having problems and need good advise!!!

[Anonymous]

i own a 1977 gs750!when trying to start it, it throws flames out the exhaust when it trys to start up!now ive checked to see if the coil wires are hooked up right and they are! somebody told me to check the timing that might be it! how do i do that and what might be wrong with it else!!!thanks!!!

[SqDancerLynn1]

Assuming that the carbs are OK & the plugs are ok not gas fouled. If it was mine I would change the coils. I had a simillar problem with my 79GS850 It would backfire sometimes when starting & sometimes when it was running it would backfire & die. Changed the points,plugs,checked timing no go -- took a new/used set of coils to fix it.

[Anonymous]

gs750 problems

yeah but when i start it and it trys to start and throws flames out the exhaust and poops!!!

[Anonymous]

gs750 problems

sorry i mean when i crank it and when it trys to start it throws flames and pops real loud out the exhaust

[feelergaugephil]

In reply

You didn't state if your GS had points! if it does it sounds like they need re-setting, if it doesn't it may be your coils or CDI box.

[Anonymous]

how would you reset the points?what is a cdi box?would maybe a exhaust valve be stuck open?

[Anonymous]

It almost sounds as if the coils are hooked to the wring cylinders and firing 360 out.

[feelergaugephil]

In reply

Your best bet is to buy a manual, Hey! I think I have a manual for one of those, let me know if you want it! cheap.
Your going to have to learn the simple basics of the timing, it's actually quite easy when you learn.
A CDI box is the basic replacement of the points, the points are on the right side under a small round cover held by 3 screws, take the screws out and see if you have points or CDI pick ups.

[Anonymous]

ok 4th cylinder has alot compression,3 has none,2 and 1 barely have any compression!can some one tell me what to do?

[Mr. Jiggles]

FYI - the GS's never came with CDI. It was either points or electronic ignition. Unless I'm mistaken, the '77s only came with points ignition.

Armyman, I'd get a manual for the bike, especially if you're unsure of yourself. I'd think that ignition would be the place to start looking for the source of the problem. If you can rule that out then I'd think about lifting the valve cover to make sure things are OK in that department.

[Anonymous]

ok 4th cylinder has alot compression,3 has none,2 and 1 barely have any compression!can some one tell me what to do?

Squirt a small amount of oil into each cylinder and re-run the compression test. If the compression goes up, you have a problem with the rings. If it does not, then the valves are bad. This just gives you some direction on how far to go with the teardown.

[feelergaugephil]

CDI

OOOOPS! my bad, about the CDI, I meant to say electronic ignition,,,

[Anonymous]

ok 4th cylinder has alot compression,3 has none,2 and 1 barely have any compression!can some one tell me what to do?

Squirt a small amount of oil into each cylinder and re-run the compression test. If the compression goes up, you have a problem with the rings. If it does not, then the valves are bad. This just gives you some direction on how far to go with the teardown.

I forgot to add that if it looks like the valves are where you are loosing the compression, check the valve lash. If this bike is new to you (or not) someone may have the valve lash set incorrectly and they are not seating.

Come to think of it, given the problems you are having, this is my guess right now.

[Don Lobacz]

Yes, check the valves if you have low compression: this valve configuration tightens with wear. Also, you may still have the wires wrong: the backfiring makes it sound that way. The best way to check is to hook up a timing light to each wire and make sure each wire is correctly firing with the matching timing mark.

[Anonymous]

ive checked the coils before they are hooked up right!left coil is 1 and 4, and the right coil is 2 and 3!i hooked them up as sitting on the bike from left to right ,1,2,3, and 4!anybody know anything else?