Markyboy27

..I experience the same issue, which can be frustrating. I find it harder to find neutral on the down-shift, but easier on the upshift from 1st gear. I'm also about to change the engine oil which may help. Rocking the bike back 7 forward whilst looking for the neutral gear can also help on occasion. Mark.

..hopefully this time I won't be hunting for an extra 10 mph or the ability to overtake jogging pedestrians & agricultural vehicles !!

..ha ha, glad you enjoyed it. I wrote a similar series about my mission to upgrade my wife to a younger model with less mileage and a more aesthetically pleasing appeal but unfortunately the overall costs were prohibitive, although performance gain in all area's (other than my own) was fantastic !

..i'd consider a dragstar 125 if you agree with the following statements: 1). You're happy with a maximum speed (flat, medium wind) of 60mph. 2). You're not too bothered about acceleration (or ability to over-take) and are content with cruising. 3). You're willing to view the bike and it's abilities within its intended area of expertise (i.e. 125 learner-legal, but still being the absolute best-looking 125 available). I've modded mine to the max and am more than happy with what i now get from the 125, but saying that i'm on a long-term plan to move up through the dragstar range to it's big brothers (and I mean big). Regards, Mark.

...did the plug-chop test and the electrode was light grey, so running lean. This made me assume the K&N filter was sucking more air so went up again to the 100 jet this morning and took a road trip down my usual test route. Performance was up a tad, mainly visible on the long 2 mile up-hill (as i made 60 almost all the way up). Plug chop was darker so that seemed about right. Came home and upper the front sprocket to 18 teeth (16 being standard, and 17 being what i'd been running) and took it out again... Progress was made ! Gear shifting is now later in each gear, which has benefitted in the respect that it puts the bike in it's 4th gear power-band during up-hills... which before was difficult as it either screamed in 4th or bogged in 5th. Top speed is pushing 77 and long up-hills are still about 60 but the benfit is in the lower gears. I'm about fed up now, so will leave it at that. The modifications list is now as follows: 1). In-line fuel valve removed 2). 18 tooth front sprocket (16 is standard) 3). 100 Jet fitted (90 is standard) 4). EMGO K&N-copy sports airfilter fitted The performance characteristics have changed as follows: 1). Top speed upped from 64 to 74mph (78 with now wind) 2). Legal cruising speed (60) now at half revs instead of high revs 3). Up-hill speed upped from 45 to 60mph. 4). Acceleration improved in all gears up to and including 4th. Total cost of bits? No more than £30 (no labour costs as did them myself). Given what i know know about the 125cc Dragstar i'd say the program is now at and end and i'll either sell it modified, or return it to standard (depending on buyer requirements). Found an '03 Dragstar 250 at a local dealer who says he'll swop with no additional cash so that's where I am ! I've enjoyed the experience and look forward to passing the mint machine onto a lucky learner who will enjoy it as much as I have. Mark.

..not bad, it doesn't struggle as much now (seems to be breathing better) and 65mph in top gear is now at about half rev's, and will (eventually) climb up when pushed to 75. It seems the K&N filter with bigger jet has made up for the 1-tooth bigger sprocket, thus eliminating the slight increase in drag caused by the bigger sprocket. So, my experimentation continues: I'd say if i now fit the new 18 tooth sprocket (one more tooth from the 17 now fitted) married with the bigger 100 Jet (the 95 now being fitted) these may also work well together, so i'd say that 80mph on the flat / downhill would be a realistic possibility but ultimately the opportunity for more power will be unlikely as 125cc is 125cc is 125cc !! There is one more option (which I won't be trying) which is to remove the air-box expansion chamber that is hidden under the tank. This seems to be a large volume black plastic affair that allows the filtered air from the actual air-filter to collect before being drawn into the actual carb itself. The K&N copy filter could possibly go directly onto the neck of the carb, thus eliminating the entire air-box and secondary post-filter air-box, resulting in the shoprtest possible distance for the air to get to the carb once filtered (a matter of a couple of inches). This seems a bit radical for me, and too far to go once you remember that it is a Dragstar after all ! Here endeth the lesson.

..new jets arrived next day and went back together fine other than the fiddly reconnection of the speedo cable to the dial (cable doesn't have a lot of slack). Bike takes a few minutes on turn-over for the juice to fill the carb again so make sure the petrol tap is set to 'Prime' (or horizontal) which will fill it quicker. I'm off now to give it a go ! Mark.

..yes my friend, i enjoy our banter and I bow to your substantial knowledge & experience !! ) Lovely DT by the way, concourse ?

...Jetting now a subject i understand, thanks to some excellent advice from some Yam biker mates and a very helpful Mikuni dealer called Steve (MC Motocarb, 0151 238 4170). Standard Jet is a 90, and increments of 5 were recommended so i've ordered a 95 & a 100 jet to play with. The carb is a Mikuni BDS26 and is well known to the guys at Motocarb. They have the full range of Jets and sent me a very good list of jets (with pictures & part numbers) in a Word Doc attachment but i had to whip the standard jet out to compare it the list. The jet size is stamped on it's head, and the stock jet style is described as 'Small Round' with a part number of 004-281. It's impossible to read the size stamped on it with the naked eye, i needed to borrow a magnifying glass to read it. Steve recommended going up in increments of 5, chopping the plug during testing to check the reaction to the richer mixture. The part number for the 95 jet is 004-283, and the 100 jet is 004-285. Chopping the plug is the only way to check if the mixture is right, which is done by going flat out in any gear when the engine is hot, then pulling in the clutch and killing the engine with the cut-out switch simultaneously. If you can do this on the approach to your garage then you can roll it in with the clutch in and whip the plugs out to check the colour. Apparently a good plug colour should be grey, a lean mixture results in a white colour, and a black wet colour is too rich. Getting the jet out wasn't too bad if you're ok with stripping your bike, as it necessitates the removal of the seat(s). take, air-box & secondary air-box (bolted to the frame under the tank. Fortunately the Mikuni carb is perfectly positioned on it's side already, so you can fairly easily get to the 4 screws that need removing in order to remove the float bowl. Beware that petrol will piss everywhere hen you release the bowl. Note: only 3 are cross-head screws, one of them is an Allen screw so don't strip it tring to remove with a phillips driver. The jet is removed using a slot screwdriver and not a hex socket. I'll let you know what happens when the new jet(s) arrive ! I love all this shit, it beats the pants off working for a Global I.T.Corporation !! Mark.

