Unlike the other recent posters problem, mine starts fine when cold, but when warm.. its tough!!
Its ported, ect... and the pilot jet is stock. Could this have anything to do with the hot startup difficulties?

Another thing, When trail riding, It loads up and wont rev very high, but If I just get on it for a few seconds down a dirt road, it clears out, screams and pulls.
Then, putt...putt... loaded up again. (more loaded up, and quicker than 2 stroke normal)
Is this an indicator that my jetting is too rich?

 

Bad reeds maybe?

 

OR maybe a choke sticking open a little?[img]i/expressions/face-icon-small-confused.gif[/img]

 

Sounds like maybe your air screw may of loosened or tightened up a bit, check your shop manual (You do have one right?) and see what the settings are for the air screw, like maybe 1 1/2 or 2 1/2 turns out. My brother had an 87 lt and for some strange reason the air screw never stayed put, so I adjusted it to where it liked it, then used some silicone on top of it to hold it in place. Voila! worked like a charm, and if it needed replacement due to mods, just peel the silicone off, and remove the screw. His did exactly what you ars saying, so it may be the prob. This didn't happen after any engine work right?

 

There are several things that could be causing the problems you describe. What are you mixing the gas at, if you are mixing at 20:1 as Suzuki suggests try 28:1 or 32:1 with a good oil, I've tried them all and seem to have the best performance with Castor 927, plus it just plan smells good when it's burned. Maybe try a hotter plug. Loading up will happen if you are milking it too much. The air screw as suggested by FireBlade could be the problem. Suzuki's shop manual says the screw should be out 1 -1 1/2 depending on temp and alt. I have mine out 2 1/2 turns that seemed to work best for me. When you are trying to start it hot and it won't start have you ever pulled the plug, is it wet with gas or dry?

 

What are you useing for a carb? When I had my motor ported and tryed to use the stock carb I could not get it right. I now have a 39pwk and and that took care of my loading up at slow speeds. I mix my gas 1/2 92 oct. and 1/2 race gas 108 at 36 to 1. It runs like a champ

 

I agree with what the other's have said,but you could also check the jetting,air cleaner,and it could be overheating,if you want to use a really good oil go with Klotz Benol.With the high compression you might have to go with a higher octane gas.When i first got my Zilla it would overheat like that,loose power,and sometime's sieze up cuz the piston was swelling up,let it cool down for a few and it would start.You may not be too rich but too lean,one way to check this is to run it and when it start's to boog down flip the choke on,if it cure's the problem,then your too lean.Just some thing's that I went through with mine.

 

Starting a 500 is alot different than most. Are you new to the zilla? It takes a while to get use to any motor. They all like to start a certain way. I use to tell people that I would give you my yz 426 if you can start it. (only if they had never ridden one ) My buddy had a cr 500 and you had to start it a certain way and the zilla is the same way hot or cold. If you are use to the zilla I agree with the other posts about your air and idle screw.

 

Easy starting cold and hard starting hot is an indication its rich, the pilot/airscrew.

Best carb info I have found is here. Duncan Racing Go to the tech page and click on carb jetting.


This is a bored out carb, right ? I had nothing but grief from my bored stock carb... I put on the 41mm Keihin and I love it. Took 15 mins to jet and make it run like a killer.

 

Forgive me if I am wrong, but aren't you the guy that has been raving about his engine builder? If so, where is he now? The great thing about having your engine built by a reputable shop is the service after the sale. If you haven't already, call this shop and explain your problem. If he is half the engine guru and stand-up guy you claimed he is, he should be extremely helpful. One call should net you a short list of possible remedies. This shop will probably be willing to bend over backwards for their biggest online supporter/pusher!