Bike bogs down and dies when hot

[Guest]

I have a 1983 gs750es, idles great starts up immediately even when it's cold, runs great until 15 to 20mins est. I notice when it warm or hot it sputters randomly on all carbs, when I was riding today my rpm was just at 6000rpm on 3rd gear, I notice when I was approaching a stop light when it reaches 2000rpm it bogs down and I need to rev it up to keep it running, at one point bike died while on a stop light(embarrassing) and won't start, it will crank but slowly like it's out of juice but my battery was fully charge when I left home, I had to push my bike on the side check what the hell was going on and found nothing after a few minutes I tried to start it again and it did I was able to ride it for a good 10 mins untill I needed to stop so then it died again and won't start like it has no juice, it was a down hill so I put it on 1st gear pulled the clutch when I reach 3mph pop the clutch and tried to start the bike untill I got home... When I got home it let the bike cool of then tried to start it and it did with out any problem... So I'm thinking my engine is over heating, oil is not circulating properly or coils are bad,( I heared the coils are heat sensitive and prone to malfunction when hot) or a mix of the things... Need some help figuring this out

 

[TxGSrider]

Might try grabbing a spare spark plug and next time it happens, immediately pull a plug wire and put the new plug on,set it on the head or some clean metal on the block or frame, and turn the starter and see if its sparking. If it is, you're probably ok and you can look at the fuel system. Plugged petcock filter, plugged inline filter if youve added one, plugged vent, kinked hose, etc. Good luck.

 

[Rich82GS750TZ]

Check that your gas cap is venting properly. Next ride, when bike dies, remove gas cap. If you hear/feel a release of pressure, you may need to clean or replace the cap gasket or even the whole cap. If the cap isn’t venting properly, the carbs will starve for fuel after running for a bit, so I’ve read.

 

[zuluwiz]

Another possibility is an air leak in the intake rubbers.

 

[Guest]

Might try grabbing a spare spark plug and next time it happens, immediately pull a plug wire and put the new plug on,set it on the head or some clean metal on the block or frame, and turn the starter and see if its sparking. If it is, you're probably ok and you can look at the fuel system. Plugged petcock filter, plugged inline filter if youve added one, plugged vent, kinked hose, etc. Good luck.

All the spark plugs are new just a week old but I did pull out all the plugs and they are all black dry like bike is running rich ground it on the cover and it has a strong spark, sparks arcs even half an inch away. Oh BTW spark plug cap is also new its an NGK and cables are also new for all four. I'm running 135 main and 115 pilot.
Will check the others and update you guys thanks

 

[Guest]

Check that your gas cap is venting properly. Next ride, when bike dies, remove gas cap. If you hear/feel a release of pressure, you may need to clean or replace the cap gasket or even the whole cap. If the cap isn’t venting properly, the carbs will starve for fuel after running for a bit, so I’ve read.

Thanks I'll check that and update you guys

 

[Guest]

Another possibility is an air leak in the intake rubbers.

I did notice a hissing sound when I tried it at home sprayed carb cleaner on all the intake boots and found on carb no. 3 where the you insert the carb in the boot bike dies when I sprayed carb cleaner.

 

[Guest]

Good new bad news then good news again... Good news is bike hs spark even if hot, petcock filter looks OK, gas tank cap is not hissing or pressure, gas is flowing properly as expected, made a bit of a mess, I remove the gas tube from the tank and gas is flowing while engine is running air leak on intake boot fixed... Bad news is timing chain broke while bike was idling at home... Good news again disassembled the engine no piston damage and no bent valves, no damaged rocker arms ar anything lucky me I guess?

 

[pdqford]

Why do you think the cam chain broke?

 

[Guest]

Why do you think the cam chain broke?

That I'm not yet sure, I'm running things on my head why, either too much mileage or chain tensioner is faulty but I did find one of the chin guide is damaged not sure if that cause the chain to break or it was damaged because the chain broke. One thing is for sure I follow the shop manual last time I adjusted the cams, 20 links exact end to end, from the center where the arrow points from the intake side to the arrow on the exhaust side and reset the chin tensioner