or synch carbs would be a starting point.

if it isnt the chain, those carbs are going off to george faster than you can say "clean and right".....with an 8 week lead time , i want to be riding first weekend in april thats nice........no sense going for the dirt nap with your pockets full, wont do ya any good....lol...

Patton wrote:

keith1 wrote:

Patton wrote:

A few questions, please.

With ign switched ON (engine not running), what is measured voltage at coils?

Is oem points ignition being used?

What is condition of battery and state of charge?

Has ignition timing been checked with strobe type timing light?

Has spark quality at each plug been visually inspected?

Have carb float bowl fuel levels been checked using the clear tube method?

Has compression test been performed?

Are valve clearances within specs?

If not already done, would address above matters to eliminate other possible deficiencies before syncing carbs.


Good Luck!

fresh top end with mtc pistons 10.5 to 1 comp, fresh jugs, refurbished head with 3 angle cut, valves blast beaded, new guides , new oil seals,
stems trimmed to length, andrews 2x cams, top end shimmed by builder/machinist, new cam chain, all new guides and rollers......im guessing compression and leakdown should be within spec...dyna ign and new accel coils and wires...battery good....
had same problem after rebuild with old coils...so we can probably rule them out...

carbs were fine on old motor/top end....just thinking i might have overlooked something stupid/obvious......thanks

While the low rpm noise may indeed be resulting only from an improperly adjusted camchain and/or out-of-sync carbs, where possible issues have been ruled out as to compression, spark quality, and battery condition, other remaining possible issues would imo include:

Voltage reaching good coils;

Ignition timing;

Float bowl fuel levels.

If camchain adjustment and carb sync fail to resolve the low rpm noise issue, would address the three areas noted, and then re-sync the carbs.

As known, carb performance at top end doesn't significantly relate to lower rpm performance governed by the pilot circuit.

Good Luck!

thanks....i ll report my progress.....

Patton wrote:

...While the low rpm noise may indeed be resulting only from an improperly adjusted camchain and/or out-of-sync carbs, where possible issues have been ruled out as to compression, spark quality, and battery condition, other remaining possible issues would imo include:

Voltage reaching good coils;

Ignition timing;

Float bowl fuel levels.

If camchain adjustment and carb sync fail to resolve the low rpm noise issue, would address the three areas noted, and then re-sync the carbs....

If not already addressed, spark quality should appear in the list of other remaining possible issues.

A good healthy fat spark at kick-over usually indicates adequate voltage reaching the coils. But it's best to actually measure the voltage.

Forgot to earlier mention --- would also test voltage across battery terminals at idle (look for 12+ volts) and at 4000 rpm (look for 14+ volts). Thinking any deficiency in charging system may produce insufficient voltage at idle rpm (perhaps drawn down by headlight) and thereby less than proper spark needed for best combustion.

The Dyna ignition is known as being a voltage hog, especially at lower rpms.

Good Luck!

one other spot to look could be the starter clutch if it is staying engaged it will make a really loud grinding noise as well. also check your cam chain tension as well as a few other people have said to check all you have to do for that is to roll the motor over to top dead center on compression and then back off the adjuster bolt and let it take up any slack if you don't here any sound from the tensioner pull it out and double check it's function. you wont need any extra hands because you set it without rotating the motor once it is at t.d.c. if the motor still has it's kicker pull the starter motor out and fire it up so it takes the starter drive out of the equation.

keith1 wrote:

PLUMMEN wrote:

check cam chain tension and or synch carbs would be a starting point.

if it isnt the chain, those carbs are going off to george faster than you can say "clean and right".....with an 8 week lead time , i want to be riding first weekend in april thats nice........no sense going for the dirt nap with your pockets full, wont do ya any good....lol...

no danger of that happening to me i work very hard at staying broke!:laugh: