OK. I finally got my kid's stock DS50 running more like it ought to. But, now looking for a little bit MORE top end... Here's what I've done so far:

1) removed slug from intake tube.
2) removed SA screen and exhaust end cap. Enlarged exhaust tip output hole.
3) bought new $12 Taiwanese race CDI box and wired it up.

...his 50 runs a LOT quicker now and isn't limited at the top end except for jetting and/or carb size. All for an hour's light work and $12 + shipping!

So, where can I buy larger jets for this carb/ Or should I just increase the carb itself? Any help greatly appreciated. Thanks!

 

Putting larger jets in a properly tuned carb won't make it run faster it will just make it run richer and hurt performance...For more power and speed you could make the engine bigger with a larger piston/cylinder or go with a bigger carb and performance pipe or do all three for really big gains....Try WRH racing or hetricks etc to see what package is good for you.

 

I agree, but the greater amount of fuel/air mixture you can get into (and subsequently out of) an engine, the greater the HP without adding cc's/inches...after all, we're just processing as much compressed air as possible. I can see that opening up intake/altering exhaust capabilities will accomplish that...then maybe shave the head a few thousandths to increase compression is probably the cheapest way to go for me.

The CDI I bought from Scooter-Assassins.com works like a charm- It removed the governor and advanced the spark. The Bomb has more low-end torque and higher top speed. Even the wire coding matched up without guesswork. I found it on Ebay for $12+7 shipping. Definitely the best investment so far.

And thanks for the WRH website---I contacted them regarding a pipe for it.

Mike

 

REmove the front variator restrictor too. It's the wedding band looking thing in between the front clutch halves. Or get a better variator for cheap. You'r bike will need rejetted with the exhaust mod and it will run MUCH better and not run hot. More air requires more fuel. Always. You can get your "Round slotted head mikuni mainjets" at most any cycle shop for $3 . With the exhaust mod you need to go up 2 jet sizes. I cant remember what stock is but it's on the jet itself. The 90s have a 77.5 to 82.5 stock depanding where they are sold. A 70cc kit will help as will a 35 tooth rear sprocket instead of the 50 for topend, or a WRH, Hetrick pipe and clutching to match will make it scream and topout about 40 mph. If you want to run good gas a 70 kit setup with the compression setup right has a lot of torque and topend. The topend is under $150 or so for the whole topend. You can even get a 15-1 setup that runs really good. They more than double the output of the 50s.

 

Wow that's all great information! Thanks a lot. I'll go the "jet" route first, then "variator" route next. I'll do a google search for Hetrick and see what I can come up regarding a pipe, as well. Thanks again!!!

 

I removed the variator ring and yes it made a great difference! Getting the crank nut off of this virgin motor was a little tedious,
but I made a tool to lock the variator while wrenching and it went easily after that. The clutch cover gasket was pretty tight too, but that's expected.

Next/final thing is to jet it up one or two sizes and re-check the plug.

The quad is now just about as fast as it needs to be for my kid until he gets better on it. What a world of difference $12 and some simple
wrenching made!

Thanks for your help!!!!
Mike

 

I read on previous emails that replacing the CDI on a DS50 (2004) with one from a DS90, and also the Main and Pilot Jet from a 90 would increase top speed since the 90 does not have a limiter. So I went to the Bombardier website and looked up the part numbers but the CDi for the 90 says C.D.I Unit (5900RPM) which leads me to believe that it is also lmited, since I would guess it will rev higher than that no? Is it one from an older ds90? I am confused as to what I need to do since I don't want to lose reliability since I have another son inline waiting for that 50.

 

FASTESTDAD, I removed the variator from my daughter's Arctic Cat DVX50 (which made it go faster), but do I need to rejet as well, or can I just leave it at that? You mentioned something about running hot that worries me.

Als, I taked to the Kymco guys at the Motorcycle show here in Toronto last weekend, and the said I should also disconnect the green wire that runs into the CDI box, because it is also a restrictor. Sound familiar?

 

I dont think the bomb has a restricted cdi. I know most of the 90 bombs dont. You'll know if it does cause it will bounce off it and cut out off and on every 1/2 second or so. Bah Bah Bah Bah and not pull. A Kymco is a Kymco not a Bombardier, DRR, Arctic cat there are a few differences in the bikes. Yes look at your spark plug if it's light tan or grey rejet it up 1 or 2 sizes and try that. If it's a nice rootbeer brown then it's OK. Darker than that and it's too rich and needs jetted down. As for using a pilot and mainjet from a 90 cause it's not restricted thats not right at all. Glad it's running well for you.

 

My son's DS50 sputters at high rpms it does not cut off. I was told by Bomabardier that was normal because of the CDI limiter. I ordered a non-restricted one from Scooter assasins, we'll see when it arrives. I wonder if I have another issue in addition to the cdi, so much for the mechanics at the Bombardier dealer.