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1984 DT50MX Filter Problem


Chrisa112
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Ive Just fitted a ''power cone filter'' from wemoto ( for my specific bike ) as Ive herd it can increase acceleration and overall power ( albeit not much ).

After fitting the filter i started the bike and a LOT of white smoke was being put out of the exhaust - presumably from the mixture having to much air in it ( correct me if im wrong there :P ) After riding around for a short time the smoke became less but was still putting out more than usual.

Basically Im asking if anyone else has had this problem and what they did to fix it!! I dont have a very good manual for my bike so im hoping i can get some more in depth knowledge!!

Thanks,

<>Chris

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The best thing in the first instance would be to get on to wemoto and ask them if any jetting changes will be required.

The free flow filter will be exactly that, BUT with std ports and pipe there really isnt all that much extra you can get in.

(Dull techy part)

The extra power that you get will be at the higher end of the rpm, the smoke will be from there being extra air in the system but more importantly the air will be moving faster and be at a relatively higher pressure compared to the original filter. This means that less fuel will be drawn out of the carb. That will mean some carb tweaks to increace the fuel flow, but here is the killer as far as swaping filters goes. You now have more air so you add more fuel, great. That means a bigger charge in the cyl, again great. Then you try and get rid of it down the std exhaust. Oh poop. Now the engine will choke its self and the cyl wont be able to scavenge properly so you get less fuel in unless you are keeping the revs on to force the cyl clear so your extra power comes only at high rpm.

Admittadly this sounds a lot more dramatic than the effect you will feel on the bike.

Dull techy bit finished with.

If they cannot help then you will have to go old school with a plug chop to see whats going on but don't whatever you do don't turn down the oil pump, it will stop the smoke but your engine will die as surely as taking it out and dropping it down a well.

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I reckon the filter was oiled before you got it and your smoke was the excess oiol from the filter getting sucked into the engine, but all the same jetting is the key to getting a bike right after any intake/exhaust changes, free flow filter = more air =less fuel which can lead to overheating and seizure, a plug chop will help to tell you what is going on , basically run the bike until it is hot then take it for a blast to top speed on a flat road and cut the engine immediately after shutting off the throttle, leave it too cool, remove plug look at colour white = weak, mix chocolate brown= about, right black= rich.

and then you can start changing jets too suit jets are notexpensive especially compared to engines, a good idea is too find a piece of road where you can coast into a layby once you have cut the engine

Merv

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Cheers guys - i went down to my local Yamaha Garage and discussed the problem with them too and they said about running the bike full blast then turning it off etcc. I havnt done it yet as i think the that the piston started to seize in the engine !! as when i throttled it the power just died and the turned back on like the piston was sticking - this problem was mostly happened when i had had the bike running and was starting it hot!

So i also tried replacing the jet to a 95 (from an 88) but it made no noticeable difference and the seizing problems still occurred! so in the end i have gone back to using an 88 jet and using the air box on the bike. but i still ahve the smoking problem !!!!! :angry:

I think i should have just not bothered !!

Although i did notice that (when changing the jets) that there was quite a bit of rust in the bottom of the carb ( which i know is very bad ) and it also had tarnished sections ( black colour ) which could not be removed by carb cleaner. I have had this problem before but could not decide whether it was the air filter or rust from the petrol tank ( as i have run the fuel straight out of the tank and it sometimes comes out brown for the first few squirts).

I just cant decide whether i should get a new petrol tank or carb or just sell the bike!!

hope some can help and thanks,

<>Chris

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Sounds like you have more than one problem there, if the cyl is worn out all the tuning in the world will do nothing more than kill it sooner.

I think the best thing for your bike would be a big blob of tlc, sounds like a top end rebuild is on the cards if it is reg siezing, and the main jet being partially blocked with carp from the tank will just as surely kill the motor, people dont realise that you will only gain from tuning if everything is running at its best.

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It had crossed my mind that i may need to re-build the engine which to be honest i don't have the time to do and i dont really want to.

I had a look at the carb today and realised that the screw holding the carb onto the inlet manifold want fully tightened so i tightened it up and then looked at the clamp that the screws goes into and realised that it had half snapped off the body of the carb :angry: so i ahd to order a new TK carb from Yamaha Which may take 6 weeks to arrive :@. although its also good as the old carb had black bits in and rust at the bottom of it! Although that could have bee nfrom the tank ( ihave just a bought a fuel filter for it :D )

pshh overall, this bike is more trouble than its worth - Im 16 and i just want to ride around and get experience !!

Thanks,

<>Chris

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Chris the bike is a fair bit older than you and probably hasnt been looked after properly

I know, and now its taking it out on me :( but i still like it because of how easy it is to get to things on it - to work on it. Also ive learnt alot about how it works from just looking at the parts and looking at diagrams in my manual!!

<>Chris

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I know, and now its taking it out on me :( but i still like it because of how easy it is to get to things on it - to work on it. Also ive learnt alot about how it works from just looking at the parts and looking at diagrams in my manual!!

<>Chris

Chris i think that is called experience.......I recon that every person on here that gives usefull advice has more than likely been through exactly the same exp you have. Its how we learn and twirling spanners on YOUR OWN bike connects you with it and is generally very rewarding.

If it makes you feel any better with your woes, i have had to sort a puncture(on an 800 mile old tyre <_< ) a siezed rear caliper :blink: and now the clutch cable has gone :angry: all this weekend so i know how you are feeling.

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Chris i think that is called experience.......I recon that every person on here that gives usefull advice has more than likely been through exactly the same exp you have. Its how we learn and twirling spanners on YOUR OWN bike connects you with it and is generally very rewarding.

If it makes you feel any better with your woes, i have had to sort a puncture(on an 800 mile old tyre <_< ) a siezed rear caliper :blink: and now the clutch cable has gone :angry: all this weekend so i know how you are feeling.

Haha ooo the tire sounds particularly good fun :blink: i know how you feel about the clutch cable though - mine has been stretching for ever now and its finally about to give up working - but hey it dosnt matter as i cant even ride my bike now :D

Cheers,

<>Chris

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