Topic: Switching to 1st Kills Engine

[AintNoEasyWay]

Hey guys, hopefully this is a simple, no-brainer fix. Last night I installed new push & pull throttle cables on my CB750 K7. Pulled the bike out of the garage to go for a test ride & when I switched to first gear, the engine died. Tried a couple more times with the same results.

I haven't changed anything else but the cables. I didn't adjust the cable tension up by the throttle yet because I wanted to test them out during the ride. Any ideas of what's going on? Happy to provide any more info that may help.

[70CB750]

Weird.

Dies as it boggs down or shuts down like kill switch?

[AintNoEasyWay]

Shuts right off as if I hit the kill switch.

[70CB750]

I would hunt for pinched wire, starting with power to coils after it shuts down.

[AintNoEasyWay]

Solid idea. The tank might be pinching a wire. I'll check tonight. Thanks, 70.

[flybox1]

Can you start it in 1st with the clutch pulled?

[Powderman]

Just curious, how would moving the shifter have anything to do with anything electrical? Clutch and kickstand cutouts I can see having an issue with but just moving the shifter lever?

[goldarrow]

Can you start it in 1st with the clutch pulled?

+1 flybox1 is on to something here, several times I had this issues with bikes that's when bikes had sat for extended period of time and clutch plates stuck together. So when you pull the clutch and slap into gear, no power transferring from motor to tranny.

Mehhhh, I normally don't type this long

[Bodi]

neutral switch or starter safety unit could be somehow crosswired to the ignition. That's all that happens when out of neutral, other than mechanical stuff. Can you electric start it in first with clutch in (motor turning over at least)?

[70CB750]

Ha, I forgot K7 is electrically complicated 

[millla03]

I would also be leaning towards stuck clutch plates. If it starts in first with the clutch pulled in that should rule out the neutral safety switch. Its a common problem for bikes that have been sitting.

If thats the case, it should just be a matter of pulling the clutch plates apart and reinstalling. Soaking them in oil before installation is a good idea, and make sure the orientation and plate order is correct.

[AintNoEasyWay]

Thanks guys. I'll try starting in 1st when I get home this evening. The bike has only been sitting for two weeks. I had a throttle cable break on my while I was on the interstate. Had to push the bike about 2 miles home. Just got the new cable in last night & installed it. Could having to push it that far somehow be related?

[Powderman]

Thanks guys. I'll try starting in 1st when I get home this evening. The bike has only been sitting for two weeks. I had a throttle cable break on my while I was on the interstate. Had to push the bike about 2 miles home. Just got the new cable in last night & installed it. Could having to push it that far somehow be related?

I don't see how it could have been related. If the bike still ran when the cable broke, you could have started the bike and walked it while it idled in 1st gear, saves breaking your ass pushing all that weight.

[AintNoEasyWay]

Thanks guys. I'll try starting in 1st when I get home this evening. The bike has only been sitting for two weeks. I had a throttle cable break on my while I was on the interstate. Had to push the bike about 2 miles home. Just got the new cable in last night & installed it. Could having to push it that far somehow be related?

I don't see how it could have been related. If the bike still ran when the cable broke, you could have started the bike and walked it while it idled in 1st gear, saves breaking your ass pushing all that weight.

Yea, I did that just to get it off the interstate. But stopped once I was back on neighborhood streets because I didn't know if there'd be any damage if I did that for too long.

[Don R]

 It doesn't help this problem but you could turn up the idle and ride it with no throttle cable.

[Powderman]

What damage do you envision by idling your bike for a period of time? Turning up the idle is a good idea and you can still use gears to get there a bit faster. I've idle walked by bike for miles before with flat tires.

[Don R]

 They are air cooled and get hot when not moving much and I'd just rather not push a bike that far. Age and experience /youth and enthusiasm?

[hello]

Can you start in neutral, then shift to 2nd then to 1st without it stalling? Your battery might be low. My gf has this same problem in her 350F.

[Airborne 82nd]

Just curious, how would moving the shifter have anything to do with anything electrical? Clutch and kickstand cutouts I can see having an issue with but just moving the shifter lever?

Not sure why you asked this did someone delete something?

I would hunt for pinched wire, starting with power to coils after it shuts down.

If the blk/wht wire from kill sw, to coil were pinched the bike would not start or run it may turn over though. Are you blowing any fuses?

Ha, I forgot K7 is electrically complicated 

The K7 & K8 are just smarter not complicated. Unless the operator is not smarter then that gets complicated.

Can you start it in 1st with the clutch pulled?

