<div class="FTQUOTE"><begin quote>Originally posted by: Quadsport_Scotty

Thanks for the compliments guys...once in a while I do get lucky in life, lol. I haven't had it out much yet, but from the few short rides I have had, I think that this thing will be a good project, and could possibly be made to kick some butt. I'm liking the idea of keeping the internals stock as long as i can, so before I ride it anymore, I'm going to go over it with a fine tooth comb and check and re-check all the specs and clearances - I'd hate to grenade it because I was too anxious to get out on it. Since I have a back injury at present, I won't be doing much riding for the next couple of months and am going to do a total tear down of the machine for restoration and mod purposes, so I have a few more questions guys...



1 - I'm surprised at the small (?) size of the carb, and figured that a 250 thumper would have had something more like a 36 or 38mm on it...why so small, and would I gain any performance or just tuning headaches going to something bigger?



2- should I think about a power jet kit for it?



3- i don't like the stock handlebars and want to swap them out for a set of Renthals, but they don't make them for my machine, which is no big deal...I can just make a custom riser for them. Do you guys like the Renthals or do you have a better suggestion for a good all-purpose bar, keeping in mind that i don't want to go oversize bars...



4- the headlight is just plain ugly! Any slick or cool ideas for a new one?



...and this just occurred to me - should all these issues be discussed here or in separate forums...don't want to tick anyone off....



Thanks, and talk to you soon</end quote></div>

36-38 is really big I think. The guys in the 230 forum have talked quite a bit of carb stuff. I don't know much about carbs.

The previous owner of my 230 put on some Moose bars on mine and they're nice. I wouldn't be able to gauge it based on the stock ones though since I've never used the stock ones. It is frustrating how most bars are over-sized these days.

I've been trying to come up with something to do with my light too. Its hard to just put a new, different one on because of the wattage restriction. My thought lately has been to maybe try and just hide it under the plastic somehow. Not sure yet though. They look good w/o lights, but I ride at night a lot.

I did put an LED taillight on mine that saved me an extra watt and a half. Plus it looks sweet.

And you can discuss wherever you like! You can find a lot of answers in the big 230 thread though if you want to check that out.

 

You won't grenade it unless you have a stage 2 or more cam. It just won't rev high enough in my opinion. I used to wind my 230 out and fan the clutch to shift gears. I'd have it pegged at top rpm (or at least what I thought was the top) and then pull the clutch to see how much it had left. It would go quite a bit. The real reason you shouldn't worry is the 1mm larger wrist pin and the 4-5mm longer rod as opposed to the 230. So, if the 230's don't grenade, you'll have a super hard time doing it to the 250.

1) You might be thinking of 2-strokes with those carb sizes. There is no way a 36 or 38 will work on this engine. You might get away with a 32mm with the stock airbox, but if you want to run a super low restriction filter, 28mm is about as big as you can go. This engine just can't suck enough air to maintain any kind of velocity thru a carb that is bigger than 28-30mm or so. If you want something tried n true, get the TM28 from mikuni. I guess there also exists a TM28 with an accelerator pump. It came on some stock bikes, but I forgot which ones. Another issue that limits carb size is the stroke length of 67mm. That's monster for a small engine like this. Its just not designed to rev out more than, say, 9000 or so. Whereas a short-stroked 250x or mojave can go much higher since the stroke is in the 50's. They also have 4-valve heads and could benefit from a larger carb.

2) Only if you install a super low restriction air filter. Not just a kn, but a BIG kn and no airbox. Then you might benefit from some sort of supplemental fuel injection. I run a dial-a-jet and I'm thinking of getting the power jet from thunder products in addition. I'm running a HUGE KN filter with the TM28 and the main jet is drilled to about the size of the needle-jet, lol. And I still need more gas even with the dial-a-jet. So, I couldn't imagine the number of power jets I'd need with a bigger carb.

3) I don't know much about handlebars. I know I didn't like the stock ones either, but I got used to them and it doesn't seem to be a big deal anymore. I'll get to it one day. [img]i/expressions/face-icon-small-happy.gif[/img] I think the stock handlebars are too wide. When I lean in a turn, my hand is waaaay too far to the outside.

4) Check out Malhombre's pics. I think he has a led light tucked under the front louvres.

These forums are about as outlaw as you'll find on the internet. There are a few rules, but basically anything goes from what I can tell. A lot of the guys that post on the big 230 thread would probably rather you post there so we can make the thread super huge, but then again, if you post here then someone can easily find the info by searching. It will get lost in the big thread. Me? I don't care. I'm subscribed to both threads.

