New to the VMAX, need help/advice

VMAX  Forum

Help Support VMAX Forum:

Cervantes

New Member
Joined
Jul 5, 2021
Messages
2
Reaction score
0
Picked the bike up a little over a month ago. Ran great for the test ride until it started to over heat when I was riding it home. Ever since then it has been a major pain in the ass to deal with. This bike has turned into a gigantic pile of work. With the lack of available/quality parts this isn't looking good. So to start off I'll begin with the cooling system.

On the way home with it I noticed it was starting to overheat in stop and go traffic. The needle on the temp gauge would rapidly climb into the red zone at lower speeds and just about to the H. It's an 88 and from what I've researched this a common problem especially with these early 1st gen bikes that have neglected cooling systems. As far as the fan not kicking on not sure. I checked aIl the related components and didn't find anything wrong. So I wired up a toggle switch to activate the fan, works great. Have been running a system flush in it for over a week and have noticed a more responsive cooling from air flow alone when riding. Even better with the fan on, keeps the needle consistently below 1/2 mark. I ordered a new radiator, thermostat, and gaskets. After several more flushes I will install those.

Now for the strange front wheel hop experienced with heavy braking. Had a driver pull out in front of me, had to hit the brakes hard. As I was coming to a stop the front end started jumping up and down like I was riding over a bunch speed bumps. Tryed to get the bike to do it again on an empty road so I could see what was going on. Hasn't happened since. I jacked the bike up to see if there was any play with steering head. Solid, no forward/rearward movement. The forks do have a huge amount of travel though. Probably dont have any fork fluid in them. So I ordered new seals and fluid. Other possibility I was thinking is irregularity in the rotor surface causing intermittent contact from the pads.

Now for the major headache. Since Ive had the bike it has left stranded a couple times with a dead battery. Did an overnight trickle charge on the battery and had it load tested. Battery Good. Put a fluke meter on the battery terminals while it was running and never got any more than 12.5 volts with the engine spun up to 3500 rpm. After talking with a shop tech it's either the stator or the rectifier/regulator unit. I ordered a rectifier and replaced it only to have it literally explode after a short test ride . Also the rectifier that was originally on there had a complete crack/ bulge on the insulation that covers the inner guts. This leads me to either a toasted stator or a short in the wiring harness.

Anybody had a similar experience with one these rigs? Any help, advise, hacks, and or tricks would be appreciated. I would like to get this bike running and get some riding in before the summer season is over instead of having sit on the center stand. I'm located in upper western Washington, Skagit county. Any people around my area that have a lead on parts or would like to meet locally would be much appreciated.

The bike came with a ton spare parts, maybe a trade could be worked out.
 

Cervantes

New Member
Joined
Jul 5, 2021
Messages
2
Reaction score
0
Here is a pic of the rectifier that didn't last long
 

Attachments

  • IMG_20210803_161002.jpg
    IMG_20210803_161002.jpg
    95.4 KB · Views: 39

Fire-medic

Well-Known Member
Staff member
Moderator
Joined
Mar 25, 2011
Messages
13,277
Reaction score
2,879
Location
Miami Florida
Add your location below your screen name and avatar you can choose (click on your name upper-right hand corner) and for your signature, tell us what bike you have, the year, and for what market the bike was built. Anything done to the bike is also helpful there, i.e., big-bore (displacement here) NOS injection, flatslide carburetors, etc.

VMX12- Service-Manual.pdf (vmoa.net)
Download this, and print-out a copy, keep it in a loose-leaf folder. You will be using it frequently.

VMax electrical resistance data.png VMax Stator ohms reading.png VMax USA 85-89 wiring.png VMax USA 85-89 wiring.02.png

A recent thread which may help: (31) battery eater | Yamaha Star V-Max VMAX Motorcycle Discussion Forum (vmaxforum.net)
 
Last edited:

one2dmax

Moderator
Staff member
Moderator
Joined
Apr 6, 2006
Messages
16,420
Reaction score
1,164
Location
Derby Kansas
We can help with many "upgrade" parts to help charging ($75 for newer regulator), braking (hayabusa upgrades for rear brakes), anti diving ($80 progressive springs), and more. Plenty of parts to support the bike. Always easiest to reach out to me at [email protected] but there is a lot of support here too!
 

Parminio

Well-Known Member
Joined
Apr 22, 2016
Messages
1,418
Reaction score
954
Location
Suwanee, Georgia
Even better with the fan on, keeps the needle consistently below 1/2 mark. I ordered a new radiator, thermostat, and gaskets. After several more flushes I will install those.
It's actually perfectly normal for a Vmax to run just below the red line. The fan shouldn't kick on until it actually gets to the red line mark. In stop and go traffic on a really hot day it can move up into the red area and the fan should be running non stop at that point. If it wasn't, you have an issue. If it was, you do not.

Normal operating range is anywhere in that area. The fan WILL NOT be running.

20210805_084122.jpg
Below the lowest red mark I made is on the cool side. The white break in the lines is hot but not deadly hot. Typically that's right about where the fan turns on. It may creep just to the skinny red line before it turns on. That is perfectly normal.

Anywhere in the thin red line is hot, but not deadly hot. You're perfectly OK there but you need to get it cooled down at that point. If it hits that thick red section at the very end just shut the bike off and wait for it to cool down if you can't get out in free traffic.

Most people completely over react to the temperature gauge on the Vmax and do things they really shouldn't be doing and have no need to do.

It's almost always a waste of money and turns out making the bike run way cooler than it should. In many cases it can actually hurt the performance and efficiency of the bike.

Running the fan full time is a no-no. The Vmax charging system is notoriously weak. It is not made to run the fan full time. At all.
 
Last edited:

JMax92

Active Member
Joined
May 21, 2021
Messages
25
Reaction score
15
Location
Canberra, Australia
G’day, I had similar problem with my Front end hopping when applying a hard brake.
I gradually worked through three fixes that my bike needed and each reduced the effect.
1 - completely strip, clean and service the front brake. I replaced the disk, hoses and seals. Found lots of corrosion in the slave cylinders and pistons that caused seriously jerky brake movement on and off. Some times the brake did not come on, and then suddenly it would lock. Cleaned it all off with plastic scourer.
2 - strip, clean and service forks replacing all seals.
3 - release and reset the steering head. Sean Morley (One2DMax) has a short video on how to test and adjust the steering head bearings, don’t forget to tighten the head bolt after.
Also had a similar problem with battery. I replaced the stator, regulator and battery.
3rd party reg only lasted 3 months, replaced that with OEM which is still going well 3 years later.
Apart from the front disk, brake lines and stator, my bike is all OEM and is riding like a dream.
Good luck
 
Top