LT80 Quad, power to starter - fixed, spark - fixed, compression... ummm

[Kitt]

So I figured out the ignition bypass and found a bad relay, but now it's turning over with no spark. Could be stator, cdi box, coil, bad ground or connection somewhere.

Any suggestions on how to troubleshoot or go about finding the problem without buying new parts to try?

[Doc]

Got a voltmeter?

[Cerberus]

Got a voltmeter?

and a wiring diagram?

[Kitt]

yes and yes

[Kitt]

[Kitt]

this may be old, I don't see a CDI box on this

[Cerberus]

this may be old, I don't see a CDI box on this

almost certainly an old diagram.

find a current one

[Kitt]

well the bike is pretty simple.

The CDI box is the only thing missing.... from what I can tell, the wire colors and components are the same otherwise. I'll look though.

[Cerberus]

well the bike is pretty simple.

The CDI box is the only thing missing.... from what I can tell, the wire colors and components are the same otherwise. I'll look though.

being that we are dealing with a loss of spark issue, a proper schematic that includes the cdi is required, no?

also, just for the sake of discussion, wouldn't it have been easier to just buy a new switch? or better yet, surgically disassemble the one you had with no key to so you could use it keyless?

just sayin..

[Kitt]

looks like the manual is the same for 1987-2006

[Kitt]

being that we are dealing with a loss of spark issue, a proper schematic that includes the cdi is required, no?

also, just for the sake of discussion, wouldn't it have been easier to just buy a new switch? or better yet, surgically disassemble the one you had with no key to so you could use it keyless?

just sayin..

ignition is bypassed with no problem... starter turns.

I just can't get a spark.

[Boston Moto]

Bad contact in engine kill switch.

I'll bill you later.

[Cerberus]

ignition is bypassed with no problem... starter turns.

I just can't get a spark.

right, which (devils advocate) begs the question whether or not something that you rigged is to blame, or a bad part.. and takes the standard diagnostic process for this machine and throws it in to question.


at any rate, it looks like the cdi is dependent on the magneto to get its juice.
i'd be checking for power at the input to the cdi, and if it is there, be suspicious of the cdi itself

i would make sure that 5amp fuse is good btw..

[Kitt]

fuse is good, cdi box has 4 leads going in... 2 of them have 12 V

[Kitt]

Bad contact in engine kill switch.

I'll bill you later.

when engine kill switch is "off" it doesn't even try to start... when it's "on" it starts - made me think the kill switch was fine.

[Cerberus]

fuse is good, cdi box has 4 leads going in... 2 of them have 12 V

then that schematic is useless, since it shows only two leads going into the "ignition coil and unit"

[Kitt]

well that's the schematic in all the manuals haha... had to work with what I had.


Have spark now (found 2 wires that had melted insulation and fused together).

Cleaned the carb, no leaks around it... it would have a single explosion here and there with starter fluid, but once i got it all back together, still no explosion. the bike has a "prime" position on the tank, so there is fuel sitting and waiting to be used... starting fluid in the intake has no effect now either.

fun - this is hours now spent on a quad that's not mine! bleh.

[Kitt]

k... Fun Fun, did a compression test. 45 pounds roughly. NOT GOOD. I think recommended is 120-130, but anything less than 100 is typically not good.

You guys recommend

1. piston/rings (about $70) - Not sure what piston I would use... the sleeve is slightly worn on one side (but the rings were horrible).

or

2. piston/sleeve kit (about $180)





**Can a mod change thread title to "lt 80 - no compression"? thanks!

[pasta-rocket]

I just read this now......sorry kitt. I thought the bike just needed a key. Thet me know what it ends up being and i will take care of you.

[BMFR6]

**Can a mod change thread title to "lt 80 - no compression"? thanks!

go to your first post, click edit, then click "go advanced" and you will be able to edit the title yourself.

but as to your best option regarding compression.... i add no value here. i would try the cheapest method but i'm cheap.

[Cerberus]

k... Fun Fun, did a compression test. 45 pounds roughly. NOT GOOD. I think recommended is 120-130, but anything less than 100 is typically not good.

You guys recommend

1. piston/rings (about $70) - Not sure what piston I would use... the sleeve is slightly worn on one side (but the rings were horrible).

or

2. piston/sleeve kit (about $180)





**Can a mod change thread title to "lt 80 - no compression"? thanks!

not necessarily in need of a re-ring job..
i used to get jaguars with bad nikisil plating that would wash down (fuel wash all oil residue off the cylinder walls) and make very low compression.. until you add a dash of oil to each cylinder and voile(sp?) it would fire up and run perfectly.

if you are already into it, i'd just hone the cylinder very gently (to create cross-hatch for break-in purposes) and re ring the current piston (unless it is damaged)

..or just do it the right way lol

[TIMMYDUCK]

Kitt,

Check the safety feature on the rear brake pedal.

That silly little bar must be locked or you will not have a proper circuit.

[Kitt]

ok, what i'm planning on doing is bringing the top of the head (with the sleeve pressed in it) to noel to have it honed and a bore mic put in it... then i'll order the $70 wiseco piston to fit the piston as is.

Scott - the sleeve doesn't look half bad (wish i knew the oil trick before I yanked it all apart). The head on the thing was loose the entire time (realized this when I finally got spark), so i'm sure it was dry as a beach in there. I did notice a lot of play in the piston to the sleeve, the rings aren't really compressed in there anymore (kind of just floating) and one is pretty worn.

I really think the sleeve is ok. I'd say it's going to end up needing a 0.5mm oversized piston, we'll see. I NEED GARAGE SPACE TO GET THE RACE BIKE READY DAMMIT.

[Boston Moto]

when engine kill switch is "off" it doesn't even try to start... when it's "on" it starts - made me think the kill switch was fine.

Meh, worth a shot. Most bikes will turn over but no spark with kill switch off.

[Cerberus]

ok, what i'm planning on doing is bringing the top of the head (with the sleeve pressed in it) to noel to have it honed and a bore mic put in it... then i'll order the $70 wiseco piston to fit the piston as is.

Scott - the sleeve doesn't look half bad (wish i knew the oil trick before I yanked it all apart). The head on the thing was loose the entire time (realized this when I finally got spark), so i'm sure it was dry as a beach in there. I did notice a lot of play in the piston to the sleeve, the rings aren't really compressed in there anymore (kind of just floating) and one is pretty worn.

I really think the sleeve is ok. I'd say it's going to end up needing a 0.5mm oversized piston, we'll see. I NEED GARAGE SPACE TO GET THE RACE BIKE READY DAMMIT.

you say the head was loose the entire time?
and it made poor compression?

strange....