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Thread: 1981 Honda XL250S

  1. #1
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    Hello everyone.

    I just purchased a nice old Honda XL250S. Its a 1981 6V, dual shock model – the last year before the 12V and pro-link style suspension. I have had it for about a month and am having a blast on it.

    Its plated and legal even though I bought it without signals – I managed to install some the other day which seem to operate reasonably well, although the flasher don’t seem to blink very well unless the RPMs are up which is disconcerting at stop lights to say the least.

    I have a few questions which I hope some members could help with.

    1. The exhaust is pretty much toasted from what I can tell. Id like install or build up my own using a supertrapp universal muffler. Has anyone done this for a XL250 or can anyone recommend where to get a mid pipe fabbed up? What does that expansion tank looking thing do for the stock muffler? Will I have to re-jet after installing the new muffler? What size muffler and midpipe should I be looking at?
    2. The brakes are pretty much useless on the street – can these be improved upon at all? What are ways of tuning or improving the drum brakes - I have heard about scoring grooves in the brake material – does this work or just build up more dirt in the assembly?
    3. Will a 12V horn work on a 6V system or does anyone have a working 6V horn to sell or trade?
    4. My home brew signal lights look pretty dorky – does anyone have the stock signals to sell or trade?
    5. Occassionaly when I try to kick start the kick seems jammed aand wont kick – is that because the compression release isn’t adjusted properly?
    6. Does anyone have a copy of the Honda manual to copy, sell or trade? The Clymer manual is spotty at best and doesn’t provide exploded views.
    7. What is a good replacement rear suspension for these dual shock models – Id like a little more ah, suspension to say the least?


    Thanks.

  2. #2
    Fargo_Wolf
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    I have the slightly smaller version. Mine is a 185 S. If you're able to, post some pics so we can see what you have to work with (See my thread in this section).

    2: I'd check the brakes first and see if a bit of adjustment is all that's needed. Failing that, I'd replace them.

    5: Based on that alone, I'd say you're trying to start it on a compression stroke.

    6: Order a Haynes Manual online. I swear by them. Linky below:

    http://www.haynes.com/products/sfID1.../productID/364

    Old Trials Guy has a bucket full of parts that I believe are for a XL 250 S. Feel free to send him a PM regarding basic parts.

  3. #3
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    Hey I just took a peak - your bike is an identical twin to mine!

    I am unable to PM Old Trials Guy - my account doesnt allow PMs for some reason :-(

    Yeah those manuals are okay, very similar to the Clymer but the factory manuals are the best.

    I will post some pics tonight when I get a chance.

    Oh yeah - the brakes are adjusted - they just are terrible - scared myself on the street yesterday in the rain I thought i was going to ride right into the car in front of me. Pretty slick after no rain for a while.

  4. #4
    old trials guy
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    Fluxone wrote:
    I managed to install some the other day which seem to operate reasonably well, although the flasher don’t seem to blink very well unless the RPMs are up which is disconcerting at stop lights to say the least.
    Invest in a cheap automotive "electronic" flasher relay asituses a timing circuit and nota bi-metalic strip. You may have to look around as not many 6v autopartsavailable.

    I have a few questions which I hope some members could help with.

