Hi ; Can somebody straighten me out on the glow plug thing please ! I am new and I have to go buy some glow plugs this weekend and i don't know what i need for a plug. Short, long, hot , cold, Fox or other, 1.5 or 2volt, gold or silver, man why don't they make it easy? I am using a 12 volt mower battery with a locking glow plug with alligator clips, the engines I have are K&B .61 .65 .40 and a.45 sportster. Thanks for any help......Veco

Everybody has their own "best" glow plug. My personal favorite are the OS 8 and OS A3.

The best plug is O.S #8plug!!!!

Don,t use that plug clip hooked directly to the battery you will destroy your new plugs instantly. To use a 12 volt battery you must use a power panel or you could use a single cell pocket ignitor.

Your K&B 61 and all the sportsters will thrive on K&B glowbar 1.5 volt long plugs. Color of the plug has nothing to do with the plugs performance and is just an individual manufacturers markings.

John

The "BEST" plug will depend upon many factors. Plugs come in different heat ranges to meet the needs of engines with different compression, timing and nitro. There are other variations on plugs such as idle bars.

A blanket statement like OS#8 is the best plug is not very informative nor is it correct. An OS#8 works well in most sport two stroke engines on moderate nitro. For high nitro/piped or four stroke applications, an OS#8 is a terrible plug.

My guess is that there are many plugs that will work well in your K&B engine. Any general sport two stroke plug will work fine.

Ditto on the 12V. 12V will fry your plug quicker than you can disconnect the battery. You need some way to reduce the voltage to about 1.5 volts. A power panel will work.

Cheers

So you are telling me that any 1.5 volt long reach glow plug will work but you have to experiment with the hot and cold , idle bar and no idle bar to see which ones are better for a particular engine . Veco

i think the idle bars are for inverted mounted engines.

BTW i use Sig plugs and they work great

Idle bars are there to prevent the fresh fuel charge from hitting the plug too quickly and causing it to cool off. This is particuarly noticeable at idle. If your engien won't idle low enough and dies by slowly loosing rpm, you might try an idle bar and see if it helps. Some engines like them, but on some it makes no difference. I've also heard (but never experienced myself) that some engines will run poorly with an idle bar plug at high RPM as the ignition gets delayed a tad.

Another variation in plugs is their length. The OS #8 is listed as a "long" plug but it's actually a "medium", there are several "long" plugs that are longer. K&B long plugs (1L, HP, RC), for example are noticeably longer in reach than the OS #8. A longer plug can sometimes have the effect of increasing the compression a little, which some engines like and some don't. On most, you won't notice a difference.

Btw, a "Short" plug is used in small engines where there isn't enough clearance for a "long" plug. Many engines below a .15 use short plugs.

Plugs are frequently rated as "hot", "medium", or "cold". A hot plug keeps the element hotter and therefore causes ignition earlier than a medium or cold plug. High RPM, high compression, and high nitro are factors that require a colder plug.

If you have a plug that is too hot, the engine will experience pre-ignition, and you might hear a frying egg sound when it's running. If the plug is too cold, the engine won't produce full power, and will idle and transition poorly. Most all sport engines run on moderate nitro are set up for a "medium" plug, and most of the plugs you pick up will be mediums. OS #8 is a medium.

In general, if the engine starts up easily, produces full power with no odd sounds coming from it, idles and transitions well, then your plug is fine. You won't get more power from changing brands of plug in most cases, so run what works. I happen to use the K&B 1L in most of my engines. Mostly because it's less than half the price of an OS #8.

Veco Montague's post above is dead on and an excellent outline. Now for your Sportsters all of them 20, 28, 45 and the 65, the K&B 1.5v long idlebar is an excellent match and yes the little 20 needs the long plug. For the K&B 61 this one works well with the idle bar but is also more tolerant of ones without and as mentioned above the K&B 1L is fine.

John

Hay; Thanks guys, that cleared up a dark area for me. Thanks again Montague ! Veco

Hey, I'm just happy to have excuse to ramble on about something and have it actually do some good for someone