Suzuki Quadracer HQ
LT500R Quadracer => LT500R - Engine => Topic started by: Marcman804 on October 06, 2015, 11:10:29 am
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Hey guy first u need to find out wat yr quad u have cuz changes were made from 87-88 an 1990 carbs had sum changes clik on lt500r engine changes from 87-90 figure out ur yr an Dave s post tells u exactly what ur original jets/slides/needles shld be an go from there.GL guy
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I get my jets from www.jetsrus.com but Im probably paying too much, IDK
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You can buy them from many different places. Just look for the trade make on the jet. Mikuni's trade mark is a square with a smaller square inside the larger square in the lower left hand corner. Keihin's trade mark is a distorted 4 point star.
We buy from the USA importer for Mikuni and Keihin. If they will not sell to you, you can get them from us.
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Where would I be able to get genuine mikuni jets? I see lots of sites when I google for genuine but where do you guys get them. The atv shop near by has mikuni jets but are from a different style carb.
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I need to replace the slide on the stock carb and I was looking on Ebay and was wondering if you guys could check this out and let me know if this would be a good replacement and if not where else could I find one. http://www.ebay.com/itm/151232466016 (http://www.ebay.com/itm/151232466016)
Also, I've been still trying to get the best jetting. I've ordered jets from MFG Supply and I have read that not all jets are equivalent or accurate as the oem jets. Do you guys think these jets are good enough?
http://www.mfgsupply.com/snowmobile/snowcarb/snowcarbjets/snowcarbpilotjets.html (http://www.mfgsupply.com/snowmobile/snowcarb/snowcarbjets/snowcarbpilotjets.html)
Thanks for all your help. This has been a real struggle but Im keeping my patience with my mighty Zilla lol.
Use only genuine Mikuni or Keihin jets. The few dollars you save by using the aftermarket jets will not offset the cost of doing a top end if you are unfortunate enough to get some jets that are not sized/dimensioned and marked correctly.
The hole size in a jet is only one of the many different dimensions that make a jet flow like it is supposed to flow.
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I need to replace the slide on the stock carb and I was looking on Ebay and was wondering if you guys could check this out and let me know if this would be a good replacement and if not where else could I find one. http://www.ebay.com/itm/151232466016 (http://www.ebay.com/itm/151232466016)
Also, I've been still trying to get the best jetting. I've ordered jets from MFG Supply and I have read that not all jets are equivalent or accurate as the oem jets. Do you guys think these jets are good enough?
http://www.mfgsupply.com/snowmobile/snowcarb/snowcarbjets/snowcarbpilotjets.html (http://www.mfgsupply.com/snowmobile/snowcarb/snowcarbjets/snowcarbpilotjets.html)
Thanks for all your help. This has been a real struggle but Im keeping my patience with my mighty Zilla lol.
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Yikes that is expensive.... but at least they still have it available. That is a plus I guess. My Cool Head is working great so far Jerry. Thanks again!
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The squish is not correct on a new Cool Head either. A stock head or a Cool Head need to be machined to correct the squish problem and the cost for machining either one is about the same.
If your stock head is beyond repair then it is cheaper to buy a new cool head. Suzuki wants over $700.00 for a new stock head.
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you could take your stock head and send it to carl bartlett or HPR and if your lucky Q might do it and all three of those guys will tell you to buy a better pipe ... but just fixing the head will do wonders for reliability and performance for your machine ... if you have a 87' have it o-ringed while they have it and ordering a pro-design head will require the same machine work done as the stock head .... they do look cooler and call the machinist prior to purchasing any domes as they all have different opinions on how to set up your motor....good luck and this bike should run with any of the bikes you mentioned if running properly
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The domes are for the cool head. You'll have to send the entire head off to get the dome reshaped if you stick with the stock head.
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Thanks man. I see some Pro Design domes on eBay? Are they decent? If so I'll get one asap. And would I need to get the entire cool head or would I be able to use the stock one? Just not trying to fork out a ton for another exhaust this close to Christmas.
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Not sure what all you've do to it but a new exhaust would go a long way. FMF falls on it's face at about 5k RPM. 4-5k RPM is about where the big boy pipes start coming alive. Have you done any head work? The dome really needs to be reshaped to solve the deto issues and it's not very expensive.
It's a labor of love my friend. And once you start adding HP, lots of stuff starts to break. (cheap/poor quality 80's suzuki metal and parts)
But once you fix everything, they can really be quite reliable. Knock on wood, my bike has survived about 5 seasons with ZERO breaks (all sand dune riding).
She's getting a little tired though, time for a top end rebuild.
