My first project 1983 Yamaha sr 500

hey guys,

i agree with tim,
i have painted two bike frames, my 175 and my 500. i took every thing apart on my 175, then painted, had the motor out and apart then painted it. turned out great and the paint job looked clean. only thing is if you paint the carb, bowls etc. get them powder coated, even with high temp paint and preped right, the fuel still eats at it.
after that i got my 500 and stripped every thing off it, except for my engine, masked it off and painted the frame. i had a seized bolt in the engine to frame mount. unwrapped it and right away spoted areas where the paint did'nt hit. the primer wash showing. so i need to go back now and paint the areas where the black did'nt hit. it is a pain.
so in the end i would say to pull the engine and save your self the hassel, do it right the first time and you'll like the end product.
as for the engine, make sure that the grease and oil is all gone before you even think of painting it. if you don't you might aswell go buy all that paint and just spray the ground, because it wont stay on. i used hight heat paint after degrease and sanding ares with fine cloth, i did some thing like 5 coats, with in the spand of 3-4 weeks, and then about 7 coats of primer over 3-4 weeks.
the high heat paint needs the proper time to cure.
it turned out great and has lasted 2 seasons of riding and now some else is enjoying it. if you are going to polish any parts, after polishing get some sealer to keep it polished, it will tinge.
any way, that is just my 2 cents.
later.
 
thanx for the advice!

but right now...i got problems with the f** carb...im trying to adjust it...it looks like its using too much gasoline..and i can tell that by the smell... and the spark plug! it gets black at once! i also found out that the last owner had "twic" the carb..buy putting a larger..(i dont know the english word for that..) in greece we call it "zigler". English and Americans call it jet...i think. and im trying to fix it so it will be stady at 1200 rpm and not smelling too much gasoline.
 
The engines in the SR and XT are REALLY light (not surprising I guess - dry sump, single cylinder, air cooled....).
They are very easy to take out of the frame. I took out my XT motor and lifted it up on the workbench by myself without any hassles (I was expecting some grief....)

Definitely take the motor out if you are painting the frame - it's easier than you think.
 
hey guys...

i fixed the carb...and when the bike is cold its working really good! but when the oil temp goes to 50 degrees and over the bikes has problems..it turns off when im in neutral..and i have a suspition that the problem is on the " multiplyer " if its called like that.

if you follow the spark plug wire up to the main wire....i hope you get me.. :p that thing that

any opinion about whats the problem?
 
hey man,
does the problem also occur when at idle, do you have to keep the bike reved up to keep it going???
this problem could be a number of things, first i would charge and load test your batt, second pull the plugs and check them - what color are they, third i would hook the plugs up and see if there is any spark, now if there is'nt any spark, its prob the coil. if there is spark check the regulator on it.

i had the same problem with my other bike, it would'nt stay running, had to rev it up at idle to keep it going, ad would quit at nutral. it was the regulator fouling up, re/re the regulator and was fine and at a load on the throttle it would miss, and after awhile even at a idle it was missing and would'nt stay on. found out that i had a bad cell in the batt and it was messing up the regulator, and causing the bike to act up.

that is my advice to you, sounds like a elecrical prob, so process of elimanation.
any way, hope you figure it out,
later.
 
i changed the battery....and i found out that if i put the carb at 1500 rpm its working fine..but i have to check for the coil...

thanx for your advice!!!!!
 
hey man,

so was the batt no good??
did the running of the bike change from batt to batt???
if you have good spark, which means the coil is good, check the points, both gap and firing point.
sounds like your right on track,
later.
 
ok people....after several days of blood sweat and tears....i decided to open the engine.....and...

i found out that the oil spring was broken due to bad assembly. the fuel valve is looking realy good but the exhaust valve is a bit damaged..think im going to replace it...now im going to clean the mess that the oil left on my piston...

and i think thats the reason the spark plug had problems...cause after 50 degrees i had these problems i sayd before...


DSC00574.jpg


DSC00575.jpg
 
AT LAST!!!

im back in the streets....the bike is running better and doesnt smell like a 2 stroke :p but.....

theres a big BUT...the carb still has problems.....you think i should buy a new one?

if yes does any one knows witch one?
 
What part of the bike is navy blue that you want to make black? Surely not the frame?

If you're talking about painting the tank / sidecovers, that's an entirely different matter from the frame. Take them off and paint them.

What kind of carb is it on there now? Probably just needs a proper cleaning/tuning. What 'problems' does the carb have?
 
