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xvs 125 you can get a bit more poke

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I'm just wondering why anyone'd want to fiddle with a 125, especially one that weighs 144kg!!

The whole point is that they're supposed to be slow - Nice, slow and safe for all the L-Platers.

If you have the option to ride something bigger, get a 250 or a 400.

The weight is not going to be that much higher and the performance will be much more suited to what you want.

Bear in mind that, if you're still learning, the 125 will get you into the habit of using observation and timing your manoeuvres, rather than relying on power - A very valuable skill for if/when you get something bigger.

For this reason alone, I loved my 125 Drag and could out-ride plenty of smaller, faster, higher CC-engined bikes in and around town!!

Remember, it's not about how fast you ride, it's about how well you ride!!

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I'm just wondering why anyone'd want to fiddle with a 125, especially one that weighs 144kg!!

The whole point is that they're supposed to be slow - Nice, slow and safe for all the L-Platers.

If you have the option to ride something bigger, get a 250 or a 400.

The weight is not going to be that much higher and the performance will be much more suited to what you want.

Bear in mind that, if you're still learning, the 125 will get you into the habit of using observation and timing your manoeuvres, rather than relying on power - A very valuable skill for if/when you get something bigger.

For this reason alone, I loved my 125 Drag and could out-ride plenty of smaller, faster, higher CC-engined bikes in and around town!!

Remember, it's not about how fast you ride, it's about how well you ride!!

...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.

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'S fair, I suppose.

So long as you don't make it dangerous to ride.

I'm a fiddler too, though I tend towards the functionality rather than looks or performance.

My bike performs well enough, so I focus on other stuff - Heated grips, SatNav, CB radio and whatever else makes it fun to ride on.

I'm making my own saddlebags at the minute!!

I like things that do stuff!!

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'S fair, I suppose.

So long as you don't make it dangerous to ride.

I'm a fiddler too, though I tend towards the functionality rather than looks or performance.

My bike performs well enough, so I focus on other stuff - Heated grips, SatNav, CB radio and whatever else makes it fun to ride on.

I'm making my own saddlebags at the minute!!

I like things that do stuff!!

...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.

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...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.

I'll count myself in as one of your Yam biker mates then eh! :)

Yep, more likely to find "more horses" (or part of a horse) this way :thumb: If you put on a less restrictive filter on, dont go mad with the re jet (Not too big a jump) though, then plug chop to see if its about right!

Glad youre enjoying it so much, youre learning fast Marky :thumb:

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I'll count myself in as one of your Yam biker mates then eh! :)

Glad youre enjoying it so much, youre learning fast Marky :thumb:

..yes my friend, i enjoy our banter and I bow to your substantial knowledge & experience !! :o)

Lovely DT by the way, concourse ?

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..yes my friend, i enjoy our banter and I bow to your substantial knowledge & experience !! :o)

Lovely DT by the way, concourse ?

I prefer bikes that are or have been used to ones that are only shown and never ridden, Having said that I still like to see them looked after and in good nick... :rolleyes:

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...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.

..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.

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..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.

..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.

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..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 !!

By all means try yes, but when the weather clears up a bit, The plug chop test is the thing to do, you may already be right with the 95 jet, Getting the right jet is more to do with the air filter change, and really nothing to do with the sprocket change.

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...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.

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Nice one Mark , I enjojed every thrilling installment, each one was like waiting for next months copy of classic motorcycle mechanics to drop on the mat! :thumb::D

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..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 !

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..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 !

Yep, Thats like a learner on a V max!!

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.

So...Will the 250 be getting the same treatment then? Smart money's on yes

naughty.gif

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Yep, Thats like a learner on a V max!!

So...Will the 250 be getting the same treatment then? Smart money's on yes

naughty.gif

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

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fascinating guys, i have enjoyed reading about this, as my bike utilises the same engine as an xvs it seems that you guys have really delved in to this. comparison wise i presume the "plastic thingie" valve has something to do with the prime function on the fuel cock, reading the manuals(owners manuals,of which i have both) not only are the positions opposite on my bike but the prime switch is replaced with a straight forward on/ off/ res gravity fed system on my bike. i have already gone down the rear sprocket route and have seen a gain in overall acceleration but adrop in top end speed and have to change up to 5th at 55mph where there seems to be no guts left and struggles to reach 60. as for the filter change the arrangement is somewhat different where there is no visible air filter housing as on the xvs it is located under the massive 20 litre petrol tank which i will be removing today to have a closer peak. i have noticed that some other threads refer to removing the baffles but can't seem to get my head round how they could be removed? i also notice there does not seem to be a mixture screw on the carb.

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...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.

F@!KIN' BRILLIANT!!!!

I've been in hospital after a heart attack and this is the first chance I've had to get back on the site. Great job, big pat on the back!! I've enjoyed reading about all of your ideas and will have a go as soon as I'm able. I knew some one out there would come up with the goods eventually. So I apolloguise if I bugged any one earlier on, but hey it was worth it!!

All the best OGRi

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im interested in doing the same to my virago 125, but just been looking into it and front sprocket has 13 teeth standard and wemoto dont stock anything but standard at the moment? am i looking at the wrong thing?

also with the new jet is it just a case of fitting the bigger one or does it need to be re mapped or jetted by pros?

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im interested in doing the same to my virago 125, but just been looking into it and front sprocket has 13 teeth standard and wemoto dont stock anything but standard at the moment? am i looking at the wrong thing?

also with the new jet is it just a case of fitting the bigger one or does it need to be re mapped or jetted by pros?

ok, just noticed you got xvs i got xv 125! so will getting a 2 teeth less rear sprocket will do the same job? and i guess this means i will need a different jet to xvs also? any ideas as it doesnt say about jet in my manual? shall i give those chaps at motocarb a ring?

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