 

You're absolutely right about me thinking of 2 strokes, Randy. All of my dirtbike and atv experience has involved 2 strokes, so 4 stroke tuning and concepts are new to me. I have great knowledge of car engines, and would assume (hate that word) that the 4 stroke in my quad should work similar? Thanks for the insight into the carb and jetting - perhaps I'll just leave well enough alone, as I always preach if it ain't broke don't fix it. But the freak in me just has to tweak something or other - the word "stock" sends shivers down my spine, lol.

Hey, atvman, where did you dig up that LED tail light...that'd be killer!

 

<div class="FTQUOTE"><begin quote>Originally posted by: Quadsport_Scotty


Hey, atvman, where did you dig up that LED tail light...that'd be killer!</end quote></div>

Its actually a trailer LED light. [img]i/expressions/face-icon-small-happy.gif[/img] You could probably find it at a Northern Tool or something.

 

Cool...by the way, what are the wattage restrictions for these bikes?

p.s.....gonna head over to the 230 forum from now on i think. thanks

 

<div class="FTQUOTE"><begin quote>Originally posted by: Quadsport_Scotty

You're absolutely right about me thinking of 2 strokes, Randy. All of my dirtbike and atv experience has involved 2 strokes, so 4 stroke tuning and concepts are new to me. I have great knowledge of car engines, and would assume (hate that word) that the 4 stroke in my quad should work similar? Thanks for the insight into the carb and jetting - perhaps I'll just leave well enough alone, as I always preach if it ain't broke don't fix it. But the freak in me just has to tweak something or other - the word "stock" sends shivers down my spine, lol.



Hey, atvman, where did you dig up that LED tail light...that'd be killer!</end quote></div>

2 strokes have an intake stroke every cycle of the crank, whereas a 4 stroke has an intake stroke every other cycle. So, you'd figure a 4 stroke would need about half the carb size of a 2 stroke, but in practice it doesn't quite work out to be half.

If you just have to do something so its not stock, pick up a TM28 and a 5L1 needle. Do you have wire-gauge drill bits? If not, get a set of those and a few main jets to drill on while tuning the carb. Also, scrap the airbox lid and slap in a kn or whatever filter. KN flows the best, but its made of paper so it might be damaged the first few times you clean it.

If you're tearing it down anyway, maybe you'll want to port it. Here is a good read on the subject: http://mototuneusa.com/thanx.htm You'll probably spend a couple days taking it all in.

Oh, I forgot all about the exhaust end of it. [img]i/expressions/face-icon-small-blush.gif[/img] There should be drain bolts on the bottom of the muffler. Just take those out and you should gain a fair amount of power. Before I made my own muffler, I even drilled more holes under there. The more I drilled, the more power I got.

Like I said, I made my own muffler, so I don't know much about the limited selection of aftermarket ones except what I've read online. And that is they are loud. Who knows if there is a power increase or not. I think atvman is happy with his muffler that he made to work from another quad application. I forgot the details, but maybe he take the time to share once again. [img]i/expressions/face-icon-small-happy.gif[/img]

Cars are somewhat similar in that they are both 4 strokes, but atv engines don't have distributors, adjustable ignition timing, or anything like that. The sparkplug fires every TDC instead of only on the compression stroke like most cars. The 250 also doesn't have multicylinders, so no need to worry about intake plenum design or complicated exhaust headers. Other than that, much of it is exactly the same as your run-of-the-mill toyota with single overhead cam, 2-valve head, and rockers.

 

Thanks for the tips about the carb...definitely going to look into that at the very least, along with the other airbox and exhaust mods you mentioned. It's somewhat mild out today where I live (about 40 degrees in the sun), so I may go out to the garage and get a head start on disassembly. Better make sure the camera has fresh batteries first, lol. I'll check in later...

oh, and since I'm off work for at least another 3 weeks or so, I'll have time to check out that porting article you sent the link for as well...love getting the dremel out for just such things!!

 

40 all the way up in Canada? Wow, its only 52 here in GA. Figured you'd be buried in snow. [img]i/expressions/face-icon-small-happy.gif[/img]

 

Haha, sorry to bust all the myths about us being in igloo's and buried up to our necks in snow...we've had a "good" winter, and the temps are starting to be a little more tolerable, but rest assured I've seen my share of -20 degree days this year. I think GA is only about 18 hours from me, so maybe i'll just load the trailer up and head down for the day, haha...lots of dunes and awesome trails down that way (or so I have read...)

 

Man you're at 40 in Canada??? What a rip, I'm at 21 in Minnesota, haha! With 6 fresh inches of snow! Although 21 feels really nice and warm with how this winter has been! haha! I almost didn't wear a coat.