    1. The exhaust is pretty much toasted from what I can tell. Id like install or build up my own using a supertrapp universal muffler. Has anyone done this for a XL250 or can anyone recommend where to get a mid pipe fabbed up? What does that expansion tank looking thing do for the stock muffler? Will I have to re-jet after installing the new muffler? What size muffler and midpipe should I be looking at?
    I have had luck buying automotive exhaust pipe. You might even luck out at your local muffler shop and have him bend up a facsimile. The expansion tank does most of the muffling using an arrangement of metal baffles. The end piece is primarily the spark arrestor. Super trapp mod will be fine but expect a lot more exhaust noise and yes, you will likely have to put in richer main jet and maybe raise the needle. Just match the pipe to the existing header pipe for dimension.
    2. The brakes are pretty much useless on the street – can these be improved upon at all? What are ways of tuning or improving the drum brakes - I have heard about scoring grooves in the brake material – does this work or just build up more dirt in the assembly?
    Love those drum brakes. Take apart the brakes and clean up the drum lining with emory cloth. They will be pitted and rusty but you should be able to get them a little smoother and shinier. Replace the shoes. Grooving the shoes is done to provide some place for mud and goo to go that accumulates in the drum. I never found it made a difference nor did drilling holes in the shoes. Years ago when racing drum brake bikes I took the wheels off every muddy ride and cleaned the shoes and drum linings and replaced shoes regularly. They suck when they are perfect and useless when neglected.
    3. Will a 12V horn work on a 6V system or does anyone have a working 6V horn to sell or trade?
    You should be able to buy an aftermarket 6v horn but try the local bike wrecker. Just about any early (1980 and before) Japanese dual sport/ enduro will have one.
    4. My home brew signal lights look pretty dorky – does anyone have the stock signals to sell or trade?
    Unless you get them cheap why not look dorky, then you will look like the rest of us....haa haa
    5. Occassionaly when I try to kick start the kick seems jammed aand wont kick – is that because the compression release isn’t adjusted properly?
    Always kick these from the top of the stroke. Finding compression or partially depressing the kickstarter prior to kicking willbypass the compression release.
    6. Does anyone have a copy of the Honda manual to copy, sell or trade? The Clymer manual is spotty at best and doesn’t provide exploded views.
    Honda manuals make lots of assumptions about reader knowledge. I actually think the clymer manual or Haynes are a better choice for most home mechanics, which includes me. Honda manuals assume you have some Honda training and have their special tools.
    7. What is a good replacement rear suspension for these dual shock models – Id like a little more ah, suspension to say the least?
    Really long shocks on these models and finding replacements could be difficult. If they go up and down and dampen a little bit that is about as good as they came from the factory. If it were mine, I wouldn't spend a lot of coin on "improvements", I would save that money up to buy a more modern bike like the prolink model with 12v electrics but that is just my opinion.
    Is this the one with the wonderful 23 inch front wheel that Honda figured would set the new standard, if so another good reason to enjoy it with the least investment and save for the dream bike. 23 tires are scarce and althought they roll over things okay steering feels heavy on these beasts.
    and the bucket of parts is off of an XR200R prolink model but nobody believes me

    otg



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    Dont worry I dont plan on trying to "upgrade" anything on this bike - its got some old school class.

    I have my eyes on a new bike for next fall - this one is pure fun.

    Yes it is a 23" front - every single spoke was loose when I got it and I managed to find a new inner tube to my surprise - though I thought I would disintegrate the rubber peeling the tire off the rim. Also, the big front wheel feels crazy on the road!

    Based on your advice I will not touch the rear suspension other than to paint the springs and clean it up a bit.

    I think my drum brakes are tuned perfect then - thank goodness its only an old 4 stroke.

    I guess I will leave the signals for now - keeping my eyes peeled for some old stock ones - the ones I made are probably better since they are flexible the way I mounted them.

    So why is there an expansion tank on these 4 strokes - Is it really the muffler since it doesnt seem to be working at all - I cant believe it would be louder with the supertrapp.

    Anyone have an old universal muffler to sell me? Outside diameter of exhaust header is measured at 1 3/16" so I guess a 1 1/4" mid pipe would fit.

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  7. #7
    Administrator JetDog's Avatar
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    Fluxone wrote:
    Hey I just took a peak - your bike is an identical twin to mine!

    I am unable to PM Old Trials Guy - my account doesnt allow PMs for some reason :-(

    Yeah those manuals are okay, very similar to the Clymer but the factory manuals are the best.

    I will post some pics tonight when I get a chance.

    Oh yeah - the brakes are adjusted - they just are terrible - scared myself on the street yesterday in the rain I thought i was going to ride right into the car in front of me. Pretty slick after no rain for a while.
    Your PM is fixed.

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    5. Occassionaly when I try to kick start the kick seems jammed aand wont kick – is that because the compression release isn’t adjusted properly?
    Fargo_Wolf wrote:
    5: Based on that alone, I'd say you're trying to start it on a compression stroke.
    Um... Don't bikes usually tend to START on the compression stroke? You know, gas vapors+compression+spark=boom and all that?

    That being said... Your problem more than likely has more to do with your kick timing than anything else.

    Next time it locks on you, STOP, let it come slightly up in the stroke and then kick through, if you've properly primed the bike and she isn't flooded, she should start.

