Carburator adjustment to sea level

[SkyKing]

I just bought my 2000 Venture MM from a gentleman in Las Cruces, New Mexico (elevation over 3,000 feet) and it was riden to Corpus Christi, Texas for delivery.

 

When I rev up the engine and back off the throttle, there is a slight backfire.

 

Someone suggested that the carburators have to be adjusted to sea level.

 

I called the service department of the local Yamaha dealer and was told that the carburators (4 of them) have to be adjusted and/or the jets have to be changed out.

 

He said if it is just an adjustment, it would take an hour and a half to adjust all four.

 

If the jets have to be changed out, it would take an hour and a half per carburator.....

all of the above at $70 PER HOUR. The carburator change out would take 6 hours to complete.

 

Is this a reasonable quote or is there something else I should do?

 

There are some intercom and a few small issues....but I will save that for some other time. Right now I just want to get my new Venture running smooth at sea level.

 

Thanks for any advise...

 

Mike

[ToRide1]

you should try and call your state House Representative with the State legislature and ask if he or she can tell you who to call about what rights you have when it comes to buying a new motor vehicles and explain the problem comely. I think the dealer as a factory rep should have to set the motor up correctly for the region at no cost to you. You will learn you have more rights under state law than you know, but is this covered?

[SkyKing]

The bike was purchased from a private individual and not a dealer. The owner's brother-in-law was kind enough to ride it from Las Cruces, New Mexico to Corpus Christi, Texas. He noticed the same thing, a slight backfire after the engine is reduced from high to low RPMs.

 

I was just wondering if the quote I received from the local Corpus Yamaha service department was fair. I am not a mechanic, but it sure seemed high......6 hours to replace the jets on four carburators......at $70 per hour. But if that is the rate and the time spent on the project is correct, then maybe that is a fair quote.

 

Mike

[ToRide1]

$70 per hour is the norm and sorry I did not understand its a used bike and congrats either way. Changing jets gets a little involved but not that hard to do and there are people here that can tell you What stock jet sizes you need to get they run about $5 dollars each and you may need to buy 8 jets! Some of the carburetors take a deferent jet size and I think it has to do with the length of the exhaust pipe and other factors.

[pegscraper]

That's a ridiculous quote. It should only take 1 1/2 hours to change the jets in all four carbs and have the bike back together and on the road. I could do it in that time, and have. Another dealer who doesn't feel like doing the job and overprices it. What a surprise.

 

Likely all the bike needs is a carb sync, or the pilot mixture screws richened up just a bit, or maybe the AIS pulled. Any of these things could cause the deceleration popping.

[GeorgeS]

Well, I have had my 1st Gen, since 1993, bought new, and I have ridden it on many long rides, at Dead Sea Level, up to 10,000 feet. ( ran just fine at 10,000 feet in Colorado )

 

I live at 350 feet above sea level, and most every ride I take on a weekend, goes up to 3 to 5000 feet.

 

Never had any problem !! The only adjustment I have ever made to the carbs, was resetting the " Idle Mix Adjustment Jets " You can do that yourself, takes about 30 minutes.

 

Mine were off about 1/2 turn, more of less. ( that adjustment only effects Idle speed mixture )

 

And replaced the diaphrams, at about 45,000 miles. You can do that youself also.

 

I would spend the money on a new set of Tires!!

[Jerry W]

I don't know if it will solve your problem, but you might sync the carbs for starters. All it takes is a long screwdriver, a Morgan carbtune and a few minutes of time. If you don't have access to the carbtune, I am going to be in Rockport for a couple of days next week and I can bring my carbtune with me. I will be in Rockport Tuesday, Wednesday and Thursday nights. Let me know if you need to do that and we can set something up.

[BuddyRich]

3000 ft is not considered high altitude. It only needs a carb sync more than likely. The factory does not rejet them for 3k feet that's for sure.

[SkyKing]

I was told by Thom this web site would be a great resource of knowledge and experience and I want to thank each one of you who responded to my carburator question. As a result, I feel much better about what to do to get the bike running properly.

 

Thank you again for the help. It is greatly appreciated.

 

Mike

[BOO]

Well, I have had my 1st Gen, since 1993, bought new, and I have ridden it on many long rides, at Dead Sea Level, up to 10,000 feet. ( ran just fine at 10,000 feet in Colorado )

 

I live at 350 feet above sea level, and most every ride I take on a weekend, goes up to 3 to 5000 feet.

 

Never had any problem !! The only adjustment I have ever made to the carbs, was resetting the " Idle Mix Adjustment Jets " You can do that yourself, takes about 30 minutes.

 

Mine were off about 1/2 turn, more of less. ( that adjustment only effects Idle speed mixture )

 

And replaced the diaphrams, at about 45,000 miles. You can do that youself also.

 

I would spend the money on a new set of Tires!!

 

 

I agree, I have ridden up 4 or 5 thousand feet and didn't notice anything with the bike.

Only thing that might have happen is the first guys dealer might have sold him the rejet and now it needs to be put back like it was. 3000 feet is not a rejet job.

Sync the carbs, put some Sea Foam in the gas tank, run a few tanks of gas. If it still backfires take the AIS off. Should be fine.

Boo

[SkyKing]

Thanks Boo. Jerry was kind enough to offer to sync the carbs when he and his friend arrive next week. Thom who lives in Rockport is also going to join us as well. We should have some fun along the Texas Gulf Coast.

 

Many thanks again to everyone who has come to the rescue. I deeply appreciate it.

 

Mike

[Guest tx2sturgis]

Synching the carbs is a good thing to do, but it probably wont stop the backfiring. Thats a symptom of the AIS, but its hidden by the stock and very quiet mufflers.

 

Normally a change in altitude from 3000 ft to sealevel is not enough to cause backfiring.

 

If the bike has had aftermarket pipes added, or the stock pipes drilled out, most likely, you can solve this by plugging the AIS system. Its an emissions control system that does not work well with free-er flowing pipes. But its easy to fix, might take you an hour, if your new and unsure, or as little as 15 minutes if your familiar with this stuff.

 

There is a good tutorial on this here:

 

 

http://www.venturerider.org/forum/showthread.php?t=485

[V7Goose]

Assuming the original owner didn't screw with the jets, you absolutely do NOT need to touch them. I do suggest, however, that you properly set the float levels. The shop's quote for an hourly rate is about right, but the stuff they say needs to be done is probably a complete ripoff, ESPECIALLY if they have not personally checked out the bike. I'd suggest you don't waste your time or money on them.

 

Afterfire on deceleration is not uncommon on these bikes, and it is usually very easy to fix. It is absolutely NOT caused by the air induction system (but the AIS can make it worse if you don't fix the actual cause). You can read LOTS more about it in this thread: http://www.venturerider.org/forum/showthread.php?t=22961&highlight=ais+afterfire

 

Without looking at it or knowing more, I'd suggest that all you need it to replace the rubber caps on the intake nipples and get a proper sync on the carbs.

Goose