pictureman36
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- Jun 7, 2011
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Hello... I ran an MT5 in 1984. Standard it did 33 mph, and was gutless. I worked at a bodyshop, and one of the guys there filleted the front pipe (ground the welded seam off) and we took some of the restrictors out. Inside the front pipe there is something that looks like a funnel with holes in it. We made them bigger, but remember you need to retain some back pressure. You will also need a competant welder to weld it back up. This added 7 mph straight away. I left the carb alone, but bought an aftermarket tail pipe 2nd hand from a mate for £15. It was a Jamma, and added another 4-5mph. On a good day, I could do 45 mph.
The same mate had an MT5 and he bought the big bore kit. Not sure whether it was an 80 kit BUT he could get 55-60 mph out of his. He ended up knocking the bottom end out after 6 months, just before his 17th birthday, so he didn't bother rebuilding it; he just flogged it on.
You will find it hard to get parts for an MT5 now; when I had one our local bike shop could get any bit you wanted. There was a Ginelli font and tail pipe which also destricted it a bit. Most of the restriction is done through the carb (we went on holiday to Corfu in 1987 and we hired an MT5 while we were there, and we got 50 mph out of it 2 up!) The US/EU model has a bigger carb.
You can fit the H100 engine, no problem, but as you point out, it then become an MT10! or MT100, and you'd have to fit the poxy H100 exhaust which ruins the styling!
If you know someone who is good with a MIG welder, I'd be tempted to go down the 'derestrict the front pipe' route, and I'd look for an aftermarket tail pipe. I'd leave the jetting alone, unless you plan to fit the big bore kit. If you do, you will most definately affect the longevity of the engine, as they weren't as bullet proof as the Yamaha equivilents.. Good Luck!
The same mate had an MT5 and he bought the big bore kit. Not sure whether it was an 80 kit BUT he could get 55-60 mph out of his. He ended up knocking the bottom end out after 6 months, just before his 17th birthday, so he didn't bother rebuilding it; he just flogged it on.
You will find it hard to get parts for an MT5 now; when I had one our local bike shop could get any bit you wanted. There was a Ginelli font and tail pipe which also destricted it a bit. Most of the restriction is done through the carb (we went on holiday to Corfu in 1987 and we hired an MT5 while we were there, and we got 50 mph out of it 2 up!) The US/EU model has a bigger carb.
You can fit the H100 engine, no problem, but as you point out, it then become an MT10! or MT100, and you'd have to fit the poxy H100 exhaust which ruins the styling!
If you know someone who is good with a MIG welder, I'd be tempted to go down the 'derestrict the front pipe' route, and I'd look for an aftermarket tail pipe. I'd leave the jetting alone, unless you plan to fit the big bore kit. If you do, you will most definately affect the longevity of the engine, as they weren't as bullet proof as the Yamaha equivilents.. Good Luck!