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    Thanks for all the advice and tips - BTW the red text is really hard to read on this green website.

    yeah the kick start issue is more of a pilot error than anything else - I just need to calm down a bit - I do get excited :-)

    After a bit of electrical tinkering - wow the 6 volt system is really sensitive to changing loads! Off the battery nothing seems to work properly - once the engine is running things are a little better but at an idle the relays dont work very well at all - I get maybe 4 flashes and then the blinkers just stay on. It seems this is a common issue and more a symptom of the crappy 6 volt system than an actual problem - anyway I like to be seen on the road so I will try and get it fixed.

    I checked into the flasher relay last night there are some two prong units available - this one looks perfect but they wont ship to canada:

    http://cgi.ebay.com/ebaymotors/HONDA-CB-CL-SL-100-125--6-volt-FLASHER-RELAY-%22$AVE-NOW%22_W0QQitemZ110402694473QQcmdZViewItemQQimsxZ2 0090616?IMSfp=TL090616032004r4195

  10. #10
    old trials guy
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    Tibarus wrote:
    Next time it locks on you, STOP, let it come slightly up in the stroke and then kick through, if you've properly primed the bike and she isn't flooded, she should start.
    This would be the starting procedure I would use on bikes that are not equipped with an automatic decompression device but those equipped with an auto decompressor often call for a slightly different technique.

    The recommended procedure for the Honda four valves with a decompressor is to kick smoothly through from the top of the kick start stroke. If you hesitate or don't allow the kick starter to fully return to the top you may not properly engage the decompressor. Trying to seek compression will have the same result.

    Engaging the decompressor serves two main purposes:

    1) it generally makes the bike easier to start and

    2) it reduces loads on the kick start mechanism and arm increasing reliability.

    My apologies for being an know-it-all but I workedin a Honda dealership for many years and enjoy sharing my experiences.

    otg



  11. #11
    Fargo_Wolf
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    Like anyone is gonna complain about your extensive knowledge of Hondas?

  12. #12
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    Fargo_Wolf wrote:
    Like anyone is gonna complain about your extensive knowledge of Hondas?
    At least I can start my bike without outside help :P

  13. #13
    DSBC Participating Member Sparkle's Avatar
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    Hi Fluxone:

    "After a bit of electrical tinkering - wow the 6 volt system is really sensitive to changing loads! Off the battery nothing seems to work properly - once the engine is running things are a little better but at an idle the relays dont work very well at all - I get maybe 4 flashes and then the blinkers just stay on. It seems this is a common issue and more a symptom of the crappy 6 volt system than an actual problem - anyway I like to be seen on the road so I will try and get it fixed."


    I think....

    The first thing to do is get a new battery....Mostly the horn, blinker, brakelight/tailight circuit on these old bikes, runs from power from the magneto system.Although the battery is in the circuit too, it'sjust there to regulate the voltage and supply power when the bike isn't generating much power such as at idle or low speeds. If your signal lights and horn work when the bike is reved up, and then dies at idle, it's the battery.

    It might look okay, and it might measure 6 volts (or more), but it's not supplying the current under load. If the battery has adequate reserve it will handle varying loads.

    just a guess.

    Sparkle


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    The electric problem seems intermitant. I got a new battery (Yuasa).

    Just gave a cursory check to the charging system which reads around 6.9V at idle - seems low. The lights do light up when its running so I think I will just try and replace the flasher relay this weekend.

    Whats the history on the charging system for these bikes. Whats the weakest link - the voltage regulator or stator? Should I just replace the voltage regulator as a good measure any way?

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    DSBC Participating Member Sparkle's Avatar
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    Hiya Fluxone:

    Otg is thevintage honda expert here....but while racing, he probably never worried much about signal lights....

    Your voltageat idle sounds okay. If your headlight is running and you have 6.9 volts to the battery, your stator is okay, and your coils too. The headlight isn't connected to the battery, it runs off a separate winding in the magnetoandruns all the time the bike is running.

    Your bike uses a combination rectifier/regulatorbut if you are measuringcharging voltageto the battery it's probablyokay too.

    The battery is connected to the neutral light, signal lights, horn, brake light, and taillight. Before you start changing parts just try a few things. Disconnect and reconnect every connector you can see near the front of the battery box.

    Undo the headlight ring and unplug and replug the connectors in the shell. 6 volts isn't much voltage and it can be stopped by just a little corrosion.Most times it's not a failed component.

    Just another guess.

