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OEM MT250 Needle valve too rich?
https://vintagedirtbikeforums.alp-sys.com/viewtopic.php?f=21&t=4698		 Page 1 of 1
Author:  MT250GUY [ Fri Nov 04, 2016 8:50 pm ]
Post subject:  OEM MT250 Needle valve too rich?
Hello, yet another question: I found the following post from ray:

"You're right, the needles are definitely different. The OEM '74 needle for the 004A carb (271002) is quite rich, and Honda made succeeding needles steadily leaner all the way to the end (092B FL250 carb). The FL250 Keyster kit is the one I'd get, as its D96 needle is super lean and it's got the cool big-knob idle speed screw. I've got specs for a bunch of the Honda OEM 70's 2-stroke needles, PM me if you need 'em."

My bike was running VERY rich; should I reconsider something other than an OEM needle jet for my 74 MT250?

Thanks!
Author:  rayivers [ Sat Nov 05, 2016 11:08 am ]
Post subject:  Re: OEM MT250 Needle valve too rich?
I'd recommend getting the Keyster KH-0218 carb kit linked below, which also has the float valve mentioned in your other post (yours looks toasted, I would definitely replace the entire float valve/seat assembly). These are quality kits, and the D96 needle included is one of the leanest (fattest-diameter) MT250/FL250 needles there are. The kit does not include the long threaded needle jet, which was only available from Honda and now exists only as NOS - I would try the Keyster needle first and see how it works.

http://www.ebay.com/itm/77-84-HONDA-FL2 ... dT&vxp=mtr

IME MT250's need to be jetted individually instead of relying on the stock jetting, which was continually adjusted by Honda during all three years of production. My friend's '74 MT250 is running the stock #60 pilot jet with a brand-new needle & needle jet and runs blubbering-rich down low, while his son's '75 MT250 ran super lean on the #60; I put a #65 in it yesterday and it runs much better, but it may need a #70 to run best (both bikes are bone stock, 4,000 & 1,000 miles respectively).

If you end up needing a needle/jet set the thread below may help, and you can search '16012' here at VDB to find a bunch more info on needle jets (the MT250 carb can use 16012-358, -360, and -373 needle jets):

viewtopic.php?f=21&t=4647&hilit=16012

Ray
Author:  MT250GUY [ Sat Nov 05, 2016 3:48 pm ]
Post subject:  Re: OEM MT250 Needle valve too rich?
Thanks Ray. Sounds like sage advice. I just bought the bike last week and frankly, looked it over pretty quickly. I took it for a quick spin, went through the gears, etc. It smoked like a beyotch, blubbered at half throttle and above, but I had an explanation: the guy had mixed some 2-cycle into the tank but the oil injector was functional and dumping even more in simultaneously. Plus I was sure the carb needed attention given the amount of rust in the tank.

Now that I've disassembled the bike I found it's been welded just forward of the right foot peg, the wiring for the stator is a bit of a mess (been re-taped and I think it's a little shorter than it's supposed to be given where it's supposed to be routed in the frame). Also the left engine case lip immediately in front of the sprocket has been snapped off about 1 inch long. That has allowed all kinds of filth, and oil to coat the flywheel windings and whatnot. I'm going to use some steel reinforced JB weld to build the lip (clamshell) back up so it will hold a gasket and keep the trash out of the electrics. The good news is the compression measures great. Another thing I found is the front sprocket can be wiggled laterally about three eights of an inch. That can't be within spec! Does anyone know how much lateral slop is ok?

Thanks

Al

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Author:  rayivers [ Sat Nov 05, 2016 6:21 pm ]
Post subject:  Re: OEM MT250 Needle valve too rich?
Well, I've seen much worse looking MT250's than yours - it's even got most of the lights! The two I've worked on had multiple problems (tank rust, pump over-oiling, carb leakage, clogged pipe, low compression, cut-up wiring, etc.), many of which I wasn't permitted to work on and still remain.

The sprocket should have an eye-shaped 'fixing plate' with two short shoulder bolts into the sprocket, which holds the sprocket with almost no play at all. I'm going to recommend a PBI 353-13 front sprocket to my friend, as with the current 14T 1st gear still feels too tall and acceleration is weak.

Your flywheel looks like it has a new nut and washer, and possibly slight coil damage (hard to tell from the photo). IMO it would be a good idea to pull it off for a look-see.

A good JB Weld fix should work well - just did a small one this morning. :) I'd highly recommend a 30 micron fuel filter, and I shook around a bunch of short sheetrock screws (little bastards were sharp as tacks!) followed by Evapo-Rust on the 2nd MT tank. There's still some fine powdery rust the new 30m filter will catch, but no more petcock-clogging chunks like before.

Ray
Author:  MT250GUY [ Sun Nov 06, 2016 6:15 pm ]
Post subject:  Re: OEM MT250 Needle valve too rich?
Thanks Ray!
Author:  Rick [ Fri Nov 11, 2016 6:14 pm ]
Post subject:  Re: OEM MT250 Needle valve too rich?
I use gravel, preferably granite or similar, not limestone, in my rusted tanks. If it's crushed it works better and I try to keep the Pebbles about marble size and smaller. Remove the petcock and put tape over that. Putting water in with it is ok and shake the dog snot out of the tank.

Try to keep away from the sealers unless you have a leak, in my opinion. I'm lucky, I live in Arizona where we have very little moisture but if you keep the tank full I can't rust.

Rick
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