OllieB

Do you know anything about the age of your battery? If the cycle was in storage for some time, the battery may have gone bad. It will take a charge of sorts but that charge won't have any depth to it. Are you starting the bike w/the electric starter or kick start? If you have to use the kick start because the starter seems weak, your battery may be bad. Need more info. A deteriorated battery may test at 12 volts but have little reserve capacity and not charge back up enough with only the bikes charging system. If you need to buy a new battery, I would highly recommend a sealed type battery known as an AGM battery. These hold a charge much longer on standing and will take vibration, etc. much better than a regular liquid acid battery. When you charge these little batteries, don't charge at more than 2 amps charger output and leave the charger on for the duration indicated by this formula: Battery Amp Hour rating divided by charger output = hours on charger. Ex: 12 Amp Hour battery divided by 2 amp charge = 6 hours on charge. Pumping 10+ amps charge into a small battery for too long a time can damage a new battery. Could also just be a bad signal flasher unit but from the description of your battery situation, you have something else going on too.

Threads do not come all the way up the sides of the hole. The plug is pressed in for a friction fit and is no more than about 1/4" long, if that much.

KirriePete, Thanks for the very detailed answer!! Wow, that is much more intensive than anything I know of here in the states. Our Basic Motorcycle Safety Course assumes you have never ridden before. They have a supply of 250 cc bikes for those w/o a bike. They show the results of heavy duty beginner use. All the basic things about bikes and riding you would expect is taught at this beginner level. Our next level course called the Experienced Rider Course (not that much experience, though) is for riders who have at least a learner's permit and a bike. More advanced skills as well as confidence building is taught at this level. Both of these courses are optional and not required as yours are. Even though there are many more hoops to jump through for you folks now, I think new riders come out with more respect for what it really means to be a bike rider. I started riding in my teens in the late '50s on a well used Cushman motor scooter and then moved up to an early '60s Honda 150 Dream. At that time, no special certification was required as long as you had a drivers license. Around the end of the '60s I sold my Honda and didn't get back into bike riding until four years ago. Maybe thirty years ago my state began to require special motorcycle certification. If you had a bike registered at the time of the law change you were grandfathered and automatically got the certification. I didn't so when I started riding again I had to take the written test for my learners. I then took the Advanced Riders Course which, upon passing, automatically earned me the full certification. Those under age 21 with only a cycle learners permit cannot ride their cycle on high speed roads, after dark or with a passenger on board until they achieve full certification. For the regular beginners drivers license (autos) our state does now have Levels 1,2 and 3 licenses for those under age 18 and you cannot get a motorcycle learners permit unless you are on at least level 2 of your auto license. If you are above 18 years of age, you can get a "Motorcycle Only" drivers license. If you are over age 18, you can get a regular (auto) drivers license after just the written test, 30 days on the learners permit, closed course driving test.

Yep, bought two sets from that seller for mine and my son's XS400s. Good quality "Made in Japan" aftermarket manifold boots.

I've seen posts about the various tests/levels for getting a bike license endorsement in the U.K. Am wondering what steps you folks have to go through there as compared to the U.S. There are differences from state-to-state in the U.S. Might even be age/experience displacement restrictions in some states though I don't know of any in my area of the country. For someone who already has a drivers license in my state all you have to do is pass a written test (not too bad) and a closed course driving test. When you take the written test, you receive a temporary (3 month) cycle permit. You can come back for the riving test within one week, There are some restrictions, but I can't remember what, while you have the learner's permit. IIRC. If you take a motorcycle safety course (and pass it!!), you can take the paperwork directly to our DMV office and get your endorsement.

On a cold start, when I pull the choke out to the 2nd notch and hit the starter button the engine will fire and die. I then push the choke in to the 1st notch and it fires right up (may need a few throttle tweaks) at a slightly elevated idle. Could be things are working fine and your bike just doesn't need the 2nd, richer setting. You can provide too much fuel on a cold start and flood out the engine. One thing we must keep in mind is that these bikes are not fuel injected. I don't say that to make folks feel dumb but because many younger - even middle aged - folks may never have owned a carbureted vehicle. If an older bike is their first bike purchase, carbs are new to them. We get spoiled by the instant start and smooth warm up provided by fuel injection. Going back to a carburetor requires a learning curve - both in maintenance and performance.

