Suzuki Quadracer HQ
LT250R Quadracer => LT250R - Engine => Topic started by: Protoolsuser81 on December 31, 2013, 07:28:07 pm
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Do they even make a pilot jet smaller then 30? Is this the reason I have to have my slide adjustment screw all the way in to idol? Everything I read says pilot jet 30-40 and nothing smaller.
If it appears to need a pilot jet smaller than # 30 there is probably something else wrong with the carb. Needle jets and needles get worn out and are frequently overlooked when trying to cure a rich condiiton at small throttle openings. Bad float valves and or the oring that goes around the outside of the float valve are also a common problem.
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They make down to 20 I know of.
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Do they even make a pilot jet smaller then 30? Is this the reason I have to have my slide adjustment screw all the way in to idol? Everything I read says pilot jet 30-40 and nothing smaller.
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just use a hack saw
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Are the plus fairly easy to hack up with out breaking the ceramic insulator?
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How does this quad run now with the 260 Main jet?
Does it idle and start ok?
How does it run when you are riding 1/4 to 1/2 throttle?
How does it run when you do wide open runs through the rpm range to the top end?
(http://i435.photobucket.com/albums/qq76/elephantrider414/Quadzilla%20Build/IMAG0165.jpg)
This is a plug chop with a barnd new plug after doing a wide open run. You have to cut "chop" the plug to read the band on the plug. You can see where one of these plugs is reading richer than the other one.
Note: Jetting is a practice of feeling how the bike runs and also some mechanical inspection. I would spend some time with googling "two stroke jetting" before going much further. There is a post on this site that was really well written too.
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I made a mistake in an earlier post when I said that a 280 main jet is too lean. I thought that you had a LT 500.
Hahaha, good cause I thought you were crazy when I read that! ;)
37.5 pilot 240 main and needle in 3 rd clip. Stock. I ran on fmf boyesen rad kn filter head shaved 195 main 35 pilot needle 4th clip. 210 main 40 pilot needle 4 th clip in winter.
When you say 4th clip do you mean the 4th clip going down on the needle? I have mine in the middle right now so the 3rd.
Appears to be a stock carb. Like the looks of that intake too,,,, If you can, take and cut the threads away from the spark plug so you can see down to the bottom of the insulator in the pics please good sir.
I can try but I would have to use a hacksaw and i'm not sure how much of a pain this would be. Does it look a little on the lean side?
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I made a mistake in an earlier post when I said that a 280 main jet is too lean. I thought that you had a LT 500.
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37.5 pilot 240 main and needle in 3 rd clip. Stock. I ran on fmf boyesen rad kn filter head shaved 195 main 35 pilot needle 4th clip. 210 main 40 pilot needle 4 th clip in winter.
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Can anyone chime in with the stock size pilot, needle setting, and main are for a 1990 LT250R?
I think the open clamp on filter will bump up the main jet pretty good.
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Appears to be a stock carb. Like the looks of that intake too,,,, If you can, take and cut the threads away from the spark plug so you can see down to the bottom of the insulator in the pics please good sir.
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Where are you at in Michigan?
We really need to take a few (maybe alot) steps back on this before you blow this quad up.
- What Model and Year Quad is this?
- Can you tell us what model carb is on it? Brand and any markings?
- What has been done to the this quad? Is it stock? Does it have a OEM airbox and filter? Can you post some pictures of this thing?
Nevermind - you said there is a filter right off the carb. Please confirm what carb and model is on this bike.
I'm in White Lake about 40 minutes north of Detroit.
It's a 1990 lt250r
Has a fmf pipe with a fmf turbine core silencer.
Only other mod is the k@n off the carb and no air box.
Engine is now .60 over and the head was milled down a bit to fix the scratches and stuff.
Compression was just over 130 when I tested it yesterday.
I will attach some pictures of the carb cause I have no clue where these markings are. Also I will attach pictures of a new plug and after winding the quad up and then killing it right away.
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there should be 2 square boxes both of them have stamps with numbers and letter in them.
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Is it a 2 vent bodied flat slide Mikuni that fits perfectly in the boots? No extra slack, not too super tight? It's more than likely stock.
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I'm pretty sure its a stock carb on a 1990. How exactly do I tell what model it is on these?
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You need to run the dog **** out of it one good time to really clear the bike out. Mine will spray out the silencer if I'm just putzing around, not really running it and my jetting is just a size fat and I run 32:1.
Plus, it's a 2-stroke. You're gunna have oil spooge on it unless you're running some crap walmart oil at 100:1 "cause race bike".
Drill out the rivets and use a nut and bolt if you have to. Go buy a rivet guns from autozone for $20 and you're set for as long as you own this bike.
For the leaky flange and coupling, use the copper coat rtv silicon stuff. Apply generously.
Go run the crap out of the bike.
Also, make sure you don't have too much oil/air filter recharged spray on your filter. That'll choke the engine.
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So I take it you ain't falling for the banana in the tail pipe trick?
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Where are you at in Michigan?
We really need to take a few (maybe alot) steps back on this before you blow this quad up.
- What Model and Year Quad is this?
- Can you tell us what model carb is on it? Brand and any markings?
- What has been done to the this quad? Is it stock? Does it have a OEM airbox and filter? Can you post some pictures of this thing?
Nevermind - you said there is a filter right off the carb. Please confirm what carb and model is on this bike.
