Subject: FL250 Maintenance Tips: Updated 6/12/2000
I will soon check the Clymer corrections against the factory Honda manual when I have time. 
That way I can correct any mistakes that are in that manual as well. 
I have noticed various mistakes in the Clymer FL250 manual. I have addressed the mistakes here:
I have the fourth edition of this manual. If you don't, page #'s might not be the same.
Here are the changes:
Manual says to remove the crankshaft seals before removing the crankshaft main bearings 
(during bearing replacement). This is wrong. On an FL250 the crankshaft bearing must be removed 
first, then the seals. Also: seals must be installed before the bearings during reinstallation. Also: 
If you put the bearings in the freezer for a while before installation they will contract (shrink) 
a little due to the cold. This will make bearing installation a little easier.
Make a note on the jetting correction factor chart that the stock FL250 28mm carb has a 120 main 
jet from the factory. Any flow mods will probably require a larger main jet to keep EGT within 
desirable range depending on air temp/altitude/fuel mixture etc.  
States that the limit on the lower steering shaft bushing is 0.8165
this is wrong. The measurement should be 0.7165
1977-1979 ignition schematic
6 volt AC points ignition system 
35 watt 6 volt AC headlight.
The ignition switch is open (no continuity) when magneto is on.
The switch is closed when magneto is off (has continuity)
Along the trail of the wires for the wiring harness/schematic, the arrow represents a male connector 
and the block represents a female connector.
1980 only ignition
12 volt AC points ignition system 
45 watt 12 volt AC headlight.  
The ignition switch is open (no continuity) when magneto is on.
The switch is closed when magneto is off (has continuity)
Along the trail of the wires for the wiring harness/schematic, the arrow represents a male connector
and the block represents a female connector.
1981-1984 CDI ignition (hands down the best factory system built for an FL250)
12 volt AC Capacitor Discharge Ignition. (no points)
60 watt headlight 12 volt AC 
3 watt tail light 12 volt AC 
The ignition switch is open (no continuity) when magneto is on.
The switch is closed when magneto is off (has continuity)
Along the trail of the wires for the wiring harness/schematic, the arrow represents a male connector 
and the block represents a female connector.
Where it shows the alternator (bottom center of the page, landscape view)
The coil shown in the center is the pulse coil. 
The coil on the right that goes up to the CDI box is the exciter coil (wire is labeled Bk/R)
The coil on the left is the lighting coil (wire labeled Y).
                    !!!********VERY IMPORTANT:*********!!!
Applies to 81-84 CDI ignition systems only:
***This particular thing has confused me more than once. 
Read the color codes / abbreviations listed in the manual. 
The wire going from the CDI box to the spark plug coil labeled B/Y is some times black with a yellow
 stripe & sometimes blue with a yellow stripe.
The wire labeled Bk/Y going from the CDI box to the right side of the pulse coil is some times black
 with a yellow stripe & sometimes blue with a yellow stripe. 
They will almost always be one or the other (the two different wires will not be the same color/stripe), 
but I have encountered odysseys that had the same color/stripe wires for both.
I have encountered odysseys that someone previous to me has hacked up the wiring harness, wired it wrong, 
& the car would not run. I attribute this to them following the uncorrected maintenance manual without having 
the joy & benefit of experiencing this before. 
DO NOT hook it up the wrong way. This invites an opportunity to damage the CDI box & other components. 
Check your machine & figure it out. Make a note of what it is. This can confuse if you are having an ignition 
problem & trying to trouble shoot it. 
                    !!!*********END OF VERY IMPORTANT:*********!!!
The last page in the Clymer FL250 Manual is for notes. 
The following is good information to add there:
Ignition Tips: 
Let there be no doubt that your FL250 Odyssey puts out 12 volt AC power, not DC. You can verify this by 
placing a multimeter on your yellow wire(power lead for the lights) coming from the stator while the engine
 is running. If you try to use AC to charge a 12 volt battery it will eventually damage the DC battery. 
The stock ignition rotating magnet-flywheel puller (fits all year FL250's, & also fits FL350 flywheels) can 
be ordered from Dennis Kirk part # 28-282 for $18.99  
Ricky Stator now rewinds the ignition coils for your FL250 stator plate. If you have a stator plate that is 
bad, he can repair it. 
I don't care for the original FL250 Odyssey points style ignition systems. I have found them to be unreliable. 
Any money wasted buying tune up kits with points and condenser would be better spent towards buying a 