...sound words, all very true. Trouble is i'm a fiddler and get as much enjoyment out of messing with them as riding them ! All mods & changes are bolt-on's, and will all come off (reverting to standard) when i buy the 250. All of this was supposed to simply lower the Rev's in top at cruising speed, which I seem to have accomplished, but with the bigger front sprocket fitted it's dipped in power slightly, hence the filter mod to get it back. Thanks for the comments though, always like a bit of banter.

..ok, here's the deal. An eBay EMGO 48mm air filter (K&N copy) will cost about £8, although on 1st inspection it doesn't look like it'll fit in the airbox. Here's how it will: remove the rubber boot from the neck of the EMGO filter, just leaving the chrome filter itself. This will then drop into the airbox recess with about a 1mm clearance (rattly) You'll notice then that the Airbox chrome shield cover will not now fit (the airfilter is about 15mm too long) so a few changes are needed: 1). As the chrome filter is a loose fit into the airbox recess it needs about 4/5 wraps of electricians tape around the circumference of the chrome housing (play about with the amount of layers until it pushes in nice & tight). 2). remove the decorative hex bolt fron the centre of the chrome cover (doesn't do anything other than look nice), which saves about 6mm. 3). Take hold of the filter and snip the solid tin support post that runs along the length of the filter and helps the filter keep it's shape. Bend the end of the post over (don't rip it out as you'll tear the mesh) so there's a 1cm gap between the post and the filter's chrome end cap. 4). Holding both ends of the filter firmly, twist the filter to 'squish' the shape, which will by default reduce it's length. This should mean that if you compress the filter between the palms of your hands it will shrink in length without any major damage to the structure of the filter mesh (the mesh folds simply curve to make the new shape). 5). Having fitted the filter tightly into the recess you can now fit the airfilter shield-shaped cover by securing it with the 5 hex screws. This will 'squish' the filter until the housing is secured correctly, ensuring the filter is pushed home into the housing recess making a good seal. 6). Now you need to re-jet the bike to ensure it doesn't run too lean. I spoke to our local shop and they said they'd re-jet it for about an hours labour plus the cost of the jet, which seemed reasonable to me. I fitted the filter this morning and will run it over for re-jetting tomorrow so will let you know how it goes. Total cost of this mod ? £50 re-jetting labour Cost of jet (?) £8 filter probably about £65 total. Mark.

Hi Brainstorm, did you eventually follow this up & fit a filter ? If so then i'd be interested in how it went. I've just bought one on eBay for £5.50 (eBay number 150291281345) and it looks as though it might fit behind the chrome air-filter cover. There's a 2cm recess into the actual boot, and a further 4cm of room between the inside of the chrome cover and the start of the inner boot, so 6cm available for the filter to sit within. There's no dimensions on the eBay item so i'm taking a gamble on this to be honest, but it seems like a low dollar risk for what could be a useful increase in HP. I've no idea about re-jetting but am prepared to give it a go myself when i find out how it's done. Cheers, Mark.

..just took another run with the 1-tooth bigger sprocket on and am pleased to say the reduction in power is negligible, but the improvement in MPH is just what i was looking for. Before i was changing up into top at 55mph, and screaming at 70. Now I change up to 4th at 55, and into top at 65which means by the time i'm up to 70 it's inthe mid-rev range. I checked again on a long uphill and I still gain, as before on the same hill i was capped at 45/50, whereas now i'm at 55 and creeping up (depending on incline). So, having discounted the petrol tank breather valve mod as ineffective i'd say I now need to look at the 48mm air filter & re-jet mod for more horses to overcome the slight power loss attributable to the bigger sprocket, and if I find more horses I can then try the 2-teeth bigger sprocket... scary !!

..wow, just test-riden it with a 1-tooth larger front sprocket fitted... did the trick perfectly ! Now i get 30 out of Second gear, 45 out of 3rd, 60 out of 4th, and... not enough power to test 5th to the max ! So as I thought, a single additional tooth on the front gives you an extra 10mph on the top end of the range but only if you can get up there. This is fine for my purposes as it's mostly flat where i comute so cruising at 60 without ringing the nuts off the engine is fine. I did buy 2 sprockets (the second beng 2 teeth bigger) but i'm reluctant to fit the bigger one as the cost will probably severely outweigh the benefit (unless i can find a continuous downhill route on a fine day with no wind !!).

..wow, just test-riden it with a 1-tooth larger front sprocket fitted... did the trick perfectly ! Now i get 30 out of Second gear, 45 out of 3rd, 60 out of 4th, and... not enough power to test 5th to the max ! So as I thought, a single additional tooth on the front gives you an extra 10mph on the top end of the range but only if you can get up there. This is fine for my purposes as it's mostly flat where i comute so cruising at 60 without ringing the nuts off the engine is fine. I did buy 2 sprockets (the second beng 2 teeth bigger) but i'm reluctant to fit the bigger one as the cost will probably severely outweigh the benefit (unless i can find a continuous downhill route on a fine day with no wind !!).