trailmaster xrx 150 carb upgrade.

[duh]

so i blew thru the stock carburetor that came with my tm xrx 150 and ponied up thinking i could get the performance 30mm carb. i bought it totally spacing off the fact i needed a bigger manifold. bought that n tried to put it on.

im running into the problem being what im thinking is a engine mount:



so when i try to line up the carb to the manifold, really the only way to make it semi-fit is to take the rubber off which isn't feasible:



i haven't yet gotten the aluminium velocity stack altho i'm going to be as soon as i get the exhaust. i'm not yet putting this carb on as it's pointless to do so without a performance exhasut. just fitting parts so as to have it fit properly later on when i put on the mods im doing all at once. my quandary is how to attach the manifold to the carb without having to suffer possible damage from vibrations if it hits that mount.

i'm not a mechanic either, and really have little engine knowledge. any advise would be greatly appreciated. sorry for the size of the pictures.

[jmansracerocket]

the bar in your pic is an engine mount, holds the engine in place as well as the bolt on the rear of the frame holding the tail of the engine up as well. Ckau I believe and masteryota have used the 30mm carb im sure they will chime in

[mb1134]

You have to buy the intake riser which will bolt to the head, then bolt the IM to that. It will raise your carb over the bar.

[duh]

where do i get this riser?

is the carb gonna sit way high? the manifold came with a couple plastic risers, but nothing more than a half inch rise. do ypu have any pictures of your set up?

[jmansracerocket]

https://www.buggypartsnw.com/index.p...ake-riser.html

I'm guessing u need this

[duh]

i shall order that part.

so basically with the riser it'll be above the bar. being above the bars not going to hinder attaching the velocity stack to the stock air filter hole at the rear do ya think?

[ckau]

that 30 will mount in.
1st- remove the through bolt and the spacer between the motor mounts and replace with two short bolt , one for each mount . that will free up the space between the motor mounts.
2nd- you will need a 30mm intake. Remove the plastic spacer under the stock intake. Mount the 30mm intake directly to the head with a gasket.
3rd replace the stock rubber connector between the carb and intake with a another rubber section of hose that is 3/8" longer. you can use the original band clamps.
The 30mm will slide in but will have to mount tilted slightly to the right so the bowl clears the passenger side motor mount. This tilt has no effect on operation or performance.
you will most likely have to re route the throttle cable over the top to reach the carb.
Order a range of pilot and main jets. Every change you make to that motor will effect jetting. like a different exhaust for example
Keihin main jets- part #99101-393
pilot jets #N424-21
A range of mains 138 through 145 and pilots 35 through 40. A combination of these should get you right.
To give you an perspective, a motor with a 30mm intake , a large valve p&p head and a 1" Id performance exhaust took a 38 pilot and a 145 main.
on a basic stock motor the biggest gain will be the instant throttle response due to the accelerator pump. but as you upgrade the head and exhaust you'll feel more advantages.

[duh]

alright, so....being someone who has little knowledge of what your talking about, and to not sound belitteling to you....i ask 'remove the through bolt and the spacer between the motor mounts and replace with two short bolt , one for each mount . that will free up the space between the motor mounts'...can you provide some pics as to what ill be facing doing this upgrade. (i just wanna see what it'll look like) it sounds simple, but what does yours look like? can i goto any hardware slash napa, etc, and get these bolts n nuts?

second, i get what you saying. when i removed the stock manifold i saw there was a spacer of the same thickness already installed. when i bought my carburetor it came with two spacers (the same size) and jets, i believe were 130 and 125. take the stock one off, attach the manifold along with the riser as stated above? the riser being the part im missing. puttingmy carb above the bar.

third :'replace the stock rubber connector between the carb and intake with a another rubber section of hose that is 3/8" longer. you can use the original band clamps.'....what this mean, and what will happen with the two line from the original stock air filter? meaning whats up with the two lines going to the original rubber intake to the air box? which is replaced by the aluminium velocity stack. im assuming some kind of filter.

[jmansracerocket]

see told you ckau would come threw

[jmansracerocket]

https://www.buggypartsnw.com/index.p...-manifold.html

that's the 30mm intake, that ckau is talking about. Just remove the engine mount bolt and bar then take that bolt with you to any hardware store and get the same size in diameter but obviously shorter length because you will need a nut on each side to hold the engine up in place. And then buy a rubber piece like ckau said to attach the carb and your intake. Im sure ckau will chime in again.

[ckau]

I'll post some pics for you but it will be Saturday before I can get to a buggy

[jmansracerocket]

im curious what did you use for a intake tube and filter ckau with the bigger carb ? I use pvc pipe since it doesn't heat soak like the polished aluminum pipe does.