reliable 12 Volt CDI system for your odyssey. 
This trick that will enable you to do a quick check of your ignition system without any tools at all. Materials 
needed: You need a spark plug hole rethreading tap from the auto parts store ($7) and a  9/16 - 18 thread 
pitch standard or jam nut from the hardware store that the tap fits tightly into when you try to start it ($0.50).
Don't buy a grade 8 nut. Buy the lowest quality nut that you can find, preferably grade 2 or pot metal. The grade 8
nuts are very hard on your tap. Procedure: Run the spark plug hole rethreading tap through the hardware store nut 
several times. Then try threading a spark plug through the freshly retapped nut. If the spark plug will thread through
the nut easily, the nut is ready to install. Sand off a clean spot on the roll cage near the cylinder head and spark 
plug lead. Then weld the nut to the chassis. If you can't weld, get someone to weld it for you. Any muffler shop 
($10 max). Then run the tap back through the nut after it after it cools. OK then kit is installed. Paint welded area 
to match roll cage. Now install a new spark plug into the nut you just welded to the roll cage. Any time your Odyssey
won't start just pull the spark plug lead from the plug on the cylinder head & install it on the plug on the roll cage. 
If it doesn't spark when you pull the starter, you know the ignition system is not firing. This can often reduce 
trouble shooting time, and you are not trying to pull the start cord while grounding the spark plug by holding it
against the cylinder head. The added bonus is you always have a spare plug handy. This tip also works for Pilots 
& FL350's. 
If you replace your factory spark plug boot, replace it with an NGK boot. These boots install on your factory spark 
plug lead easily. They feature a positive locking device that uses splines to lock the boot onto the spark plug. It will 
ensure a positive connection between the spark plug lead and the spark plug and will ensure
that the boot will not fall off during riding. (I have seen old worn out boots that would actually fall off while 
riding. This tip also works for Pilots & FL350's. 
Engine Tips:
You can use a 83-84 CR250 head gasket. The CR250 head gasket is made of copper and will fit the 77-84 FL250. 
You will gain a little compression & performance because it is thinner than the FL250 gasket. Heat transfer between 
the head & cyl is improved. Also this head gasket can save you money. This head gasket can be reused many times if 
it is removed carefully without bending or creasing. All you have to do is clean it. Then heat it up until it glows red 
hot & slowly dip it in water. This will anneal the copper (make it soft again)(copper anneals differently then iron or 
steel, it does not require slow cooling to soften).Heating can be done with a propane torch or on the kitchen burner.
The Honda part # for the copper head gasket it is 12251-357-020. This tip was contributed by Frank Callas. 
Viton engine seals: I have found these crankshaft seals to be superior to the butyl rubber seals that come in the 
standard rebuild kits, if the kit you bought has seals in it (some don't). The Viton seals are rated to withstand temps 
up to 500 degrees F, while the standard seals are only good for like 280. They don't cost very much more, so they 
are worth the extra money to me. They don't seem to be as subject to hardening like the butyl rubber seals. Anyway, 
that is what I always use and they work good. Part #'s for the viton seals: I buy these seals from Motion Industries, 
Inc. They are nationwide, so you should be able to find them in your yellow pages under bearings. 
The part # for the clutch side viton seal is:  
1  00403  R 91628
30X55X10 ADL  Seal
The part # for the ignition side viton seal is:  
  2 00403 Z 20000
25X55X10 ADL
Use good main bearings. Spend the extra $10. The cheap China bearings ain't no good. Don't use them. FL250 main 
bearings are part # 6306.
Fuel systems tips:
If you are having trouble with rust in your gas tank you can install a Kreem gas tank prep kit. This will eliminate the 
rust in your tank if installed properly (follow the instructions carefully!). It will also coat the inside of your tank 
with plastic so it will not rust again. It can be ordered from Dennis Kirk part # 31-52 for $25.99
If your stock fuel pump is bad you can replace it with a Mikuni fuel pump for much less than a stock replacement. 
It can be ordered from any ATV parts house for about $20. I will post the part number next time I run across it.
Transmission & Axle Tips:
If you remove axle for any reason, you will have noticed that you have to remove the right side bearing carrier and 
parking brake to get the axle out. This is because the lip that butts against the transmission is to large to fit through
the bearing on the bearing carrier. If you grind the lip down a little or get it turned down slightly it will slide right 
