DRIVEABILITY ISSUES

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HAMMER65

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Good morning all, I can ride around town okay, but out on the highway trying to maintain 70mph, my Max spits ,sputters, and backfires. Even with this issue, if I twist the throttle back, she will accelerate.
In general when I crack it open, she goes like a bat outta hell, just doesn't want to maintain speed in 5th gear. Help!
 

Fire-medic

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Sounds like you're due for a carburetor tear-down and cleaning. When was the last time you changed the fuel filter? What does the floor of the gas tank appear to-be/look-like?
 

HAMMER65

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Sounds like you're due for a carburetor tear-down and cleaning. When was the last time you changed the fuel filter? What does the floor of the gas tank appear to-be/look-like?
I was recently inside one of the carbs, they look clean. Vacuum slides move freely. Fuel filter, unknown, I have had the bike since last April. I guess I will be changing it now. Thanks
 

Fire-medic

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Tell us what the gas tank looks-like inside, it should be shiny metal everywhere. It is not coated from the factory. If it isn't shiny metal everywhere inside, and it's not been coated by a prior owner, you have some tank-cleaning to do. You probably found a contributing cause to your running issues too.

Take your gas filter to your local auto parts store and you should be able to match it-up cheaply. When you remove it, try blowing through it, see how-much resistance you have. A plugged filter will be hard to blow-through. Also, cut it open and see what's in-there.
 

MaxMidnight

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Given that it responds to w.o.t. then I wouldn't have thought it is a fuel starvation issue.

When did you last syncjhronise the carbs?
 

Fire-medic

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Given that it responds to w.o.t. then I wouldn't have thought it is a fuel starvation issue.

When did you last syncjhronise the carbs?
Well MrMax, you know I frequently request a disassembly to removal of the jet blocks, and especially the removal and cleaning of the pilot jets, in these trying circumstances. It certainly could when the 'fuel starvation' occurs off-idle, where the pilot jet plays an important part in the throttle response and fuel flow until the needle taper starts running fuel delivery.

VMax pilot jet.jpg
 

MaxMidnight

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Well MrMax, you know I frequently request a disassembly to removal of the jet blocks, and especially the removal and cleaning of the pilot jets, in these trying circumstances. It certainly could when the 'fuel starvation' occurs off-idle, where the pilot jet plays an important part in the throttle response and fuel flow until the needle taper starts running fuel delivery.
Mr Medic, I don't disagree with what you say with an off idle situation but as the revs rise the influence of the idle jets reduces.
As we are talking about an issue at 70 mph when the revs will be approaching 4K so I'm not sure what the relevance of your comment is.
 

HAMMER65

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Tell us what the gas tank looks-like inside, it should be shiny metal everywhere. It is not coated from the factory. If it isn't shiny metal everywhere inside, and it's not been coated by a prior owner, you have some tank-cleaning to do. You probably found a contributing cause to your running issues too.

Take your gas filter to your local auto parts store and you should be able to match it-up cheaply. When you remove it, try blowing through it, see how-much resistance you have. A plugged filter will be hard to blow-through. Also, cut it open and see what's in-there.
thx
 

MaxMidnight

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I haven't, only bought it last April. I was thinking about that.
I would always start with the basics first i.e. carb synch, fuel and air filters. It would also be worthwhile looking at the HT system while you are at it and in particular for any arcing (best done in the dark (but not an enclosed space! 😦)

Could you also put the year of the bike in your signature? (Click your name at the top RH corner and then signature) Also your location which can be entered 'Account details' is appreciated.
 

HAMMER65

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I would always start with the basics first i.e. carb synch, fuel and air filters. It would also be worthwhile looking at the HT system while you are at it and in particular for any arcing (best done in the dark (but not an enclosed space! 😦)

Could you also put the year of the bike in your signature? (Click your name at the top RH corner and then signature) Also your location which can be entered 'Account details' is appreciated.
Thank you
 

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