help!bike won't idle when hot

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daves86vmax

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my 86 has been running fine for the first week that i've had it running mostly just to work and back,28 miles each way all highway and only in the 70's with my temp needle about a needles width below halfway up on the temp gauge.I got stuck in heavy traffic for the first time yesterday and it heated up in no time to about a needles width below the red and the hotter it got the worse it would idle,if I did not keep revving the motor it would die.Once I got on the highway it would seem to run ok but soon as i would stop again it would start heating up again and the idle would drop and the motor would die.How hot should it run in heavy stop and go traffic and where should the temp be during normal highway riding?I just replaced the fuel filter,fuel tank,drained and filled all fluids including the coolant(didn't change thermostat because I could'nt find one)and took carbs down and cleaned them,What causes it to idle rough the hotter it gets?Appreciate any help.Thanks Dave:bang head:
 
As long as the needle is out of the red, you will be OK. This sounds like a charging issue. Check your voltage at the battery at idle. When the charging system isn't working at 100%, it doesn't charge the battery at idle/low RPMs and the heat makes it worse. You want 13+ volts at idle.
 
I don't know much about bikes but i'm learning.If it is the charging sys. what charges the battery?Is that the reg/rect?I know from reading other posts that thr r/r in these early models were, to say the least,innadequate.I've seen many upgrades for that part on here.If that is it what is the best r/r to replace the orig. with.The battery is new so thats the only elec part i've replaced.thanks
 
Dave, the R/R is a big part of the charging. The flywheel has little magnets and when they pass the stator AC voltage is induced. Since the Vmax operates on DC voltage the R/R converts that AC to DC by using six diodes. The other side of the R/R is a voltage regulator which prevents overcharging the battery. There is a sticky in the Electrical section which has a fault finding .PDF. Take a look at that and follow it step by step. A couple of things to keep in mind about this diagram is that the Vmax has three white wires coming out of the stator. Also, there are less than 4 colors coming from the R/R so you can ignore section D entirely.

If it turns out to be the R/R just order one from a 2007 model. There's a separate ground wire (black) on the late model version...just extend the wire so it's long enough to reach the negative battery post.
 
I don't know much about bikes but i'm learning.If it is the charging sys. what charges the battery?Is that the reg/rect?I know from reading other posts that thr r/r in these early models were, to say the least,innadequate.I've seen many upgrades for that part on here.If that is it what is the best r/r to replace the orig. with.The battery is new so thats the only elec part i've replaced.thanks

The problem with the older R/R is that the ground for it is the casing of the R/R and it grounds to the frame. Over time, corrosion and other crap builds up and the ground resistance builds up. You can run a ground wire from the negative battery post and attach it to the the mounting bolt of the R/R. This basically duplicates the ground of the later models. But before you go out and buy stuff, check the charging voltage of your bike. A lot of charging issues are caused by melted/burned/corroded connectors and the infamous "splice".
 
I did some checking with the fault flowchart and the r/r checked out o.k.,but not so lucky with the stator,it failed the first and third test.I think i'll still upgrade to a newer r/r anyhow but where can i find a good stator at a fair price,and do i want to stay with an o.e.m. stator?I found one on oldbikebarn.com for about 129.00.Seems awfully inexpensive so probably not o.e.m.Also on that site they said the same stator fits up to a 2001 vmax along with some other cruisers and if thats true cheapcycleparts.com sells an o.e.m. stator for an 01 for around 260.00 or so,does that seem high?
 
I would stick with OEM.

Yamaha charges $321 for a new '01 stator. You can get it from MonDak Motors I'm betting for under $240 with discount. Contact info for this vendor is on the VMF links page.
 
just wondering,on the charging fault flow chart stator test,is it normal to pass one or even two of the three tests and be bad or does it absolutely need to fail all three in order to be bad.I apologize if i repeat some of these questions guys but i,m trying to get a really good understanding of these bikes.thanks
 
just wondering,on the charging fault flow chart stator test,is it normal to pass one or even two of the three tests and be bad or does it absolutely need to fail all three in order to be bad.I apologize if i repeat some of these questions guys but i,m trying to get a really good understanding of these bikes.thanks

What step of the test are you asking about?
 
If you go to the fault finding post go to the 4th page and of the three stator tests my readings for the first test were .7-.7-.7,the second I had the O.L. reading and for the third test the reading was .47-.48-.35 which according to the chart the third test shows the stator to be bad,correct?
 

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