through the bearing. From then on you can remove the axle without having to remove the bearing carrier.  
If you remove the parking brake drum and grind away all the drum so it is just a spacer, this will reduce the weight 
of the axle assembly and the car will accelerate quicker. You can remove all parts of the parking brake to eliminate 
unnecessary weight on the odyssey. 
If you race dirt oval track you can get the center section of the axle turned down to about 1" in diameter. Do this 
while having the turned section tapered back out to the original diameter near the edges where it passes through 
the tranny & bearing carrier. This will allow the axle to flex a little and the car will not bounce as bad when you 
hit bumps on the track. Also the axle is less likely to bend because it will flex instead of bending. It will also 
driven weight so the car will accelerate quicker. This tip was contributed by Frank Callas. 
The 77-81 FL250 transmission has a weaker chain than the 82-84 FL250. The two chains are interchangeable. If 
you have your transmission open for any sort of maintenance you can replace the weaker chain with the 82-84 
heavy duty chain. Part # for the heavy duty chain is: No. RK 50KB-42 LE (Takasago). If you break a chain under 
full throttle it will usually do some serious damage to the gear case. If you have the gearbox open & the chain is 
loose, my advice is to change it. 
The manual says to use 10W30 or 10W40 motor oil in the gearbox. I use 90 weight gear oil with climbing lube 
additive or some STP mixed in to help thicken the mixture and allow the oil to climb the gears. I have had far 
fewer gearbox failures since I went to the thicker oil mixture.
Suspension Tips:
The front hubs (drums) from a FL350 Odyssey and the old Honda Fourtrax will fit your FL250 if you would like 
to change the front bolt pattern from 3 on 100mm to a  4 on 110mm bolt pattern. I got mine at a salvage yard for 
$20. This will allow you to purchase front wheels in 8" or 10" diameter with pretty well any offset & width you 
want to run. The aftermarket 3 on 100 wheels are very limited for sizes/offsets/widths nowadays (lately they 
can only be ordered 8"diameter 6" width with no offset as far as I know). The 350 drums are aluminum, the 
fourtrax are steel, so the 350's are lighter. I usually cut the drum surface off so it is just a hub. I am sure there 
are other Honda hubs that will work, but these I know will work. If you have 4 on 110 mm front hubs & ride with 
350's much you can borrow a spare tire from them if you get a flat & don't have a front spare handy. Also the 
FL350 Odyssey/Honda Fourtrax hubs come with sealed bearings and that is good for riding in the mud. 
The FL350 & Fourtrax hubs add about 1 & 1/2" of offset to the front end. This helps eliminate ball joint 
interference if you want to file down the steering stops or remove them from the knuckle completely. The 
factory ball joints have a tendency to hit the inside of stock wheel after the steering stop had been removed from
the knuckle. Adding offset will space the inside of the wheel away from the outer ball joint.
Removing the steering stops from the steering knuckle will allow you to turn in a tighter radius. The FL250 odyssey 
will spin a donut in a very tight circle after this mod has been made & helps to reduce the need for reverse. Just 
be sure to check for ball joint hitting the inside of the wheel before you cut the stop off completely. 
The sealed front wheel bearing part #  for a stock 3 on 100 front hub FL250 is 6004 (Timken or SKF). The sealed 
rear axle bearing part #  for the bearing carrier on the parking brake side (right side) is 6007. 
The next time you remove your front & rear hubs take the cotter pins to the hardware store and buy hair pin cotters. 
Replace the stock cotter pins with the hair pin cotters. The hair pin cotters are reusable, easy to install, allow 
for quick hub changes, and you are never caught without a cotter pin (often you end up not having the right 
size cotter pin when you need one). Buy the stainless steel pins if they have them. They resist corrosion better than 
cad plated pins. This tip also works for Pilots & FL350's. 
The next time you pull your front j-arms (front trailing arms) off your FL250 Odyssey to clean & lube the bushings, 
drill a hole & tap it for a grease fitting (usually a 1/4 x 28 thread pitch tap for the grease fitting). Do this in a 
location between the 2 bushings that is accessible with a grease gun. >From then on you can use a grease gun to 
lube the j-arm bushings instead of having to remove them. 
On just about every FL250 I have ever seen there is excessive up and down play in the steering column. You can 
grab the steering wheel and pull the steering shaft up and down in the column because it is not shimmed tight. 
I had an Odyssey that the steering wheel would buzz while I was holding the wheel. This is something I can't stand. 
