Hey guys!! I need to know if any of you would be willing to answer a few mechanical questions via telephone about my vmax. Our phone service at our house is HORRIBLE for internet right now so looking it up on the net is next to impossible. Shouldn't take but a few minutes.
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Probably best if you ask the questions online so that way who ever your going to talk to is able to know if they can help or not before they call you.
That or just talk to Morely. He can pretty much answer anything you got.
That or just talk to Morely. He can pretty much answer anything you got.
Hey everyone, This is Mrs_Max's husband aka her mechanic. The biggest question I have is about high rpm loss of power. It pulls very hard up to about 8800 rpm then it has a distinct loss of power. I can audibly hear the left side exhaust change pitch when this happens. 8800~9500 rpm just flattens out without any power.I have cleaned & synched the carbs. I have adjusted the vboost to completely close and open at both ranges of the servo. Any help on this one last little problem would be greatly appreciated so the wife can have a completely great running Max. Oh, vboost is starting at around 6500 rpm.....is that ok?
twistedmax
Well-Known Member
Sean will tell you better then I, but it sounds like maybe a valve adjustment is in order?
The Beekeeper
Well-Known Member
I wouldn't think the valves would need to be adjusted at that mileage if it is accurate, sounds like it's leaning out, possibly fuel delivery, fuel pump and filter good?......Any lines kinked?....Let's see what the experts say..........:biglaugh:...........Tom.
twistedmax
Well-Known Member
Shouldnt by any means .............................But stuff happens, has it always run like that?
Brand new fuel filter on it. Fuel pump seems to be working ok but, I have not put a pressure gauge on it to find specific pressure. I set the air screws @ 2 1/2 turns out per factory setting. I have drilled the stock exhaust so that may have it in a lean condition.
The bike has been a work in progress since we bought it. It had sat up for a very long time before we aquired it from the previous owner. I have been steadily getting it better & better from day one that we bought it. So, I really can't compare it to what it has always run like.
No....but, after searching this forum, I saw a post on that. i may break the carbs down again and do that adjustment tonight.
Miles Long
Well-Known Member
Have you checked the spark plug condition, all four, immediately after giving the bike a hot supper...6500rpm +? (and letting the engine cool down, of course!) Is the base ring a nice light tan color? Are the plugs the OEM recommended - Denso X24EPR-U9, or NGK DPR8EA-9, gap 0.031-0.035 in.?
A few people on this forum very experienced with reading plugs - if you have them out, post a high-resolution pic. They may indicate a carburation problem.
Cheers!
A few people on this forum very experienced with reading plugs - if you have them out, post a high-resolution pic. They may indicate a carburation problem.
Cheers!
The vent does need to be attached at the top corners of the airbox as noted. It will also run richer with the pipes drilled out. A smaller main may help it pick up some power and crispness. And, as long as my phone isn't dead you can call too.
If you don't get an answer right away just try again a little later.
Sean
316-619-8411
If you don't get an answer right away just try again a little later.
Sean
316-619-8411
cgswss
Well-Known Member
How about some background? Was the bike running good, then you made some changes and it isn't good now? Have you pulled the plugs to look at them? The very best thing you could do to take a look inside the engine is to do a plug chop. Then you can see if your are running rich or lean. Does the engine run up to 8000 rpm then flatten out in each gear, or just at top end? On motors I build in the past, if you run good up to say 8000 and then it falls flat, that normally means the carbs are too rich. the other think that could cause it is the timing is off.
And there are a number of other things I can think of off hand but you can narrow it down a lot by checking the plugs after a plug chop. If it were running lean, I would expect to hear a lot of popping when you back off the throttle.
I'm sure none of this will solve the problem but it may get you looking in the right direction.
And there are a number of other things I can think of off hand but you can narrow it down a lot by checking the plugs after a plug chop. If it were running lean, I would expect to hear a lot of popping when you back off the throttle.
I'm sure none of this will solve the problem but it may get you looking in the right direction.
dannymax
Well-Known Member
I'm leaning towards carbs....a plug chop is a good place to start. 4th gear @ 4k go wot to redline and hit the kill switch.
You will have to plan your spot for this....obviously. :biglaugh:
Not sure which way you drilled the pipes but can you spin some temporary allen plugs in just for testing....altho I'd be pretty surprised it the drilling would affect much of anything.
And yes, the boost kicking in at 6k - 6500 is normal.
Question for ya....is this a new issue or has it been present all along?
You will have to plan your spot for this....obviously. :biglaugh:
Not sure which way you drilled the pipes but can you spin some temporary allen plugs in just for testing....altho I'd be pretty surprised it the drilling would affect much of anything.
And yes, the boost kicking in at 6k - 6500 is normal.
Question for ya....is this a new issue or has it been present all along?
Was out visiting an old friend. The bike has been a work in progress since we bought it. It had sat for a very long time with previous owner. I finally broke down and cleaned the carbs last weekend with the help of a friend who works on ATV's. It was our first venture on a vmax. This helped the bike tremendously. I will pull the plugs tomorrow and take a look at them. They are recommended NGK. I am also going to adjust the floats since that is something we overlooked during the cleaning process . I will report back with plug condition and pics after a nap. No popping on decel. It falls flat mainly in 3Rd and 4the gear. Or should I say that's when it's most noticeable. Have not topped it out yet because of lack of safe space.Thanks for the help guys.