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Be careful trying to jet the carburetor by "reading" the spark plug. I have many 55 drums full of burned pistons that customers said that the spark plug indicated their jetting as safe. Cold weather requires the jet sizes to be increased not reduced in size.
How does one tell if the jetting is correct if not by the plug? Needing bigger jets in the winter is something you learn pretty quick in Michigan. I'm spraying premix all over and mu plug is black and everything past half throttle is just bad (sputtering like its loading up). All these signs made me think the jet size needed to come down. 260 did the same still but it was a lot better.
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Cold weather requires the jet sizes to be increased not reduced in size.
Cold contracts heat expands. If it's cold increase your main jet one size for every so many degrees.... I don't know the formula... being from so cal where if it gets colder than 40* the girlfriends high beams come on
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better start riding it harder...
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Awesome info guys!
I did a full carb rebuild and I want to say the pilot was a 30 but I'm just going off memory. I dropped the main jet down to a 260 today (it's very cold here in Michigan) and it still seems pretty rich when reading the plug.
Quick question….Do i need to adjust the long needle that is attached to the slide up or down with that clip and what does that do exactly?
Be careful trying to jet the carburetor by "reading" the spark plug. I have many 55 drums full of burned pistons that customers said that the spark plug indicated their jetting as safe. Cold weather requires the jet sizes to be increased not reduced in size.
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Also…I have a Fmf turbine core silencer and I couldn't get in the back half where the turbine is when I was repacking it today, because it has rivets, and I have no tools for this. I did repack the front half though, however I'm still getting oil out of the front manifold (all over the front of my engine) and also out of the end of the pipe a bit. Nothing crazy out of the pipe but when you rev it you can see it on the snow and it drips when I park it. It was even blowing some oil out of the rivets on the silencer as well. The worst part is right out of the manifold where the pipe just slips over.
I wish there was someone who could make these for a lt250r. http://www.eddie-sanders-racing.com/product_p/billet%20exhaust%20flange.htm
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Awesome info guys!
I did a full carb rebuild and I want to say the pilot was a 30 but I'm just going off memory. I dropped the main jet down to a 260 today (it's very cold here in Michigan) and it still seems pretty rich when reading the plug.
Quick question….Do i need to adjust the long needle that is attached to the slide up or down with that clip and what does that do exactly?
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If it runs well and does not miss-fire, the jetting is not excessively rich. It takes a lot of combustion heat and heat in the exhaust system to burn the two stroke oil. The only way to keep heat in the pipe is by riding the bike hard. If you spend the majority of your time at low RPM and partial throttle you will always have oil dripping out of the exhaust flange and muffler even when the jetting is spot on and running a 50:1 premix ratio.
The LTs were not designed to be used as putt putt putt quads. That is what 4 strokes were designed for. If you are running stock carb a 280 main jet should be too lean.
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The little screw is your pilot air screw. Factory setting is 1 1/4 turn out from bottomed out. The big screw is your slide height screw. If you have it turned all the way in just to idle your pilot jet is to rich. Find out what size pilot jet is in it. The carb slide screw should only be turned in enough to get the slide 1-2mm open at idle. Your main may be rich as well, but until you have the slow speed circuits right I wouldn't change it. The only other thing I can think of is possibly the needle jet is worn, it will totally mess up your you tuning on all throttle circits. Set the pilot screw first, then find out what pilot jet is in it and we can go from there.
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I'm not familiar with the stock carb since mine had a pwk39 when I bought it.
Here's a guide to help you understand what the functions of the carb itself, and they sell any parts you might need
http://www.sudco.com/Carburetor02.html
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I could use.some carb setting help.as well. The big screw on the carb you tweak by hand needs to be turned all the way in for it to idol. What is the other little screw below this one that you need a little flat head to turn and what should that be set and when should it be tweaked? Also my needle is set at the middle.slot which I belive is the third notch down. When should this be changed and what does going up or down change?
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Will do.
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If premix is coming out of the end of the pipe after warm up and running it, its pretty damn rich.
Run it again, shut it off and pull the plug right away. See if it is wet with premix. Post some pictures.
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I bought some repacking today already and planned on doing that tomorrow as well. I pulled the plug a few times while doing a heat run and then letting cool down but I'm not sure exactly what it should look like. Any pictures of good and bad you could link me with for the plug test?
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well pull plug and tell us what it looks like. but i would change the packing.
got any insulation at your house, if so use it. it wporks fine, just does not last as long.
i would bet there is none in your silencer,
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I purchesed this used a few weeks back. The top end was blown and I just got it all back together and this was my first run. Fuel and oil is brand new, the pipe I cleaned out and powerwashed the inside. I'm running a 32-1 mix and the main jet I used was a 280. The k@n is mounted right off the carb and was a little dirty and I will clean it tomorrow. I had the head cleaned up by my local shop so the compression might be higher then normal because of being milled down or whatever its called. I will check that tomorrow as well.
What should I do if the compression is high? Also what is a acceptable level?
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Well that's a symptom of what you described. Yes it can be jetting related.
If your thinking jetting you need to read the plug.
Afew factors to think about: how old us your premixed fuel? When was the last time it was ran? Clean air filter? What's the compression?
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It's also making a mess all over the front of my engine as well. All this is from the packing in the silencer? I thought my case had a leak but then realized its gas and oil all over the front of the engine. Then I checked the tail pipe and realized it was dripping from there as well. Not a jetting issue huh?
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sounds like the packing needs replaced to me
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It's gas and oil mix coming out of the tailpipe. Does this mean the main jet is to big?