Running carb with cover off

[Rollin'Rocker]

Howdy folks, I just joined today to ask this question but first want to thank everyone here for sharing your stories and experiments and ideas. I've been learning lots from many of you since getting a used GT-5/mtnbike combo a few weeks back. This is one of the best forums I've found online of any sort, less flaming and more useful info and good humor than on most. You've already saved me money and time, and maybe once I learn some more I can repay the flavor.

But enough with the niceness. Question is, how bad for a carb is it to run it without the cover? It's a GT-5 made in August 2010 and came with the red cover carb, not sure if it's speed or the other one. The motor was missing a fair bit at mid-throttle when I got it, so after changing to the forum favorite NGK B6HS (helped a lot for only 1.99 at O'Reilly down the street), I took off the carb cover to see if it was clean, and put it back on tight, where it stayed for a few rides and dozen miles or so.

Yesterday I found a post here saying that the guy was having more luck at WOT with his choke wide open too, so I tried it and suddenly it was pulling nice and hard for me, too fast in fact for safety's sake (the bike just doesn't feel like it was meant to go much over 30). But then when I stopped I saw I had no red cover, nor the black plastic gasket that was under it. I screwed it in real tight, so how did it come out? No idea, but I did put in a tablespoon of Berryman's B-12 in a full half-gallon tank the day before. Might that have dissolved some plastic or...? Weird.

Anyhow, I had to ride it home and it went just fine. I saw on another post here that someone said they'd had better luck with this recalcitrant carb (CNS, I think?) with the cover off. But that seems likely to get dirt and dust in the carb and engine. Or not? I guess I'm going to get an NT or maybe one of the dax dellortos, but I really want hill power more than top end.

Should I not ride it until I get a new carb? Or is it good to go and I can just keep going until the new carb?

I really appreciate any opinions, and once again thanks for making this such a very useful forum.

Ride on!

 

[ocho ninja]

I hear to keep the cover without the foam filter element just keep big stuff like rocks and stuff out of the engine.
The foam filter is only if you live in very dusty places or travel trough dirt roads often.
Other than that most of the stuff is blown out since its only a two stroke.

 

[2door]

It is never advisable to run any engine without some sort of filtering over the inlet of the carburetor. Yes dragsters do it and other racing applications but those engines are regularly torn down and rebuilt. Unless you want to see a shortened life span for your engine you should filter the incoming air. If you plan to change the carburetor anyway don't waste money on a replacement for the CNS but try a piece of pantyhose stretched over the inlet of the carb and secured with a nylon zip tie or a twisted length of wire to hold it in place. Even a rubber band will suffice.

As for running with the choke open; the choke should always be wide open after the engine starts. Never run with the choke partially closed, even the fuel enrichment circuit on the CNS that is sometimes refered to as a choke.

Tom

 

[nightcruiser]

If you have the CNS carb (that has two cables going in the top) with the red plastic cover and foam filter maybe its better you lost the cover! That's the same carb I have, I love the carb but the foam in the red air filter always seemed to clog up with oil and choke off the air. I got a high flow style air filter from SickBikeParts.com and I am very happy with it. With the red cover, foam insert and black ring in place the air filter cuts the air flow quite a bit, so running without the filter may make your mix go lean, so make sure you don't run her too hot with the filter removed.....

And btw, the carbs with the two cables have an enrichment jet instead of a regular air choke. The air choke you want to keep open (un-choked) when the motor is warmed up, the enrichment jet you want to turn off (let slack in the cable) when the motor is warmed up.

 

[crassius]

look around a bit & you'll find some nice after market filters you can get - tie an old stocking over it or cheese cloth or something till you get the new one 'cause unlike 4-strokes, everything that goes into the carb first hits your crank & mains down in the bottom and may never come out

 

[Rollin'Rocker]

Hey youse guys, thanks for the info, all of it useful. Hence using the thanks button four times, which seems rare here: I've seen guys with thousands of posts and only four thanks! Anyhow, hoping to raise everybody's thanks average, so thanks very much.

I just ordered an NT and will donate the old carb to someone who wants it. If someone can provide a link to tips for installing an NT on the GT-5, I'd appreciate it. Other than just screwing it on tight, is there anything else worth modding or doing? Will my stock cable slide right in at the right length? Looking forward to seeing how it changes the ride.

Thanks again for sharing!