If  you shim the column tight with steel washers it will always bind at some point when turning the wheel. I found 
plastic washers make great shims. I make the washers by cutting them out of a plastic antifreeze jug. The material 
is thin enough that you can install a couple until you eliminate the slack (but not to tight, just snug). Install them on 
the bottom of the steering shaft in-between the tie rod mount & the bottom of the column tube. Put a little grease
on the washers and the steering shaft during assembly. Then the slack is gone and the column will not bind. Also: 
If you decide to eliminate the slack, it is an ideal time to measure your bushings while shimming the column.. Also 
the plastic washer trick can be used to remove the slight side to side play that the throttle trigger and the brake 
lever have as well.  
Clutch Pulling Tips
The stock FL250 drive clutch puller can be ordered from Dennis Kirk and the part #  28-287 for $19.99  
(does not fit FL350 clutch)
Another trick that all the racers do is drill a small hole in the frame on the left side of the chassis in line with 
the clutch bolt. This will allow you to slip an extension through the frame rail. You can then use a impact tool to 
loosen the clutch bolt & remove the clutch with the puller. On a racing Odyssey this is important, because
clutch adjustments and maintenance are done often. 
If you are at the race track & don't have access to compressed air you can still remove the clutch bolt for tuning 
quite easily. Take some good quality clean nylon rope (use nylon because it does not shed particles like regular rope)
and coil it down into the cylinder head spark plug hole. Then turn the engine until the piston comes up towards top 
dead center & presses against the rope. This is known as a piston stop & will allow the clutch retaining bolt to be 
removed with a ratchet. You can then remove the cover on your Powerbloc clutch to add or remove tuning weights. 
This is just for cover removal. Do not use this for removing the clutch hub from the crankshaft. You will be 
applying to much force against the piston. This tip was contributed by Frank Callas. 
If you make a clutch face holding tool that slips over both clutch faces on a Powerbloc it makes changing weights 
a breeze. All you need is a 3' long piece of 2"x3" box steel. Cut it down the middle so it forms a C channel. 
There is your tool. slip it over the clutch faces and it will prevent the spring from unloading while changing 
the weights. 
If you rear drive unit (driven clutch) will not come off the transmission (which is usually the case), you can use 
a puller 8" jaw gear puller. Sometimes it will shear the snap ring off the clutch. If this happens you can then take 
a harmonic balancer puller and use it by installing long bolts through the fixed face of the drive clutch. You will 
have to drill through the fixed face and use nuts on the long bolts after you stick them through the fixed face. 
There are a couple of real small holes in the fixed face. Drill them up just large enough to stick the bolts through. 
It usually helps to keep soaking the shaft with PB Blaster or break free solvent from the top and bottom. Sometimes 
it takes several months to get them to loosen up. I have had some that took a over year. If you heat cycle them about 
once a week
that will help also. I use a propane torch and just heat it up real good, then let it cool. If you try to use an Oxy torch 
it will sometimes melt the aluminum. (I've done it before). If you get mad at it you can take a grinder with a cutting 
and cut the mother off, but be very careful when you get to the shaft area. Don't cut into the input shaft. They cost 
over $120 new. When you get ready to install your rear drive unit make sure the shaft is clean and free of burs. 
I polish all rust away using a grinder with a scotch brite pad. Use antiseize on the shaft and pully and key. Lots of it! 
 If you need to service or repair the Salisbury clutches The factory Honda maintenance manual has all the 
information  and list all the necessary tools. It cover the procedures in detail. The Clymer manual does not have 
the information on the factory clutches other than how to remove them. The FL250 has Salisbury 700 rear
drive unit from the factory. It does not have backlash slippers like the Comet 90D or Salisbury 790 & 770.
Other Tips
Motion Pro makes a replacement throttle cable & parking brake cable. Part numbers are 02-0016 for throttle 
and 02-0137 for the parking brake.
If you have an FL250 and need a maintenance manual, you can order one (part # 36-52) for $25.99 from 
Dennis Kirk(1-800-328-9280). 
I wrote this to help you get your Odyssey up & running so you can go have fun! Print this and tape it in the 
back of your Clymer FL250 manual for easy reference.
Hi Hoser, I finally had time to go dig up the FL250 piston interchanges for you. Here's the info:

