85 Max running horrible under acceleration

[yellowandfast]

Took the max out for a 115 mile ride on sunday, ran perfect!

Took it out today and once I try to make with some hard acceleration it misses and stutters like crazy, I dont have my service manual right now so I dont know what the coil reistances shoud be, anybody got them memorized.

If its not the coils Im thinking its in the carbs/fuel system although very unlikely that a problem could happen overnight in that area.

I already check charging voltage and its 13.8-9 at 2k rpms

any help would be great!

thanks

 

[The Beekeeper]

This happend to me last fall, swore it was an ign problem the way it was acting, plugs looked good but changed them anyway with no effect, after some research on here I ended up performing the shotgun method on the carbs with amazing results!.................Give it a shot.................Tom.

 

[yellowandfast]

do you have a link?

 

[dannymax]

Think it's in the VMF Links button above.

 

[dannymax]

http://vmax.lvlhead.com/tips/shotgun.htm

 

[one2dmax]

Yep, probably plugged up the pilot jet circuit.

Sean

 

[yellowandfast]

I will dig into it tonight and see whats up.

I cant believe it could happen just like that, the bike ran perfect and then bam.

It was great off idle but as soon as I would goose on it, it would miss and stutter like an ignition problem.

I did notice ever since it got cold it would snap or pop when it was warming up, like it was lean.



Jeremy

 

[The Beekeeper]

It can happen while your riding it, was on a cruise with a friend, I was doing rolling burnouts and being a hooligan with the bike running perfect, next thing I knew giving it any medium to heavy throttle resulted in what you described, I tried running Seafoam through it to no avail..............Good luck with the procedure and post results!..........................Tom.

 

[dannymax]

I will dig into it tonight and see whats up.

I cant believe it could happen just like that, the bike ran perfect and then bam.

It was great off idle but as soon as I would goose on it, it would miss and stutter like an ignition problem.

I did notice ever since it got cold it would snap or pop when it was warming up, like it was lean.



Jeremy

I agree, it's hard to buy but that's exactly the way it happens sometimes!

 

[KJShover]

+1

It can happen real quick. There has been several members who had cleaned thier carbs, sync'ed them and had them act up during a ride quickly there after.
Crud comes loose from the tank, Dirty filter, missed gunk in the carb, poor or no carb sync, fuel pump issues are some of the culprits.

 

[yellowandfast]

So Im cleaning my carbs and discover that it has 90 pilots and 170 mains??

My book says it should have 150's and 152.5s amd 37.5 pilots.

the only change on the bike is it has the k and n drop in and it has super trapp slip ons.

Any reason the previous owner would put huge jets in it like that??

Anybody think that this could be the reason it ran this way??

Thanks


Jeremy

 

[KJShover]

Any reason the previous owner would put huge jets in it like that??
Anybody think that this could be the reason it ran this way??

Its a common misconseptioin that you have to jet up when you use a drop-in filter and slip-on mufflers.

It could cause your problem, being fed more fuel that is needed. What do your plugs look like?

 

[yellowandfast]

They are on the darker side but nothing I would be concerned with.

 

[[email protected]]

Im guessing those are dynojet brand jets? A 170 mikuni main would be huge. A 170 dj jet is close to a 160 mikuni. Still way big. 150 mikuni mains should be pretty good with your setup according to what others have had success with.

 

[yellowandfast]

Got it put back together.

I dont know what brand jet they are, but after the clean up it idles much smoother. And now I have also noticed that my idle is slightly higher than it was before, sitting now at 1050 as compared to 800.

The bike now starts easier and the off idle response is MUCH better, before it would always pop when I give it a quick jab, now just a smooth rev up.

Havent been able to drive it yet because of the rain but I will take it out tomorrow and give it some hell.


I cant imagine this bike making more power than what it had before, but I am pretty excited that it might!!


Jeremy

 

[deekjx]

I may have to do this. The bike I bought was idling low, I just turned up the idle screw for now but it still behaves a little off. Twice it hesitated when I opened the throttle. It's not all the time. I may just start with some start your engine first.

Sent from my ADR6300 using Tapatalk

 

[KJShover]

What I do to help maintain a certain a level of clean carbs is, I fill a 5 hour energy bottle full of seafoam and about every third fill up, I put it in.

 

[yellowandfast]

Got it figured out, after riding with new plugs in it i have determined that its lean.


It is in the mid to lower 50's here and after talking to a local shop owner he said he has had to increase jet sizes on the 85 and 86 maxes due to cold weather.

The bike will not even rev past 5 grand and the plugs are as white as when I installed them.

 

[Rand-5107]

Look in the carb section for 65fury's carb thread his bike was lean and he had huge mains. It was due to the wrong emulsion tubes supplied with a keyser carb kit. It took sending his carbs to Sean Morely to discover this.

 

[deekjx]

Can't you fix a lean situation by adjusting the pilot screw or is this just for the idle condition? I suppose the fuel your jets are spitting out can't be adjusted without changing the physical jets themselves?