83 xs400 - needs a new monoshock

I've been lurking for a while, this is my first post.

I'm 28, spent four years in the Army (out about a year ago), divorced around that time, no kids. I'll never make the marriage mistake again.

I bought my first bike this summer, an 83 xs400 for $750. At this point I have put about 8000 miles on it, can't get enough. I put cafe bars on it and ride it for everything its worth at this point, every time i'm on it I top it out, often for a substantial portion of the ride. My mileage was good at first but has gone from 50mpg -> 35mpg.

It has a few problems:

Won't start when its below 35f out. Starting fluid typically works, but one morning it was 20f out and I couldn't get it started for the life of me.

When I have the throttle wide open and its at the top of 5th, it 'pulses' if you will, bursts of power/not power. Its not enough to effect the top speed (I think) but noticeable.

Rear shock is worn out, I have it adjusted to the tightest setting but I bottom it out all the time (225lbs with gear on) and I'd like to be able to put another on the back. Additionally, it does a fair amount of floating as I ride down the road.

My dealer doesn't sell the rear sprocket anymore, the original chain was worn out, I replaced it without replacing the sprockets, because of that, but its quickly wearing out. I'd like to replace all three when this chain wears out.

The seat cover is torn up, I'm thinking about stretching an ebay seat cover over it, the foam is mostly intact.

The fuel tank is small, the paint job doesn't look all that good, missing yamaha badges, etc... I'd like to possibly replace tank/seat to cafe the bike, but I'm not looking for 100hrs worth of project, and I'd rather not bust the welder out.

It's normal for a carbed bike to be difficult to start in the winter. Unlike a fuel injected bike which adjusts your fueling on the fly a carbed bike is jetted for a particular altitude and temperature. If you want to run the bike in the dead of winter you should ideally rejet for those conditions.

The pulses you feel at WOT are due to fuel starvation. You'll feel the same thing if you ever start running out of gas. Colder air is more dense. Your relative fuel mixture has become leaner due to the ambient temperature. As temperatures fall gasoline also just becomes less volatile. On a hot day you can see the fumes above gas clearly. When it gets cold enough in some places in the world the fuel will actually become hard to ignite even when a flame or spark is applied directly.

More modern carbed motorcycles often have provisions for installing carb heaters. My old 1996 GSX-R 750 did.

I'd check ebay for a used low miles rear shock.

Ebay also appears to have sprockets for your model.

Welcome Pat!

Never say never! 10 years ago I said I'd never be caught on a bike, and here I am...

I agree with BC, the surging at WOT is a lean condition.

Chains and sprockets are available aftermarket. Take a look at JTSprockets.com They have the sprockets you need.

I have a stock rear shock off my Maxim if you can't find anything locally. Shipping from Canada will be expensive, likely over $30, but if you are stuck send me a PM.

Using a l;ighter viscosity oil will help with the cold starting,Also Im assuming you have the choke pulled all the way out?
I don't have any problems with my bike starting during cold weather except when its been in hibernation all winter.

I also got a monoshock I cld part with off my 82 maxim..I also have a larger maxim tank I might could sell or trade as well....riding that cold is always gonna give you a hassle unless u tune for it..