rshutchinson
XS400 Addict
Won't rev over 5000 rpm - Solved
I've been trying to figure out why the bike won't rev over 5000 rpm. I can't get onto jetting the carbs properly because of it. Won't rev over that in neutral or on the road, no matter if I pin it or try to feather through it, just won't go. It doesn't bounce off it like a rev limiter, just kind of loses power and bogs, like it's missing on a cylinder. Tried adding a frame ground to the battery, no help. Read that someone had reversed the plug wires and that was his problem but didn't solve it for me.
Tested coils
New plugs
New wires
New gas
carbs 100% clean - diaphragms tested and good
Can't seem to find any exhaust leaks at the head
New carb holders and gaskets, both have nipple capped off
Float heights set to 2mm below the mating surface using clear tube
Valves in spec, going to double check now that it has ran for a bit.
180 compression in both cylinders
Up next is to sync carbs on the bike, double check pickup coil position and try another TCI I have.
Any other things you can think of I can try?
The bike will idle all day, revs great in neutral up to 5k and you can drive it with some feathering of the throttle and popping out right exhaust but I think that's the carb settings I've got right now.
Second, is there a way to test the solid state regulators on these?
I only ask because the bike may be overcharging or charging strangely. I've read through plenty of charging threads on here but they're all about non-charging. One thread was asking how to test solid state reg's but said replacement was only option so that may just be it. I'm going to order an XJ650 reg/rec combo for the future anyway so I have it when it's needed.
The battery had limited use and worked fine up til yesterday where I believe it developed a dead cell. Shows 11-ish volts with key off, 8 with key on and 3 when trying to start. Just find it strange how it had no problems up til then but I guess that's just how they go. Wanted to make sure the charging system didn't kill it before I fry another new battery.
I've tested my rectifier which tested good. Tested the alternator and they're all at 0.7-0.8 ohm after subtracting my lead resistance (most accurate I can get with my meter) so it's in spec and 4 ohms across field coil. When running I could smell what I believed was acid and I get 14.5 volts at the battery at idle. Now this seems high, however the only load aside from the motor at idle is an LED taillight and small LED speedometer so it is quite bit less load than stock bikes. Headlight was not on. When I was revving the engine to 4k - 5k the voltage dropped to around 13.5 but this was only a few seconds worth of testing. Didn't get to test much more than that before the battery crapped out completely.
I've been trying to figure out why the bike won't rev over 5000 rpm. I can't get onto jetting the carbs properly because of it. Won't rev over that in neutral or on the road, no matter if I pin it or try to feather through it, just won't go. It doesn't bounce off it like a rev limiter, just kind of loses power and bogs, like it's missing on a cylinder. Tried adding a frame ground to the battery, no help. Read that someone had reversed the plug wires and that was his problem but didn't solve it for me.
Tested coils
New plugs
New wires
New gas
carbs 100% clean - diaphragms tested and good
Can't seem to find any exhaust leaks at the head
New carb holders and gaskets, both have nipple capped off
Float heights set to 2mm below the mating surface using clear tube
Valves in spec, going to double check now that it has ran for a bit.
180 compression in both cylinders
Up next is to sync carbs on the bike, double check pickup coil position and try another TCI I have.
Any other things you can think of I can try?
The bike will idle all day, revs great in neutral up to 5k and you can drive it with some feathering of the throttle and popping out right exhaust but I think that's the carb settings I've got right now.
Second, is there a way to test the solid state regulators on these?
I only ask because the bike may be overcharging or charging strangely. I've read through plenty of charging threads on here but they're all about non-charging. One thread was asking how to test solid state reg's but said replacement was only option so that may just be it. I'm going to order an XJ650 reg/rec combo for the future anyway so I have it when it's needed.
The battery had limited use and worked fine up til yesterday where I believe it developed a dead cell. Shows 11-ish volts with key off, 8 with key on and 3 when trying to start. Just find it strange how it had no problems up til then but I guess that's just how they go. Wanted to make sure the charging system didn't kill it before I fry another new battery.
I've tested my rectifier which tested good. Tested the alternator and they're all at 0.7-0.8 ohm after subtracting my lead resistance (most accurate I can get with my meter) so it's in spec and 4 ohms across field coil. When running I could smell what I believed was acid and I get 14.5 volts at the battery at idle. Now this seems high, however the only load aside from the motor at idle is an LED taillight and small LED speedometer so it is quite bit less load than stock bikes. Headlight was not on. When I was revving the engine to 4k - 5k the voltage dropped to around 13.5 but this was only a few seconds worth of testing. Didn't get to test much more than that before the battery crapped out completely.
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