G9 Ignition Timing

[patrickl]

Good Evening from Australia. I have a 1994 G9 Gas Cart Serial No. JG5-313698. This afternoon I checked the ignition timing with a timing light and I can see that the ignition is firing at approx. 30 deg BTDC at all rpms. I would like to know if this is correct. I expected to see it firing at close to TDC at idle and then advance to 30 deg when speed reached approx. 3000 rpm. If my cart has a problem what years use the same ignitor unit? Thanks Pat

[G1-G9]

91-95 G9s all use the same ignitor.

[patrickl]

Thanks for your reply. I also need to know if there is an advance curve. Currently the timing is fixed at approx. 30 deg BTDC. I expected to see it firing close to TDC at idle and then advancing towards 30 deg as the speed increased to around 3000 rpm. Pat

[sho305]

In the manual you can download someplace here, it says it is in fact 0 degree at idle/starting and ramps up to 28 or 30 at 2500rpm then stays there. Check connection at ignitor sometimes pins go bad though it may not help you. Also check ground wires. But yes I think it works as you say (when correct). You can change a wire and use a G2 ignitor but it has a rev limit in it and G9 does not. They are expensive but don't go out very often. Sometimes they go bad when hot, sometimes you can squeeze them and they work, but only a way to know for sure the ignitor is at fault which you already know.

[patrickl]

Thanks Sho305. I will do more testing today with a timing light after checking the wiring associated with the ignition. The numbers painted on the ignitor are JG5-01 and J4T044. The first number is a Yamaha number and I think that the second is a Mitsubishi number. I would also like to know the correct spark plug number. The G2 manual says NGK BR5ES and a Spark Plug Cap with a resistance of aprox. 5 k Ohms. Seems strange to me that a resistive spark plug is used with a resistive spark plug cap - hence the query about the correct spark plug number. The cart came to me running rough, lack of power and the need to occasionally use the choke. I found that the insulating block between the carb and the cylinder head was cracked and sucking air. This block has been replaced and the cart is running much better and the need to use the choke is gone. However, I think its still down on power. Compression pressure is good -165psi -, fuel pump is pumping OK, valve clearance is fine. Today I will check out the ignition wiring, recheck the timing curve and service the carburettor. I would have thought that starting would be difficult if the timing was fixed at 30deg advance. Thanks, Pat

[patrickl]

I did some more testing on the advance curve. The ignition fires at close to TDC at cranking speed but by 1350rpm the ignition is firing at 25-30 deg BTDC and remains solid as the rpm increases. The manual says that it should ramp from 0 - 30 deg BTDC as the speed increases from 1000 rpm to 2500 rpm. So currently if the revs drop below 2500 rpm there is too much advance. I will wait until I have the opportunity to borrow an ignitor to do more testing. The cost of an ignitor here in Australia is expensive so I need to be sure that the performance of the cart will improve significantly before I ask the owner to spend hard earned dollars. The cart starts easily, runs fine at cruising speed but seems to bog down climbing steep hills at low revs. This is where I think the correct advance curve will help. Pat

[nobuckbuild]

I think you are chasing a problem that does not exisit , they all slow down going up hill it has more to do with the clutches than ignition , the ignition either works or it doesnt , the carb issue you had and imagine you are still having is the carb must be super clean and all intake both before and after the carb must be sealed on these for them to run correctly, its the nature of these carts to bog due to way to much intake air or leaks

[G1-G9]

For a 8-9hp engine you are going to slow down on any steep hill. I would upgrade your secondary clutch and you will see a big difference. Like Buck said the ignitor either works or it dosen't. I would check out Don Plowmans clutch kit. Best upgrade you can do for your stock cart. Well worth the money.

[patrickl]

Thanks Buck and 61-69. I no longer have any air leaking around the carb flange or air box. The carb has been cleaned and the float level checked so I am confident that there is no issue there. I realise that the cart will slow down on the steeper hills but in this case I think that performance could be better.
The cart is running fine but I will now wait for the opportunity to borrow a ignitor to do some testing. Thanks for your help. I will report back my findings but it may be some time down the track. Pat

[sho305]

You should use the plug for newer yamaha carts, bprs2es iirc, it would be listed for a G16 I think. Was told this by a dealer its more resistant to fouling and not much different. Has worked great in our G9s.

Issue with engine power is it affects the CVT, and the CVT will also affect engine power. If low on power the CVT does not shift right as its tuned for X power. If a problem with CVT then it does not shift right and you don't get the proper rpm to get your power. If it bogs you are either low on power or more likely the CVT has a problem. The engine tends to run or not, they don't lose much power before the oil rings finally go out and they smoke oil.

I would check the CVT first. A worn belt will hurt power 1" wide is the wear limit if you are close to this you lose power mostly under high loads like hills, new is 1 3/16" wide. Second the primary can break weights or bad rollers depending on what one you have, but that usually results in it reving up and you lose top speed as it wont shift out all the way. They take one pump of grease or it comes out on the belt. The secondary check the plastic pads on the ramps, it also takes one pump the zerk is in the edge of the primary sheave at edge of cover and near the ramps on the secondary. Also check the tension cable its under the generator pulley it holds the engine under high torque, if broken or missing it will bog on hills. You can make one out of threaded rod or bolt the right size and a heavy washer welded to it like an eye bolt. It should be slightly loose at rest, when the engine mounts move it holds it, when the engine pulls closer to the trans under high loads. Check that stuff and see what you get.

If the CVT is working right and its running well it should rev up a hill unless its very steep or you have lots of weight on the cart. On grass a stock cart should about spin the tire before it bogs unless the cart has a lot of weight on it for extra traction. The cart can bog if you go less than about 3mph and have lots of traction it cant rev going that slow.