sezian Posted January 22, 2009 Share Posted January 22, 2009 I'm currently 3/4 of the way through the restoration of a 1981 DT175MX, with powder coated frame, swinging arm etc, new plastics and full s/s nut and bolt replacement. As yet I haven't touched the engine, it was running well when I bought the bike having ridden home approx 20 miles everything seemed fine, however top speed was just over 60 mph with the revs just under the red line. Front sprocket is one tooth up on standard, rear sprocket standard. The exhaust is standard ( in good condition ) with a standard end can, are standard cans restrictive ? I do have an expansion rear pipe that I was give as a spare, is this worth fitting ? I was also told the reeds are carbon as opposed to the standard steel, not checked yet, do these make any difference ? I'm hoping to increase top speed but not expecting miracles, have ordered a new front sprocket 2 teeth up from standard to slightly raise the gearing but need to know what other mods are cost effective that will give a performance increase. The engine was re-bored approx 2000 miles ago with new piston etc, I will remove carbon build up on head and piston crown but want to know if polishing the ports will help ??? Any information, advice or suggestions would be much appreciated. Thanks. Link to comment Share on other sites More sharing options...
Moderator Airhead Posted January 22, 2009 Moderator Share Posted January 22, 2009 Hi sezian, welcome to the forum, I'm gonna tune mine this year too, I've got a ported barrel to fit, a Gianelli expansion pipe, a new Mikuni VM28 round slide carb, boyessen 2 stage reeds, all ready to fit am also on the look out for a spare airbox to modify and fit a K&N filter, got most of the parts but havent started on the work yet. Link to comment Share on other sites More sharing options...
sezian Posted January 22, 2009 Author Share Posted January 22, 2009 I guess what you're planning is a lot bolder than what I have in mind, sounds like it will be a real screamer and will probably reach the dizzy side of 70 mph when you've thrown what sounds like over £500 at it. Are you able to help with any of the questions I've posted. Thanks. Link to comment Share on other sites More sharing options...
Moderator Airhead Posted January 22, 2009 Moderator Share Posted January 22, 2009 I'm currently 3/4 of the way through the restoration of a 1981 DT175MX, with powder coated frame, swinging arm etc, new plastics and full s/s nut and bolt replacement. As yet I haven't touched the engine, it was running well when I bought the bike having ridden home approx 20 miles everything seemed fine, however top speed was just over 60 mph with the revs just under the red line. Front sprocket is one tooth up on standard, rear sprocket standard. The exhaust is standard ( in good condition ) with a standard end can, are standard cans restrictive ? I do have an expansion rear pipe that I was give as a spare, is this worth fitting ? I was also told the reeds are carbon as opposed to the standard steel, not checked yet, do these make any difference ? I'm hoping to increase top speed but not expecting miracles, have ordered a new front sprocket 2 teeth up from standard to slightly raise the gearing but need to know what other mods are cost effective that will give a performance increase. The engine was re-bored approx 2000 miles ago with new piston etc, I will remove carbon build up on head and piston crown but want to know if polishing the ports will help ??? Any information, advice or suggestions would be much appreciated. Thanks. Youre right about the two teeth increase this will give more top speed but its never going to be much faster then a comfortable 65, but anyway these arent a motorway bike as they are far too light and as you sit there in an upright position you present a very big frontage for the wind which doesnt help with top speed., I cant remember how restrictive standard end cans are maybe a little but i do remember that half the total weight of your bike is there in that end can so i siggest you take it off, wrap it up carefully and lose it up the loft somewhere and get yourself something like This After that i would just suggest you strip the carb down and give everything a good clean. as for the reeds, you need to make sure they are not curved and not seating, fibre reeds do have a shelf life and eventually the adopt this curve and wont seat properly., Also have a look at the filter screen in the fuel tap (petcock) just unscrew the bowl and its in there. Thats about it, after youve done all your going to you could try a plug chop test to see if the jetting is right....good luck with it Link to comment Share on other sites More sharing options...
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