Quantcast

running super rich

Yamaha Star V-Max VMAX Motorcycle Discussion Forum

Help Support VMAX Forum:

Seve Moreno

Active Member
Joined
Aug 7, 2019
Messages
28
Reaction score
0
My stock 98 vmax is running stupid rich and I can not for the life of me find out how to adjust for this. this is a new bike to me. the guy I got it from let it sit with gas in everything for 2 years. I have cleaned the carbs and found that the jets in the holder where both screwed in all the way. this was giving me the very rich setting and popping at 3000RPM. I've tried adjusting the mixture screws but no setting helps. do i need smaller pilot jets?
 

MaxMidnight

Well-Known Member
Joined
Dec 1, 2007
Messages
1,893
Reaction score
122
Location
Cumbria, England.
Where is it running rich? Idle, mid range, full throttle etc?

Can we assume that the air filter is clean , better still replaced?

Before changing anything check what jets you have in the carbs.
See this

Also have a read of this
 

Seve Moreno

Active Member
Joined
Aug 7, 2019
Messages
28
Reaction score
0
It's rich everywhere. while riding or at idle. I run through a tank of gas in something like 25 - 30 miles. and no I do not have a gas leak I did check for that. at idle it's very clear its extremely rich by the smell
 
Last edited:

mabdcmb@yahoo.com

Well-Known Member
Joined
Jun 15, 2008
Messages
6,423
Reaction score
150
Location
Pittsburgh, PA
Maybe a stuck float. Open a float drain screw and see if gas just keeps pouring out. Smell your oil. It may be filling the crankcase.

Not sure what jets were "all the way in" if the mix screw, all the way in is lean, out is rich. No other adjustable jets in there. Well, the needle I guess but that's just shimsand clips and only aftermarket is adjustable . Lowering the clip raises the needle, makes it more rich. Raising the clip lowers the needle, leans it out. The blunt end is the reference point
 

MaxMidnight

Well-Known Member
Joined
Dec 1, 2007
Messages
1,893
Reaction score
122
Location
Cumbria, England.
What colour are the plugs; are they all the same?

If one is different from the rest then you need to check out that carb.
If it was a stuck float though, I'd expect that you would see fuel coming from the overflow.

You say that it is rich across the range; I can't see how the idle, needles AND main jet would all be rich...unless a master screw-up craftsman has set the bike up! :eek:

You didn't say when the air filter was changed. Try a short run without it and see what difference that makes.
 

sdt354

Well-Known Member
Joined
Aug 8, 2008
Messages
5,870
Reaction score
122
Location
Southern N.E.
The float adjustment/or stuck float, like Danny and Mike mentioned are where I'd start. No other tuning or adjustments will correct the mentioned issues. A/F screws cranked all the way in sounds like someone tried to compensate for the said issues. Good carb. link from Steve.
 

Seve Moreno

Active Member
Joined
Aug 7, 2019
Messages
28
Reaction score
0
Ok sounds like I need to check the floats. But I've cleaned the bowls about 3 times already. The A/F screws dont seem to do much of anything for me from all the way out to all the way in. This is pretty concerning to me. I just changed the spark plug . They were all 4 black and oily. This was expected since it's running so rich. Any suggestions or help on how to check the floats?
 

Seve Moreno

Active Member
Joined
Aug 7, 2019
Messages
28
Reaction score
0
So I searched and found how to dry measure the floats. From what I can see they at supposed to be at 1.117in and all of mine are just under that measurement. I dont know what else to try.
 

MaxMidnight

Well-Known Member
Joined
Dec 1, 2007
Messages
1,893
Reaction score
122
Location
Cumbria, England.
Which bit of 'You didn't say when the air filter was changed. Try a short run without it and see what difference that makes.' don't you understand - an answer would be appreciated!
 

Seve Moreno

Active Member
Joined
Aug 7, 2019
Messages
28
Reaction score
0
I will run it without the filter today. I havent changed it and I don't know if the previous owner has or not. But I can tell its the stock filter so maybe its never been changed. then ill do a wet float check. thanks for the suggestions.
 

caseyjones955

Well-Known Member
Joined
Jun 11, 2015
Messages
2,325
Reaction score
102
Location
Black Hills, South Dakota
I highly doubt it will be ridable without the air filter. The CV carbs rely on that restriction offered by the factory air box/filter assy. If it's that rich I would worry about it queefing fire with open carbs, I would strongly suggest not riding around w/o the filter in place.

Mine was poisonously rich when I got it. I did a lot of jetting as the PO stuck in a DJ jet kit with the Kerker install, ended up going leaner than stock @ 4000' and removing all the DJ crap. Also adjusting the floats even a little made a significant difference in how she ran. I used this page as a reference and set the floats to the leanest edge of the acceptable range. I had trouble getting a consistent reading as I have no jack or center stand, and nobody to hold the bike up while I check. http://www.factorypro.com/Prod_Pages/prody11.html

When you open her up record all your jet sizes and other stamping on the jets as DJ and MK do not follow the same numerical values. I went from burning the eyes of folks riding behind me to 120-130 mi before reserve but it was a complete re-tune. I dont know if jetting or floats are the issue in your case but it's where I started and it turned out to be nothing more than being grossly mistuned.
 
Last edited:

Seve Moreno

Active Member
Joined
Aug 7, 2019
Messages
28
Reaction score
0
Yes, I have checked those jets a few times. made sure they were clear. from what I understand those jets are the air jets correct? these were the ones that were screwed all the way down. Both main and pilot.
 

rebeltaz83

Well-Known Member
Joined
May 8, 2013
Messages
754
Reaction score
211
Location
Anderson, SC
No, the jet block is inside the bowl, with the float. That's where the main jet is located. I might suggest getting a book, or a download version atleast so you can identify the parts inside the carb. There are O rings and gaskets in there, if you un screw the jet block I'm sure you'll need gaskets, and at this point in the game I'd get everything and thoroughly clean them, and assemble them with new hardware, and bench set the floats with the carb. Assembly off the bike, much easier to make adjustments if need be. Or send them off to Dannymax, or one2dmax. Get them back, slap them on and ride.
 

MaxMidnight

Well-Known Member
Joined
Dec 1, 2007
Messages
1,893
Reaction score
122
Location
Cumbria, England.
I haven't changed it and I don't know if the previous owner has or not. But I can tell its the stock filter so maybe its never been changed.
Perhaps I'm missing something here, but why are we discussing float levels, jet blocks etc. when the basics haven't been done?

Until you are confident that the carbs are able to get sufficient air you are wasting your time with anything else.

Change the air filter!
 

sdt354

Well-Known Member
Joined
Aug 8, 2008
Messages
5,870
Reaction score
122
Location
Southern N.E.
Shine a light through the filter and see if it's restricted. A wet check of the floats cost nothing, and it's one of the things you'll need to know how to do if your going to work on your carbs.
 

caseyjones955

Well-Known Member
Joined
Jun 11, 2015
Messages
2,325
Reaction score
102
Location
Black Hills, South Dakota
There are a few youtube vids regarding wet float level checks. I found them useful. I cant recall if it was on Venture of Vmax, but it would be the same proceedure either way.
 

Seve Moreno

Active Member
Joined
Aug 7, 2019
Messages
28
Reaction score
0
I havent been able to do much lately but I did manage to get a new air filter and try it out. nothing has changed. I've synced the carbs again and keep messing with the
A/F screw and nothing. Next, I need to get a clear hose to wet check the floats I guess.
 

Latest posts

Top