Good Luck. +k2
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Yeah I understand that. I just want to experience it in its full potential. Right now my Raptor and my brother's Banshee would tear it a new @ss. It's not terribly slow, I can feel the power down low but just seems like its running out of steam on the top side still. It's not breaking up but just doesn't have that wide open feel like most 2 strokes I've ridden. The Banshee seems to keep pulling hard in the upper RPM's as the Zilla hits a wall. I'm thinking it may be the exhaust. I have the FMF and I've read so far that its pretty much at the bottom of the barrel. What do you guys think I should do next to help it out on the top end.
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I'm getting so frustrated with this, almost ready to trade it for LTR450.
If you're going to have one of these that runs well you best get used to wrenching on it, there's always something to fix +k2
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I finally got around to trying my buddy's 250r cdi on my zilla. It solved the problem but its still not as fast as I thought it would, I was hoping this thing would be faster than my Raptor. I'll do some research and see what I can do to unleash more power out of the beast though. A little disappointed but I know it has lots of potential.
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Breaking up on top is a rich condition or an electrical problem.
An electrical problem could be a loose connection at one of the bullet connectors, a bad component (spark plug, spark plug cap, stator, coil, CDI box, kill switch or wiring harness). It is a process of elimination
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I have no idea what a roost boost is? Would a bad cdi cause it to break up?
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you're not running a roost boost are you?
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I got the power valve closed shut and took a flat piece of metal and closed it where the spring would go just to make sure it stayed closed while riding... it's still breaking up on the top side. This is with the 380 main and 30 pilot. I'm beyond frustrated
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Thanks man. Thats exactly what I needed to hear... Im going to give that a try as soon as I get home from work, just sucks it gets dark so early now. Will I need to replace the gasket on the sight glass? I definitely want to keep it and get it running right because these things are pretty rare, most of the people around where I live never even heard of them, and they are shocked knowing its a 500... 2-stroke lol. Again, thanks for everyone's help and advice.
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I also noticed when I take the cap off the adjustment for the powervalve it turns very freely... should there be some resistance or is that right? And I punch the throttle really good and I dont see much movement in the sight glass if any at all. Do I have to remove the cylinder to further check the power valve? I'm getting so frustrated with this, almost ready to trade it for LTR450.
Remove the cover with the sight glass on the lower right hand side of the cylinder. Use a pair of needle nose plyers and try to move the rod up and down. If it moves up and down, remove the exhaust pipe and look to see if the valve is fully open or fully closed.
If it is stuck fully open, there will be a huge loss in power in the mid to high RPM range. If it is stuck closed there will be some power loss in the 4000 to 5500 RPM range.
If the valve malfunctions it is best for it to be stuck closed. If the valve is stuck open, it will often cause the piston to overheat if the engine is run hard in the RPM range where the valve should be closed.
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I also noticed when I take the cap off the adjustment for the powervalve it turns very freely... should there be some resistance or is that right? And I punch the throttle really good and I dont see much movement in the sight glass if any at all. Do I have to remove the cylinder to further check the power valve? I'm getting so frustrated with this, almost ready to trade it for LTR450.
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How hard is it to get to the rod? Would I have to remove the entire cyclinder? Anyone know where I can get some pics or a vid?
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You can unhook the power valve linkage and then yes you can lock the Powe valve. Just make sure you remove the rod so it doesn't try to engage.
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Yeah it turns pretty freely, its not binding or anything. Is there anyway I can turn it so its closed and then lock it down without the spring or is the spring necessary? I read on one thread where a guy put a dime between the cap and the valve, not sure exactly what this did but was wondering if that would lock it in place?
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wow!
Order a new spring from somewhere like Bikebandit.com.
I like to use them because the shipping is fast. Not usually the best price, but that spring won't likely vary in price much.
Does the PV turn freely? Hope it's not stuck.
Also, it will be a good idea to go ahead and replace the rubber seals that you can get too.
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I finally got around to taking the cap off of the power valve adjustment and the spring was a mangled piece of s##t (I attached a pic). Is there anywhere I can get just the spring or is there anything I can do as an alternative? And also, if the spring is not working would that cause the power valve to remain open or would it remain closed.
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Thanks man. If it wasn't raining I'd give that a try right now. I'll do it tomorrow hopefully when the weather let's up. But I also tried to see if the powervalve was working by leaving the bike in neutral and giving it some good revs, I didn't see any movement inside... could this add to the problem of it being rich?
I don't think so but I honestly don't know.
If the PV is stuck open (it's supposed to closed at higher RPM) it will hurt your performance on the top end.
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Thanks man. If it wasn't raining I'd give that a try right now. I'll do it tomorrow hopefully when the weather let's up. But I also tried to see if the powervalve was working by leaving the bike in neutral and giving it some good revs, I didn't see any movement inside... could this add to the problem of it being rich?
