LT50A intake restictor - Off-Road Forums & Discussion Groups
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post #1 of (permalink) Old 08-11-2002, 08:27 PM
MattFisher
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LT50A intake restictor

2002 LT50A:

I removed the intake adaptor between the carb and cylinder, heated it with a propane torch- and the steel restrictor just fell out. It's held in with an adhesive. 10 minute job.

A little more top-end, maybe 18 or so total MPH (up from about 14). I can still run faster than my little guy can go on it. Where it really helped was in the much-needed takeoff and midrange. It will actually climb some of the hills around here. It's harder to start, however. Playing with the fuel screw on the side helped a bit, but it's still a little bugger.

Is there even a pilot jet in the carb? I pulled the plug after a full-throttle run (is there anything else?). Looked nice and brown. So I think it's lean only down low. The intake and exhaust probably preclude it from really making any more power up top.

I'd like to fab up a less restrictive spark arrestor, add 2 teeth to the rear sprocket, a more water resistant airbox, and get the jetting right. I think that should suffice for a sub 40# rider.

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post #2 of (permalink) Old 08-19-2002, 02:00 PM
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Re: LT50A intake restictor

I have posted the basic mods for this machine a few times. Yes there is a pilot jet. You need to remove the 1st of the two pilots (they are stacked). ALso install a better air cleaner.
post #3 of (permalink) Old 08-20-2002, 09:26 AM
MattFisher
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Re: LT50A intake restictor

Yes, you've been more than helpful, Raptor720. Thank you.

I searched and was unable to find a complete list on this forum for the mods. You had posted them on a different board, but they changed formats and the info went away. If you post the complete list again, I promise to save it :-)

I think the reason it was a bugger to start before was because I stood it on end to pull the plug. Oops. It's started easily the last 2 days.

If I read another post correctly, there are no different sized jets available for this carb, hence your suggestion to use numbered drill bits. However, I thought I saw somewhere that Holley(!) jets would work. Correct/any specifics?

As to a better air cleaner, I'd suspect that only a sock type is available. Any ideas on some type of actual airbox, one that might be somewhat water resistant?

Thanks again.
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post #4 of (permalink) Old 08-20-2002, 12:54 PM
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Re: LT50A intake restictor

I would need to look for a copy of that post. I know my post was published in MX America back East about 5 months ago.

The air filter I always used was a K&N RU-0200. To adapt it to the carb, I used the air filter adapter from one of those Go-Peds. If you need it shielded from water, I suggest you find the stock rubber baffle that many people removed from the LT.

If you want more engine power, add two base gaskets to the cylinder and make the adjustments to the deck height to bring the squish down to .035"
post #5 of (permalink) Old 08-20-2002, 10:52 PM
MattFisher
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Re: LT50A intake restictor

I think it was on ATV Scene.
post #6 of (permalink) Old 08-21-2002, 01:29 PM
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Re: LT50A intake restictor

I've been reading all of your posts and posts from Raptor720 and have been learning a lot. I bought my daughter a 2002 LT50A and I was looking to get a little more bottom end out of it if possible. I don't care about top speed right now because when she needs it I'll get her a bigger quad. There are a lot of sand hills in the areas we ride and it really takes power to get up them which she doesn't have right now. I took the pipe off to remove the restrictor washer they said was there and there wasn't one there. I thought that was strange. At the end of the spark arrestor where the exhaust hole is there is a cap with 2 screws on the bottom holding it on. I know if you take that off you can remove the baffle but it looked to me that if I take off the cap and put the screws back in to hold in the baffle it would be Ok. It looks like it would free up the exhaust a little better. Have you heard anything bad or good about doing this?

I didn't know there was an intake restrictor. Where is the intake restrictor located? I'm assuming between the intake manifold and the cylinder. The last thing I need to do is make it harder to start though because my wife has a hard enough time now when she brings her out.

Thanks for any comments.
post #7 of (permalink) Old 08-21-2002, 08:34 PM
MattFisher
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Re: LT50A intake restictor

The restrictor is located between the carb and the cylinder, inside the L shaped manifold. 10mm wrench, 3 bolts and the manifold is free (don't loose the gasket). You'll see a steel insert with a hole the size/shape of a keyhole inside the manifold. Use a propane torch to heat the manifold, the insert will fall out when the adhesive that holds it in melts. Re-attach manifold with the gasket you saved [img]images/icons/smile.gif[/img], and fire it up.

The starting issue I had turned out to be caused by my tipping the bike up on end for easier access. I've found that it actually starts easier when cold or hot than before the mod. It doesn't like to start when lukewarm, so just make sure it's good and warmed up before tuning the critter loose on it.

The top speed isn't much higher, but it accelerates much better.
post #8 of (permalink) Old 08-22-2002, 07:20 AM
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Re: LT50A intake restictor

I'll give it a shot this weekend and let you know how it goes, thanks for the help. Don't get me wrong, I know it's still an LT50A but why not try to help it a little. Besides, my wife won't let me buy my daughter a Z400 yet so I'm stuck. It's something about the fact she only weights 30 something pounds, doen't make sense to me...
Thanks.
post #9 of (permalink) Old 08-26-2002, 11:49 PM
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Re: LT50A intake restictor

There is also an exhaust restrictor.

I removed both and put a Gradon-Proline pipe on the bike. The bike does about 28-30mph now.



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post #10 of (permalink) Old 09-11-2002, 09:12 AM
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Re: LT50A intake restictor

I finally took out the Intake restrictor last night and it seemed to make a big difference in the low and mid range power. Thanks for the help. I will say it was a little more difficult to remove on my daughters quote than you described but I got it out. I heated up for quite a while with a torch and really had to work with it with a big screw driver to finally get it free. I wanted to say this so that if anyone else tries this they doen't get discouraged, it will come out and it's worth the trouble.

I noticed Raptor720 mentioned an air box mod that can be done. Have you tried this or is there a better way? The stock airbox really sucks. I'm going to try to find the K&N filter he recommended but meanwhile if anyone else knows anything please let me know.

I may try the Proline pipe some day but right now I want to stay on the neighbors good side. I find it impossible to get 28 mph out of this little thing considering at 15 mph the engine is completely rev'd out. Any more RPM's would probably cause fireworks. Anyway, thanks for your help.
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