bobzdar
Well-Known Member
Hi guys, first post here - I just picked up an '85 vmax with 69k miles. Description was that it ran well up until last year, then sat over winter and wouldn't run due to the carbs being gummed up. The owner apparently spent a bunch of money on the carbs with no luck (new diaphrams and some other stuff, says he sent them out for around $900 worth of work) and then sent them to someone else who said they needed so much work they weren't worth doing and to just buy some good used ones. He mentioned something about it needing a mixture screw and the jets were messed up? At this point he decided to sell for that and other reasons. Only other issue he said was the somewhat typical slipping in 2nd gear for the early vmaxes.
Now, I have and do all of my own mechanical work and have rebuilt a bunch of carbs but have never messed with Mikuni's, so don't really know their inner workings. I picked the bike up Monday and decided I'd clean up the carbs and put them on to witness for myself what they're doing. I got them on, charged the battery up and somewhat surprisingly it fired up pretty quickly. I had to mess with the choke some to get it to idle but it idles pretty smoothly and with no issues or strange noises. However, as soon as you crack the throttle it dies. Messing with the choke and the throttle I can get it up to about 2500 rpm from the 1k idle before it dies, but it does not appear to be getting any shot of fuel when the throttle is cracked. You can tell it tries to rev up but just dies due to lack of fuel. Now, I left the air box off and all of the vacuum lines off to watch what the carbs were doing, do the vacuum lines need to be hooked up for the carbs to work? Where's the best place to start? My first thought is to check and see if the fuel pump is up to snuff and/or filter is clogged, just pull the line to the carbs and see how much fuel it pumps for a second or two (obviously into a cup)? If the fuel system is ok, where to go from there?
The bike has a supermax seat, progressive front springs, a new clutch and some other stuff, but is otherwise bone stock - dark blue metallic in color. I want to get it running and ride it a bit and then really go through it over the winter.
Now, I have and do all of my own mechanical work and have rebuilt a bunch of carbs but have never messed with Mikuni's, so don't really know their inner workings. I picked the bike up Monday and decided I'd clean up the carbs and put them on to witness for myself what they're doing. I got them on, charged the battery up and somewhat surprisingly it fired up pretty quickly. I had to mess with the choke some to get it to idle but it idles pretty smoothly and with no issues or strange noises. However, as soon as you crack the throttle it dies. Messing with the choke and the throttle I can get it up to about 2500 rpm from the 1k idle before it dies, but it does not appear to be getting any shot of fuel when the throttle is cracked. You can tell it tries to rev up but just dies due to lack of fuel. Now, I left the air box off and all of the vacuum lines off to watch what the carbs were doing, do the vacuum lines need to be hooked up for the carbs to work? Where's the best place to start? My first thought is to check and see if the fuel pump is up to snuff and/or filter is clogged, just pull the line to the carbs and see how much fuel it pumps for a second or two (obviously into a cup)? If the fuel system is ok, where to go from there?
The bike has a supermax seat, progressive front springs, a new clutch and some other stuff, but is otherwise bone stock - dark blue metallic in color. I want to get it running and ride it a bit and then really go through it over the winter.