More lovely TOMOS problems...

I just got a new cylinder stud for my 2002 TOMOS LX and after putting it on and torqueing down in a criss-sroos pattern at 10 ft/lbs, i was not able to go faster than 35 mph in which before hand, i was able to do at least 40. The problem is that when I hit 35, the engine starts to studder and be on the verge of 4-stroking but doesn't completely 4-stroke. When I go down a hill, it 4-strokes. So, I am thinking it is a problem w/ the needle in the carb or something in the electrical. My jet size is correct so I know it is not that and I did blast every part of the carb I could get to w/ carb cleaner except the needle. Also, I did wire up a key ignition switch 8 months ago and used thin speaker wire for that but I don't think that is the problem either. So, any input on what the problem is would be nice.

Re: More lovely TOMOS problems...

it don't make sense that curing a compression leak could steal power.. Did anything else change?

maybe that engine was accidentally but perfectly tuned to run with the leak. Now that the leak stopped it needs adjustment of some kind.. very weird.

Re: More lovely TOMOS problems...

Matt Permahos /

I am having a similar problem. I took of my cylinder head and it seems that when it goes down a hill it is 4 stroking.

Re: More lovely TOMOS problems...

mine sounds really weird when i go down hill fast too.. It's like it wants to backfire but it doesn't actually do it.. seems to be louder when the throttle is closed. There's a marked change in the sound of the engine. I don't worry about it. I think it's just like a car when you slow down on compression.. the wheels are turning the engine instead of the engine turning the wheels so it's gonna sound different.

However, when you have the throttle closed, no fuel enters the engine. No oil enters the engine either. So, racing down a steep hill and then closing the throttle to slow down doesn't sound like a good thing for a 2-stroke motor. No lubrication and high RPMs..

Re: More lovely TOMOS problems...

Matt Permahos /

yes but there is definetly a difference in performance and in speed for me and probably for bassman too. I think are problems are the same.

Re: More lovely TOMOS problems...

ok.. well.. Why did you take the head off and was anything at all deliberately changed by you?

Re: More lovely TOMOS problems...

do a compression test.. a real one with a compression testing gauge..

since you ran that engine with a broken stud (if i recall corectly), i'm thinking that the head is already warped or something..

Re: More lovely TOMOS problems...

Lance Baresic /

I'll give that a shot but should I also check the carb needle and the electrical system?

Re: More lovely TOMOS problems...

it can't hurt to look at everything everywhere.. something may have been jerked around..

but if nothing except the head bolt was altered and performance suddeny changed, i would concentrate my efforts to mechanical things related to the head/cylinder/gaskets/bolts.

Re: More lovely TOMOS problems...

Lance Baresic /

I'll check it out tomorrow, thanks for the help.

Re: More lovely TOMOS problems...

Matt Permahos /

Bassman, i think that joew was right. I lowered my jet and it runs over 40 now. There was probably a leak before and now there is not a leak so your jet is too high. what jet do you have now?

Re: More lovely TOMOS problems...

Lance Baresic /

I know my jet is correct since this is the jet I used w/ my stock airbox and custom exhaust. Therefore, a #56 is correct. I also know there aren't any leaks by the carb, airbox, and intake manifold by the reed valve. I'll double check the head and float/needle.

Re: More lovely TOMOS problems...

Lance Baresic /

I checked through my moped yesterday and today and I think my carb is the source of the problem since my electrical is fine and there are no leaks.

Re: More lovely TOMOS problems...

but did you check compression anyway?? i have to check, but i think i might have a tester somewhere in my garage......

Re: More lovely TOMOS problems...

damn.. i dont anymore... sorry lance

Re: More lovely TOMOS problems...

Lance Baresic /

Found the problem guys. All this time it was the damn spark plug. I had a Champion L86C plug but I think I ruined it when I was running a little lean for 2 weeks. Also, with this spark plug, I noticed that it runs best in cold weather and worse in hot weather. So, should I get the same plug or a hotter one? If I run a K&N or no filter, I would need a hotter one right and wich Champion plug would be right?

Re: More lovely TOMOS problems...

i wonder how else a leak between the head and cylinder could be determined.. spray soapy water around the head and look for bubbles? sounds kinda stupid for some reason..

Compression checks also check the rings and main seals and case gaskets.. and if you have a leak somewhere else it might appear to be a head gasket but it's not.

I wonder if there's a head-to-cylinder-specific test you ccan do..

Re: More lovely TOMOS problems...

wow.. such a cheap, easy fix.

my guess is some people use different heat ranges for different weather situations if they are serious about performance.. And other changes, like with the air cleaner, might dictate using some other plug... but i dunno about selecting, other than by doing plug chops and examining it.

Re: More lovely TOMOS problems...

About no fuel going into your motor wile going down hill, if your motor is running you are still getting fuel and oil in the motor, just verry little, but enough oil to keep things going.

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