Oh Boy, fighting the jetting fight......:(

[TourMax]

Ok. Cautiously optimistic time again.

Paj1 - drilled to “90”.
Paj2 - drilled to “180”
Pilot jet - 42.5
Main jet -145 (still have to do plug chops to know if good or not)

Idle mixture screws - between 2-3 turns out.

Sync - level across the board on the mercury stix.

CO% - 3.5 across all 4 (give or take a decimal)

HC - still high across all cylinders. 2/4 are worst offenders, but i already thought i had valve seals going away on those. 1/3 still roughly double expected, but its been idling so long on the ega i think everything is just saturated.

Lambda - showing in the .880 range. Not bad.

CO2 - variable across the board. Worst on 2/4. Suspect valve seals, as mentioned above.

Idle rpm - rock solid steady on the dash, about a 50 rpm “flutter” on the ignitek diagnositics screen.

Looks to be ready for road testing....again.

May get to it tomorrow. May not. Lots on the docket for tomorrow and the bike is low priority.

 

[caseyjones955]

Got my fingers crossed for ya. I know exactly how much fun it is to get those carbs in and out. Looking for a happy story here.

 

[TourMax]

Got my fingers crossed for ya. I know exactly how much fun it is to get those carbs in and out. Looking for a happy story here.

Not sure if you’ve tried the vboost manifolds on you venture yet, but you seriously have to drop the front engine mounts to get the carbs out when using vboost in a venture frame.

I’ve actually gotten quite fast (wish i didnt have to though) at the proceedure: carbs out, adjusted and back in the frame in about an hour.

Getting that “erector set” of venture plastic and parts back on around the engine is about another 45 mins to an hour also... yeesh.

 

[TourMax]

So, test ride complete.

Not bad. Not dialed in, but not bad.

Pulls pretty clean from low rpms everywhere.

Even pulls the overdrive 5th below 80kph (never would before).

There’s a “stutter” transitioning from about 1/2 throttle.

2/3/4 plugs are pretty clean, just a faint hint of brown on the center insulator. I thought the stutter was rich, but it may actually be a lean condition. I’m still waiting for an air filter, so that could be my slight lean conditon.

#1 plug is a different story. Pig rich. Entire plug is fluffy carbon soot, except the very tip of the center electrode. Not sure exactly sure what to think of that. Lots of things it could be. Not completly sure which to look at first. I think I’ll just start with a visual check of what i can access without pulling the carbs. Then a wet fuel level check. Then a sync re-check and confirm that th air jets are clear and the throttle plate isnt hard closed.

 

[caseyjones955]

Glad its getting closer. I forgot about the Vbopst manifolds being taller, I dont have them in yet, I can barely get them out without dropping mounts, saw a vid of fitment with vboost and im not looking forward to it. If nobody buys mine ill be going down this road, otherwise the vmax will be the carb guinea pig.

 

[TourMax]

Glad its getting closer. I forgot about the Vbopst manifolds being taller, I dont have them in yet, I can barely get them out without dropping mounts, saw a vid of fitment with vboost and im not looking forward to it. If nobody buys mine ill be going down this road, otherwise the vmax will be the carb guinea pig.

Things i ran in to with full vboost on the venture:

1. Frame interference. It all fits, but barely. Carb removal requires dropping the front mounts and even then , they barely come out.

2. Throttle cables. Stock venture routes them outside the frame. With vboost installed, they have to be routed inside the frame as movingg the carbs higher means there is no clearance at the carb cable brackets. Moving them inside the frame causes the cables to be tight and it is difficult to get them to not stick during throttle movement. Ive almost got mine right, ut there seems to still be some binding at the cruise control cable junction. You might be ok if not installing cruise control and just using the smaller cable junction housing.

3. Choke. Stock venture choke arrangement does not fit with vboost. Not at all. One guy that i know of dented the frame tube to get the choke bracket to fit. As the frame is already not anpillar of stiffness or strength, I chose to bend and reshape the bracket instead of risking compromise of the “backbone” tube. This meant i had to go fron a screw holding the cable clamp on the carb to a bolt. Yes, its a PITA, everytime.

