|
|
Post by tommyboy on Jun 9, 2008 0:12:19 GMT -5
Hello there.
I just picked up a 1980 SR500 that looks to be in great shape. I'm trying to figure out it's personality and kick starting temperament, among other things. But I have a couple questions I'm hoping you guys can help me out with.
First- I'm not super familiar with riding a single, so my concerns just may be a result of inexperience. But when I'm cruising around on the thing, it wobbles just enough for me to get fixated on it. Especially at higher RPM's, regardless of the gear. It's almost as if the front wheel is out of alignment, but that's not the case.
Second, I'm trying to figure out the right recipe for kick starting. Choke on or off? A little twist with the throttle while kicking? I know I just need to spend some time- just wondering if there's any advice to avoid flooding the thing. It's got a VM36 Mikuni carb, 310 main jet, and 35 pilot jet.
Lastly- what should my sparkplug gap be set to?
Thanks in advance!
|
|
|
|
Post by aero on Jun 9, 2008 3:20:35 GMT -5
Ref the wobbling feeling, check you tyre pressures, adjustment of the headrace bearings (too tigh or notchy will cause the bike to wobble). Importantly do a safety check of important nuts and bolts; like the front wheel spindle and the clamp on the bottom of the forks. I once picked up a XS400 where this clamp was undone, it wobbled badly at speed but seemed ok round town, although a bit vague in the steering.
If all that is ok check the wheels are true when you spin them, then that the alignment of the wheels is good (although if it were wrong you'd get a strong pulling off to one side). Something that causes the bike to wobble is a major concern, but you should be able to easily identify the fault(s).
|
|
|
|
Post by StewRoss on Jun 9, 2008 4:05:31 GMT -5
Hi, Plug gap is 0.028" to 0.031"... As well as the things Aero indicated check the wear in the swing arm bearings...side to side play of the arm with the bike on the centre stand... Starting is a bit of an individual thing once you've changed the carby...but this should get you in the right area at least: ...onto compression, de-comp in, ease the kickstart over a short way, let it return to the top...release the de-comp, no throttle, kick it firmly all the way through to the bottom...when cold use the enrichment (choke) lever...when hot don't... SR  |
|
|
|
Post by joneill4 on Jun 11, 2008 19:22:58 GMT -5
When I first got my '78 it was a freakin wet noodle above 50mph. I changed the steering stem bearings and the swingarm bearings. Mega improvement! It's still not quite right though. When I nail the throttle exiting a corner, something moves. It kinda feels like I'm riding on a flat, but I'm not. I'm guessing rear wheel bearings, but it doesn't feel loose by hand. It's still a million times better than when I got it.. Best O'Luck, John
As for starting, this has been done here before. No two guys had the same method. I have some non-stock Mikuni, but I don't know what it is. For me it's no gas, no choke. I push the starter slowly down until I feel resistance, and bring it back up to parallel to the ground. I jump up and give it my all. With the lever in that position it can't really give you much of a kick-back. Always one kick when cold, and three or four when hot.(Darn small gas tank!)
|
|
|
|
Post by canucksr on Jun 11, 2008 19:33:08 GMT -5
Could be the rubber dampers between the wheel and sprocket...if you've got the cast wheels.
|
|
|
|
Post by wotavidone on Jun 12, 2008 1:11:32 GMT -5
Its hard to get my head around why it should wobble at higher rpm regardless of gear.
One would think if its loose bearings in wheels, head stem, swingarm, etc, that it would either wobble all the time, or perhaps at certain road speeds?
The other thing worth checking is the tyres themselves, particularly whether they are the correct size.
If the tyre is too big or too small for the rim, that's been known to cause problems on lots of bikes.
Original size for my '78 is 3.50-19 4PR for the front and 4.00-18 4PR for the rear.
They look big, and feel big too, but they don't wobble much. They do cause the bike to speed wobble a bit at 60 mph plus, but not as much as the old skinny low profile tyres that were on it when I bought it.
My 360 yam trailie used to speed wobble when over 90mph. The cure was to not try to stop it. The harder you dragged on the bars trying to stop it, the worse it got. I used to slide my backside towards the rear of the seat, get down over the tank and try to relax, not easy at 100, but it would reduce the wobbles to a sort of slow oscillation that you could learn to love as part of the charm of the bike.
So experiment with weight distribution too.
Mick
|
|
|
|
Post by joneill4 on Jun 12, 2008 10:06:10 GMT -5
Good point about the engine speed vs road speed, Mick. Have you checked your motor mount bolts? Do you have a center stand? Will it do it with the tire off the ground?...or in neutral?
|
|