    Sparkle



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  16. #16
    old trials guy
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    From what you describe your bike electrical system is working fine. They just had feeble electrics and signals, lights and brake lights all struggle at low rpm. My best recollection is these have a pretty simple generator:



    One winding supplies the CDI igntion and the other provides juice for lights. Output from the coil will be AC and itshould havea rectifier somewhere to provide DC to the battery and the battery pretty well regulates the voltage to lights etc. As you can see by the picture it is a simple system. Reliable but modest output. At low rpm if you apply the brake lights it will slow the signals to a halt and the horn won't sound. Rev it up and it gets better.

    The next model change featured 12v electrics and they were marginally better.

    otg

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    Thanks for the diagram and advice - I wont be too quick to change items.

    I am recharging the battery now and will give the wiring harness an inspection tomorrow.

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    Hmm - battery fully charged this morning - 6.5V. Everything worked like a charm, blinkers , neutral, hi, lo.

    Rode about 20k this morning and its still working fine!?

    Planned maintenance this afternoon:

    1. F/R Wheel spoke tensioning/truing
    2. F Brake drum scrub, cable clean/lube
    3. Chain lube
    4. New plugs -NGK D8EA (0.8-0.9mm gap) - I do lots of idling on this bike so should I go hotter next time? The current old plugs are the same and are carbon covered black but otherwise okay.
    5. Compression test.
    6. Re-test charging system, inspect wiring harness, voltage reg/relay

    I checked/changed the oil the other day after having already commuted about 4 days/90k since its first kick in probably 2 years. Oooops! There was practically no oil in the tank, I "topped up" about 1.2l. I have since done another 40k and everything seems fine - I hope i didnt do too much damage on that near dry engine.

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    Just completed my simple tune up but didnt get a chance to test compression - my gauge doesnt fit :-(

    There is no smoke, so I am not too worried. I dont know if its my imagination but it seems to run way better with the new plugs - I wasnt expecting such a difference - the old plug was actually an NGK DR8ES-L. I replaced with the NGK D8EA, I had to open the gap a little bit to .035" (I didnt have a metric gap tool).

    I understand 8 is the heat rating and L means its rated a half step up, so is the older plug a half step hotter? Which is better for lots of idling - the hotter one?

    Signals still working, seems to be charging, front wheel nice and true, brakes cleaned and adjusted, clutch adjusted, wire harness seems okay.

    After a short ride about 25k - its shifting a little better and seems to like downshifting/engine braking a little better - no nasty back fires. Was it all the carbon on the plug before?

    Brakes are still sucky but at least reliably sucky, the rear is noticeably better. Now I can really tell how bad the forks need a rebuild - a little more preload would be nice too.

    Next up - grease the swing arm, continue my search for a muffler and look for some cheap rubber - the sidewalls are totally cracked.

    What is the quietest I can get this bike - should I look for something diff than the supertrapp?

    Not looking too bad for an old gal.


    My home brew front signal mounts - strip of HDPE and some bolts..




    Rear Signals.


  20. #20
    old trials guy
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    Fluxone wrote:
    Just completed my simple tune up but didnt get a chance to test compression - my gauge doesnt fit :-(
    If it starts well and holds an idle it the compression is fine.
    I understand 8 is the heat rating and L means its rated a half step up, so is the older plug a half step hotter? Which is better for lots of idling - the hotter one?
    Heat ranges in NGKs are backward, the smaller the number the hotter the plug. If I recall the major difference with the D8EA is that it has a slightly protruded electrode. Colder plugs have less insulative material around the electrode and hotter plugs have more insulative material which means they retain heat better. Too "hot" a plug can result in detonation and too cold may collect deposits. I would stick with the D8EA.
    Signals still working, seems to be charging, front wheel nice and true, brakes cleaned and adjusted, clutch adjusted, wire harness seems okay.
    Everyone should take note that when you buy a new battery make sure you trickle charge it for a few hours. The charging system on many bikes is so marginal it may struggle getting a new battery up to full charge.
    After a short ride about 25k - its shifting a little better and seems to like downshifting/engine braking a little better - no nasty back fires. Was it all the carbon on the plug before?
    Since transmission and engine share the same oil your low oil situation would have caused the oil to get hotter than normal. The proper amount of oil will likely have made both transmission and engine happier.
    Brakes are still sucky but at least reliably sucky, the rear is noticeably better. Now I can really tell how bad the forks need a rebuild - a little more preload would be nice too.

