Super Hot Tomos (I mean temperature unfortunately)

My Tomos Bullet (1990) was having trouble idling, and was getting super hot, then not starting up after I would ride it for a while. After a good carb cleaning, and some advice from a local scooter repair guy, its idling better and running smooth, however, it still gets very hot very fast, and then starts shutting down when I stop at a light (after maybe 20 minutes of full throttle city riding. It's better when its cooler outside or raining. The scooter repair guy says that the engine is running too hot and I should get a cooler spark plug. My question:

1. Is he right? I had a Bosch w8ac before, and he gave me a NGK B7HS, which works as well, but he says a higher number is a cooler plug.

2. Where do I find a cooler plug/how do I know it fits?

3. Is there anything else I can do to cool down my engine?

thanks in advance,


Re: Super Hot Tomos (I mean temperature unfortunat

Whats a plug chop look like after a good run? Getting hot usually means it is running lean, no? What reasons would it run lean? Air leak in intake, around reed, carb, oil injection? Whats your compression look like?


Re: Super Hot Tomos (I mean temperature unfortunat

Tab Patterson /

Is your oil injector working properly???

Re: Super Hot Tomos (I mean temperature unfortunat

yea,bleed the injector pump then pull the feed tube going to the eng. run the ped (very short time!!) see if it's pushing out 2 stroke oil.

Re: Super Hot Tomos (I mean temperature unfortunat

What does a 'cooler' spark plug actually do? Whats the difference?

The ceramic insulator in a cool plug has a short path to it's metal base. So, heat from the tip of the plug is more quickly removed. Otherwise, the hot/cold plugs are physically identical.

A spark plug's design does nothing to remove heat from an engine.. the engine might weigh 500 pounds and the plug a few ounces.. How much heat can the plug absorb? Almost none.

Plugs have heat ranges for the sake of the plug.. the idea is to prevent plug fouling in the conditions in which the plug is forced to operate.

The tip of the plug must remain hot enough to burn away any oil or other contaminants so it doesn't foul and can fire properly. If the plug gets fouled (is your ignition weak?) then try a hotter plug.

Use a cooler plug if the plug shows signs of overheating. Otherwise the plug electrodes will be destroyed and the plug will die.

If the engine shows signs of overheating, look elsewhere for the cause.

The condition of the plug after a proper plug chop reflects the condition of the engine.. Plugs do not cause the condition.

interesting reading for those who care..

Re: Super Hot Tomos (I mean temperature unfortunat

Tab Patterson /

Well, it is possible that the oil pump is pumping, but not enough. A lean condition (jetting or leaks) or lack of lubrication are the only 2 things that I can think of that would make an engine run like that. Well, also if there was no airflow over the fins.

Re: Super Hot Tomos (I mean temperature unfortunat

Note: No oil injector on the Bullet--it takes premix. So that's probably not the problem. I have noticed that when I start it up in the morning, I get a lot of bluish smoke coming off the cylinder where the exhaust pipe is attached, also the end of the exhaust is always a little wet with oil--could these be a clue to my problem?

Everything seems quite tight with no leaks. What is jetting? And what do you mean by lack of lubrication?

Re: Super Hot Tomos (I mean temperature unfortunat

Tab Patterson /

You shouldn't see any smoke from the cylinder. Sounds like a bad leak at the exhaust gasket.

It is normal to see oil on the end of the exhaust.

Now it sounds like you are running lean. Somebody either drilled out the airbox...or removed the air cleaner...or put the wrong fuel jet in the carburator. Could be a combination of all three. Hard to tell over this here intarweb.

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