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Discussion Starter #1
Hi.
I have bought an FMX.
Currently I have more important problems solve with it, but in future I would like to at least upgrade exhaust + carb jet + air filter.
I have done exhaust manual rework for my suzuki gs500 in past. I just cut off old can and welded new straight can onto it. Also removed catalytic converter. So I should be capable to do similar mod on this FMX.
I have checked exhausts on ebay, but they are around 900 GBP for mufflers + headers. Very expensive. Half the bike price. ;(
Is the original head just a straight pipe, so I could only modify (or maybe buy) cans / mufflers? Or does header pipes have any catalytic converters or other blockage in them?
Also, if headers are straight or I cut out any blockages from them, are they wide enough as they are originally, or are aftermarket header pipes bigger? (Because if they are too tight I may have to buy headers then anyway even if there are no block in them.)

Thanks :cheers:
 

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Discussion Starter #3
Is aftermarket (like arrow, or else) header pipes bigger in diameter than originals? Or are they same as originals with removed catalytic converter?
 

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Is aftermarket (like arrow, or else) header pipes bigger in diameter than originals? Or are they same as originals with removed catalytic converter?
Best check to see if distributor puts that info out or contact the maker for specs - though they'd still need to be the same size as OEM at the header manifold.... header / link could differ if it's designed to be used in conjunction with aftermarket link pipes and cans.
 

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Discussion Starter #5
I was hoping that someone in this forum has bought aftermarket straight exhaust system including header pipes and could easily tell.

To explain the situation: I would like to get few extra KW from the bike, but I don't really want spending 900 on it. So I could try to trash the catalytic converter and make mufflers straight. BUT if performance header pipes are bigger diameter, then it would make sense to buy them instead of only taking out catalytic and leaving diameter the same. Because I hope that performance exhaust is calculated to give better performance.
 

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FMX is 37 horsies as standard - are you aiming for top end or mid to low range improvements? Do you plan some dyno runs to get the fueling right? As tuning it will cost to get right unless you wing it.

For more horsies and speed you can get for instance a Transalp 650 that has 55 donkies straight out the box...
 

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Discussion Starter #7
I plan to make/buy straight pipes;
buy dynojet kit, to insert corrent more aggressive main jet ( i think I don't really need the dynojet, maybe just any brand but different sized main jets kit);
high flow air filter to fit bigger jet and exhaust.

Don't want to dive too deep and spend lo
 

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What do you use the bike for?

If it’s something like city use and you don’t need the top end speed, you could make it a lot more fun with gearing options.

Tuning can take forever to get right but gearing gives an instant hit. I bounce from one to another every now and then and it completely changes the bike. I tend to go back to low revs thump thump thump sooner rather than later though.
 

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Discussion Starter #9
Yeah, I'm considering sprockets too. I plan to have 2 sets of wheels: supermoto and dominator (if they fit) for offroad. Then I could have different sprockets on yhose wheels suiting different drive conditions. :///

By the way. I have removed my mufflers and inspected header pipes through open holes. I still don't know whether performance exhaust headers would have bigger diameter to enhance performance, but I am sure now that there are no catalytic converters in fmx exhaust. Because I tried to put a wire as far as I could into header pipe, and there is nothing blocking the pipe. I thought there would be something in those thuicker parts of headers, but they are just thicker because there is some white metal mesh pipe, with many holes in it, but it doesn't narrow down the header pipe overall.
 

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Discussion Starter #10
So to let everyone know, I finally got the V5 document for the bike. I was waiting for good 4 months... Now I registered it, did MOT, insurance, it's legal now. Changed oil, will pick up new tyres today. Front fork started peeing, ordered new seal and oil kit, will change them soon. Finally I can start riding it. Even tho it's winter now and temperatures are at 0 or below 0 celsius. :thumbup:
I consulted some friends, who are bikers / professional at repairing bikes. They said that I shouldn't expect too much of an improvement from a dynojet kit. But when reading forums, people say that even straight pipes give it more power feeling. Has anyone experience with this slight tuning of this engine?:thumbup:
 
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