Hey all, I just recently got a 1979 CB400T that I’ve been fixing up / upgrading easy stuff here and there. When I got the bike, I was told it wasn’t running when the previous owner got it and he just “tweaked the carbs” to higher idle and it ran. With that said, I ended up ordering a carb repair / rebuild kit. Replaced a few of the pieces inside, cleaned it out and re-attached.
Kickstart works, electronic start does not.
The problem: It seems to have trouble starting (via kickstart) cold. It will start with some effort if the Throttle Stop Screw is turned in a lot of the way in. When it does start, it kicks up to like 4,000 RPM then I immediately have to turn the Throttle Stop Screw all the way out until I get to the specified 1,200 RPM from the FSM.
Alternatively, I left it today where the Throttle Stop Screw left it at 1,200 RPM but tried to leave it sitting off for 6 hours to see how it would do cold starting where it “should be” but it barely stays alive unless I give it some throttle until it’s warmed up, then it’s good.
Other notes:
Do you think the “fast idle” screw needs to be adjusted? I’m having trouble wrapping my head around balancing the Throttle Stop Screw, 2 Pilot Screws, and Fast Idle Screw.
Kickstart works, electronic start does not.
The problem: It seems to have trouble starting (via kickstart) cold. It will start with some effort if the Throttle Stop Screw is turned in a lot of the way in. When it does start, it kicks up to like 4,000 RPM then I immediately have to turn the Throttle Stop Screw all the way out until I get to the specified 1,200 RPM from the FSM.
Alternatively, I left it today where the Throttle Stop Screw left it at 1,200 RPM but tried to leave it sitting off for 6 hours to see how it would do cold starting where it “should be” but it barely stays alive unless I give it some throttle until it’s warmed up, then it’s good.
Other notes:
- Pilot Screws are both 3 full turns out on each carb
- No jumping idle when spraying carb cleaner around the intakes
- Cleaned out the carbs pretty thoroughly with carb cleaner, and sat the whole carburerator in a pine-sol/water mixture for 3 days.
- New Spark Plugs, Oil Changed with the filter, runs seemingly well when actually running I just can't seem to get this idle / start figured out
Do you think the “fast idle” screw needs to be adjusted? I’m having trouble wrapping my head around balancing the Throttle Stop Screw, 2 Pilot Screws, and Fast Idle Screw.