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take the carb off.
Unscrew the top screws on the carb and pull the slide out.
pull up the spring back so you can see down inside the slide. there are 2 screws down there. Take them out and you should be able to get the needle out.
There is a c-clip on the needle. If you raise the c-clip to the next position it drops the needle and will lean out the bike at mid-ish throttle. Moving the c-clip down the needle with raise it making it richer.
If it feels super rich at mid throttle, raise the clip 1 position at a time until it feels nice and crisp.
Good luck spanking that shee!
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Im going to go down on the mains, just ordered 4 different sizes but how do I just the needle position if its not the jetting? And again man, I appreciate all of the help. Once I get it running right, I'll let you know how bad I smoked him.
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dont touch the pilot if it idles. It's likely the needle position or main.
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Thanks for that info man, the bike idles perfect!!! I have the stock airbox in place for if Im going to be in mud and I also have the air filter directly on the carb. Im looking now to see if there is a bigger filter I could try to see if that will lean it out some until the new jets come. Just wondering if I should go down any on the main or the pilot. The bottom end is amazing but it breaks up horribly still on the top side. My brother has an extra Keihin carb from his Banshee, would I be better off using that and if so what would be the best starting point on the jets. I wanna get this thing right asap, my buddy with his honda 450 is talking trash lol.
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The important thing is that you have a tube coming off the carb to an air filter. Lots of ppl eliminate the air box, as did i, open filter is def the best so long as you arent mud riding and clean it regularly. Most still use the stock tube we just make a bracket to support the air filter at the airbox location. SB Designs still makes a bracket i think. You can find in his store on this site.
It's great you got the bike idling. But there are a lot stuff you need to do.
First thing i'd do is set the slide height.
Using the thumb screw (large screw with the spring on it) turn it counter clockwise until the slide is at the very bottom of the carb - as far as it will go-
Make sure your throttle cable is adjusted out so that the slide can go all the way down.
Set your slide height to 3mm-ish by turning the thumb screw clockwise. You will see the slide move. (take off the air filter, etc, so you can see the slide in the carb)
Once you have that set NEVER touch the thumb screw again. :))
All future idle adjustments will be done with Air/fuel mixture screw.
Second, Adjust the throttle cable.
Set the throttle cable so that it's not in a bind or has any slack. The adjustments are at the handle bars. Careful not to get it too tight so that it raises the slide. Make sure the slide is able to rest at the previous adjusted location.
Third, take note of how many turns your air/fuel screw is set too.
The air/fuel screw is a small flat headed screw on the opposite side as the thumb screw.
Turn it clockwise until it's tight.
Turn it back counter clockwise 1 1/2 turns. This is a common starting point.
Fourth, Start your bike.
Let your bike warm up blipping the throttle to keep it running and for lubrication.
from here, you need to do some fine adjustments to the air screw to set the idle.
The thresh-hold i like to use is 3/4 turns out - 2 1/2 turns out.
Turning the air screw out (counter clockwise) allows more air into the pilot system and leans it.
Turning the air screw in (clockwise) allows less air into the pilot system and richens it.
If your bike is idling high, it needs less air. if it's idling low or wont stay running, it needs more air.
Slowly turn the air screw which ever way you need to get your idle right. TAKE NOTE OF THE AMOUNT OF TURNS!
I like to adjust it 1/4 turn at a time until i get close and finely adjust it from there.
If you cant get your motor to react to the air screw adjustments or you have to go below 3/4 turns out or over 2 1/2 turns out, your pilot jet needs to go up or down in size.
It seems intimidating, and it is at first, but you should catch on really quick once you dive into it.
We'll worry about setting your needle height and main later.
Good luck! +k2
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So once I get my jetting much closer I should use that to fine tune it. I have an idea of where the screw is but want to be sure exactly where its located. And as far as my jetting, the plug is still really black, should I go down on main to 370 or 360 or go smaller on the pilot?
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The air screw is a fine tuning circuit for the pilot jet. The air screw changes the amount of suction placed on the idle circuit and the transition hole that is feed by the pilot jet.
The slide stop screw controls the idle speed.
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I have the stock airbox setup but it seemed to run better with the open filter. I got a bigger 6" Uni filter and it did help a little but its still rich. I guess I'll keep playing around with the jetting. Since I have a decent idle, should I change the main or the pilot jet? And I also, I have been reading other's posts where they are mentioning the air screw, I thought this was for how fast the bike idles down after letting off the throttle but it seems people are stating as it assists in jetting.
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I also need jetting help ...
87' big reed
87.50 bore
Ported professionally
Clamp on K&N with tube
41.5 mm pj carb
Good ole FMF pipe
Just need a starting point switched from a mikuni tm38ss stock carb
Do you have the 1987 TM 38 carb body or the 1988 to 1990 TM 38 carb body?
