Tomos engine diagram

Thanks Fred, for the info; neat trick on using the car battery to juice the strobe light. I finally have a use for my vette since i lost my license!!! Anyways, does anybody know where i can find an exploded view diagram of a Tomos engine so I can learn what I'm getting into before I get there?

Swarm and Destroy as you can,

Lane

Re: Tomos engine diagram

Re: Tomos engine diagram

That was interesting.

Especially the part about using a hotter plug.

Apparently Tomos uses a real cold plug so that the general public doesn't seize or melt pistons.

And they must figure if you are going to start modifying... then you are taking the reliability into your own hands.

Because... normally... the more HP an engine makes... the colder the plug.

Thats what I get for applying general knowledge to a specific situation.

Re: Tomos engine diagram

Ron Brown /

Fred,

This same site shows a dark brown spark plug and recommends a hotter plug to correct for a rich mixture. I'm confused too. The following came from the NGK web site:

_____

Let's make this really simple: when you need your engine to run a little cooler, run a colder plug. When you need your engine to run a little hotter, run a hotter spark plug. However, NGK strongly cautions people that going to a hotter spark plug can sometimes mask a serious symptom of another problem that can lead to engine damage. Be very careful with heat ranges. Seek professional guidance if you are unsure.

With modified engines (those engines that have increased their compression) more heat is a by-product of the added power that normally comes with increased compression. In short, select one heat range colder for every 75-100 hp you add, or when you significantly raise compression. Also remember to retard the timing a little and to increase fuel enrichment and octane. These tips are critical when adding forced induction (turbos, superchargers or nitrous kits), and failure to address ALL of these areas will virtually guarantee engine damage.

_____

There are spark plug selection guides which sugest that a hotter plug may overcome oil fouling for a while, but in general, a hotter plug should only be used when normal deposits a building up on the plug because the tip temperature us too lw to burn them off.

In other words, I think your mind is right and I am suspicious of this Tomos site. I have a hard time believing that you can run too cold a plug as standard in a 2 cycle and not suffer from fouling or at least have to clean it way too often.

Ron

Re: Tomos engine diagram

That's because these moped plugs are specially made with extended tips which "burn off" deposits much better... so they can run a little colder without fouling.

I'm guessing that Tomos site knows what they are doing... but I would certainly watch the plug closely... and like I said...Tomos must have been very worried about reliability to put such a cold plug in.

Or ..... actually......... maybe it is the same as the "too large a main jet acting as a governer" that some used....... hmmmmmm

There are probably knowledgable old Italian guy who know very well how to make one of these go 60 with no trouble...except the brakes!

Now... if only I could make my ped make another 100HP .

Re: Tomos engine diagram

Ron Brown /

I guess thats one way to correct for the cold plug!

Re: Tomos engine diagram

I'm quite sure 60 mph is possible, I got mine up past 50, and from what I have

been seeing, there is still timing I can play with.

I've gotten confused, are you guys saying that a hotter plug would be better ?

Re: Tomos engine diagram

Ron Brown /

Fred,

Back to the serious side of the discussion, the Tomos site talks about jetting correctly to match the mods. How does this fit with a hotter plug compensating for a rich mixture? It would seem that the only reason for a hotter plug would be to prevent deposit build up.

Looking at the spark plug construction details on the NGK site, it is true that a colder plug lowers combustion chamber temperature to some extent, but the main function is to maintain the plug tip temperature within an acceptable range.

The plug is cooled by transferring heat from the tip to the body of the plug which, in turn, transfers the heat to the head. The same total amount of heat is present, the heat range of the plug simply controlls the rate of cooling of the plug tip to maintain the correct tip temperature.

Other than by preventing pre-ignition, a colder plug should not significantly change the combustion chamber temperature. On the other hand, if the plug tip gets too hot, pre-ignition and/or pieces of the plug tip falling into the combustion chamber, can do severe damage to the engine.

I think I will stick to jetting until the color is right, then adjust the heat range.

Ron

Ron

Re: Tomos engine diagram

Ron Brown /

Ray,

Read my post to Fred for my opinion. On the jet size, the main jet is in the body of the carb, directly below the center of the throttle slide. You can access it by removing the float bowl. The size will be stamped on it. I would not bother getting another size unless your plug color is off.

Ron

Re: Tomos engine diagram

I am talking about a genuine (and reliable) 60 MPH... not an indicated 60

Your speedo is prob 5 mph over.

You could prob make it do 70 if you didn't mind it lasting 60 minutes before death.

That Tomos site recommends going to a hotter plug with the first stage of mods... which is totally foreign to my experience.

But maybe Tomos puts in extra cold plugs stock so that no matter what kind of goof ups its owner does... nothing melts down.

Re: Tomos engine diagram

I'm just curious, why do you think my speedo may be 5 mph over. Are these

speedo's not that accurate ? I'm not doubting you, just curious if there is

something else I'm not aware of ( and a long list that is ).

When I had it wound out, the needle was just a couple of degrees past pointing

straight at me. Now, it did sound like it did not want to run at that speed for too

long. My cat makes the same noise when you step on it.

When I took my old piston out after the first 100 miles, it had a buildup of black

gunk on it. How normal is this. It was not very thick, but it wasn't exactly bright

and shiny either.

It's a shame the tomos only has two speeds. It feels like if there was a third, you

could really make it giddyup.

Any ideas on changing the gearing <G>

Re: Tomos engine diagram

Ron Brown /

Ray,

I suspect the black is because you are running a little rich, assuming your oil/gas mix is correct. You need to do a plug chop and see what your mixture is like.

I think the Tomas site talked about replacement sprockets for higher gearing, but keep in mind that you will loose acceleration and head wind/hill climbing power.

Ron

Re: Tomos engine diagram

Well, the mixture was factory set, and the gas mix supplied by the dealership.

I'm not too worried, After the upgrade, I needed to remount the header pipe for

the BiTurbo. When I took it off, I was lucky and the piston was all the way down.

Top of the piston, and the cylinder walls were clean and shiny. I was so happy.

I'm going to get a few miles on it, get the muffler welded into one correctly shaped

piece, and then do a plug check like you suggested. Thanx

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