    Next up - grease the swing arm, continue my search for a muffler and look for some cheap rubber - the sidewalls are totally cracked.

    What is the quietest I can get this bike - should I look for something diff than the supertrapp?
    Weld or pop rivet a piece of larger diameter tubing over the old spark arrester and weld or rivet an end plate on it with an outlet hole. I have seen a couple done like this.
    Not looking too bad for an old gal.
    She looks great, I even like the dorky signal mounts, they will flex rather than snapping off and probable cheap.....lol

    otg

  21. #21
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    So the current plug I have is slightly hotter than the L - perfect. Thanks for all the insight its been really helpful for me.

    Just got back from a short night ride, pretty dark and wet but my lights are working nice and strong. I made a tiny adjustment on the carb to richen it up since I stalled it while idling twice yesterday. Its ticking over strongly now my guess is somewhere below 1200rpm but seeming much more steady.

    Nice idea on the muffler-muffler, I think I may try it out.

    Tomorrow is frame and fork maintenance, chain adjustment and maybe check the valve clearance. After that it is pretty much good for another few 1000k. I have to say what a nice solid engine this is - a true classic piece of engineering.

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    OTG,

    ha ha - you are right the front tire was absolutely flat - the first picks were from when I brought it home before any cleaning or maintenance. I have since replaced the 23" inner tube and trued the rim - the rubber is probably dangerous still though as its cracked and hard. I have about 200k on it now and it has softened up a bit again so I may just replace the rear rubber.

    OTG, you have been a great help for a new Honda owner - had i not got your advice I probably would have bought all new parts - as it is I managed to either fix, tune or fab my own pieces so far. I did spluge and order the OEM clutch/brake lever, headlight and mirrors (I love the chrome) - though for those of you with similar bikes dont bother with the OEM headlight a 6V generic replacement can be had for $27 that fits the Honda assembly - damn it and I paid $65 for mine - should have checked the Motovan catalogue first.

    I was wondering if members could provide any additional tuning advice on these older 4 strokes. The bike is pulling okay for a 250 but seems a little "flat" after a few WOT blasts - could it be running rich for an extended period after WOT. Generally if I am nice the engine is predictable but if I get excited then the engine seems get stuck in a bad mixture or something.

    In addition I may try and service the throttle cables today - perhaps they are just slow responding.

    have a good sunday everyone - I was already out for a ride this morning its a perfect day.

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    just a quick update - I was unable to find a solid state relay for the blinkers so they still only blink while the RPMs are up - the electrical is 100% functional - 6V system is just plain crappy.

    I have an OEM replacement relay (mechanical) which was about $5 so I will try that. I am not expecting any difference - but who knows it may help.

    Also the bike is running pretty great - though the clutch release is a little jumpy - is it just my crappy shifting or can I adjust the release.

    Still looking for something to make it quieter - I decided I am not putting an ounce of energy into the existing muffler assembly.

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    Well the 6v system continues to plague me - but I have mostly dismissed it as a mere annoyance.

    Been riding every day on the street with decent reliability - the brakes still suck and top speed is about 106km/hr with me in a t-shirt and sneakers but it is a joy to ride.

    I am looking for a little tuning advice - I have stalled it a few times coming up to a stop - not where I stall by the effect of engine braking but by the sudden RPM change when stopping quickly.

    Also at WOT the engine seems to miss or bog at times - where should I start the maintenance. Are these two issues connected - am I running too lean?

    Any quick advice out there?

  25. #25
    old trials guy
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    Fluxone wrote:
    I am looking for a little tuning advice - I have stalled it a few times coming up to a stop - not where I stall by the effect of engine braking but by the sudden RPM change when stopping quickly.

    Also at WOT the engine seems to miss or bog at times - where should I start the maintenance. Are these two issues connected - am I running too lean?

    Any quick advice out there?
    With the spark arrestor missing and reduced back pressureit will likely be running leaner than normal. Have a look at the spark plug. It should be a very light tan color. Light grey is lean. White is really lean and needs immediate attention. Check your air cleaner and make sure it is clean and not too heavily oiled. That can also cause lean running.

    Adjust the mixture screw. First set the idle. Next, turn the mixture screw in to about 1/2 from stop. Slowly turn it out and the idle should increase. Keep going until you get maximum idle but no further. Turn the idle down if it is idling too high. You might have to give it a few tries to find the sweet spot.

    I hope this helps.

    otg





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