April 2010 18
You must have some secrets to make old engines shine like new again… Hopefully, one or two that do not require taking it completely apart, repainting it, and putting it all back together again! The motor runs solid, but it looks like crap! Any suggestions?
Cleaning up an old air cooled motor can be a LOT of work. All sorts of dirt and oil and gunk can collect between the fins over a couple dozen years. Often times the old Jap motors are painted, and the paint will start bubbling and flaking off allowing the aluminum to oxidize underneath.
This is one of my old Yamaha TX500’s – it has an unpainted head.
And here is a more typical sight – a painted head.
The best way by far is to pull the head and cylinder off and have them media blasted. The whole thing will look brand new after. …… but that isn’t your question.
Generally to clean the fins up I’ll start with a wire brush. I have a couple different sizes of wire brush, one thats larger with long bristles, and another that is smaller like a toothbrush with short brass bristles. Have a look at your local hardware store and see what they offer.
I’ll scrub with the brush as best I can which will generally clean up all the flaking paint and larger clumps of junk. It’s typically best to power wash the motor first to get it as clean as possible to start with.
*note: you should always be mindful of the gaskets when power washing and scrubbing with wires*
After the big gunk is gone , spray it down with some degreaser in any areas that need it.
I’ll then use an emory board (a ladies nail file) and use it to sand up the tops and bottoms of each of the fins. This often does a great job. You can also use a fine grit sand paper, fold it a few times, then push it in and out.
I then will rinse the motor and use an oil like wd40 or similar to give the motor as much shine as I can. The oil will burn off a bit once the motor is hot again, but it’ll stay pretty clean.
*note: if you are going to be painting don’t use any oil*
Really that’s about as good as you can do without disassembling the motor and giving it a hardcore cleaning. If you spend a saturday afternoon with a few tools, put in some elbow grease, you can definitely clean those old nasty fins up quite nicely.
The Kawasaki KZ550 motor I repainted, because it just wouldn’t look ‘good’ otherwise:
The Yamaha TX500 motor I ended up scrapping, but thats another story.
I bought a Nighthawk exactly like yours and love it. I don’t have a manual for it and it has been impacted by being left outside too much. I can’t get the seat to release to gain access to the airbox to ensure it doesn’t need service. It looks like the mechanism by the helmet mount doubles as a seat release but the seat seems to hang up in the front and won’t lift open. The mechanism seems to release only the holder in the rear. Should the seat flip up from the rear or open sideways as most of them do? Is there an additional broken cable not releasing it in the front? Also, do you know if there is another fuse locaton other than what is under the side cover? I have lost tach and speedo lighting.
I conc ur with your “perfect commuter” statement. It will pin the speedometer, making it safe to operate on short hightway stints and smooth and easy to handle in city driving conditions. I really like it and I’ve had Harleys and big cruisers. This is so easy to handle.
The seat lifts from the side and is held down with the same latch you are referring to. It should be a keyed latch – twisting the key one way will open the helmet lock, twisting it the other way will unlatch the seat.
In some cases I’ve had damaged seat locks and ended up just taking a drill bit and drilling the lock out – that has always worked like a charm for me.
Additional Notes from a reader:
I too have an 82 Nighthawk and had problems with the seat. As it turns out the problem wasn’t with the seat, it was with me. On one side you have the “key’d” latch, but there is another lever on the opposite side of the bike that released the seat for me. I don’t know if that would solve your problem or not…but figured I’d check to be sure you were releasing BOTH SIDES.
I have a 86 ktm 250 that I’m in the process of restoring.
I was browsing through pictures on the web and came across your project 86 ktm 500.
This is my first time doing a restoration on a dirt bike and so far everything has been going good but the problem I’m having is finding information for my bike.
I wish I could find a service manual but I have had no luck.
So I just wanted to ask if you or anyone else here has any sort of documents or information about this bike they are willing to share?
What sort of information are you looking for? Most 2 strokes are pretty similar. I have PDF manuals for lots of late 90’s KTMs, which honestly, aren’t THAT different.
Finding a manual for an older KTM can be tricky, and finding the parts can be too – but they are GREAT rides and tons of fun as a hobby.
I’ll upload the manuals I have so you can see them. What specific questions do you have about the bike? If you’re looking for torque specs you can use later model bikes as guidelines, everything will be pretty much the same.
Here’s my 500mx you were referring to:
Evan wondering if you have a service manual for my bike.
Thanks again for all the help you got a great site here.
I have the service manual for many of the Suzuki GS750 models – however, the GS750E is a different animal.