+1 flybox1 is on to something here, several times I had this issues with bikes that's when bikes had sat for extended period of time and clutch plates stuck together. So when you pull the clutch and slap into gear, no power transferring from motor to tranny.

Mehhhh, I normally don't type this long

If the plates are stuck wouldn't the bike try to leap forward and stall as if the clutch was not pulled? The op did said "Shuts right off as if I hit the kill switch".
But I'm not sure if that is where Fly was headed. I must be thinking back-asswards seems like if the clutch plates were stuck together there would always be power transferring from motor to tranny. Help me understand

Thanks guys. I'll try starting in 1st when I get home this evening. The bike has only been sitting for two weeks. I had a throttle cable break on my while I was on the interstate. Had to push the bike about 2 miles home. Just got the new cable in last night & installed it. Could having to push it that far somehow be related?

I don't see how it could have been related. If the bike still ran when the cable broke, you could have started the bike and walked it while it idled in 1st gear, saves breaking your ass pushing all that weight.

Yea, I did that just to get it off the interstate. But stopped once I was back on neighborhood streets because I didn't know if there'd be any damage if I did that for too long.

Wait in the op you said the bike shuts off when you put it in first gear isn't that your whole problem??

[AintNoEasyWay]

Airborne, the bike was sitting for two weeks because one of the throttle cables broke & I was waiting on a new cable to get here. I pushed the bike after the throttle cable broke. I think you're confused about the event time line. I wasn't having trouble switching into first until after I installed the new cable.

I'm able to start the bike right up in 1st gear & ride. I wasn't able to test it beyond that because it's been raining the past two days. It pulls in 1st gear if I start it there. A couple times I was able to start it in neutral & switch to 1st properly. But for the most part, switching to first from neutral is, like i said, a kill switch effect.

[Gene]

I don't know nothin' from nothin' - but - is it possible the neutral switch is somehow shorting out the bike?  You're in neutral, click into gear, idiot light goes off (elec signal), bike goes dead.

I'm prolly way off and this scenario is impossible . . . but it's the only connection I can think of.

[Airborne 82nd]

Airborne, the bike was sitting for two weeks because one of the throttle cables broke & I was waiting on a new cable to get here. I pushed the bike after the throttle cable broke. I think you're confused about the event time line. I wasn't having trouble switching into first until after I installed the new cable.

I'm able to start the bike right up in 1st gear & ride. I wasn't able to test it beyond that because it's been raining the past two days. It pulls in 1st gear if I start it there. A couple times I was able to start it in neutral & switch to 1st properly. But for the most part, switching to first from neutral is, like i said, a kill switch effect.

OK now I follow you. Now does it shut off as soon as you pull the clutch in before you move the shifter. Check the wire on the neutral sw. see if it is loose or dirty

[Patrick]

I've messed a bit with the K7 wiring on my K5 and nothing electrical makes sense, unless you pulled loose a wire when you were installing he new cable. But, if you have not adjusted that new throttle cable, check when the bike is idling that all four pipes are equally hot. It may be that the carbs are no longe opening properly with the new unadjusted cable and you are not firing on all four.

OK, I feel like typing some more, so that's why this is edited.

The clutch switch on a K7 exists only to potentially provide a ground for the starter circuit. The starter circuit gets its ground either from the neutral light or the clutch switch. Neither of those really ties into the running electrical system, except as a source of power. If either somehow were grounded or bad in a way that could affect the whole electrical system, I think the result would be a bit more dramatic than the bike dying.

So I have to go back to the carbs. You need to bump you engine a bit to get the bike to stay running in gear. If it is running on only two cylinders it can die as soon as you pull in the clutch when the clutch adds that stress to the engine. So even if it sounds like the engine is revving, it may have little torque.

But... check your coil wires. One might have come loose when you played with the tank.

Patrick

[AintNoEasyWay]

Airborne, the bike was sitting for two weeks because one of the throttle cables broke & I was waiting on a new cable to get here. I pushed the bike after the throttle cable broke. I think you're confused about the event time line. I wasn't having trouble switching into first until after I installed the new cable.

I'm able to start the bike right up in 1st gear & ride. I wasn't able to test it beyond that because it's been raining the past two days. It pulls in 1st gear if I start it there. A couple times I was able to start it in neutral & switch to 1st properly. But for the most part, switching to first from neutral is, like i said, a kill switch effect.

OK now I follow you. Now does it shut off as soon as you pull the clutch in before you move the shifter. Check the wire on the neutral sw. see if it is loose or dirty

I'm able to pull the clutch in & just hang out. No trouble there. Only when I press down the shift lever does the bike shut off.