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Search Tags: Airbox mod, Jetting, XL250R
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Title: Airbox mod jetting
  
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ZX12R
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Author



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Posts: 14
From: Canada
Registered: 07/02/2008
Time spent: 0 hours

(Date Posted:07/02/2008 7:39 PM)

I just picked up an 85' XL250 [dual carb], I was going to pull the airbox snorkle and was wondering if anyone had any thoughts on a starting point for jetting? It's currently all stock with #102 in the primary and #122 in the secondary. I was going to order the next size larger jets but I found this great XL site and thought I'd check and see what everyone else is using after opening up the airbox.

Any thoughts would be greatly appreciated!
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woosh
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1#



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Registered: 03/05/2005
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RE:Airbox mod jetting
(Date Posted:07/03/2008 7:57 PM)

You gotta remember they are pretty lean to start with. I hae a dual carb 350 and I put on a super trapp and went up one size on the jets and its still way lean. A plug chop will tell you where you are. 
ZX12R
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2#



From: Canada
Registered: 07/02/2008
Time spent: 0 hours

RE:Airbox mod jetting
(Date Posted:07/06/2008 12:38 AM)

Thanks whoosh! I gave it a thorough going over after I bought it and performed a plug chop just to see if the previous owner had played with the jetting. Everything appears to be stock and the plug is nice and tan at high and low rpm chops. I guess I'll go ahead and order some jets before I do any playing with the airbox. Not sure if I'll need pilot jets too or not but maybe I'll go ahead and pick some of them up too. I tried calling Honda to see if they could order me jets but was told they were not available so I guess I'll try a few other sources.
woosh
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3#



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RE:Airbox mod jetting
(Date Posted:07/06/2008 12:19 PM)

I would have to say whoever told you they werent available is full o it I bought a bunch last year they are just flat head screw type kehin jets. And the pilot on my 350 is to small but pressed in I am going to use the xr carbs on it they are better. I have seen xr350r carbs used on an xl250 I think apexspeed did it but he is real good at tuning. I went for a long high speed ride on the 350 and it died on me cause it was so lean when I pulled the plug it was pretty white I hope I didnt burn the valves. That was just from adding a supper trapp. Do you still have the stock pipe on your bike?
ZX12R
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4#



From: Canada
Registered: 07/02/2008
Time spent: 0 hours

RE:Airbox mod jetting
(Date Posted:07/06/2008 1:37 PM)

I should have figured the dealer was full of crap, it wouldn't be the first time they have done that to me. I'm thinking the guy that was working was just too lazy to look it up. I found slot head [KJ prefix] jets in the Dennis Kirk cataloge so perhaps I'll order them from there and hopefully they'll be the right ones.
I sure hope your 350 turns out to be OK! Have you had chance to check it out yet?
I still have the stock exhaust on mine but I'll be opening it up some once I get the jets. I noticed it does seem to run pretty hot and was thinking I might check out adding an oil cooler once I get the jetting/airbox and exhaust mods done. I'm not planning on beating on it or anything, it's mostly going to be used for short highway hops and trail riding and such but still found that it seemed to run a bit hotter than I would like so we'll see.  As far as 350 carbs, although tempting, I'm thinking I'll keep the stock carbs on it and just open up the airbox a bit and call it a day.
I did a top speed run with it and managed to get 83mph on the speedo and if the airbox mod helps get it up a bit more I think I'll be happy with that. At least for now anyway, I can already see myself picking up a 350 or 500cc XL engine off ebay and stuffing it in there........
ZX12R
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5#



From: Canada
Registered: 07/02/2008
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RE:Airbox mod jetting
(Date Posted:07/12/2008 3:13 AM)

Well, no update yet as I'm still waiting for the main jets.
ZX12R
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6#



From: Canada
Registered: 07/02/2008
Time spent: 0 hours

RE:Airbox mod jetting
(Date Posted:07/20/2008 12:08 PM)

Well the jets are in, soon as I get chance to do some tuning I'll report what I find works the best incase anyone else with a XL250R is ever looking for some help. Unless of course they sent me the wrong jets............
ZX12R
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7#



From: Canada
Registered: 07/02/2008
Time spent: 0 hours

RE:Airbox mod jetting
(Date Posted:07/24/2008 6:14 PM)

Well I got the XL250R running pretty good. I pulled the snorkel and cut a 4" x 4" hole in the top of the air box and then 8 3/8ths holes in the air box door and, ground the welds out of the exhaust headers and opened up the exhaust. Final jetting is #105 primary and #107.5 secondary. I didn't have a larger pilot jet but will be ordering one today as the airscrew's turned in a little further than I would like and the needle is stock. Top speed run netted 92mph speedo [88.61mph Gps]

Best stock 1/4 mile time........16.48@74.01mph

Best after mods.....................15.93@79.37mph
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cornflakejoe