henrywillms
Hero member
- Location
- Canada
My RGS has been running great all summer but on the last few rides it has a problem I have not been able to fix so far. Winter is almost here and I would like to resolve it before I run out of time for road testing. Looking for some ideas to diagnose the problem and hopefully fix it. My RGS is a low mile bike I try to keep it well maintained. It has run good last year and this year and I did not make any changes to the bike.
Problem description
Intermittent occurence:
Problem can occur on a whole ride, like for an hour or not at all on the whole ride. It sometimes occurs upon initial start up. If the problem occurs and I stop and restart the bike it can still be present. On the other hand if on initial start it is running great it can stay good the whole ride. Problem can also start during a ride when it had been running great. It is NOT a problem that cuts in and out in short intervals. It's more like it has good days and bad days. I would say it is a problem 70% of the time and ok 30%. It occurs over the whole RPM range.
Bike Specs
Corsa motor with 50k km
WITT optical ignition
Newer coils from Wolfgang maybe 10 years old
Dellorto carbs set up with the usual jets etc and were running good. No visible corrosion/gunk.
NGK 5ohm plug caps
was running B8ES plugs and replaced with BR8ES...no difference
Intake manifolds from Wolfgand last year, been on for two summers
Symptoms when problem is occurring, when it is not there are no symptoms:
Bike starts up as normal when cold
When warm it starts ok but I may have to fiddle with the throttle or enricher a bit to get it to idle. Before the problem or if the problem is not occurring it starts with no such fiddling when warm.
At cruising speeds, RPM in the 3500 to 4500 range its seems a bit sluggish and kind of tractor like. Still rideable and adequate power. It's NOT like dropping a cylinder if you had fouled a plug.
As you slow down for a complete stop it may give a little pop from the exhaust and it will not idle, you have to rev it just a bit to keep it running. Normally it idles fine.
The problem is really felt during acceleration. It is not running as crisp and is down on power. You can still pass cars on the highway no problem, just not the same quickness. When accelerating hard and up-shifting you notice a delay when you close the throttle and then re-open it quickly. There is a little stumble at that time before it accelerates again. And as said earlier it is not accelerating as fast as it should before or after shifting, and across the whole rev range from 3500 to 7000 RPM.
Some of the symptoms are similar to a worn spark plug cap when engine vibrations at certain RPMS when a worn cap does not contact the spark plug. I have had that problem before but this is happening at all RPMS and not consistently.
Fixes and checks
I checked the Dellorto carb bowls to make sure they were clean....all clean, I did not dismantle or clean the carbs. I run all the normal jets etc and it had been running great.
I replaced the 3 spakplugs with new BR8ES from a reputable supplier. The plugs in there did not have many miles on them and they all looked similar and burning good.
One sparkplug cap was a little loose fitting compared to the others but was still making good contact. It was still gripping the threads on the plug terminal and I had to pull it to get it off. I changed it anyway just be sure.
I checked the electrical connections on the coils were tight. I did a wiggle test on the battery, fuse box and Witt box connections. Fuses were all tight. I checked the optical pickup for any moisture or oil, and its saw no wiring problems, visually.
Gas flows good to carbs. Filters clean.
I did not check valves or compression. Valves were checked maybe 3000km ago and holding their gaps.
Intake manifolds were new last year and bike ran fine for two summers after installing them.
Battery is charging at 13.2v with lights on, 14v with lights off, while running at highway speeds.
I did not check the carb balance.
Thoughts guys what to check or replace next?
Problem description
Intermittent occurence:
Problem can occur on a whole ride, like for an hour or not at all on the whole ride. It sometimes occurs upon initial start up. If the problem occurs and I stop and restart the bike it can still be present. On the other hand if on initial start it is running great it can stay good the whole ride. Problem can also start during a ride when it had been running great. It is NOT a problem that cuts in and out in short intervals. It's more like it has good days and bad days. I would say it is a problem 70% of the time and ok 30%. It occurs over the whole RPM range.
Bike Specs
Corsa motor with 50k km
WITT optical ignition
Newer coils from Wolfgang maybe 10 years old
Dellorto carbs set up with the usual jets etc and were running good. No visible corrosion/gunk.
NGK 5ohm plug caps
was running B8ES plugs and replaced with BR8ES...no difference
Intake manifolds from Wolfgand last year, been on for two summers
Symptoms when problem is occurring, when it is not there are no symptoms:
Bike starts up as normal when cold
When warm it starts ok but I may have to fiddle with the throttle or enricher a bit to get it to idle. Before the problem or if the problem is not occurring it starts with no such fiddling when warm.
At cruising speeds, RPM in the 3500 to 4500 range its seems a bit sluggish and kind of tractor like. Still rideable and adequate power. It's NOT like dropping a cylinder if you had fouled a plug.
As you slow down for a complete stop it may give a little pop from the exhaust and it will not idle, you have to rev it just a bit to keep it running. Normally it idles fine.
The problem is really felt during acceleration. It is not running as crisp and is down on power. You can still pass cars on the highway no problem, just not the same quickness. When accelerating hard and up-shifting you notice a delay when you close the throttle and then re-open it quickly. There is a little stumble at that time before it accelerates again. And as said earlier it is not accelerating as fast as it should before or after shifting, and across the whole rev range from 3500 to 7000 RPM.
Some of the symptoms are similar to a worn spark plug cap when engine vibrations at certain RPMS when a worn cap does not contact the spark plug. I have had that problem before but this is happening at all RPMS and not consistently.
Fixes and checks
I checked the Dellorto carb bowls to make sure they were clean....all clean, I did not dismantle or clean the carbs. I run all the normal jets etc and it had been running great.
I replaced the 3 spakplugs with new BR8ES from a reputable supplier. The plugs in there did not have many miles on them and they all looked similar and burning good.
One sparkplug cap was a little loose fitting compared to the others but was still making good contact. It was still gripping the threads on the plug terminal and I had to pull it to get it off. I changed it anyway just be sure.
I checked the electrical connections on the coils were tight. I did a wiggle test on the battery, fuse box and Witt box connections. Fuses were all tight. I checked the optical pickup for any moisture or oil, and its saw no wiring problems, visually.
Gas flows good to carbs. Filters clean.
I did not check valves or compression. Valves were checked maybe 3000km ago and holding their gaps.
Intake manifolds were new last year and bike ran fine for two summers after installing them.
Battery is charging at 13.2v with lights on, 14v with lights off, while running at highway speeds.
I did not check the carb balance.
Thoughts guys what to check or replace next?
