86 ATC 250r spark plug

[Dynofox]

What are you guys running for plugs in your 250r's? I was thinking of trying a br8es since I've heard a few guys with trx R's having better luck not fouling with them. Anyone know what the correct gap is?

[deathman53]

I've always used b8es plugs, I just used them right out of the box. Some say it fries your cdi, others your stator. I'm told it really only can affect your lighting, by making the light flicker abit. I never had a problem or had the lights flicker from the b8es plug. I used a br8es and it seemed less pwerfull.

[JLurch58]

Thats what I run....since I have no lights lol I have never had a problem. Don't buy them at the bike shop though.......advance auto has em for 1.69

[nate b]

i use br9es in summer and a br8es in the winter. if its jetted right you wont foul a plug.

[Dynofox]

i use br9es in summer and a br8es in the winter. if its jetted right you wont foul a plug.

What do you gap the plug to? Thanks!

[skippy]

like he said.. right out of the box, no gapping needed.. i use the b8es's too..

[Red Rider]

like he said.. right out of the box, no gapping needed..
I would never trust that. I always check the gap on new plugs before installing them, and they always need adjustment. Every once in a while I'll find one that is set perfectly, but it's rare.

[HaggLE]

Straight from NGK website
HONDA 250cc ATC250R
Spark Plug Part No. Plug Gap
Recommended Plug BR8ES 0.8
Iridium Option BR8EIX 0.8

The "R" in the plug name indicates that its a resistor type. They were standard issue for all things of the era. Heres the blerb regarding resistor plugs.


from NGK website A resistor type spark plug is one that incorporates a 5 K ohm resistor to suppress ignition noise generated during sparking. (Radio frequency interference).

Radio frequency interference is commonly exhibited by the crackle sound coming from the car radio and there is now an Australian Standard covering R.F.I. which is considered
a type of pollution.

As R.F.I. can also cause premature failure to other electronic components in a modern vehicle, it is important that resistor spark plugs are used to prevent this possibility.

As for different heat ranges, here is the blurb on that

Heat range selection is vital to ensure optimum performance of spark plugs.

A spark plug's optimum operating temperature is between 450 degrees C and 870 degrees C. Spark plug tip temperatures outside this range can occur when an incorrect heat rating is selected. Viz:

When the heat rating is too high:

The spark plug temperature remains too low and causes deposits to build up on the firing end; the deposits offer an electrical leakage path that gives rise to loss of sparks.

When the heat rating is too low:

The spark plug temperature rises too high and induces abnormal combustion (pre-ignition): this leads to melting of the spark plug electrodes as well as piston seizure and erosion.

NGK Spark Plugs pioneered the use of a copper cored electrode in 1958, which enables a spark plug to heat up quickly and also dissipate heat quickly giving an ultra wide heat range. It is essential to use a spark plug that fits a specific engine and its conditions of use.

The old spark plug is very complicated and can cause serious damage to your engine if you chose the wrong one. Hope this info atleast helps somebody.

[Dynofox]

Straight from NGK website
HONDA 250cc ATC250R
Spark Plug Part No. Plug Gap
Recommended Plug BR8ES 0.8
Iridium Option BR8EIX 0.8

The "R" in the plug name indicates that its a resistor type. They were standard issue for all things of the era. Heres the blerb regarding resistor plugs.



As for different heat ranges, here is the blurb on that


The old spark plug is very complicated and can cause serious damage to your engine if you chose the wrong one. Hope this info atleast helps somebody.


Thanks! :)

[Billy Golightly]

I always just run a B8ES out of the box as well. The main reason for the resistor is for as mentioned, to keep interference out of radio frequencies. The FTR (Riding Club) has a mandate for Resistor type plugs now since they went to electronic scoring to keep the machines from screwing up. I doubt it would interfere with the CDI any but I am not qualified enough to say for sure :)

[AZ250R]

BR9EGs & EVs for me. The smaller magneto plugs last longer for me... they have more concentrated sparK??? Not sure but they do run a long time before I fowel em! :beer

[md1985250r]

Honda manual says BR9ES in normal temps, BR8ES in cold weather.

The gap is 0.7-0.8 mm.

[trikezilla]

[QUOTE=md1985250r]Honda manual says BR9ES in normal temps, BR8ES in cold weather.

do you think that would work for the 83 R?? ^ ^ ^ ^

i run a br8es, but the dennis kirk mag. says the stock plug is the br9es?? the stock plug is br8es right??

[TimSr]

B8ES, N3G, or B7ES for trail riding.

[nate b]

i GAP MINE AT .024"

[HaggLE]

nate b - c'mon everyone else is talking metric.

TimSr - I would only be running a 7 plug in extreme cold. It seems like a very hot plug to me considering others are saying that they are using upto 9's.

[TimSr]

Ive never seen a Honda Manual, but normally they spec out going one heat range in either direction from their stock size for tuning, and its factored into your carburetion setup. Since probably 75% of self tuned bikes out there are setup way too rich, a hotter plug probably wouldnt hurt many of them!

A hotter plug will help with fouling plugs during warmup period in cold weather, but once you reach operating temperature, cold air makes a bike run leaner than normal, and a hotter plug makes that problem worse. Other than to prevent fouling during warmup, Im clueless as to the logic behind using a hotter plug in cold weather, unless it is so cold that you are not reaching operating temperature, but then, going one or even two heat ranges its awful hard damage a motor. (yeah, I know what all the books say, but Ive never seen a melted piston from a hot plug that didnt have some lean carburetion issues to go with it.) Going one hotter is an easy way to help compensate for track carburetion when you are going trail crawling.

[HaggLE]

It causes the whole combustion to happen at a hotter temperature. If this temp is too high for the aluminium in the piston it could blow a hole in it. Ive seen this happen on 4-strokes and a lean mixture on a 4 stroke isnt as deadly as it is on a 2 stroke so it can happen.

The hotter plug in cold weather story is that the engine can get warmer faster. But as you say, it has to be so cold that it can barely reach operating temp.