vmax carburetion

cougar1985

cougar1985

New member
Joined
Jan 26, 2006
Messages
290
Age
67
Location
sault ste marie ontario
have a 1994 vmax 600 ,ive had it for 3 years now and it just does not run right in the 25 to 40 mph range.it loads up and i have to hammer it to clear it out.the needle has been adj,carbs are spottless ,air mixture done and still runs like this and the plugs are sooty,oilly black.now i know it has std mains .according to the factory manual it says to replace main jets with next smaller size.i will double check but im sure mine are 156.3 ,next down would be 153.8.am i on the right track.or no matter whats in there go one smaller?
 
Can you hear any burbbling at that point? Mine had a similiar stumble but got much better after tuning the clutches and dropping the gear ratio. It may be that the clutches are fighting each other. Are they (or one) getting hot?
 
dont know if you,d call it a burbling ,but it definately sounds like it,s loading up.ive checked the plugs after and their black and oily.at higher speeds it runs great ,still the pugs are not a good color and if you go strictky by the manual,it says to replace main jet with next lower one.honestly it,s the only thing i havnt done yet,it does seem to shift correctly .i suppose the only way to find out is to go one smaller and check it out ,or maybe 1 heat range hotter on the plugs?im pretty sure i did that once and the results were not any different.
 
cougar1985 said:
does not run right in the 25 to 40 mph range.QUOTE]

wouldn't that be on the needle? maybe you need to move you needle clip down a notch? something to try. or maybe a bad oil pump?

Shawn
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daman i will check ,i think it is on 3.it use to be on 2 and i had the same symptoms then.how would you know if you had a bad oil pump?oil consumption does not seem too bad to me but im not really familar with yamaha oil injection ,etc.
 
Newfoundlander said:
try dropping your pilots one size probally loading up the plugs on the bottom end I had the same trouble on my mm700
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that might be worth a try.what are the drawbacks if thats not it?poor running ,engine damage or ?yes my pump adjustment was set but i will certianly check again.
 
ok ive read that blasted manual a hundred times and from 1/4 throttle to full you adjust with the mains.for high alitude tuning you can do the pilot.under carb tuning in the man it says ''if the low-speed performance is still poor in high elevation under extreme conditions,the standard pilot jets may need to be replaced to obtain proper pilot air/fuel mixture.i dont think this applies to me as im only at about 400 to 600 above sea level .i suppose i will have to go down one size on the mains and go for a spin then check the plugs to see how its preforming.its the last thing i can do that hasnt been done a hundred times.
 
fleet man said:
Check piston wash too. That would be another indicator of overall rich/lean condition.
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exactly what is piston wash and how do you check it?are you pulling the plugs and looking at the top of the piston for coloration?
 
cougar1985 said:
exactly what is piston wash and how do you check it?are you pulling the plugs and looking at the top of the piston for coloration?
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cougar you don't know what wash is by now and you've been a member
how long????...:)

click
 
settings on your '94 should be..

oil pump 29mm
m/j 156.3
p/j #52.5
p.a.j needle Q2.5(not a Q but circle with a line through it)
p/s 1-1/8 out
float height 20.3-24.3mm

can you verify how far off you are on these??

lets get a starting point here
 
yes i must admit i dont pay attention some times,lol.im going out to check soon on all the spec you just gave me.i know the jet is the standard one the needle was moved one richer last year by a mech .i think he went the wrong way so id have to go 2 up to get a good starting point.ive never done the needles on these carbs before and the service manual really isnt much help so im going to have to wing it very carefully.
 
cougar1985 said:
yes i must admit i dont pay attention some times,lol.im going out to check soon on all the spec you just gave me.i know the jet is the standard one the needle was moved one richer last year by a mech .i think he went the wrong way so id have to go 2 up to get a good starting point.ive never done the needles on these carbs before and the service manual really isnt much help so im going to have to wing it very carefully.
Click to expand...
thos were stock setting's,so lets see how far off(witch way)you are...

i'm sure compression is good??
 
On a '94 vm there is no plastic washers,only a clip and 5 positions on the
needle, just to clear that up..:)
 
daman said:
On a '94 vm there is no plastic washers,only a clip and 5 positions on the
needle, just to clear that up..:)
Click to expand...

I had cleaned the carbs on my 95 vm500 a month or so ago, and couldn't remember if there was or wasn't. however according to ronnies microfiche there is.

http://www.ronniesmailorder.com/fiche_section_detail.asp

Part number 17. 2 required. but I don't know for sure. either way its an easy job!
 
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