71' back fire help, please!?

Reno71 · Full Member Joined: Aug 04, 2009 Posts: 34

i am working on my xs as some may know. I am having a realy bad back fire after getting it on the road. sitting it stays idle, warms up, then after a bit, or after i start my way down the road i get a back fire that is pretty bad, i am going to change the point tomorrow and hope it helps, but any other help would be appreciated! Thanx in advance. Question

650rider · WebMaster Joined: Feb 09, 2005 Posts: 431

Could be a hamster in the intake... maybe?

Good luck with your project.

pumps

You don't mention what you've done so far so let me suggest just doing a regular tune up per the manual.
www.knucklebusterinc.c.../XS650.pdf
Go to the vault and read
650rider.com/index.php...pic&t=6798

Reno71 · Full Member Joined: Aug 04, 2009 Posts: 34

worked over the tune up, changed plugs, points, and cleaned my air filters. going to check my fuel/air mixture tomorrow. thanx for the link!!

royfisk

Go back to basics, and ask yourself what causes back firing?
Ignition timing
valve timing
valve adjustment
These are the most common. Also note check the valve timing too. Because if the gear on the cam has moved you will have a cam timing issue that will haunt you for awhile. Dont assume that it has not moved cause they do move.

Reno71 · Full Member Joined: Aug 04, 2009 Posts: 34

well, thanks for all the help. I have gone back and redone points, DOUBLE CHECKED TIMING!!!!, and now i just have to deal with a weird pull to the left. Another post here we come.

Reno71 · Full Member Joined: Aug 04, 2009 Posts: 34

Oh yeah, after the timing was fixed, it runs like brand new. Guess it shows all you have to do keep up on the details, anyone ever read this as referance, please remeber, change the points, redo your timing!

tacoswild

pull to the left could be a few things like bad tires, or a bent frame or swingarm, but the most likely is the back wheel just isn't bolted on straight. If you've got the alignment marks on both chain pullers the same already you've got too double check against the front wheel with straight boards.

gordo

RENO, RIDE 'ER ON THE BACK WHEEL, NO MORE PULL! Just kiddin' wit ya. Like Taco stated, check the rear wheel alignment to the front. A good, straight board will work, but how I do it on the center stand. I get it all eyeballed up, looking pretty straidht as I can see, then measure from the center of the front wheel bolt to the center of the rear wheel bolt. If you got a six foot level around, that's the best piece of straight wood I know, other than the one I came with. Could even be a triple tree out of alignment.Good luck & let us know what you find.,,,Gordo

Reno71 · Full Member Joined: Aug 04, 2009 Posts: 34

Awesome, thank you guys. I also need new tubes and tires. but i still want to replace the rubber up in the bars, and new bars to think of it. ill will update when i can.
also does anyone know if 1972-73 YAMAHA CT-2 CT-3 175cc - GAS CAP will fit on a 71 xs1b?

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