4. Fuel line. Since the vboost raises the carbs, it closes off the space where the fuel line is routed. You can either go up over the frame tube, or do what i did and machine out the center of the rear carb rack bracket. This lets me run the oem fuel line to the carbs. It also necessitates reshaping the choke linkage, which means reshaping the choke levers on each carb.

5. Coolant line. The coolant line from the rear head to the sensor housing now has very little room to run over the carbs as yamaha intended. You have to either run it under the 3/4 carb bracket or squeeze it into the remaining space above them. Below means you need to find something to keep the bracket from rubbing through it, above means you have to watch that the #3 choke lever doesnt rub through it. A hudden hazard of runniing the line under means it ends up right against a metal bracket behind the fairlng side plastic. I had the line under and I switched to over. Time will tell if over damages the coolant line or not...

6. Coolant line in the valley. Stock venture has a small coolant line running from the center of the “V”. The vboost manifolds sit right over it and block the line “nipple”. You either have to take a chance and bend the small nipple and hope ther s still enough to clamp the line too and not leak, or buy a vmax breather cover which has a longer, angled nipple.

7. Airbox. Stock vmax wont fit unless you move the battery. You can try pod filters or cut down the venture box, but that was a major fubar for me. I went to coil on plugs, moved the ignitek module and fuse panels to the lh side fairing pocket, then relocated my agm battery on its side and up into the forward space vacated by the front coils and ignitor box. This meant building a new battery tray as well. Also had to make brackets for the map sensor and vboost actuator.

8. Controlling Vboost. I looked at using oem yamaha boxes and even manual control. Ended up buying an ignitek to do ignition duties and also to run the vboost. Works great imho and greatly simplifies many things. Not cheap though...

Theres probably a few other details i’m forgetting, or maybe i just dont want to think about it anymore...:rofl_200:

 

[caseyjones955]

I am printing this off as soon as I get home. Two things jump out at me, I gotta have my cruise, I oft just go sailing across the plains to absorb the blissful vastness, cruise is golden! I haave COPs and ignitek installed in anticipation of converting. Ive got a couple irons in the fire for alt intake/carb configs.

 

[TourMax]

Well.


Sucking back fuel at a prodigious rate.



Be surprised if I crack 20 MPG.



seems to run fine, except it will "load up and bog down" at times for no apparent reason. It stumbles and threatens to die like it's gone lean, but will clear with an RPM or gear change. It will be good for a while and then it will return. 5th gear loads it up the most often, which is a bit odd because it acts like a mid range lean condition, but 5th is low throttle opening to 1/2 throttle at the worst of times.



It does it whether I'm holding the throttle steady or the cruise is motoring along.



I am, to date, running without an air filter. Haven't gone far, just enough to test out the driving.


Still seems to be acting lean, which could be explained by the no air filter condition. But I'm not so sure. Tried adding choke, made no difference when it started stumbling.


One bizarre thing I noticed: I've got highway pegs on the crash bars and when I put my feet forward. It starts to immediately stumble. Move my feet back to the normal pegs and it clears immediately. I thought it was a coincidence at first, but it does it every time no matter where I am or in what direction I am traveling. I almost want to say it's somehow disturbing hte air getting to the carbs, but the airbox is buried up under a couple acres of plastic body work so I'm a little puzzled by the whole behavior. I still want to say it's coincidental, but it does it each and every time I put my feet on the forward foot rests.....:ummm:

 

[one2dmax]

That can be a common occurence on the Vmax as well with engine guards and a foot position change. The overflow vent tubes seem to be pretty critical to have in the correct position up by the opening of the box. A filter will also let the carbs function properly and I think you're spending time chasing issues that are going to be different when it's installed.

Finally, we are seeing more and more of the older anolog boxes failing. So, you may have a CDI issue compounding the problem.

 

[TourMax]

That can be a common occurence on the Vmax as well with engine guards and a foot position change. The overflow vent tubes seem to be pretty critical to have in the correct position up by the opening of the box. A filter will also let the carbs function properly and I think you're spending time chasing issues that are going to be different when it's installed.

Finally, we are seeing more and more of the older anolog boxes failing. So, you may have a CDI issue compounding the problem.

I believe so too, i’m not making any further changes until I get a filter in there.

