Hey guys just found this forum. I have a quadzilla that was on a stock bore till about a month ago. The skirt of the piston broke off and seized up. I bored it .010 over and put a wisco piston in it. well actually It was bored out to the correct mm value but what ever. Fired right up. and had a bad vibration. I brought bottom end back to shop. (they put the new crank bearings in) and they said they were fine. Motor bogged down and would die at high rpm with (Pre blow up) carb settings. I have the carb running i believe to be very rich and stumbles on itself on bottom end but clears out and comes to life top end. The only other work done to the bike is a FMF exhaust and FMF reed valve. The vibration seems to go atleast dampen while riding. Please help i want to be able to stay up with the new sprot bikes off the line.

Everybody expects the bike to perform and it sucks when it dosen't

if you have any ideas please help

thanks

 

Zillas are notorious for wallowing out the cases around the main bearings. Are you running pump gas? Stock carb? How did it run before the rebuild? There's some people here who know alot about zillas but Macdizzy or Planetsand might be a better source for info.

 

Did you line up all three timing marks? On the drive gears and crank. Alot of people only line up the marks on the gears. and dont know there is a timing mark on the crank shaft to. Also did they just replace the bearing? Did they balance it also very important. Make sure the counter balancer is tight. Did you replace the seals? You should also do a leak down test. Cause if you have an air leak you wil never get it running right. As far as the new sport quads. Your zilla should walk all over them mine does.

 

have not done leak down test. Three timing marks? I thought you line up the mark on the crank with the mark on the balance shaft. what other mark are you supposed to line up? I followed the service manual. They put in new crank bearings and seals. they split the case (don't have the correct puller) so iff if it is inside then i didn't do it. Motor ran fine before blow up. was loosing power but also loosing alot of compression. The cylinder was egg shaped enough to bore it but was flawless other than that.

pump gas 93
stock carb

balance the crank? if that is the case no.. the crank was fine before the piston went.

I just rebuilt it following the same steps that i did for my LT250R over 5 times now.

thanks for the responses

STeven

 

If you followed the service manual, you should have seen ALL 3 timing marks.. Go back and look again, there is one mark on the crank that lines up with the two on the counterbalancer gears... ALL 3 MUST LINE UP!

Changing the pipe/reed parts will require a change in jetting... Therefore your old (Pre-explosion) jetting will need to be adjusted.

Anytime the motor has been disassembled, a leak down test should be preformed... It can find problems before the gremlins get to it.


Rooster is right on the $$$ with his advice!


IF you still have vibrations after you correct the counterbalancer timing issue, let us know... we'll help you look further.
Lets hope your cases are in good shape (Assuming so, since it wasn't vibrating prior to kaboom)

Otherwise, Get it jetted right! And go kick some butt...
http://www.eric-gorr.com/twostktech/carbtuning.html

Regards,

 

Not to hijack this thread... but.....

Anybody interested in a chrome LRD adjustable pipe for an LT500???

I might know of one that should be comming available in the near future.... PM me.

 

The good news is the engine can remain in the bike. If you pull the clutch cover you can remove the nut on the crank. Its a left handed thread. You can stop the crank by removing your spark plug and drop a piece of 1/2" rope into the spark plug hole. With the piston down drop in about 6 inches of rope then turn the crank nut the piston will come up and stop on the rope this is very safe. I have done it many times. Then look for the punch mark on the crank shaft then look for the two punch marks on your drive gear and counter balancer line up the three marks and your good to go.

 

I just got my zilla running also and it had a little vibration when i first started it. I hadent mounted the head mount to the frame yet becuase i firgured it wouldnt matter. Plus I was excited and wanted to hear her run. Well needless to say the head mounts do make a difference. My little vibration diaspeared after mounting the head. Make sure all your mounts are tight.

 

I will check it out. when I have it open i will hopefully be able to see what your talking about.

I knew it would need jetting but wanted to get these gremlins before sinking any more money into it.

will check mounts

thanks for all the replies

steven

 

Ok guys I took it apart and was looking at the drive gear and don't see a thing. When you say drive gear are you talking about the gear that is in mesh with the clutch basket? I took off "that gear" I wish i had a difital cam. MY crank and balancer gear line up do to dot. what other gears are there? It says in the manual to line up all three like you guys have mentioned and in the picture they show and cirlce the two dots lining up on the balancer gear and the balancer drive gear. WTF. where is this other gear? Is is the gear that drives the clutch basket if that is the case there are no dots marks on it.

also providding i get this figured out. what is the best way to test for air leaks. Like NASCAR did/does with a can of either and spray every where air shouldn't be going in?

I't been almost two months now dealing with this

thanks for any more help in direction me in the right direction.