LT80 quad

[Andyjack]

Hi quad is up and running now, starts fine, revs and ticks over fine but when riding its bogging a bit. If your sat with engine running its fine but when you set off your having to rev it very slowly to go otherwise it drops its revs. And i mean very slowly, try rev normally and revs just drop off then when your going its bogging slightly. I have tried adjusting air screw but doesn't seem to make a difference. Any ideas. Seems like an air problem but not sure.

[Gwbarm]

It does sound like a carb problem have you cleaned and adjusted the carb.

[Andyjack2024]

Yes its a new carb on it. Im going to take it back off and check the pin depth ect from the old carb, or maybe try putting the old carb back on, thanks

[Gwbarm]

If this is an aftermarket carb you might want to check the jet sizes against the original carb. From my expierience aftermarket carbs are kind of hit and miss. Sometimes they work great and sometimes they do what you are describing. 

[Andyjack2024]

Well im thinking about putting the old carb back on and see how it goes. Originally i changed the carb due to it not starting but it was an electrical fault on ignition. So il see how it goes, thanks for input u appreciate it

[Gwbarm]

The old one should be fine it may not look as nice as the new one, but as long as all the passages are clear and float actually floats it should work. I would probably go through it really well take out the emulsion tube and clean it and there is a tiny jet down in a hole thats easy to miss.

[Mech]

I agree, try the original carb after you've given it a good clean. As Gw says, take out all the brass bits, blow gently through every drilling to work out where the drilling goes, then give it a good blast from the engine side of the drilling, against the usual air or fuel flow. You don't want to force any dirt stuck in a hole in any tighter. And clean the jets with a slither of some hard wood that you've whittled down to a fine three sided point. It needs to be three sided point so it scrapes slightly as you rotate it. And that emulsion tube Gw's mentioning, which is the long tube the slide needle drops into, it has very tiny holes up the side of it that need careful cleaning with a bit of wood, and the drilling that tube fits into needs careful cleaning too. It has to hold a certain quantity of fuel and if there is too much crud in the drilling it effects acceleration. The tiny holes in the emulsion tube are very tiny and hard to see if they are clean sometimes, but they are drilled on opposite sides of the tube so you can look right through from one side to the other. Those holes, well all the jets really, need to look like nice round holes. If they look a bit not quite round or a bit fuzzy, clean them some more with the wood.

[Andyjack2024]

Thank you for the great advice, i have a carb cleaning kit, it has like a feel-a gauge type set up with small cleaning brushes and small thin metal pieces of long wire for cleaning the jets ect would you use that or stick to the wood ?. 

[Mech]

All the books, and myself always say never poke steel or any metal through a jet. If the wire's skinny it will get a big bit of dirt out, but it won't get the varnish and verdigris out, and if it's a tight fit it might damage the jet. Jets need to be the right size, and nice round holes, and some of them are tapered holes.. Get a bit of hard wood, hickory or something like that, and slice a big slither off with a knife, then lay the slither on a bench and carefully slice it down to a slender three sided taper. One bit/whittling will probably do most of the jets, then reshape it finer for the tiny holes in the emulsion tube. Poke it in gently and rotate it. If it breaks off by mistake(which it shouldn't if you are careful), then char/burn the bit of wood out on a gas cooker or some such thing.

[Andyjack2024]

That is a really good idea especially if it gets stuck, thank you i really appreciate your help. Thank you. Il start shaping some wood in morning and have a go. Il update when it's done. 🙂

[Mech]

If you look, or try the tapered wood in the jets, you will find some of them are tapered holes. You need to clean them from the big side.

The reaming out is a bit fussy and most of the time jets just have some particular hunk of dirt that you can see and get out, but if the jets are gummed up or corroded or anything then reaming them with the wood is the cure. I always do it..

[Gwbarm]

Thats a great idea, never thought of using wood to clean the jets, i guess i figured with my luck the wood would break off in there and then i would have to get that out, i have a set of carb jet tools of different sizes all hooked together so you dont loose them, you only get the size you need out. I think they are made of soft aluminum so it doesnt ream the jet out.

[Mech]

Oh yeah, never seen a set like that. I've got welding tip cleaners in a holder, but we should never use those !

Are the ones you have round section or square or triangle. I can't really see round section ones doing much good getting varnish or verdigris off.

The wood works really well, and if a bit gets broken off you just burn it Gw..  Simple and nothing gets hurt or reamed out.

[Andyjack2024]

These are the cleaners i mentioned 

[Mech]

Er matey.. Those are welding tip cleaners, and they do ream holes out. I'm pretty sure. Unless you are sure they are aluminium I wouldn't use them for jets.

The wood's the best.. Guarantee it. Try it. I've blown and given things a quick clean before with the wood, then because the hole looked a bit fuzzy or out of round I've reamed it some more (with wood), and the holes come clean and gain diameter that you can see sometimes. Varnish is quite hard..

Edited October 24, 2024 by Mech

[Andyjack2024]

I will definitely try the wood thanks. False advertising i guess no wonder stuff get knackered 

[Mech]

Ha..  hard case. "They do welding tips.. they must be able to do carb jets too.".. 

[Gwbarm]

Thats the set they sell for cleaning carbs but i agree i think they are welding tip cleaners.

[Mech]

Yeah and they are hardened and those ridges start new off being quite abrasive.

Wood everyone..  If it gets stuck in the jet it only needs a bit of a charing and it will come out again.. no harm done. And it gets them cleaner than any bit of wire will..

[Gwbarm]

The set i have doesnt have the ridges they are smooth. I ttok another look and the metal is shiny and doesnt really feel like aluminum.

[Mech]

I haven't seen a set like that Gw.. Without ridges they would be better than a tip cleaner, and better than some scratchy bit of wire brush bristle(which a lot of people like to use), but I'd suspect they would have trouble getting varnish/build-up off.

Do they go down small enough to do really small jets on bikes ? I've seen cleaners advertised for jets but they never did small jets, let alone the tiny holes in the emulsion tubes.

I've been using wood for.. Err.. something like fifty years.. haha.. and it's always worked fine.

[Gwbarm]

They do go down really small , and right, dont do much for caked varnish, it would be great if they made little brushes to get that off, but hard to make a brush that small, i would guess. 

[Mech]

I thought that the ultra whatever cleaner you had did a pretty good job of cleaning things. I was very impressed by some before and after photos.

[motox88]

I recently discovered those cleaning tips on Amazon.  I have used them many times on several machines now.  Sure beats using old speaker wire! 

 

[Joeboe]

I wish they still made the 2 strokes.