My vent lines are actually run like the stock venture. They go back and down behind the rear cylinder to terminate by the rear mono shock. I may have to look at routing them up by the airbox intake opening like a vmax. Probably have to make those little clips/brackets....

My ignition (and vboost) is handled by an ignitec box, so should be good there...

 

[TourMax]

Air filter showed up. Only a week and a half late. :damn angry:

Popped that in and moved the fuel bowl vent lines from the stock venture location behind the engine to up under the airbox cover. I don't have the little brackets that hold them, so I just taped them to the inner sides of the fairing panels in the area.

i changed nothing else and took it for a short ride.

The tendency for it to stumble when I put my feet on the highway pegs seems to be gone. It will also run down the highway now without stumbling. So that's all a step in the right direction. Not completely sure why behind the engine was fine for a stock venture engine and not for the Vmax modified one, but you can't argue with results. Has to be somehow a change in the atmospheric pressure "nuances" in the different locations and a different pressure drop between Vmax intake specs and venture. Meh, can't argue with results.....

The stumble past 1/2-ish throttle is still there, although it is much less prevalent. I'm thinking needles up on clip might fix that condtion.

WOT seems flat. Bogs right down, but will clear if I hold it long enough.

Off the top of my head: still slightly lean at half throttle (currently on middle clip) and rich at WOT (currently 145 mains).


Way to early to tell from just a short ride, but mpg looks to still be in the crapper overall...

 

[Traumahawk]

You might have said it in an earlier post, but have you set the float height, or do you know what it is set at?

 

[TourMax]

You might have said it in an earlier post, but have you set the float height, or do you know what it is set at?

17mm, all four.

 

[TourMax]

man o man.

Sometimes, you just can win for loosing.

I had 1,2 and three adjusted to near perfection on the EGA.

But #4 was just confusing the hell out of me.

No matter what I did, CO stayed low, HC stupid high and CO2 low. Even with the fuel screw nearly out.

I figured it had to be something mechanical causing the poor fuel burn, as carb adjustments essentially had no effect. It was like it didn't have compression (tested already, it's good), ignition misfire (confirmed good already) or it wasn't getting enough air (showed dead even with other cyls on the carb stix).

WTF is going on?

Then, in an attempt to blow out the idle screw circuit again, I pulled the airbox cover off.

Looking down the throat to get ready to blow compressed air through to pop the needle out, I notice I can't see the PAJ.

What?

Sure enough, one tiny little section of the airbox boot had rolled over and was blocking (or partially blocking) the PAJ. The rest was on perfectly normal, sitting on the carb bodies normal and the clamp was right where it should be.

Jesus, this thing needs to just stop fucking with me!

So, I'm going to blow the circuit out (because it's apart now anyways) and put it back together.

Then back to the EGA and see what we get....

 

[Fire-medic]

Well, that's the beauty of doing things yourself. You caused the issue when you re-installed the airbox, you found the issue when trying to determine the readings you got. Sounds like things should be good now.

If there's a lesson for the rest of us, it should be that the little things can have a significant effect.

 

[TourMax]

Test ride center complete.

Rips down the highway fine.

Feet on the higway pegs is no longer an issue.

Pulls from low rpm.

Pulls OD 5th fine.

Cruise pulls nicely everywhere, although it tends to run up the speed slowly over time.

Still the slightest hint of a stumble in the midrange as you roll the throttle open quickly. Pretty sure raising the needle one clip will clean that up.

Maybe a little soft on wot.

Mpg is still an unknown. Need to run at least one tank through before i can get an idea of it.

 

[TourMax]

Alrightly. Took it for a burn and torched a half tank off.


Driveability:

Pretty good. Pulls from 2000 rpm in every gear without much protest. Still has the "stutter/shudder" mid range if I roll into the throttle quickly. I take that to be a transient lean condition as it will clear out of it on it's own as RPM comes up.

Cruise pulls well, except for a funny little "surge" it will get into every now and then when adjusting speed. I believe this is because my throttle return is still a bit "sticky".Ie; cruise rolls off, speed stay the same, throttle finally rolls back but cruise has already gone lower so it speeds back up and the cycle repeats. No surging at all when I hold throttle instead of cruise control.

