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Post by chew652 on Aug 9, 2006 21:41:21 GMT -5
I bought a '79 sr500 a couple of weeks ago. The cosmetics are rough but it was somebody's baby once. It has Konis,SS brakeline,SS Super Trapp,the hi flo oil line to the exhaust rocker,K&N filter , fork gaiters and drag bars. It wouldn't run very well in the upper gears. I replaced the battery eliminator with a regular battery ,no change. As I came back from a run I noticed it was running very rich. Lots of black smoke and carbon. I tried running without the airbox cover and snorkel and lo and behold the top end was great. I took the carb apart and saw that the slide had been filed and it had a #320 main jet. I cut some holes in the air box cover and reinstalled it( need it to hold in the filter) and added a couple of discs to the super trapp. The PO had 4 in there<I now have 6.
So the question is(Finally). What is the original length of the stock slide (or the correct modified length) and how many discs for the super trapp? I don't know what head pipe I have and I am reluctant to take it off just to find out. I seem to have run through the first tank of gas rather quickly, so I'm wondering if the carb is still way too rich. Any suggestions are appreciated. Runs great though.
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Post by kentrex on Aug 25, 2006 2:55:31 GMT -5
Tough call without checking the bike out. Have you done a plug chop? Best way to tell how the bike is running under load at full throttle. Stock jet is 300 I think with the needle in the middle position. If you're getting around a hundred miles before reserve you're doing ok. My own SR ran like a pig when I got it, the carb was a mess, I stripped and cleaned it and replaced all the jets using a Keyster carb kit. I also installed new diaphragms. A couple of hours work and the bike was transformed. However you have a good runner already...cliche` time...If it aint broke etc  Ken |
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Post by rodentrancher on Aug 27, 2006 11:47:40 GMT -5
Just removed the slide from a '78 carb - it appeared, as far as I could tell, to be stock. It measured 2.030 inches long with my vernier caliper.
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Post by chew652 on Aug 27, 2006 12:24:35 GMT -5
Thanks guys: Since I posted I have added 2 more discs to the Super Trapp for a total of 8. I have put in the correct sparkplug as the PO had a cold one in there. This morning I found the coil hanging loose with one screw. I cleaned the K&N and found it to have a lot of oil in it. I have also ordered a Keyster rebuild kit. The bike runs real strong now but it still shows a bit of black smoke off idle. We'll see what the rebuild kit does. Thanks again.
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Post by pathumper on Aug 31, 2006 11:24:54 GMT -5
I have a 79 SR500 that I have fiddled with for a few years. I replaced the air box with a slip on K&N and put on a full supertrapp exhaust with 12 disks. I "mintonized" the stock carb and settled on a 330 main. It's been a while but I think I also upped the pilot jet. It runs great with this setup and makes all the right noises. ;D
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Post by chew652 on Nov 4, 2006 17:46:34 GMT -5
Follow up: I now have 12 discs in the Supertrapp , new diaphragms in the carb and a #20 pilot jet. Runs real strong and the smaller pilot jet seems to have cleared up the black smoke at idle. Mileage has been bad (35mpg approx.) Will have to see if the pilot makes a difference there. A thread on another sr500 sight points at the needle position as being very significant as to fuel mileage. The bike runs so strong now I hate to mess with it. I also added a non vacuum pet c o c k from MikesXS www.mikesxs.com/mikesxs-fuel_system.php?category_id=4.1 because the vacuum one has caught me out a couple of times now. Nothing like kicking your brains out and finding you knocked the little vacuum hose off the carb when yiou were fooling with the throttle cable. |
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