Carb question

[Mopheos]

When I am sitting at a light on my 85, I get a pretty significant gas smell and my exhaust seems very rich to me, like some of the gas is not completely burning. If I rev it up, I get a slight greyish smoke which again, smells like unburnt gas. Does this sound like a mixture issue? If the carbs are out of sync, would that produce such symptoms?

 

[KJShover]

When I am sitting at a light on my 85, I get a pretty significant gas smell and my exhaust seems very rich to me, like some of the gas is not completely burning. If I rev it up, I get a slight greyish smoke which again, smells like unburnt gas. Does this sound like a mixture issue? If the carbs are out of sync, would that produce such symptoms?

A sync would never hurt you. You might have a few things gummed up, or your A/F screws are a tad rich. I'd run a coupld of shot glasses of seafoam through your tank. Check the sync and A/F screws.

 

[RagingMain]

Check your air filter as well. Dirty air filter will cause a bike to run rich

 

[naughtyG]

I would also drain your fuel bowls into a clean recipient and take a good look at what comes out.

If it's clean gas you're good. If there's dirt in there you may be getting sticking needle valves and dumping fuel into the cylinders. In that case you will need to check your tank, your fuel filter and prolly give the carbs a good clean.

BTW, is your '85 all stock? Airbox/flter, carbs/jetting, exhaust/slip-ons etc?

 

[Mopheos]

NaughtyG,

The only thing I know for sure that is not stock is the exhaust, which is a Holeshot 4 to 1. I don't know if the carbs have been rejetted. The air filter box has K & N filter in it. I had the airbox off the other day poking around, and I noticed the two nipples on the bottom of the box were not connected to any hose. I found the rear hose and pressed it on, but I have no idea what connects to the front nipple on the bottom of the airbox.

What is the A/F screw that KJ mentioned?

 

[naughtyG]

The only thing I know for sure that is not stock is the exhaust, which is a Holeshot 4 to 1. I don't know if the carbs have been rejetted. The air filter box has K & N filter in it. I had the airbox off the other day poking around, and I noticed the two nipples on the bottom of the box were not connected to any hose. I found the rear hose and pressed it on, but I have no idea what connects to the front nipple on the bottom of the airbox.

What is the A/F screw that KJ mentioned?

I believe the front nipple is simply an overflow/vent and does not connect to anything. The rear one is the oil sump vent which you connected correctly.

If you have a Holeshot it's most likely been rejetted, but if it hasn't it would most definitely be well on the rich side and explain your heavy gas smell. How does it run?

The Air/Fuel mixture screw is found at the bottom of each carb slide cover. It is set and plugged at the factory, but most plugs have been drilled so that the A/F screw can be adjusted. Before taking them out, you must make sure to carefully screw them all the way counting the exact amount of turns needed to seat them, so you can set them back to the same place afterward.

 

[Mopheos]

[/QUOTE]If you have a Holeshot it's most likely been rejetted, but if it hasn't it would most definitely be well on the rich side and explain your heavy gas smell. How does it run?[/QUOTE]

I guess the only way to tell about the jetting is to disassemble the carbs and read the jet specs. The bike runs in a couple of ways: when taking off in first, it sounds kinds like it's choking, or like the plugs are trying to foul, but then once the RPM's pick up under normal acceleration, it sounds and runs pretty awesome. If I hit the gas hard, it sputters and chokes abit until 6000 RPM, at which time the friggin thing time-warps and I find myself in the next county.:biglaugh: When I got the bike, the PO said the shop had adjusted the throttle cables and it was idling at about 1600-1700. Before I got my service manual and knew what I was doing, I think I adjusted the sync screws on the right side to decrease the idle. Now when the bike warms up, it is hard to keep it idling without holding the throttle a little to keep the rpm's at about 1000. Guess I need to buy a sync gadget now and re-sync things. Does the forum have anyone who sells tools like a sync tool?

If I adjust the A/F screw, which way do I lean it out abit? Thanks for your help.

 

[naughtyG]

Ok so it really sounds like you need a good sync first! See if there's a member near you who has a Carbtune or similar - it's a very easy 10mn job on the Max!

You can buy a sync tool on fleaBay for just about $100. Buy the Carbtune from their own website (http://www.carbtune.com/), or something like this on fleaBay: http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=220418968485&viewitem=&sspagename=STRK%3AMEWAX%3AIT

Or you can even make your own sync tool for about $15 with a bit of clear tubing, a few staples and a piece of wood - check out how Richwrench did his.

Before you touch your A/F screws, make sure to record where they are set to so you can go back there. It's impossible to really set them properly without lots of equipment beyond the scope of the home mechanic. Then you turn them in (clockwise) to lean out the mixture, and out (counter-clockwise) to rich it. Also bear in mind that they only really affect your idle mixture setting.

 

[Mopheos]

Thanks NaughtyG! I'll see about the carbtune around here, and maybe I won't need to mess with the A/F screws. It looks like these carbs are waaaay easier to sync than the carbs on my xj650. This forum is pretty awesome.

 

[naughtyG]

They're super-easy to sync!

http://www.vmaxforum.net/showthread.php?t=3959

enjoy

 

[Mopheos]

NG, do you have the thread for Richwrench's homemade sync tool? I'm apparently not very good at the search just yet. Thanks.

 

[naughtyG]

Here's a picture of it. You need a piece of plywood, some clear tubing, a couple of T pieces, a few nails/staples and some ATF fluid. To restrict the airflow inside the tubes, Rich used a few pieces of coax cable (as found at the back of your TV/cable box).

The only thing to watch out for is that the ATF will get sucked out (hence the long lengths) so don't connect / disconnect with the motor running.

When syncing you just make sure all four levels align. Whole thing costs less than $12.

http://www.vmaxforum.net/showthread.php?t=5852&highlight=carb+sync+tool