'89 LT500 weak spark and hard starting

[toocheaptosmoke]

I've been getting a crash course in zilla's the past few days, my friend just got one and we've been working on it. It's in really nice shape overall but has a few issues that need fixed.

The first thing I found is this thing has very weak spark, you have to kick it over pretty fast to get any spark at all. The first thing I found was a bad plug boot and wire, replaced those. Then I took the coil off the frame and cleaned all contacts, then started fixing the hacked and corroded wiring between the CDI and coil. Got no improvement after all that. How were the ignition on these engines? Are there any common problem areas to look for? I have a spare coil from my 250R I can swap on to try, but I'm not sure if the two are compatible.

Another thing is the jetting, I only rode it a little but I could tell that it wasn't running at its full potential. Main jet is a 460 and the pilot is a 22.5, haven't checked the jet needle or needle jet yet, but assume they are probably still stock like the pilot. I think it might need a bigger pilot, seems a little on the lean side off idle. Haven't done any plug chops yet to see though.

Now I know what all the fuss about quadzillas are about, need to save up some cash and pick one up. Any help is appreciated.

[slammed2Stroke]

Sounds like a dead coil to me. My buddys LT250 was doing the same thing. Replaced the coil and it started right up

[FPMXer]

Did you try a new plug? Also remove the stator cover and make sure the counterbalancer seal is not leaking trans fluid in there and the stator and mag are now wet giving you the weak spark.

[miatv]

by jetting it sounds like a 87 zilla. spark is not real great, at least on mine. mine does run fine though. if you cleaned all the conections you should be fine. hard starting is common with the 87 carbs. also there is a little trick to starting one of these bikes. you need to get the piston at top dead center on the compression stroke. kicker only rolls the motor 180 degrees per kick. fresh race gas and you should be ok. still need to do plug chops. maybe bump the pilot? good luck.

[toocheaptosmoke]

I'll throw my spare coil on and see if that improves things then. I did try a brand new plug.

I'm pretty sure it's an '89, has a 7 stud head I believe. When I get a chance I'm going to pop off the exhaust and have a look inside the motor to see if any port work has been done. Might have an aftermarket pipe, unless the zillas came stock with a sectional pipe? Might work on it some more this weekend, will let you guys know what we find.

[fulltiltrider]

Originally Posted by miatv

by jetting it sounds like a 87 zilla. spark is not real great, at least on mine. mine does run fine though. if you cleaned all the conections you should be fine. hard starting is common with the 87 carbs. also there is a little trick to starting one of these bikes. you need to get the piston at top dead center on the compression stroke. kicker only rolls the motor 180 degrees per kick. fresh race gas and you should be ok. still need to do plug chops. maybe bump the pilot? good luck.

Should have good spark. These ignitions arent to bad for stock. In fact alot of guys say not to buy aftermarket, use oem parts.

These bikes start just fine when tuned properly. By properly I mean a little rich on the pilot. Mine starts as easy as my r, 1st or 2nd kick. My zilla is also around 200psi. I wouldnt want to even think about having a hard time starting it lol

[miatv]

factory main jet in 89 zilla with a stock carb, was a 350, pilot 22.5. for a stock factory bike. bump your pilot a little. i run a 28, but all bikes are not the same. don't change your main without doing a plug chop first. factory pipes are one piece for the front pipe. compression should be around the 160 or a little above. stock. really once you learn how they start, its pretty easy. mine may not start as easy as fulltilts, but its not bad either and i'm running a stock carb too.

[fulltiltrider]

Yeah, I dont have a stock carb. Its a later model 38 bored to 42.5 setup by ftz on alky. But I also had my 39pwk on gas on there and with a 58 pilot, it started the same way

[miatv]

i think the pwk starts and runs better than a bone stock carb. it least it did when i ran one before.

[toocheaptosmoke]

Mojavezilla (owner) and I worked on it some today. I swapped on a coil from my R and a non resistor plug cap, spark seemed to improve, we now had a decent blue spark, but it still was a little intermittent. We still had spark with the stock coil and a resistor cap, but it was orangish and intermittent as well. Took off the flywheel cover, counterbalance seal was alright, has a little seapage but nothing major. Didn't pop the flywheel but couldn't see any thing visibly wrong. No rust or corrosion. Still trying to see if it could be anything else before we try a new coil, will see if my flywheel puller fits tomorrow.

Also, took off the pipe, can any one identify it? I looked into the exhaust port and everything looks stock and unmolested. In the box of spare parts I found a cylinder with "Trinity II" engraved on the side, thinking the carb may still be jetted for the modded cylinder. Also got a question about the "power valve" on this engine. I'm familiar with the RAVE type systems on sled engines that use a slide to change the exhaust port duration. But, I can't really see how the hole on the bottom of the exhaust passage works, where does it go? And what does that knob change?