The stocker SR carbs and junkers. There's no point in rebuilding em when you can rebuild something better. I've heard that keihin flatslides are good but i've settled on a Mikuni VM36 for mine. That'll be fine with an opened up exhaust and intake. If you're working the motor (1st or 2nd oversized, cam, etc) i've been told it's best to go to a vm38.

Incidentally did you sort out the running issue? I had exactly the same trouble with mine. I know the compression was down due to a leaky head gasket but after pulling the bike down i notided the two wires running to the coil were pinched against the frame ??? (idiot PO i guess). I also assumed it was rubbish oil that needed a change and i figured the PO had probably just filled it with multigrade too. I haven't found any other problems that might cause it but i haven't cracked the engine yet. What exactly was your problem with the "oil spring"? Was the problem in the pump?
 
Here's some good info on tuning SR/XT motors:

http://caferacer.com.au/content/index.htm

Look under VMX and there's a few downloads for engine building tips.
 
You can also get onto www.sr500forum.com . There's lots of info there plus the old sr forum is at http://sr500forum.proboards.com/index.cgi
 
guys thanx a lot for your replies!!!!!
Staffy i will try to explain it....under the piston..there is a round pice of metal that holds the oil not to get in the cylinder..that pice was broken..

its like.. one of them are for the compretion..and the other one is for the oil..the one for the oil was broken.and there was oil in the cylinder...on the spark plug.i hope you understand me now :)

now about the carb...its a mikuni for sure...and it says 48U..thats all...now the "problem" is that when the oil goes to 50-60 degrees the bike loses its Idling.

lets say....WHEN THE BIKE IS COLD: im going with 60km/h and 3500 rpm...i see the traffic light, front brake...slow down..clutch,second gear...brake more first ...neutral...and the rpms are steady! like 13000

WHEN THE BIKE WORM: (50-60 degrees) im doing the same thing but as i change gears i nead to accelerate...like " cluch brooom 2 cluch brooooommmm 1 and then the rpms are like 500-1000

i will try to pout a new carb on...and a new intake.ill take off the old air filter!
 
Aaaaahhhhh, oil ring. Gotchya. Well the one thing we had in common was poor compression then so that could be it but doesn't explain why it still does it. Mine used to stall if i left it in neutral or with the clutch in at the lights without a bit of throttle. By the time i pulled it off the road it was really struggling to idle at any time. One great thing was it used to stall if i pulled the clutch in and held it while moving. Doing a rolling bump start at 100km/h is great fun ;D

I can't remember the model designation for the stock carb but i think that might be it. The mikuni VM36 is a simpler carb worth looking at. The stock one is about 34mm i think. I was asking the same question only weeks ago so theres a bit about them here http://www.sr500forum.com/forum/viewtopic.php?f=10&t=1776&start=0&hilit=vm36

They tend to feel like they want to stall sometimes but if it is stalling there's a problem. I still haven't figured out my stalling issue cause the bikes still in bits, but i am gonna look at replacing the coil, getting a new cdi off of a guy named Aero (on the sr500 forum, i've heard nothing but good things about his cdi's, he even got a small article in classic bike magazine in england). I'm replacing the carb with a VM36 and adding some restriction to the exhaust (my exhaust used to run a pipe with a muffler that had very little restriction in it.)

I cant recommend enough getting onto the sr500 forum. If you ask all the right questions theres some really great guys there that'll walk you right through to the end, just like here on dtt.
 
Might be an idea to check your ignition timing. My XT was doing the same thing when I first got it fired up (I had to re-build the top end before I could start it - stuck exhaust valve), and the timing was something like 20 deg retarded BTDC. It would get fairly hot at the lights and just stall without warning (not nice in traffic :eek:).

Anyway, 5 minutes with a timing light and I got it back in the ballpark. I'm still experimenting with fine tuning the timing, but it's not doing that stalling thing anymore and it's running pretty strong now ;)
 
well...yesterday i fixed the valve timing and today the bike was running like new!!!!!!!

i tried something this morning..i turned the carb when is dead cold:p to work at 2000-2500.when i get to the traffic light i just pull the throudle(correct me if im wrong..this is the thing you pull back to accelerate,on your handle bar)HAHahHAHAhAHHA :D :D my "Motorcycle English" sucks :p

so for a while youcould hear the bike a litle bit high,but when it got worm and the rpms felt down..they went at 1000-1500,so the driving was better today.

ill let you know what it will happen tonight!
 
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