Trailmaster 300 xrx Need Main Jet
 

Anybody know where I can find main jets? The jet is really big. I've tried mikuni and Keihin but no luck. Pics below

I've added a Uni filter and drilled the exhaust. The stock size is 128. I tried to drill it out with the tiniest bit I could find, now it's running too rich. Either I drilled it too big or just screwed up the orifice. It's bogging down really bad at WOT, but runs like a striped ape until I go wide open. It would be nice to replace a jet instead of having to buy a new carb, since I'd also have to buy a new intake since the stock intake is for a bolt on carb.

I know of no other jet like the jets used in the 300 trailmaster, in fact not even trailmaster sells the jet by itself.

Solder the hole and redrill with a smaller bit.

That's what I was afraid of. Don't know why they'd build them that way.
So, is there an intake/carb setup any can recommend that would fit? I like the pumper carb and the electric "choke" and it would be nice to find an easy swap that would be more e readily tunable.
I've been looking around at ebay and online and I see carbs forvthe Manco Talon 250, 260, 300cc and they look almost identical to mine.
Would this be what I need? Are jets available for these carbs?

Manco never made anything larger than a 150 engine and used the same carb as on all other 150 gy6 engines, so it will not work. Talon made by carter in the later years had a 250 and 300 but those carbs will not work either. You will need a carb with a flange mount. I have but one time worked on a 300 trail master but it wasn't a carb related problem. I have called in the past 3 trail master dealers for advise on jets or carb replacement. All 3 have told me they have no source for jets and they have yet to find a flange type carb that will bolt up to the intake. The only other vehicles I have ever seen with the same type intake as you have are the old CT style Honda engines used in the 50cc, 70cc, 110,cc buggies/dirt bikes and they will be too small and will not line up with bolt holes. You will either have to get another stock carb with the proper metric drill bits to drill the jet out or fabricate a new intake and go with a slide carb. Answer to your opening question, EPA.

This is one of the setups I was talking about
http://m.ebay.com/itm/TUNED-CARBURET...-/370839819389
Looks like the throttle linkage is on the other side, but I thought it might work.
I've found an original carb. Theyre not cheap. But if that's what I gotta do...

Gonna say it again , I Know it's not Kosher , I know it's rigged , but in my defense , I Know it works in a pinch . If your main needle has no variable slots for the e - clip ( hence no e - clip ) fashion up some Tiny washers ( spacers ) to place under the head of the needle to raise it's height in the seat of the jet . I'VE DONE THIS TO THREE DIFFERENT CARBURETORS ON 150'S WITH 100% GOOD RESULTS !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! :party:
Definitively rule out the possibility of actually still being too lean , Cost -- Free .

Guess my opening statement in my previous post should have stated : Are you sure it's too rich , and not the opposite . Strong bottom , and raped ape mid - range , and puking out at top - end would make me suspect lean , or restricted fuel delivery situation . Stay On It , Good Luck . :cheers:

My spark plugs are always dark. I took the air filter off and revved the engine, at close to wide open, fuel was sparying out of the back of the carb like crazy. That's why I think I may have messed up the jet when I drlled it. Unless my symptoms mean something else.

Does it have good compression ? And also , when you went to the UNI ,You didn't plug off any crankcase vent hoses that went to the stock air box ? They have to be open .

No way to check the compression, but as I said everything runs great until I get close to wot. I didn't plug any unused hoses. I did put some tiny K&N type air filters on them.

The jets for the Yamaha Majesty look very similar (it's a clone of that engine) but I have no way of knowing just from looking at pics online. If I can find the measurements somewhere, I might give them a try. Still cheaper than buying a new carb.

Is it possible to try and use a reducing threaded bushing to change thread size to the smaller more standard jets?

I wondered about that myself. I'm so notoriously stubborn I might even try to get a machine shop to fab me up some jets. Sure, that would end up costing more, but....stubbornness! :-D
I just don't get why a manufacturer (especially a cheap one!) wouldn't just go with a standard jet. That's like building an AR15 that only takes proprietary mags lol.

This really works. Some solder and a small set of drill bits is pretty cheap. There's a chart online that compares drill bit size to jet size.:cheers:

Yep, I'm keeping that as an option too.

Found Some!
 

Finally got a set of main jets, all the way from Japan. After much googling, I found a set for the Yamaha Majesty yp250 which is just what I need. The Linhai is a clone of this engine, which Yamaha stopped using in 1999 and was never sold in the US. So yeah, it wasn't a simple matter. Also found the impossible to find bowl gasket from a source in the UK which has almost every part (except main jets!)

Installed the 135 jet, set the idle and mixture. Just got back from a quick trial run, hit 44mph (speedo) without a hiccup all the way to WOT!
Happy guy!

Sweet

Glad you found jets to work.

http://japan.webike.net/products/1057378.html
Took some time, but I found some! :-D