Ta200 Carb Tuning

[AllanB]

Here is a brain teaser.

Before the bike went it for it's full rebuild the carb was working fine, 120mpg (45km/litre) although running a tad rich.

When I got it back it was running like crap, drinking fuel (100 baht = 20km), revs all over the place and revs not dying between gear changes, saw the outer cold start cable was broken, so fitted new one, no change, black sooty plugs, wet with petrol. Took it back, they fitted a new carb/engine hose/manifold, which was split.

Got it back with white spark plug .but ran badly, opened the throttle and it died-ish, ran a little better when warm, next morning wouldn't run, other than tickover.

Stripped it today, labeling everything so it would go back the same way, found nothing except the LHS vac tube was not connected, cleaned everything all jets clear, put it back together, one very tiny 3mm washer left over??? Set mixture screw at 2 turns and fired her up.

Would start but not rev, just died.

Turned off the fuel, drained the float chamber, plenty of fuel in there.

Removed the hose between carb and air-box, exposing the inside of the carb, started as usual, but when i opened the throttle, the needle plunger bounced and the engine died.

Been staring at the damn thing, brain now as dead as the engine when I open the throttle.

Any suggestions? A shinny shilling to the successful problem solver.

[VocalNeal]

When I raced karts, sometimes the performance would drop off and the answer was in the carb, there were rebuild kits available but general consensus was it is better to buy a new one than rebuild an old one. I resisted this thinking it was rubbish but eventually I ponied up and bought a new one. It was like night and day, even thought I spend many hours of TLC on the old carb.

So go to Honda and find out how much a new one is. If OK simply buy a new one and bolt it on. Saves all the hassle and frustration.

If you want I will go and ask if you are not near a Honda main dealer.

Edited March 7, 2013 by VocalNeal

[AllanB]

Sorted it.

As I said when I took the carb off and marked all the hoses I found an extra vacuum hose disconnected, so when I put it back on, I reconnected the hose. However, it made no difference to the running and when I pulled it off again, no difference.

So assuming there was an error in the vacuum connections somewhere, I traced all the vacuum tubes in order to make a diagram. That's when i found yet another disconnected vacuum hose tucked away under the tank, I found it's correct place and the bike now revs.

So two hoses left disconnected. That is why I always do a diagram, shame they don't.

TIT.

[KRS1]

the 3m washer goes underneath your needle,without it your bike is running lean.

yes you can tell the difference when riding, its probably vibrating a bit more than it should right now.

[KRS1]

Yes, of course, didn't scroll down to find this...doh!

When I got the bike back, the plug was black, this screw was 1 turn out, just put a new plug in took it to 3 turns out and still sooty black after 5km.

That carb has a fuel cutoff circuit, it uses a diaphragm, they often develop pin holes. The gasket set for that carb will come with the diaphragm about the size of a 1 baht coin. The choke circuit gasket also comes with the gasket set, as well as a complete set of orings, one for the air screw the other for the choke circuit.

[AllanB]

the 3m washer goes underneath your needle,without it your bike is running lean.

yes you can tell the difference when riding, its probably vibrating a bit more than it should right now.

That is exactly what I now have. Where exactly does this was fit? Do I remove the needle, if so they took it out.

..........getting there I hope.

[Neilly]

the 3m washer goes underneath your needle,without it your bike is running lean.

yes you can tell the difference when riding, its probably vibrating a bit more than it should right now.

That is exactly what I now have. Where exactly does this was fit? Do I remove the needle, if so they took it out.

..........getting there I hope.

The washer goes on the needle under the clip

[KRS1]

yes it goes under the needle top, but there will be no clip.If you have taken the carb apart before then you should know where the needle goes.

But just incase...you have to reach inside the diaphragm /plastic slide hole with needle nose pliers and pull the needle retainer out, you'll have to twist softly to pull it out and the needle will follow.

The carb in that pic above is from a regular slide carb, much like an NSR150.Dissassembly is different from the CV carb on your bike. Your carb is easier to deal with, no throttle cable to deal with. Tap the top screws on the carb before attempting to remove them. Dont be shy, give them a good wack.

Neilly illustrated accurately where the washer would go, but your bike wont have a clip, and the slide will look different, yours will be black plastic with a rubber diaphragm on top, make sure you align the notch in the diaphragm with the notch on the top of the carb during reassembly.

The washer goes under the needle's seat (top hat) when its in place it lifts the needle up and the fuel passage becomes larger do to the taper of the needle and the elevation from the washer.(richer)

airscrew between 2.75-3.25

Edited March 9, 2013 by KRS1

[Neilly]

yes it goes under the needle top, but there will be no clip.If you have taken the carb apart before then you should know where the needle goes.

Neilly illustrated accurately where the washer would go, but your bike wont have a clip, and the slide will look different, yours will be black plastic with a rubber diaphragm on top, make sure you align the notch in the diaphragm with the notch on the top of the carb during reassembly.

Ah...my bad then KRS1

More like this then

[AllanB]

Thanks lads, fitted the washer and it now runs okay.

The mechanic must have taken it out when i complained about a sooty plug, actually caused by a leaking carb manifold. Fortunately for me he stored it in the float chamber for safe keeping.

Wasn't that nice of him..................

TIT !!!!!

[KRS1]

Glad youre rolling properly now.

[Neilly]

Thanks lads, fitted the washer and it now runs okay.

Fortunately for me he stored it in the float chamber for safe keeping.

Wasn't that nice of him..................

TIT !!!!!