Need a Tomos Expert

Ok heres the deal, This is my friends 90-93 bullitt top tank style tomos, Im not sure on the year, but anyway, my friend asked to fix it a while back, so I did and got it running, but didnt put on an air filter yet, I let my friend ride it and they were riding in the woods, and he fell and must have sucked in dirt etc. because it wouldnt run, I got home and took it apart and cleaned the carb and got it running again. I gave it back to my friend, and now he's asking me to fix it and paint it (like 5months later from the last time i fixed it)

The moped takes very long to start up and it doesnt idle at all, when you approach a stop sign it will die before you fully stop, So today I took the head off and I noticed that there (very hard to explain) but it looked like shit baked onto it, and on the piston, it looked the same and i remember from my moped (batavus) that the piston is like evenly covered with carbon but on my friends tomos it was very uneven there was a part with no carbon at all, and when i took a paper towel and wiped around the clinder's wall, it hard dirt and crap on it, after I put it back together and cleaned the carb it ran a little better but it still didnt really idle for very long.

Well any help is appreciated thanks.

Re: Need a Tomos Expert

Speak of the devil, and he may soon appear!

Re: Need a Tomos Expert

what are you talking about?

Re: Ree is a Tomos Expert

A guru named "ree".

I bet you couuld find an answer in the forum archives. I'm a Tomos novice, but I've never had a question Ree couldn't answer....He's been on less frequently, lately, but he'll answer you.

while you wait for him to answer, get familiar with the site 'search' and look for answers to TOMOS problems

he checks once a week, at least--- I tore my 1992 bullet all apart, knowing if I get stuck on the rebuild, he'll know any problem I run into.

yeah, he knows the TOMOS inside and out.

In fact, I think he's been on the inside and outside of a TOMOS at the same time.

(just kidding Ree--- referring to your accident....)

-Wayne

You might say that, yeah.

Reeperette /

Considerin that the impact drove bone fragments into the frame, yeah...I bet you could say I've been "inside-and-out" of a Tomos.

>>90-93 bullitt top tank style tomos<<

Nice wheels, the Bullet is one of the best mopeds ever, and lucky fer you - easy to fix.

Other than how much of a pain in the arse it is to get the carb out, that is.

>>but didnt put on an air filter yet, I let my friend ride it and they were riding in the woods, and he fell and must have sucked in dirt etc. because it wouldnt run, I got home and took it apart and cleaned the carb and got it running again<<

Yeah, now...do you mean no air FILTER, or no Air BOX ?

Just gotta make sure here.

It's a three-piece setup, a metal grate lookin thing, that's actually the air filter, it's round and goes in the back of the carb...a rubber boot kinda thing that holds it on, and connects to the plastic "airbox" buried behind the carb in the frame.

Cause you need the filter, and the boot to hold it on, but you do not really need that airbox, tho I would check jetting to make sure you are not too lean on your mix, gettin that much air in there.

>>The moped takes very long to start up and it doesnt idle at all, when you approach a stop sign it will die before you fully stop<<

Are you running CDI or Points type ignition ?

Cleaning the points and replacing the plug would be first starts on this, as well as doing a "plug chop" to make sure the mixture is at least close to correct.

Also a quick compression test is in order.

>>So today I took the head off and I noticed that there (very hard to explain) but it looked like shit baked onto it, and on the piston, it looked the same and i remember from my moped (batavus) that the piston is like evenly covered with carbon but on my friends tomos it was very uneven there was a part with no carbon at all, and when i took a paper towel and wiped around the clinder's wall, it hard dirt and crap on it, after I put it back together and cleaned the carb it ran a little better but it still didnt really idle for very long.<<

That might indicate a previous seizure of the moped, and thus possibly be a compression-loss issue.

Reccommendations

Clean the Points/Check CDI.

Replace Spark plug.

Hone the lower cylinder and replace piston rings.

(It can be honed, it's cast, and a brake hone might do the job if it'll go down that far.)

Check Piston for damage, and clean it up a bit.

Since you're going to be "down in there" anyway, pull the carb and clean it too, and show the owner how it's done.

Write down the jet size and lemme know what that is too.

Do alla that, and a coule of "plug chops" to see how lean/rich the mixture is and lemme know.

IF you still have compression problems, there is a workaround, Tomos cylinder and rings are normally 38mm, but they do make a 38.50mm piston and rings kit in case one has to bore it up 0.50mm after a slight seizure, but we'll get to that if nothin else works.

Just get as much detail as possible with each step, and get back with me, even if it does solve the problem, knowing how helps the rest of the forum with similar problems.

-R

Re: You might say that, yeah.

The jet is 53 and the carb is brand new so its not the carb, compression is good and spark is good, now how do i check/clean the points?

points

how can i check to see if its cdi or points cuz im not sure

Re: points

take off the flywheel cover (the one thats also the front sprocket guard) and spin the flywheel around while lookin in2 it with a flashlight, if its got points, you'll see them in there. you can acess them through the openings in the sides of the flywheel.

your point gap should be .35-.45mm(.014-.018in) and a .019in spark plug electrode gap

-Garret

Re: Need a Tomos Expert

A quick question, is it ok to use engine degreaser on the piston, or a very fine sand paper to clean the carbon off the piston?

Re: Need a Tomos Expert

Ron Brown /

Nick,

You should never use sandpaper on your piston, it is almost impossible to get all the abrasive cleand off. As for de-greaser, grease is good. You can use hot soapy water if you wish, then oil it down immediately with 2 stroke oil.

Use a scraper to remove the carbon, but be sure you dont gouge anything.

I like credit type plastic cards for most scraping. They are tough enough to hold up and do not scratch metals.

Keep in mind that you do not need to remove all the carbon. As long as there are no obviously thick carbon deposits, some discoloration does not matter. After all, it will look that way after the first few miles anyway.

Ron

« Go to Topic — end of thread

Want to post in this forum? We'd love to have you join the discussion, but first:

Login or Create Account