Erratic Idle when hot

[andyrpsmith]

I wonder if any of you guys can help.

It's the old problem:

It has been plaguing me for the last year or so. Erratic idle when hot leading to it just dying.

Rear coils both were cracked so I did the COP'S conversion including resistors in line on the rear, cleaned and balanced the carbs/set idle to 1000rpm. This really helped and the bike went well for the rest of last summer, although I did feel the v-boost surge was less after the mod.

Earlier this summer I took the bike to work and as before reached about 2 miles from work after the motorway and it started missing and dropping revs at idle. So I thought if rear coils were cracked 99% chance front would be so I decided to buy 4 new coils (£280). Fitted them today (yes both front were cracked), ran well while warming up, v-boost good - bike feels nice and lively. Wait at petrol station for free pump and revs falter for a while and bike just dies - same old problem back! I'm really at a loss now. Could it be a TCI problem? That will be expensive! I thought the dyna replacement was no longer available? Note: just looked at Exactrep have the Dyna 3000 for £285.
Or could it be the pick up, is this expensive/difficult to replace?
Welcome some advice. Thanks.
Andy

 

[tugla]

how is your charging system voltage at idle. there are a few fixes to help. also some mods to the r&r to help this issues. been few guys having same thing you have when the fan kicks in the bike wants to stall....

how warm is the temp guage getting when you have this issue?

 

[andyrpsmith]

Charging all good, I did the solder joint to the crimp in the wiring loom last year. Today the cut out was at normal temp not with the fan kicking in.

 

[Miles Long]

how is your charging system voltage at idle. there are a few fixes to help. also some mods to the r&r to help this issues. been few guys having same thing you have when the fan kicks in the bike wants to stall....

how warm is the temp gauge getting when you have this issue?

+1. One of the best - and least expensive - mods for our bikes is an on-board voltmeter. If voltage falls much below 12 volts when idling, the bike will act erratically, sometimes to the point of stalling.
Could also be caused by clogged A/F screws and orifices. Happened to me a few years ago. I did the "peashooter" cleaning method, which helped a bit, but eventually did the Shotgun procedure, that cleared up the poor idle/stalling problem completely. Has run smoothly up to present. I drop in some Seafoam additive, every second tank or so.
Cheers!

 

[andyrpsmith]

I've done the shotgun procedure, took the carb covers off etc. All OK and clear.

 

[Miles Long]

I wonder if any of you guys can help.


.......Or could it be the pick up, is this expensive/difficult to replace?
Welcome some advice. Thanks.
Andy

Checking is easy. Remove seat and l.h. side cover, find the two-wire (orange and black) pickup coil connector. Measure the resistance, on the coil side of the connector, between the terminals. Should be 80.8 - 121.2 ohms @ 20degrees C
(room temperature, bike cold). Last time that I checked mine it was 101.6 ohms.
Then I would start and warm up your bike to operating temps, or preferably till it starts to stall. Then quickly shut the bike off, and check the resistance again. If still within range, the p.u. coil is probably not your problem.
If it is the problem, there have been some post recently of alternatives to the O.E.M. part that are less expensive. Check back before buying from the dealer!
Cheers!

 

[Damon]

What is the voltage level at idle while engine/stator is @ 1000rpm ~ 1100rpm & the engine is @ operating temp? You have already confirmed/replaced plug coils. Confirm ohm readings of pickup coil. What is the condition of your plug wires & resistor plug caps? When was the last time your valve clearance checked and/or adjusted? I have seen when a valve adjustment was needed the idle rpm & vacuum readings would be bouncing all over due to leaking intake valves once engine was @ operating temps. allow the engine to cool completely down then thing would be normal until back @ operating temps.