BVD, P.O. = "Previous Owner" The kit I received from MikesXS does have the brass idle mixture screw but it wouldn't really matter the metal type. Yep, that's the kit I got. I haven't replaced these on my carbs yet because you really need to take the carbs off the engine to get the screws out easily and I am waiting on the butterfly shaft seals to be back in stock at MikesXS before I do the complete job. Besides the o-ring, the idle mixture screw itself can be damaged if someone tightened it too hard and deformed or broke off the tip. This would cause inaccurate gas flow at what you would think to be a proper setting. AFAIK, the only difference in a carb rebuild kit of the same model would be different jet sizes for different size engines. I really haven't searched out sources for a complete kit so can't help you there. Also haven't opened my carbs since this was done by the PO so I don't know jet sizes in them or any other XS400 carbs. Others here with more knowledge can help you there. On my bike, I am betting on vacuum leak(s) to be the cause on my bike. After I replace the various seals I will then do a valve clearance and timing check and balance the carbs and see what happens. While the carbs are relatively simple, there are several areas which can cause problems: bad gaskets, leaking seals-butterfly shaft, choke rod, o-rings, improper float level setting, malfunctioning float valve, clogged jets-sometimes with almost microscopic deposits hard to see and settings-idle mixture screw, slide diaphragm & needle setting (if adjustable) and carb balance. Hope this helps.

Interesting post. My 1980 XS400 does the same thing. I researched thoroughly in the forum and decided to check the idle mixture screw adjustment. The caps had also been removed on my bike by a P.O. The jets were set to about 2+ turns up. I increased them to 2.5 turns and the problem got even worse. I tried 3 turns with an even higher fully warmed up idle - now over 3K rpm. A couple days ago I set them back to 2 turns and now the warmed up idle is just under 2K rpm. Tomorrow, I'll drop it to 1 3/4 turns out and see what happens. I find these results curious! I don't get lean backfire and the bike runs very well otherwise. The factory setting was supposed to be 1.5 turns out and that may be a little too lean for some engines but maybe not for others. When you don't know the history of what has been done previously to these bikes, it makes corrections a little more challenging. Now, I know the o-rings on the idle mixture screws can become tired and leak. I have a new set of screws, springs, etc from MikesXS and will replace the originals when I pull the carbs off. At the same time I will install new choke rod rubbers and butterfly shaft gaskets - when they are in stock again.

Yep, always vertical or you will get a wildly incorrect reading! If your bike has a center stand (not familiar w/750), use that or as stated above.

Not familiar with your bike but is your electrical system still only 6V or is there a step down for the lights? Just curious. About LED stop/tail bulbs: they work best in lights where the lens and reflector are specifically designed for the light output of LED bulbs. LED bulbs project light in a much narrower angle than do filament bulbs. Basically, you have to experiment with different design LED bulbs to see which work best with your older design lens/reflector. Sometimes, installing LED bulbs will result in tail/stop lights that are dimmer than when using filament bulbs and you don't want that. I experimented with a couple designs in my scoot tail/stop lights until I found those I was satisfied with. What works for one design tail light may not be OK in a different design light. I just ordered a set of LED 1157 bulbs for my '80 XS400 to see how they will be. If your tail light contains 2 bulbs, replace just one with the LED version so you can see how it compares with the filament type bulb.

Great pics and write up. Congrats, you are doing a good job. Tank looks great! My son did that with my Dad's old 1976 Batavus moped gas tank. Going to install new idle jet screw kit, choke rod rubbers and butterfly shaft seals on my carbs but MikesXS is out of stock on the butterfly shaft seals and I don't want to tear things down until I have all the parts. My son has a 1981 XS400 and we are helping each other.

No, got them from the ebay seller below. Bought some from him a couple years ago that worked great in my scoot tail lights. Won't know how they are until I try them. Not the cheapest out there but very good quality. http://cgi.ebay.com/ebaymotors/2pcs-1157-13W-High-Power-LED-Red-Stop-Tail-Bulbs-_W0QQcmdZViewItemQQhashZitem2eaf747d53QQitemZ200512142675QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories#ht_798wt_1167 Rode in the dark this evening with the new Candlepower headlight and SilverStar Ultra H4 bulb. Very bright, good down the road projection and great side to side lighting. Don't do a lot of night time riding and it is always on 2 lane roads. This setup will work great. I like SilverStar bulbs - have them in my scoot and three cars. Never had a problem and they improved lighting in all applications. The set in my scooter is the original SilverStar (not Ultra), is about 6 years old and was in a car for the first few years. My next move is to install a headlight modulator. Have one on my scoot. Some folks don't like them but I'm for anything that increases my visibility to oncoming cars. Besides, the modulator only works in daylight on the high beam. You can always switch to low beam if you don't want the light blinking. The first one, model S75H4.

Thanks. Well, got the new unit installed. Didn't have to do any bracket switching. Everything matched up perfectly. Only mod was to cut about 1/8" off one side of the tab on the new unit to allow it to be rotated a little more clockwise so the lines in the lens were perfectly horizontal. Will test it tonight. Most likely will have to do an alignment. LED tail bulbs should be here later next week.