Vboost; still a good kick in the pants, screams from 5-6000 to redline quick a spit. But, it does feel like it "lays down" a bit afte the intial vboost hit. Trying to decide if that's lean or rich. I want to say rich because it just seems to go "soft" without any missing. Stay soft too, doesn't seem to clear with rpm.


But MPG.

Oh boy, mpg......

Calculated out at 27 mpg on that half tank.

An easy 8-10 mpg under what it should be. And I was taking it easy on it. Mostly 50-ish mph running, no vboost other than the initial couple shots to redline to see how it behaved.

More work is required, but at least I'm getting closer.

I almost want to drop the needles a clip just to see what that does for the above engine "behaviors" and the low mpg.

Maybe I should order some 90 jets and 170/180 set for PAJ 1 and PAJ2 to replace the ones I drilled out and see where that goes.


Or I coudl take the CO % from 3.5 down to 2.0% and see what happens. That woudl be leaning out the pilot circuit, where the bike lives (for the most part) when on cruise or just tooling around.



Truthfully, I'm also kind of at that point where I just don't want to spend any more time and money fussing with it.....just "fed up" I guess...

 

[D-Max2012]

Don't know if this might help, but I figured you've tried damn near everything else..

Rundown of my issue.
For the longest time after getting my used 91 max, I had this stumble rolling from 4-5K, no matter what gear.
Did all the testing you could think of. Changed out carb and v-boost boots, Needle changes and adjustments. Diaphragm replacements. Pressure leak down tests. Float levels. Synced carbs,, you name it, I did it. :bang head::bang head::bang head:

Pulled the carbs to clean conventionally with air and carb cleaner. Did this 6 times, testing in between each re-build - Same Shit. :bang head::bang head::bang head:

Tore down the carbs fully, to have an ultrasonic cleaning (4 times).
Surprisingly, the solution came out looking like mud, after all that conventional cleaning. Tested again.. This Damn bike!!!:bang head::bang head::bang head:
After seeing this, I decided to nip the shit at the source and coat my tank.. I got tired of seeing my fuel come out looking like weak iced tea color. While waiting a full week for my tank to fully cure, I pulled all the fuel lines and pump to clean out.

Ultrasonic cleaned the carb parts again, 3 more times, till the solution was 100% clear. Put the carbs back in and re-tested.. WTF?? SAME DAMN STUMBLE!!.. :bang head::bang head::bang head:

Decided to try some Seafoam in my tank.. 1/2 bottle added to a full tank of fuel.
Did this for 3 fill-ups. After using about 2.5 tanks of Seafoam and fuel mix, I noticed that the transition between 4-5K was smooth and strong. :clapping::clapping::clapping::clapping::clapping:

So it looked like, whatever the Seafoam was able to clear out, was not coming out with regular or ultrasonic cleaning..

This has been 4 years now.. So far, still working great. :eusa_dance::eusa_dance:

 

[one2dmax]

You'll likely get your best fuel mileage running 75-80 mph which is a better sweet spot for the cam overlap. I got my best mileage actually running close to triple digits.

 

[TourMax]

Ok, so, despite what felt like a lean stutter, i went ahead and dropped the needles one clip position.

#1 had been showing pig rich, 2/3/4 were showing ok if not a little lean.

So i figured I’d chase #1 and see what 2/3/4 did.

I did note that the carbs were pretty “wet” when i popped the diaphragm covers off.

Just got back from a short test ride.

Mid range stutter is gone. Power seems up. Vboost doesnt hit as ferociously as before, but its still evident when it kicks in. It screams to redline just as before, but now the speedo keeps much closer pace with the tach needle. The bike gains speed noticably more quickly.

Seems smoother all around and perhaps less of a “load up” feeling. Feels “lighter” all around the throttle.

Had cruise on for only a short stint, but it seems like its acting much better and not gaining speed like it was. Cant really say about what previously seemed like a “surging” on cruise as i didnt have it turned on long enough.

Dropping the needle one clip should also net some mpg gains. More so if it was running rich enough to quench some of the combustion cycle.

I’ll look to burn off a half tank tomorrow and see what i get back in mpg.

Lean stutter that was actually a rich stutter and not a “bog”.

Go figure.

This sob has been fighting me tooth and nail the whole way, but i think ive got the bastard on the ropes now...