[ckau]

OK… here ya go…..
This is a 150 with a 155BB kit, 30mm pumper carb , 30mm port matched aluminum intake , a p&p head with 30mm intake port, 28 mm exhaust port, large valve set and NYC performance springs. Using a 25mm Id exhaust with a straight through muffler.
This motor is almost 10 years old. A good old dependable workhorse. It’s been used and abused. Serves as my experimental platform and at the moment looking pretty rough. I’ve ran with packs of 250’s with no problem keeping up. They’ll out distance me on long open roads but on the trails…….
The carb installation is simple . The same technique was used on Masteryota’s Dazon so I see little or no difference using the technique in any swing arm configuration. Throttle cable and fuel line routing will depend on the model.
First remove the upper motor mount though bolt and spacer /sleeve. Replace the through bolt with a shorter bolt through each mount tab. A 3/8 x 1.5, ¾ washers and surelock nuts. .Make sure the bolt heads are facing in towards the center. That’s the hard part!
The rest is standard carb installation. My original rubber coupler was shot so I replaced the rubber coupler with some stuff found at the local DIY store. I cut the carb to intake coupler 3/8 “ longer to allow a little more wiggle room to get the carb positioned plus it afforded more surface contact area for the band clamps.
The carb sits in slightly cocked to the right get the accelerator pump base off the right side motor mount. The same rubber pipe is used to connect a 6” long velocity tube to the carb inlet. The stock airbox most likely will not supply enough air to this carb. I’m not 100% sure on this as I tossed the stock box years ago and started using the filter shown knowing these filters defiantly supply enough air. The velocity tube is a aluminum tapered unit 2” on the filter end down to 1,¾” on the carb end using a 2” opening UNI filter. You don‘t have to use this particular tube . A length of pvc same diameter as the carb opening works fine. UNI‘s come with different mount diameters so get one that fit’s the pipe. Fashion a mount to secure the velocity tube secure . This gives the carb extra needed support and keeps everything connected. The 30 is heavier than a 24mm. Vibrations and bumps can work the connections loose. This filter and tube system is a huge performance improvement over the stock box.
This thing can really suck some gas so go up to a minimum of 5/16 fuel line and a large capacity inline filter.
The vacuum line running from the intake nipple to the slide diaphragm on top of the carb can remain stock.
I don’t know how to help you on jetting. There are so many variables to account for it’s hard to say even where to start. Try starting with what’s in the carb and work from there? It’s not that difficult to get these 30mm dialed in. They react to changes very noticeably so it’s easy to tell which direction your headed. It does take patients, a lot of jet changes and the better part of a day’s fiddling with it to get it right.
keep in mind your now packing a large mass of air and fuel into the motor. Your not going to see much benefit without up grading the exhaust to let this load out! It will pay you to do the exhaust first as you will have to start all over on the jetting when changing the exhaust pipe.
This is all I can think of at the moment, any other questions, just ask.

[2SlickNick]

I love the idea of replacing the long single pivot bolt with 2.....
Free's up space.

[duh]

Thanks for that.

so should I change the piece thats below my gas tank to get a better flow of gas? Is that what you meant by the 5/16?

[ckau]

Originally Posted by duh

Thanks for that.

so should I change the piece thats below my gas tank to get a better flow of gas? Is that what you meant by the 5/16?

I was refereeing to the size of the fuel line... As in inside diameter.
These buggies come stock with 1/4" line. There isn't enough fuel flow volume to feed the larger 30mm, Replace the line from the tank connection to the carb.
Same problem with the inline filter. The stock filter won't flow fast enough. you need a larger filter with more capacity.

[jmansracerocket]

im really considering buying a 30mm pumper carb now lol, along with matching 30mm manifold there has to be some kind of gain with the combo especially since I have a big valve ported head, cam, exhaust, intake and with that more air equals more fuel equals more power. I like the fact that ckau stated that u get rid of the little plastic spacer that connects to the manifold the port whole size is somewhat restrictive once you do all the bolt on performance stuff and im sure for big bore guys getting rid of its will help.

[duh]

sweet. thanks for the help, i keep y'all posted.

this isn't going to happen tomorrow..more like in a couple months when ive got enough scratch to do all the mods at one.

again, appreciate the help, and ill keep y'all posted.

[jmansracerocket]

not to high jack the thread but I just ordered the 30mm intake along with the 30mm pumper carb cant wait to try it out. Don't tell the wife!

[duh]

just an update.

recently purchased and installed a performance exhaust along with an adjustable c.d.i., coil, and iridium sparkplug. haven't gotten around to getting that intake riser to put a 30mm carb on yet but that's probably the next step.

the problem now is that once it gets up to 17-22 mph it backfires and loses all power. idk what to do.

[wildbob]

did you re-jet the carb?

[duh]

yup, to 130.