g9 jerking when starting

[Mike Mac]

First I would make sure the battery is good, load test it. Then I would take off, or just loosen the starter belt. Then try the starter alone, does it run smooth, don't run it long with no load, might over rev, and throw windings. Just short bursts. Don't know on this, but play it safe, high torque motor and all.

Brushes can be put in them, or possible bad bearings. I did mine. Easy job.

She just looks like she knows what its all about!!

[KFX700#319]

Well i messed weith this thing and messed with it....got it to start pretty easily in neutral but it is still jerking i am going to buy a new battery tomorrow and see what it does.... When belt is not on starter turns easily and does not hesitate or stop.. However i did notice that it seems to jerk worse when i pull choke on..when it is in gear it does it alot more....been having to start it in neutral and let idle down but not stall and then put in gear..also deos not seem to have much power at all..hardly go up small grade in yard..i did compression check and it is a lil over 180 psi does this sound correct?

[yamahag9er]

Wow 180 psi is right up there. Maybe your valves are out of adjustment and the motor isn't firing right.

[Mike Mac]

Ok, I would start with basic maint. With 180 #, Grounderpounder says to adjust valves, to .004 cold. 175 # is said to be normal. Then I would pull clutch cover off primary clutch and check for a bad weight on the clutch. There will be 3 weights inside on the sheave. Look to see if one or more are out of position or loose. You want to catch this one sooner than later, safety factor as well as cost.

Don't buy a battery till you Load test the old one, and don't jump it. Install it with its own cables. And now start looking for less than very clean elect. connections at all main junctions. Positive and negative.

I think I would also put a new spark plug in. its cheap.

Also not good for tranny to shift on the fly, you will break a gear!! Or worse.

[KFX700#319]

I just rebuilt the clutch new weights...it does it even with the belt disconnected...so i am not thinking the clutch....i put a new plug in it does same thing....i took the battery to get checked.....if it is bad i will get new one and install....valves were adjusted before i put engine in to. 004......i will check them again if new battery does not fix problem......then i will disconnect all wires and clean and reinstall......what about flywheel key possible sheared off?????........it also does not have much power so would that have any thing to do with the jerking...bad spark?...dont know just tossing it out there...i really am not sure. .....Thanks

[yamahag9er]

Didn't realize you just had the engine out. I am assuming with 180 psi of compression you either rebuilt or reringed it? You may be like a tooth off on the crank and cam or crank and ballancer or something like that. I saw one off by a tooth and it did run, but it would about rattle the teeth out of your head.

[KFX700#319]

i just got the enigne and the exhaust valve was bad so i put on a different head i didnt have bottom end apart.. is 180 psi too much compression?

[yamahag9er]

Well I don't know if it is to high, but that is probably about as high as I have heard of on a stock motor.

[KFX700#319]

installed new battery...didnt help any i took a video of it maybe this will help is there any way to have the starter generator checked..if i pull the plug out and turn it over it will turn just fine...no jerking....thinking maybe the starter generator may not be powerful enough to turn over on compression stroke.. i can turn the engine over by hand and it just feels like a compression stroke not grabbing or nuttin... i checked valves they are ok...

[KFX700#319]

VIDEO OF JERKING WHILE STARTING