3AJ coughing past 3500rpm
 

hello,
it's a 1990 3AJ, couple of days ago, she started to cut out few times in miliseconds after passing 3500rpm's, but day after day it got worst. it's like someone is playng with kill switch round 4K every few seconds.
this morning it was non stop, poor thing, it was tearing her apart, so i slow it down and under 3500 she's pulling and going fine, tickover is at 1300 or so, and she sounds helthy. also starts fine.
i tuoght it has something to do with second carb, it's membrane, but it's too impulsive, so coud it be electricity?
planning to look at the carb, in the meantime, any ideas?
thanks

update: i have just checked out second carb's membrane for tears, holes, rupteres, and it looks just fine, so i ruled this out.

by the way, when i close throtle in driving, she sais bang-bang so, could this two be related?

Try checking for fuel blockage or low fuel level in carbs, most probably in second carb. If petols not flowing it would cause backfire and engine cutting out as the revs increase but will run ok at lower revs.

Hi Brian
I had a similar problem on my 1vj once and it turned out to be the coil, it started and ran fine upto 3500rpm and then pulled back and die . it only did this under load . check the plug cap also.

well, i've checked fuel level in left carb, looks ok. took her for a ride, and noticed following:
she was totaly fine running for some 10-15 minutes, then, she started missing her beat again, this time, it wasn't so pronounced in acceleration (fine there), but was nightmare with flat throttle and decrease of throttle. it was so pronounced, it realy shaked me for/aft on the seat.
totaly confused now :confused1:

:helpsmilie:

Hi
I had a similar sounding problem with my 2003 xt600e when i first got it. It would stutter and hiccup on full throttle acceleration. Turned out to be a dirty air filter. I was surprised a new filter cured it as i was expecting something more complicated. The xt's must be sensitive to air filter condition. Maybe even take the filter out and take it for a run. Won't cost you a penny

Hi Oakrad
I have a similar problem with my 3AJ.
After riding for 15 mins or when engine got hot bike would miss above 3500 rpm if I let engine cool down (20 minutes) bike would run fine untill it got hot again.
My carbs seem ok I changed the coil, HT lead and cap, new spark plug cleaned air filter, checked tappets used a differnt CDI but not fixed.
I then changed the stator for an aftermarket stator. This fixed the problem of the missfire above 3500 rpm but the bike felt very low on power when accelarting. I then tried another aftermarket stator with a differnt pick up and bike seems fine.
So I think my bikes stator and pick up were the cause of my missfire.

When you clean the carbs make sure you remove and clean the small filter under the float needle as this can get blocked and also cause a missfire as bikes runs low on fuel but if you stop bike will start and run fine at low speeds.

Where are you located Oakred?

Does any one have a pick up for a 3AJ they want to sell.
Thanks