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Irregular speed. (Pulsing)

Old 07-02-2010, 08:18 PM
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Irregular speed. (Pulsing)

Hey all,

I just bought a 1999 with only 2000km on it. So, needless to say there are a few issues with the carbs I'm sure. Just wondering if anyone has come across this.

The revs pulse about 200 rpm up and down when I run it around 4000rpm. So, even when riding it pulses a little slowly, and when I just hold the throttle at 4000, it pulses a little quicker. Does it in all gears, and neutral, so it's not drive train related. But, it idles great, starts great, under hard accel runs great.. So, I'm not sure what it would be.

Any ideas??
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Old 07-02-2010, 08:21 PM
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is th pulse regular or irregular?
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Old 07-02-2010, 09:34 PM
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Sounds like a lean surge. What exhaust and air filter are you using, and has it had any carb work?
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Old 07-02-2010, 10:01 PM
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Originally Posted by VTRsurfer View Post
Sounds like a lean surge. What exhaust and air filter are you using, and has it had any carb work?
The pilots could be clogged as it has to have sat around for a long time.....
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Old 07-03-2010, 08:43 AM
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the bike is completely stock. the guy bought it in 2000, and it literally has only 1977km on it. The pulsing is very regular. Plus it does have that back pop coming into the air box once in a while when I bleep the throttle from idle.

Do you guys think I can just run some carb cleaner through it, or will I have to pull it all apart?
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Old 07-03-2010, 09:04 AM
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Oh, and another question, I just openned up the tank, and noticed it's got a fair bit of rust in there. Does anyone know of an easy way to clean, and possibly fix this?
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Old 07-03-2010, 09:14 AM
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Originally Posted by dustinwild View Post
Oh, and another question, I just openned up the tank, and noticed it's got a fair bit of rust in there. Does anyone know of an easy way to clean, and possibly fix this?
there are a few sealers out there but if it was me i'd find a used tank. in the future, this is the first thing i check when buying a used bike.

you probably have rust in the pilot jets ( and elsewhere ).


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Old 07-03-2010, 09:15 AM
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Tim, I got the bike for $3500 canadian.. So, if I even have to buy a new tank for it, oh well! Just would rather fix it.
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Old 07-03-2010, 09:56 AM
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Originally Posted by dustinwild View Post
Tim, I got the bike for $3500 canadian.. So, if I even have to buy a new tank for it, oh well! Just would rather fix it.
if you want to go the sealer route look into kreem, but if not done right you'll be back cleaning crap out of the carb's and trying to reseal. i'd think spending a little extra on a good used tank 'could' save you a lot of work down the road. try ebay... in the mean time if your going to run it as is i'd get a couple of inline gas filters from your local auto store.

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Old 07-03-2010, 10:56 AM
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Buy a new tank and pull the carbs and install new pilot jets and clean everything else....
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Old 07-03-2010, 04:05 PM
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I skipped right over the low mileage in the opening post. That plus the rusty tank (it must have been stored without much gas in it), I'm surprised it started at all. Do what 8541 says.
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Old 07-03-2010, 05:47 PM
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This is one of the best tank cleaner / sealers - the Kreem stuff is not so good:

http://www.caswellplating.com/aids/epoxygas.htm

Try that before the expense of a new tank.

You need to clean your carbs and jet properly - many threads on that. Petcock needs to be clean, and you may want to put fuel filters on the feed tubes to keep an eye on the gas, and for extra rust insurance.
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Old 07-03-2010, 06:05 PM
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I would never use any of those products unless it was on a tank that could not be replaced. The best bet and the least amount of headaches would be to source a tank that doesn't have any rust in it. Any other solution runs the chance of whatever you put in the tank coming off and causing countless problems. Of course YMMV but in the long run I would just find a clean tank, end of problem.
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Old 07-03-2010, 06:55 PM
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+1, there should be some clean tanks out there off of crashed bikes.
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Old 07-03-2010, 08:07 PM
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I agree, but that is an expensive route, no harm in trying to clean the tank first. The acid may even get all the rust and no need to seal.
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Old 07-04-2010, 01:12 PM
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The rust actually comes off with I rub it with my fingers, just reaching inside the filler cap. I read on one forum that a guy threw aabout a cup of bb's in the tank, then wrapped it in a sleeping bag, then stuffed it in his dryer for an hr or so, making sure the tank doesn't move around at all, with no heat. He said it came out shiny on the inside after he rinsed it out. Gonna try this, and clean the entire fuel system, carbs, petcock, etc. I'll let you guys know how I make out.

The problem with getting a used tank, is I don't think I will find a used one that will be in as good of shape as the rest of the bike. It's literally brand new, paint is spotless. It seriously looks like the bike was just rolled out of the showroom. So, finding a used tank of that finish, might be hard to do. Can't wait to scrub in the tires, and see how she runs with clean carbs. Brakes haven't even been set in yet!

Last edited by dustinwild; 07-04-2010 at 01:14 PM.
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Old 07-04-2010, 01:27 PM
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ok - a real cheap, but worth a try fix is fill the tank with a strong mixture of "Tang" Orange drink. The citric acid may do the trick. Then flush it out with water, then kerosene. BTW, this is an old plumbers trick for removing rust stains from iron rich water in sinks, toilets...


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Old 07-07-2010, 11:27 PM
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Okay, so I cleaned out the tank, got it looking pretty good, pulled the carbs apart and checked the jets. They were completely spotless. Everything inside the carbs were totally clean. So, not sure if this is a problem. I just ordered some Two Brothers pipes, and a K&N filter for it, so I may have to rejet anyway when I get all that, so if it's still an issue, hopefully that will fix it. Anyone out there have some Two Bros pipes?? Are they decent?
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Old 07-07-2010, 11:52 PM
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Originally Posted by dustinwild View Post
Okay, so I cleaned out the tank, got it looking pretty good, pulled the carbs apart and checked the jets. They were completely spotless. Everything inside the carbs were totally clean. So, not sure if this is a problem. I just ordered some Two Brothers pipes, and a K&N filter for it, so I may have to rejet anyway when I get all that, so if it's still an issue, hopefully that will fix it. Anyone out there have some Two Bros pipes?? Are they decent?
Did you check the pilot jets or just the mains?
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Old 07-07-2010, 11:53 PM
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Both, pilots, and mains.
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