Author Topic: 86 TRX250R Dies After Warming Up (Read 5064 times)

chadm86_250r · « **on:** August 13, 2015, 02:41:43 PM »

Hello All,

First time poster here and apologies if this is in the wrong location.

New 250R owner here with a problem someone might have experienced.

I recently purchased a pair of 86 250R's, they both appear to be and are supposed to be stock with the exception they both have FMF exhaust systems on them and one has aftermarket headlights and a graphics kit. They both had the stock tires, grips, etc. and neither one look like they've ever had the top ends or any other part of the motors apart since new in 86. They both even appear to have the original grips in good shape.

The compression is good in both machines with no air leaks anywhere, the jetting is good with the plug looking like it should after a plug chop, the problem I'm running into is that after riding one of them for about 30min and its good and warm it will die and doesn't like to start(or won't on occasion) right away. It will fire up just fine after cooling a little bit. I have swapped the CDI boxes from one to the other to check that but it didn't change anything. It appears to be something electrical and I'm sure I will find it eventually but thought I would ask if anyone had run into this problem before and might be able to point me in the right direction quicker.

Thanks Ahead,
Chad

wilkin250r · « **Reply #1 on:** August 13, 2015, 05:32:21 PM »

First step would be to determine if the problem TRULY is electrical. Did you pull the plug and look for spark? If it's an air-leak problem, there's no sense in changing electrical components.

If it doesn't spark, we found your direction. If it DOES spark (and thus indicate that it's likely not electrical), then spray a little starter fluid down the intake boot and try to fire it up. If it starts for a few seconds and dies, then you have a fuel delivery problem.

rk88r · « **Reply #2 on:** August 13, 2015, 05:36:05 PM »

Coils act that way sometimes. Try swapping it between machines.

chadm86_250r · « **Reply #3 on:** August 13, 2015, 08:45:27 PM »

Think we got it figured out but won't be totally sure till Saturday. Both bikes came with NGK BR9ES plugs in them. Tried running BR8ES plugs and it hasn't died since. Is it possible that the BR9ES plugs were getting a little to wet at lower rpms and slightly fouling then the fuel was evaporating off and the oil was thin enough to fire again after a little bit of time?

chadm86_250r · « **Reply #4 on:** August 13, 2015, 08:48:30 PM »

Thanks for the reply wilkin250r, the plug was getting spark at all times. No air leaks that we could locate. We had already eliminated a fuel delivery problem. Our original thought was that maybe the coil had a weak spot and once everything was up to normal operating temperatures that after expansion we were getting a weak spark.

broken1 · « **Reply #5 on:** August 14, 2015, 10:43:05 AM »

You could also try the non resistive plugs, B8ES. A BR9ES is a little cold & unless its blazing hot in your area an 8 should fix your problem.

jcs003 · « **Reply #6 on:** August 14, 2015, 04:08:37 PM »

have you had the stator cover off?

john

Pumashine · « **Reply #7 on:** August 14, 2015, 08:42:15 PM »

Quote from: chadm86_250r;57108

Think we got it figured out but won't be totally sure till Saturday. Both bikes came with NGK BR9ES plugs in them. Tried running BR8ES plugs and it hasn't died since. Is it possible that the BR9ES plugs were getting a little to wet at lower rpms and slightly fouling then the fuel was evaporating off and the oil was thin enough to fire again after a little bit of time?

Thats the reason I quit running nines 10 years ago. They would foul to easy.

udontknowme · « **Reply #8 on:** August 14, 2015, 09:08:55 PM »

tried 9 plug on gas engine before and they die in short order. more like foul out in short order i guess. wasnt aware the heat range selection had anything to do with ambient temp. thats news to me

chadm86_250r · « **Reply #9 on:** August 16, 2015, 12:03:04 AM »

35 mile ride this morning with the BR8ES plugs in both bikes and no issues, great!

thesmith87250r · « **Reply #10 on:** August 16, 2015, 12:10:30 AM »

Nice.

Tinman · « **Reply #11 on:** August 17, 2015, 06:55:22 PM »

I could never get the br9es to work right, so i ran the gold tipped b9ev(no longer available? switched to irridium) and no airbox lid

89 250r bought new dec. 88
27 years later and it hasnt killed me yet

pantera1975 · « **Reply #12 on:** August 17, 2015, 11:16:07 PM »

ive always ran br9es and br9eix. is there jetting to do switching to 8's

Tinman · « **Reply #13 on:** August 18, 2015, 02:20:35 PM »

if I was running wfo at the beach and using 8's then i would raise the needle and put the air box lid back on verses a leisurley trail ride in the mountains.

JesseA420 · « **Reply #14 on:** August 18, 2015, 04:18:36 PM »

if running stock ign u may want to squeeze ur plug gap down a tad to around .020", it helps on old stock igns