motor spins up great on starter but slows to a stop

[greenbraes]

Hi Guys

I have just got back to the project (GS1000E), sat for maybe 4 mounths in the garage. New battery fully charged, engine spins up great on the starter for maybe 5 to 10 seconds then slows right down to a stop (engine has not fired up). Turn everything off for 10 seconds and it does the same again. The wires coming off the battery are not hot, just warm and no more. Any help much appreciated. Some info that may help. The bike was starting and running OK 4 mouths ago but did sit for 17 years in a shed before that, oil is new, clutch is new and not binding, valves clearance is all good, carbs are cleaned and set up. One thing though, when the throttle is closed the engine is slow to spin, open it and it spins fast before it slows to a stop.....

cheers RB

[Steve]

I am a bit confused about this statement:

..., engine spins up great on the starter for maybe 5 to 10 seconds then slows right down to a stop (engine has not fired up).

If the engine has not fired up, how can it "spin up great on the starter"?

Are you saying that the battery does not last very long?

If you have a standard wet-cell battery that has not been maintained for the last four months, it is likely somewhat discharged.

.

[steve murdoch]

I was thinking the starter over-heating and seizing but it doesn't sound like it is spinning long enough for that to happen.
Plus it would take longer than 10 seconds to cool off.
Are you positive the battery is fully charged?

[greenbraes]

the battery is brand new and been on charge with the 'charged' light on the charger for a few hours....when I say the engine is spinning up I am meaning the starter motor is turning the engine over pre running..it turns over/cranks fast to start with...I have not managed to 'start' the engine yet..it has not pulled enough fuel through to the carbs

I have got the old battery on charge...it is pretty much duff but at least it will give me an idea if it is the new battery

cheers

RB

[tom203]

Ten seconds ain't long enough to overheat starter motor, but its brushes/springs could be tired and back off commutator as they get toasty.

[greenbraes]

charged both new and old batteries up, engine turned over a few times and stopped, all I get now is a clicking from what I think is the starter solenoid. I pulled the plugs an the still no movement in the engine from the starter, put it in gear and the engine turn OK from turning the back wheel. both the old and new battery are not turning the engin over...going to take the starter off and have a look at it....anything you guys can tell me what to look for?

cheers..yet again

RB

[hampshirehog]

Yep, sounds like worn brushes or a dirty armature on the starter motor. The manual will give you minimum brush length - you can go a little shorter but not much in my experience.

[JTGS850GL]

Check the voltage at the battery when cranking and check it at the starter motor. Should be very close. If not then you have a dirty connection. You might want to clean the thick ground wire connection at the back of the motor as well. Could be a bad starter motor but could also be a bad starter solenoid or dirty connection.

[greenbraes]

thanks forthe info guys..I have ordered a new solenoid and a set of brushes..will get the starter out in the morning and get it cleaned up and looked at

cheers

RB

[JTGS850GL]

I wouldn't have ordered any parts till the problem was diagnosed. Don't you have access to a volt meter?

[greenbraes]

I do yes, the brushes cost ?6 (this is including P&P) and regulator has been given to me for nothing (old stock getting cleared out)...I'm sure some new brushes won't hurt....I'm away from home for a few days now so thought it would be good to have some bits available for me when I get home

RB

[greenbraes]

well got home today...took the starter cover off and found it was the wrong cover for the starter motor, the terminal had been shorting out a bit on the cover...the indent for it was not in right place...sorted this out and still no go..so out came the motor and found it from an early GS1100 (1980)..not the GS1000..hence the cover was wrong..anyway stripped the motor down found it full of gunky goo..cleaned it all up..found one brush just about done, replaced brush and motor back in and engine now cranks like a new one...well happy...hampshirehog you hit the nail on the head..

cheers for the help guys

RB

[steve murdoch]

Thanks for reporting back and glad you got it sorted.