  The following pistons are a direct interchange with the FL250:

  73-74 250 MT,CR,MR - Does not have reed cutaway

  75-77 250 MT,CR,MR - Does not have reed cutaway

  77-84 FL250 - Does not have reed cutaway

  78-80 CR250 - Has Reed Cutaway (431)

  81-84 ATC 250R - Has Reed Cutaway (431)

  The list above is a guideline for the piston you are looking for (FL250 interchange with reed cutaway). Since 
you have a reed cage, order the 431 style 
  (78-80 CR250 and 81-84 ATC 250R) and you will have a good chance of getting one with the reed cutaway 
already there. 

  The 78-80 CR250 and 81-84 ATC 250R - pistons are supposed to have the reed cutaway out of the box, 
but I am looking at a Weisco 431 I have that came 
  without cutaway. Don't ask me why, I don't know. It just means I have to cut the damn thing (that sucks, huh? 
Go figure?). I have ordered 431's before and  they came out of the box with the cutaways. 

  All these pistons are available through Weisco. I know you hate Weisco's so I tried to reference them 
through ProX. None of these pistons are available through ProX as far as I can tell. There are probably 
factory Honda pistons available through your Honda Dealer if you want a factory Honda piston. I have 
  not researched Sudco, so they may be available through them (if Sudco & ProX aren't the same co., 
ain't sure).

  Hoser: " I get 2.792 using a snap gauge and calipers I get 2.799 using the snap gauge 
  and 2-3" micrometer I can verify 0 on the calipers but can not find my gauge blocks 
  to verify the micrometer. (wonder where the hell they are hehe) ."

  Usually if I can find my t-gauge, I can't find my caliper or my micrmtr, so you are doing better than me :-)
  According to 1" = 25.4mm. Then: 2.799"x25.4 = 71.0946mm bore on that Mossbarger cyl you have. 
Stock FL250 bore is 70mm. If the bore cleaned up at   2.799 you should be able to order a .050 
(71.25 Weisco) piston and then bore your cyl to match. I think Honda only does .020" increments, 
so a Honda   piston would be a .060" not .050". That would be a 71.5mm bore @.060".

  There is also a KTM 300 piston that will work when you reach a past - .080" situation if you are 
willing to do a little machine work & cannot locate another  cylinder. If this happens to you, email 
or call me and I will give you the details. (That KTM thing is between you & me OK. I can't give 
out tricks, especially if   they can screw up real good if they don't know what they are doing).

  You had asked me about a long rod setup for your FL250 crank. The part # for the 10mm longer 
rod is Vesrah K5464, or Niks ProX 04971, or Weisco/Hot 
  Rod CR156. It is from an 87-89 TRX250R. Marv has told me he will build the rod in Titanium if I want one.