How long is the tube between the carb and K&N?
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I also need jetting help ...
87' big reed
87.50 bore
Ported professionally
Clamp on K&N with tube
41.5 mm pj carb
Good ole FMF pipe
Just need a starting point switched from a mikuni tm38ss stock carb
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Its a 3" filter.
That is a small air filter and may be the reason you are needing to run small main jets. The jetting specs that most guys are giving your are based upon having the stock rubber boot between the carb and a much larger air filter. A LT 500 with anyones big or small filter clamped on the back of the carb, will not usually produce as much power as one with the properly designed intake system.
I would suggest that you get an air box or use the stock carb to air filter boot then maybe some of these jetting recommendations will work
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Its a 3" filter.
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What size is the uni that you have clamped onto the carb?
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Ok I installed the new slide, did the leak test and there were no leaks. I have V3 reeds, FMF exhaust, Uni open filter on the carb. I tried the 400 main and 40 pilot but it was still rich when I did the plug chop. So then I went to the 380 main and the 35 pilot and its still rich. What other changes should I make, what are other ways to fine tune the carb? I read on here about setting the needle but I'm not familiar with this, could someone elaborate? It idles perfect and the bottom end is strong but breaks up on the top side when wot. Thanks for all the help so far guys.
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Thanks man. So what jets should I start with after I do the leak test? Im going to go ahead and order them now so after I do the leak test I'll have a fresh starting point.
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Your Raptor will miss fire if it is extremely rich or lean. A two stroke will miss fire when it is extremely rich but will usually burn the piston before it is lean enough to have a lean miss fire.
A rich oil mixture only causes a miss fire when the mode of operation (running the engine at moderate loads) is not generating enough heat to keep the spark plug burned clean.
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Thanks for the info. This is an 88' jug. I am familiar with a leak test, I do this on my turbo car occasionally but we call it a boost leak test. Could it be too rich with the jets that are in it? I just checked the plug and it looks blackened like it may be rich but then again the mechanic who put my engine together told me to run the gas with a little extra oil while its being broken in. Would it break up on the top side if its too rich? I know my Raptor does this when its lean but not sure what happens when its too rich. Sorry for all the questions, again thanks for all the help from you guys. I'll do the leak test as well when I get a chance.
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You may want to think about getting a new slide and do a leak down test. 52 pilot is MASSIVE. Stock pilot is 22.5. Without knowing much else -if you're running an airbox lid, porting, have an airleak, etc - i'd say 380 is fairly close. My guess would be 400 - 380 if your bike has an '88-'90 jug on it. With a pilot of 27.5-30. But than again, your slide looks crazy worn and that will affect the pilot size.
Only buy genuine Mikuni jets. Also, buy a few sizes and start big and work your way down.
You don't have to be an expert, but you will learn. Trust me, very few shops know how to jet well or even work on a 2stroke. Let alone a zilla.
First things first. If it were me, i'd do a leak down test first. If you have air leaks in the motor, you will never be able to tune it.
If you dont know what a leak down test is, here is an example of one.
http://www.suzukiquadracerhq.com/lt250/lt250r-leak-down-test/msg47754/#msg47754
You can literally build one at lowes for less than 20 bucks although you may have a hard time finding a gauge that one reads about 10 - 20 psi. You only need to pump in about 5-7 psi.
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I'm in Virginia and my elevation is 455 ft (139 m). No I don't know how to tune the pilot circuit, would I need to be an expert to do this or can I read it in the manual or online? I see the jets online at www.mfgsupply.com (http://www.mfgsupply.com)am I safe to order the 420 main and 35 pilot? Can't wait to get this beast running good.
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Mine had a 440 main and a 35 pilot so you could be a bit lean? In the manual it has jetting guidelines ... Good luck
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Main is too lean.
Try a 420 main and a 35 pilot.
Could also depend on your elevation, what are you at?
And do you know how to tune the pilot circuit?
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I recently bought a Quadzilla and had it rebuilt. I went with the 517 Wiseco kit in the rebuild. Well it had no airbox with the Uni filter directly on the carb and it would break up on the top end so I thought that was the cause and put the stock airbox setup on it. It still breaks up so Im guessing its the jetting at this point. It has the stock Mikuni carb from what I was told by previous owner, FMF exhaust, and I put new Vforce 3 reeds on it. I took the carb apart and the large jet says 380 and the smaller one says 52. (Sorry Im new to carbs, other bikes are fuel injected). Well what do you guys think I should run in the carb with the mods I have? Thanks for the help. The bike is a monster down low and I can only imagine how fast it will be with the correct tune. Posted a pic of the jets and carb.