HoughMade, Got the headlamp in the mail today and will install it later tonight. What mods did you need to do? (haven't eyeballed the setup yet)

I guess you are asking me about the headlight. If you clicked on the link, you will see that I ordered a new headlight lens/reflector unit designed to accept an H4 bulb. Don't think you can easily or reliably "break the seal" of the original sealed beam unit but who knows! The original sealed beam headlight still works but is miserably dim at night. High beam is more like modern day low beam.

The increase MAY NOT be too much but these charging systems are VERY marginal, just like the one on my scoot. If you compliment the headlight bulb with a set of the right design LED tail/stop bulbs you will end up in even better shape than the original setup. As it is now, my stock headlight dims some (normal) when I apply the brakes. With LED tail/stop bulbs there should be virtually no difference in the headlight brightness when applying brakes. With 2 5w tail light filaments illuminated, the amp draw is about 1 amp. With the tail and stop filaments illuminated in both bulbs (2 x 26w) , the amp draw is almost 4.5 amps! With 2 LED tail/stop bulbs the amp draw never even gets up to 1 amp even with full tail/stop illumination.

Just ordered the 6 3/8" replacement reflector (see link below) into which I will install an H4 SilverStar Ultra 55/60w bulb. Also ordered a set of LED tail/stop bulbs to offset the increase in amp usage. Since LED bulbs use virtually no amps (much less than 1 amp), the increased drain of the H4s on the charging system output is basically nullified by the LED bulbs drop in amps consumed. Did the same with my scooter a couple years ago with great results. My XS400s stock sealed beam bulb is 35/50w so the new bulb will up the watt demand by 15-20 watts (depending on low/high beam) or an increase of 1.25-2.08 amps. The 1157 tail/stop bulbs consume up to 4.33 amps when both filaments in both bulbs are illuminated. By the math, even with a brighter headlight bulb, you reduce the amp drain on the charging system when installing LED tail/stop bulbs. One caution, you must match the LED tail/stop bulb design to the design of the tail light lens. Not all LED bulbs will be as bright as the filament type in the original lenses because the lenses were designed for the old style bulbs. In my scooter, I tried two different bulb designs and the second design is actually brighter than the filament bulbs. Have ordered an LED design that I think might work well in my XS400 tail light but won't know until I receive and test the bulbs. The light emitted by an LED is much more directional than that emitted by a filament and old style reflectors/lenses don't always catch and reflect the light from LEDs as well. http://store.candlepower.com/ca631quheleu.html

Yep, seems these bikes will not start/run with a dead battery - even with the kick start. If money is not an issue, I would recommend getting the better type battery known as an AGM battery. Also listed as maintenance free batteries. These batteries have a different type of internal construction to hold the acid, discharge on standing at a much slower rate and generally have more cranking amps then the standard liquid acid battery. Since you are new, please update your profile info telling us where in the world you live. In the U.S., NAPA carries the AGM batteries with a 1 year over-the-counter free replacement warranty. Many places only give a 6 mo. warranty. Stay away from Walmart batteries. Decent price but lower quality.

I defer to the folks with experience on this but I have seen used ones listed on ebay for much more reasonable prices. I would go that route before I would attempt some other questionable modification. I am only familiar with Pertronix units for cars. If that is what you mean, I really don't know if it would be possible to adapt one of those to our bikes.

Try the ebay seller below. Located in Indonesia and has patterns for many older bikes. If he does not have one for your bike, contact him and he will direct you to send him your tired, old and tattered cover and in 2-4 weeks you will receive a repro replacement FREE! Just bought one for my '80 XS400 and found it to be a pretty accurate copy. http://stores.ebay.com/Pit-Replica

What I'd like to know is whether or not the 5 hole muffler was standard in 1981 or if it was retrofitted to my son's bike and if the change required an increase in jet size? His bike has a hesitation that we haven't gotten into yet.

Looks good! My son's 3.00 X 18 is not as skinny as yours. Like I said, with our two bikes side-by-side, both tires look basically identical in size - just like your new tire. It is interesting how there are such variations in the same size tire. Have encountered that before. Replaced the stock tires on my scoot last year and the Shinko tires I installed (same size) are beefier than the O.E. Chinese brand tires. Also handle much better!

Thanks guys. The pic makes the holes look slightly out of alignment but when you view them in person, they are perfectly aligned. My son's XS400 is definitely louder than mine. He likes his sound (young guy) and I like my softer sound (old guy). LOL

Would like some clarification about exhaust pipes on the XS400 series. The pic below is of the muffler on my son's '81 XS400. The muffler on my '80 XS400 does not have the four holes in the end. I have seen pics that look the same as that of my son's as well as ones that look like mine. Was one optional or were these holes drilled after the bike was bought to make the exhaust freer flowing? They look to perfect to be done later, though. Would the carb jetting then be different on bikes w/holes in the muffler end? Thanks!!

I think the 100/90 looks just right on the O.E. rim. My son has an '81 XS400 with a 3.00X18 tire and side-by-side it looks exactly the same as my 100/90 on these rims.