For what it’s worth, here is the manual for the standard GS750’s.
If I stumble upon the correct one for your bike I’ll make sure I let you know.
Something I noticed when I got my bike is that it didn’t have a brake stay and instead it had a piece of aluminum angel bar bolted to it,which held it directly to the swing arm.
The aluminum angel was bending from use and I figured stock was best so I bought a brake stay.
I have been looking at newer bikes and I haven’t seen brake stays,the caliper just bolts directly to the swing arm.
So I was wondering if there is an advantage to have the caliper bolted directly to the swing arm and if so what is it?
Well – long brake stays were used in the days of drum brakes to keep the brake from rubbing as the swingarm went up and down. Having a long brake stay kept the brake and the brake activation lever (attached to the frame) parallel as the rear wheel bounced up and down.
With a disc brake you don’t really need a long brake stay to the caliper because there isn’t an activation arm, it’s controlled through hydraulics. There are some older dirtbikes with disc rears that have a long brake stay – but that’s pretty much phased out these days. Generally the calipers will mount to an axle spacer and slide into a slot in the swingarm to hold it steady. This is just a more simple and lighter solution. They both work though.
I just thought there may be some reason they had them,like I was thinking maybe having the brake stay makes the swing arm go in when you press the brake which maybe makes it easier to stop or maybe softens the brake so it’s not so harsh.
That’s all I could figure.
hey bro to tap that stripped plug hole do I have to pull the motor or try to cheat some how to get the head off ? do not really want to chance getting shavings in the cylinder
Off hand I can’t say for sure if the head can be pulled from the XS triple without yanking the motor. I’m pretty sure it can, but I’m not positive.
Another option is to use a small vacuum attachment to suck out the shavings as you twist the tap. But really the safest option is removing the head and doing the work on a bench.
Good luck pete. Let me know how it goes.
thanks evan you is the man bro APPRECIATED
Thanks again Evan for the tip in the cold start issue ! I cleaned the carbs and put a new air filter in and it cured my problem !
I have another issue with the bike… 1983 GS750E
When you start up the bike it has a clacking sound coming from the clutch but when you pull the clutch lever in it goes away also when the bike warms up the sound completly goes away. any insight into my issue would be greatly appreciated.
Hey Jay – glad the air filter worked out for you.
Rattling clutches on startup can be a few things.
It can be wear on the fingers of your clutch basket. If the bike has been ridden hard the clutch basket can have ridges worn into it which can cause the plates to sit a little awkward. Only way to know for sure is to open up the clutch and look. It’s easy to do, and if the groves aren’t too deep you can sand them smooth in an hour.
It can also be a sign that your clutch springs are starting to weaken. Again, you’ll have to open the clutch and measure them to be sure.
The easiest thing – try a different oil. Oil will drain off the clutch plates when the bike sits, so they can be dry on initial start up causing them to rattle a bit. Switch oils to a different brand or slightly heavier weight and see if it changes.
Storing the bike on the center stand may help too.
I’ve decided to get my bike running again after 10 years of storage. I’ve removed the triple carbs and began the cleaning process per Evan’s article. However, the jets don’t seem to have slots for removal as Evan’s photos, how do I take them out??
Hey BillG, thanks for the question.
The Yamaha XS triples have constant velocity carbs that work on vacuum pressure – most bikes of the era have similar setups. The XS triples however do have a slightly odd arrangement in the carbs. The main jet and idle jet should both be removable with a flat head screw driver. I believe on the XS850 they may be under little covers that need to be removed to get access.
That said, there certainly are a variety of other jets and passageways in all carbs that are pressed into place at the factory and cannot be removed. You’ll see them on the intake side of the carb and sometimes down in the bowl as well. To clean jets that are pressed in you’ll have to force cleaning fluid into them and blow them out with compressed air. I like to use a small plastic syringe for this. You can get a small syringe at a hardware store for a couple dollars. I’ll fill it with cleaner, then force the fluid through the jets. I also reverse bleed my brakes with the same tool.
Have a look at the exploded diagram below. You are looking to pull out the pilot jet (#14), and the main jet (#17). The others will mostly likely not be removable.
This is what the components inside your carb should look like:
Here is the Yamaha service manual for your bike – well, technically the 750, but they’re mostly the same. Scroll down to the carb section and it will give you a little (not much) advice.
These carb diagrams may help a bit as well, but they aren’t of the best quality.
Good luck getting your bike back on the road. I’d love to see a photo! Let me know how the carbs go.